Armani  Conroy

Armani Conroy

1613916769

Coding Dart Server Side. But Why no Framework ?🤔

Welcome to another video in this video we are going to code a backend server using Dart.

  • I am not going to use any framework, because none of them are maintained or reliable enough to push an app in prod.
    
  • I mean you can say Aqueduct, But that isn't very stable and also hasn't been maintained well in past few months. The last commit ever made was around 6 months ago.
    
  • and other frameworks like angle, shelf, http_server, redstone, rpc have tons of problems.
    
  • But since you all have been asking so much, I will try to code a server side API but before we do that, let me see If I can find my intro to play.
    

#dart #flutter #mobile-apps

What is GEEK

Buddha Community

Coding Dart Server Side. But Why no Framework ?🤔
Bulah  Pfeffer

Bulah Pfeffer

1648873833

A Collection of Flutter and Dart Tips and Tricks

Table of Contents

  • LazyStream in Flutter and Dart
  • Cancelable APIs in Flutter
  • Asset Data in Flutter
  • API Caching in Flutter
  • FutureGroup in Dart
  • Flatten Iterable<bool> in Dart
  • Caching Temp Files in Flutter
  • Custom Lists in Dart
  • Optional Chaining in Dart
  • MapList in Flutter
  • Future<bool> in Flutter
  • Async Bloc Init in Flutter
  • Firebase Auth Errors in Flutter
  • Debug Strings in Flutter
  • Keyboard Appearance in Flutter
  • Get String Data in Dart
  • Stream.startWith in Flutter
  • Optional Functions in Dart
  • AnnotatedRegion in Flutter
  • Unordered Map Equality in Dart
  • Iterable to ListView in Flutter
  • Password Mask in Flutter
  • Fast Object.toString() in Dart
  • Copying Bloc State in Flutter
  • Iterable Subscripts in Dart
  • useState in Flutter Hooks
  • Folding Iterables in Dart
  • Custom Iterables in Dart
  • Class Clusters in Dart
  • Iterable +/- in Dart
  • Periodic Streams in Dart
  • EmptyOnError in Dart
  • Stream<T> Initial Value in Flutter
  • Double.normalize in Dart
  • Hide Sensitive Information in Flutter
  • Iterable.compactMap in Dart
  • useEffect in Flutter Hooks
  • Merging Streams in Dart
  • Isolate Stream in Dart
  • Network Image Retry in Flutter
  • Reusable APIs in Flutter
  • ListTile Shadow in Flutter
  • Transparent AppBar in Flutter
  • Constructors on Abstract Classes in Dart
  • @useResult in Dart
  • @mustCallSuper in Dart
  • Object.hash in Dart
  • Expanded Equally in Flutter
  • Random Iterable Value in Dart
  • Hardcoded Strings in Flutter
  • Manually Scroll in List View in Flutter
  • AsyncSnapshot to Widget in Flutter
  • Breadcrumbs in Flutter
  • Unique Map Values in Dart
  • Smart Quotes/Dashes in Flutter
  • Haptic Feedback in Flutter
  • Localization Delegates in Flutter
  • Extending Functions in Dart
  • Paginated ListView in Flutter
  • Immutable Classes in Dart
  • Card Widget in Flutter
  • List Equality Ignoring Ordering in Dart
  • Shorten GitHub URLs in Dart
  • Time Picker in Flutter
  • Throttled Print in Flutter
  • Map Equality in Dart
  • Unique Maps in Dart
  • Raw Auto Complete in Flutter
  • Title on Object in Dart
  • Compute in Flutter
  • Filter on Map in Dart
  • Type Alias in Dart
  • ValueNotifier in Flutter
  • Object to Integer in Dart
  • Image Opacity in Flutter
  • Covariant in Dart
  • Custom Errors in Streams in Dart
  • Shake Animation in Flutter
  • Throw Enums in Dart
  • Future Error Test in Flutter
  • Generic URL Retrieval in Dart
  • Custom Error Widget in Flutter
  • Handle Multiple Future Errors in Dart
  • Future Error Handling in Dart
  • String to Toast in Flutter
  • Waiting in Dart
  • Loading Dialog in Flutter
  • Compact Map on Map<K,V> in Dart
  • Query Parameters in Dart
  • Multiple Gradients in Container in Flutter
  • Filter on Stream<List<T>> in Dart
  • Generic Route Arguments in Flutter
  • Generic Dialog in Flutter
  • GitHub API in Flutter
  • ChangeNotifier in Flutter
  • Refresh Indicator in Flutter
  • FlatMap in Dart
  • OrientationBuilder in Flutter
  • Linear Gradient in Flutter
  • Bloc Text Editing Controller in Flutter
  • Blurred TabBar in Flutter
  • Play YouTube in Flutter
  • ListView Background in Flutter
  • Integer to Binary in Dart
  • Split String by Length in Dart
  • Image Tint in Flutter
  • SlideTransition in Flutter
  • Expansion Panels and Lists in Flutter
  • Complete CRUD App in Flutter
  • SQLite Storage in Flutter
  • Circular Progress with Percentage in Flutter
  • Opening URLs in Flutter
  • Commodore 64 Screen in Flutter
  • Animated Lists in Flutter
  • CheckboxListTile in Flutter
  • - Operator on String in Dart
  • Dart Progress for Future<T>
  • Move Widget Shadows with Animation
  • Gallery with Blurred Backgrounds in Flutter
  • Custom Path Clippers in Flutter
  • Frost Effect on Images in Flutter
  • Custom Clippers in Flutter
  • Check if Website is Up or Down in Dart
  • Section Titles on ListView in Flutter
  • Circular Progress in Flutter
  • Displaying Scroll Wheels in Flutter
  • Post Messages to Slack with Dart
  • Unwrap List<T?>? in Dart
  • Avoiding UI Jitters When Switching Widgets in Flutter
  • Detect Redirects in Dart
  • Proportional Constraints in Flutter
  • Displaying Cupertino Action Sheets in Flutter
  • Rotating List<T> in Dart
  • Displaying SnackBars in Flutter
  • Custom Tab Bar Using ToggleButtons in Flutter
  • Hashable Mixins in Dart
  • Flutter Tips and Tricks in Terminal
  • Searching List<List<T>> in Dart
  • Cloning Objects in Dart
  • Color Filters in Flutter
  • Flattening Lists in Dart
  • Managing Duplicates in List<T> in Dart
  • FlatMap and CompactMap in Dart
  • Equality of List<T> in Dart
  • Constants in Dart
  • Displaying Scrollable Bottom Sheets in Flutter
  • YouTube Ad Remover in Dart
  • Fade Between Widgets in Flutter
  • Sort Descriptors in Dart
  • User Sortable Columns and Tables in Flutter
  • Content-Length of List<Uri> in Dart
  • Recursive Dot Notation on Maps in Dart
  • Allow User Selection of Text in Flutter
  • Placing Constraints on Widgets in Flutter
  • Animating Position Changes in Flutter
  • Transitioning Between Widgets in Flutter
  • Doubly Linked Lists in Dart
  • Reordering Items Inside List Views in Flutter
  • Custom Stream Transformers in Dart
  • Expanding Stream Elements in Dart
  • Consume Streams for a Duration in Dart
  • Shortening URLs in Dart
  • LimitedBox Widget as ListView Items in Flutter
  • Generically Convert Anything to Int in Dart
  • Validating URL Certificates in Dart
  • Displaying Popup Menus in Flutter
  • Implementing Drag and Drop in Flutter
  • Dismissing List Items in Flutter
  • Animating Widgets with Ease in Flutter
  • Displaying Tool Tips in Flutter
  • Displaying Assorted Widgets Inside TableView in Flutter
  • Page Indicator with Page View in Flutter
  • Animating and Moving a Floating Action Button in Flutter
  • Fading Network Image Widget in Flutter
  • Transparent Alert Dialogs in Flutter
  • Network Image Size in Dart
  • Animated Icons in Flutter
  • Custom Scroll Views in Flutter
  • Parallax App Bar in Flutter
  • JSON HTTP Requests in Dart
  • URL Timeouts in Dart
  • Detecting URL File Types in Dart
  • Paginated Lists in Dart
  • Requesting DELETE on APIs in Dart
  • Animated Containers in Flutter
  • Hiding Widgets in Flutter
  • Simple Opacity Animation in Flutter
  • Vignette Widget in Flutter
  • Drop Down Button Configuration and Usage in Flutter
  • Expandable List Items in Flutter
  • Infinite Scrolling in Flutter
  • Infinite Arrays in Dart
  • Custom Color Picker Component in Flutter
  • Displaying and Reacting to Switches in Flutter
  • Displaying Bottom Bars in Flutter
  • Displaying Buttons on AppBar in Flutter
  • Displaying Bottom Sheets in Flutter
  • Converting Enums to Radio Buttons in Flutter
  • Check Existence of Websites in Flutter
  • Images inside AlertDialog in Flutter
  • Returning Values from AlertDialog in Flutter
  • Simple Grid View in Flutter
  • Rendering Bullet Points in Flutter
  • Retrying Futures in Flutter
  • Containers as ClipOvals in Flutter
  • Rich Texts in Flutter
  • Wrapping Widgets in Flutter
  • Sweep Gradients in Flutter
  • Stream and StreamBuilder in Flutter
  • Blur Effect in Flutter
  • Convert Enums to Strings in Dart
  • Replacing Text in TextField in Flutter
  • Aspect Ratio in Flutter
  • Zoom and Pan in Flutter
  • Resizing Images in Flutter to Fit Screen Height
  • Validating URLs in Flutter
  • FrameBuilder for Network Images in Flutter
  • Adding Shadow to Icons in Flutter
  • Calculating Median of Lists in Dart
  • Generic Functions with Reduce in Dart
  • Passing Back Data From a Screen to the Previous One in Flutter
  • Flinging an Animation in Flutter
  • Fade Animations in Flutter
  • Throttling User Input in Flutter
  • Censoring TextFields in Flutter
  • Customizing TextButton in Flutter
  • Multiline TextFields in Flutter
  • Filtering TextField Input in Flutter
  • Focusing Manually on TextFields in Flutter
  • Data Streams Over HTTP/HTTPs in Dart
  • Catching Nonexistent Accessors or Methods in Dart
  • Using Expando in Dart
  • Implementing Custom Maps in Dart
  • Dynamically Calling Functions in Dart
  • Factory Constructors in Dart
  • Calculating the Sum of List Items in Dart
  • Removing Duplicate Strings in Lists in Dart (Case-Insensitive)
  • Implementing Range in Dart
  • Converting Lists to Maps in Dart
  • Implementing Hashable in Dart
  • Random Name Generator in Dart
  • Capturing Stack Traces in Dart Exceptions
  • Removing Duplicates from Lists in Dart
  • Optional Spread Operator in Dart
  • Calling Optional Functions in Dart
  • Odd-Even Sort in Dart
  • Implementing Zip and Tuples in Dart
  • Swapping Values in Lists with XOR in Dart
  • Waiting for Multiple Futures in Dart
  • Using Queues as Stacks in Dart
  • Custom Iterators in Dart
  • Iterables as Ranges + Transform in Dart
  • Errors vs Exceptions in Dart
  • Custom Annotations in Dart
  • Classes as Enums in Dart
  • Spread Operator in Collection Literals in Dart
  • StreamBuilder and StreamController in Dart
  • Almost Equal in Dart
  • Enum Associated Values in Dart
  • Implementing Comparable in Dart
  • Implementing Custom Integer Types in Dart
  • Custom Subscripts in Dart
  • Dart List Enumeration with Index
  • Applying Mixins to Other Mixins in Dart
  • Parameter Types in Dart
  • Custom Exceptions in Dart
  • rethrowing Exceptions in Dart
  • mixins and JSON Parsing in Dart
  • mixins vs abstract classes in Dart
  • Drawing Shapes in Flutter with LayoutBuilder, CustomPaint and CustomPainter
  • Generic Type Aliases in Dart
  • Callable Classes in Dart
  • Synchronous Generators in Dart
  • Implicit Interfaces in Dart
  • const Constructors in Dart
  • async-await Over Raw Futures in Dart
  • Initializer List and Default Values as Convenience Intializers in Dart
  • Extract Elements of Certain Type from Lists in Dart
  • Type Promotion in Dart
  • Extract Minimum and Maximum Values in List<num> in Dart
  • Functions as First Class Citizens in Dart

 

LazyStream in Flutter and Dart



import 'dart:developer' as devtools show log;
import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show NetworkAssetBundle, rootBundle;
import 'package:async/async.dart' show LazyStream;

extension LocalFileData on String {
  Future<Uint8List> localFileData() => rootBundle.load(this).then(
        (byteData) => byteData.buffer.asUint8List(),
      );
}

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() async {
  final stream = LazyStream(
    () async {
      final allData = await calculateAllData();
      return getImagesData(allData);
    },
  );

  await for (final data in stream) {
    'Got data, length = ${data.length}'.log();
  }
}

Stream<Uint8List> getImagesData(
  List<Future<Uint8List>> allData,
) async* {
  for (final data in allData) {
    yield await data;
  }
}

Future<List<Future<Uint8List>>> calculateAllData() async {
  final futures = Iterable.generate(
    3,
    (i) => 'images/image_list${i + 1}.txt'
        .localFileData()
        .then((data) => String.fromCharCodes(data)),
  );
  final result = Future.wait(futures);
  final lineSplitter = const LineSplitter();
  List<Future<Uint8List>> allData = [];
  for (final string in await result) {
    final urls = lineSplitter.convert(string);
    for (final url in urls) {
      allData.add(
        NetworkAssetBundle(Uri.parse(url))
            .load(url)
            .then((byteData) => byteData.buffer.asUint8List()),
      );
    }
  }
  return allData;
}

Cancelable APIs in Flutter

import 'dart:developer' as devtools show log;
import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show NetworkAssetBundle, rootBundle;
import 'package:async/async.dart' show CancelableOperation;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension LocalFileData on String {
  Future<Uint8List> localFileData() => rootBundle.load(this).then(
        (byteData) => byteData.buffer.asUint8List(),
      );
}

CancelableOperation<Uint8List> getImageOperation(String url) =>
    CancelableOperation.fromFuture(
      NetworkAssetBundle(Uri.parse(url))
          .load(url)
          .then((byteData) => byteData.buffer.asUint8List()),
      onCancel: () => 'images/template.png'.localFileData(),
    );

void testIt() async {
  final operation = getImageOperation('http://127.0.0.1:5500/images/1.png');
  final cancelledValue = await operation.cancel();
  final result = await operation.valueOrCancellation(cancelledValue);
  result?.log();
}

Asset Data in Flutter


import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show rootBundle;
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension LocalFileData on String {
  Future<Uint8List> localFileData() => rootBundle.load(this).then(
        (byteData) => byteData.buffer.asUint8List(),
      );
}

void testIt() async {
  (await 'images/template.png'.localFileData()).log();
}

API Caching in Flutter


import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show NetworkAssetBundle;
import 'dart:developer' as devtools show log;
import 'package:async/async.dart' show AsyncMemoizer;

extension Log on Object {
  void log() => devtools.log(toString());
}

@immutable
class GetImageApi {
  final String url;
  final _fetch = AsyncMemoizer<Uint8List>();

  GetImageApi({required this.url});
  Future<Uint8List> fetch() => _fetch.runOnce(
        () => NetworkAssetBundle(Uri.parse(url))
            .load(url)
            .then((byteData) => byteData.buffer.asUint8List()),
      );
}

void testIt() async {
  final api = GetImageApi(url: 'http://127.0.0.1:5500/images/1.png');
  (await api.fetch()).log(); // fetched
  (await api.fetch()).log(); // cached
}

FutureGroup in Dart



mixin FutureConvertible<T> {
  Future<T> toFuture();
}

@immutable
class LoginApi with FutureConvertible<bool> {
  @override
  Future<bool> toFuture() => Future.delayed(
        const Duration(seconds: 1),
        () => true,
      );
}

@immutable
class SignUpApi with FutureConvertible<bool> {
  @override
  Future<bool> toFuture() => Future.delayed(
        const Duration(seconds: 1),
        () => true,
      );
}

extension Flatten on Iterable<bool> {
  bool flatten() => fold(
        true,
        (lhs, rhs) => lhs && rhs,
      );
}

extension Log on Object {
  void log() => devtools.log(toString());
}

Future<bool> startup({
  required bool shouldLogin,
  required bool shouldSignUp,
}) {
  final group = FutureGroup<bool>();
  if (shouldLogin) {
    group.add(LoginApi().toFuture());
  }
  if (shouldSignUp) {
    group.add(SignUpApi().toFuture());
  }
  group.close();
  return group.future.then((bools) => bools.flatten());
}

void testIt() async {
  final success = await startup(
    shouldLogin: true,
    shouldSignUp: false,
  );
  success.log();
}

Flatten Iterable<bool> in Dart


extension Flatten on Iterable<bool> {
  bool flatten() => fold(
        true,
        (lhs, rhs) => lhs && rhs,
      );
}

void testIt() {
  assert([true, false, true].flatten() == false);
  assert([true, true, true].flatten() == true);
  assert([false, false, false].flatten() == false);
  assert([true].flatten() == true);
  assert([false].flatten() == false);
}

Caching Temp Files in Flutter



@immutable
class NetworkImageAsset {
  final String localPath;
  final String url;
  NetworkImageAsset({required int index})
      : localPath = Directory.systemTemp.path + '/$index.png',
        url = 'http://127.0.0.1:5500/images/$index}.png';

  Future<bool> downloadAndSave() => NetworkAssetBundle(Uri.parse(url))
      .load(url)
      .then((byteData) => byteData.buffer.asUint8List())
      .then((data) => File(localPath).writeAsBytes(data).then((_) => true))
      .catchError((_) => false);
}

void testIt() async {
  await Future.forEach(
    Iterable.generate(
      3,
      (i) => NetworkImageAsset(index: i + 1),
    ),
    (NetworkImageAsset asset) => asset.downloadAndSave(),
  );
}

Custom Lists in Dart



import 'dart:developer' as devtools show log;
import 'dart:collection' show ListBase;

class LowercaseList extends ListBase<String> {
  final List<String> _list = [];

  @override
  int get length => _list.length;
  @override
  set length(int newLength) => _list.length = newLength;

  @override
  String operator [](int index) => _list[index].toUpperCase();

  @override
  void operator []=(int index, value) => _list[index] = value;

  @override
  void addAll(Iterable<String> iterable) => _list.addAll(iterable);

  @override
  void add(String element) => _list.add(element);
}

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() {
  final myList = LowercaseList();
  myList.addAll(['foo', 'bar', 'baz']);
  myList[0].log(); // FOO
  myList[1].log(); // BAR
  for (final item in myList) {
    item.log(); // FOO, BAR, BAZ
  }
}

Optional Chaining in Dart



@immutable
class Address {
  final String? firstLine;
  final String? secondLine;
  const Address(this.firstLine, this.secondLine);
}

@immutable
class Person {
  final Person? father;
  final Address? address;
  const Person(this.father, this.address);
}

extension GetFathersFirstAddressLine on Person {
  String? get firstAddressLineOfFather => father?.address?.firstLine;
}

MapList in Flutter



extension MapToList<T> on Iterable<T> {
  List<E> mapList<E>(E Function(T) toElement) => 
    map(toElement).toList();
}

Future<bool> in Flutter



Future<bool> uploadImage({
  required File file,
  required String userId,
}) =>
    FirebaseStorage.instance
        .ref(userId)
        .child(const Uuid().v4())
        .putFile(file)
        .then((_) => true)
        .catchError((_) => false);

Async Bloc Init in Flutter



class App extends StatelessWidget {
  const App({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return BlocProvider<AppBloc>(
      create: (context) => AppBloc()..add(const AppEventInitialize()),
      child: MaterialApp(
        title: 'Photo Library',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        debugShowCheckedModeBanner: false,
        home: BlocConsumer<AppBloc, AppState>(
          listener: (context, state) {
            // handle loading
            if (state.isLoading) {
              LoadingScreen().show(
                context: context,
                text: 'Loading...',
              );
            } else {
              LoadingScreen().hide();
            }
            
            ... rest of your code goes here

Firebase Auth Errors in Flutter



const authErrorMapping = {
  'user-not-found': AuthErrorUserNotFound(),
  'project-not-found': AuthErrorProjectNotFound(),
};

@immutable
abstract class AuthError {
  factory AuthError.from(FirebaseAuthException exception) =>
      authErrorMapping[exception.code.toLowerCase().trim()] ??
      const AuthErrorUnknown();
}

@immutable
class AuthErrorUnknown implements AuthError {
  const AuthErrorUnknown();
}

@immutable
class AuthErrorUserNotFound implements AuthError {
  const AuthErrorUserNotFound();
}

@immutable
class AuthErrorProjectNotFound implements AuthError {
  const AuthErrorProjectNotFound();
}

Debug Strings in Flutter


extension IfDebugging on String {
  String? get ifDebugging => kDebugMode ? this : null;
}

class LoginView extends HookWidget {
  const LoginView({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final emailController = useTextEditingController(
      text: 'foo@bar.com'.ifDebugging,
    );
    final passwordController = useTextEditingController(
      text: 'foobarbaz'.ifDebugging,
    );
    
    // rest of your code would be here ...

Keyboard Appearance in Flutter


class LoginView extends HookWidget {
  const LoginView({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Log in'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: const [
            TextField(
              keyboardType: TextInputType.emailAddress,
              keyboardAppearance: Brightness.dark,
            ),
            TextField(
              obscureText: true,
              obscuringCharacter: '◉',
            ),
          ],
        ),
      ),
    );
  }
}

Get String Data in Dart


extension ToList on String {
  Uint8List toUint8List() => Uint8List.fromList(codeUnits);
}

final text1Data = 'Foo'.toUint8List();
final text2Data = 'Bar'.toUint8List();

Stream.startWith in Flutter


import 'package:async/async.dart' show StreamGroup;
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension StartWith<T> on Stream<T> {
  Stream<T> startWith(T value) => StreamGroup.merge([
        this,
        Stream<T>.value(value),
      ]);
}

void testIt() {
  Stream.periodic(const Duration(seconds: 1), (i) => i + 1)
      .startWith(0)
      .take(4)
      .forEach((element) {
    element.log();
  }); // 0, 1, 2, 3
}

Optional Functions in Dart



typedef AppBlocRandomUrlPicker = String Function(Iterable<String> allUrls);

extension RandomElement<T> on Iterable<T> {
  T getRandomElement() => elementAt(
        math.Random().nextInt(length),
      );
}

class AppBloc extends Bloc<AppEvent, AppState> {
  String _pickRandomUrl(Iterable<String> allUrls) => allUrls.getRandomElement();

  AppBloc({
    required Iterable<String> urls,
    AppBlocRandomUrlPicker? urlPicker,
  }) : super(const AppState.empty()) {
    on<LoadNextUrlEvent>(
      (event, emit) {
        emit(
          const AppState(
            isLoading: true,
            data: null,
          ),
        );
        // pick a random URL to load
        final url = (urlPicker ?? _pickRandomUrl)(urls);
        HttpClient().getUrl(Uri.parse(url)); // continue here...
      },
    );
  }
}

AnnotatedRegion in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: AnnotatedRegion<SystemUiOverlayStyle>(
        value: SystemUiOverlayStyle.dark,
        child: Column(
          mainAxisSize: MainAxisSize.max,
          children: [
            Expanded(child: Container(color: Colors.blue)),
            Expanded(child: Container(color: Colors.yellow)),
          ],
        ),
      ),
    );
  }
}

Unordered Map Equality in Dart



import 'package:collection/collection.dart';
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension UnorderedEquality<K, V> on Map<K, V> {
  bool isEqualTo(Map<K, V> other) =>
      const DeepCollectionEquality.unordered().equals(this, other);
}

void testIt() {
  final dict1 = {
    'name': 'foo',
    'age': 20,
    'values': ['foo', 'bar'],
  };
  final dict2 = {
    'age': 20,
    'name': 'foo',
    'values': ['bar', 'foo'],
  };
  dict1.isEqualTo(dict2).log(); // true
}

Iterable to ListView in Flutter



extension ToListView<T> on Iterable<T> {
  Widget toListView() => IterableListView(
        iterable: this,
      );
}

class IterableListView<T> extends StatelessWidget {
  final Iterable<T> iterable;
  const IterableListView({
    Key? key,
    required this.iterable,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: iterable.length,
      itemBuilder: (context, index) {
        return ListTile(
          title: Text(
            iterable.elementAt(index).toString(),
          ),
        );
      },
    );
  }
}

@immutable
class Person {
  final String name;
  final int age;
  const Person({required this.name, required this.age});
  @override
  String toString() => '$name, $age years old';
}

const persons = [
  Person(name: 'Foo', age: 20),
  Person(name: 'Bar', age: 30),
  Person(name: 'Baz', age: 40),
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: persons.toListView(),
    );
  }
}

Password Mask in Flutter



class PasswordTextField extends StatelessWidget {
  const PasswordTextField({
    Key? key,
    required this.passwordController,
  }) : super(key: key);

  final TextEditingController passwordController;

  @override
  Widget build(BuildContext context) {
    return TextField(
      controller: passwordController,
      obscureText: true,
      obscuringCharacter: '◉',
      decoration: const InputDecoration(
        hintText: 'Enter your password here...',
      ),
    );
  }
}

Fast Object.toString() in Dart



@immutable
class AppState {
  final bool isLoading;
  final Object? loginError;
  final String? loginHandle;
  final Iterable<String>? fetchedNotes;

  @override
  String toString() => {
        'isLoading': isLoading,
        'loginError': loginError,
        'loginHandle': loginHandle,
        'fetchedNotes': fetchedNotes
      }.toString();

  const AppState({
    required this.isLoading,
    required this.loginError,
    required this.loginHandle,
    required this.fetchedNotes,
  });
}

Copying Bloc State in Flutter



@immutable
class AppState {
  final bool isLoading;
  final LoginHandle? loginHandle;
  final Iterable<Note>? fetchedNotes;

  const AppState.empty()
      : isLoading = false,
        loginHandle = null,
        fetchedNotes = null;

  const AppState({
    required this.isLoading,
    required this.loginHandle,
    required this.fetchedNotes,
  });

  AppState copiedWith({
    bool? isLoading,
    LoginHandle? loginHandle,
    Iterable<Note>? fetchedNotes,
  }) =>
      AppState(
        isLoading: isLoading ?? this.isLoading,
        loginHandle: loginHandle ?? this.loginHandle,
        fetchedNotes: fetchedNotes ?? this.fetchedNotes,
      );
}

Iterable Subscripts in Dart

// Free Flutter Course 💙 https://linktr.ee/vandadnp
// Want to support my work 🤝? https://buymeacoffee.com/vandad

import 'dart:developer' as devtools show log;

extension Log on Object? {
  void log() => devtools.log(toString());
}

extension Subscript<T> on Iterable<T> {
  T? operator [](int index) => length > index ? elementAt(index) : null;
}

void testIt() {
  Iterable.generate(10, (i) => i + 1)[0].log(); // 1
  Iterable.generate(1, (i) => i)[2].log(); // null
  Iterable.generate(10, (i) => i + 1)[9].log(); // 10
  Iterable.generate(0, (i) => i)[0].log(); // null
}

useState in Flutter Hooks



import 'package:flutter_hooks/flutter_hooks.dart';
import 'dart:math' show min;

@immutable
class VirtualTab {
  final Icon icon;
  final String text;

  const VirtualTab({
    required this.icon,
    required this.text,
  });
}

const tabs = [
  VirtualTab(
    icon: Icon(Icons.picture_as_pdf),
    text: 'All PDF files',
  ),
  VirtualTab(
    icon: Icon(Icons.ac_unit_outlined),
    text: 'Data page',
  ),
  VirtualTab(
    icon: Icon(Icons.person),
    text: 'Profile page',
  ),
];

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final tabCount = useState(1);
    return DefaultTabController(
      length: tabCount.value,
      initialIndex: tabCount.value - 1,
      child: Scaffold(
        appBar: AppBar(
          bottom: TabBar(
            tabs: tabs
                .take(tabCount.value)
                .map((tab) => Tab(icon: tab.icon))
                .toList(),
          ),
        ),
        body: CustomTabBarView(tabCount: tabCount),
      ),
    );
  }
}

class CustomTabBarView extends StatelessWidget {
  const CustomTabBarView({
    Key? key,
    required this.tabCount,
  }) : super(key: key);

  final ValueNotifier<int> tabCount;

  @override
  Widget build(BuildContext context) {
    return TabBarView(
      children: tabs
          .take(tabCount.value)
          .map(
            (tab) => Padding(
              padding: const EdgeInsets.all(8.0),
              child: Column(
                children: [
                  Text(tab.text),
                  TextButton(
                    onPressed: () {
                      final newLength = min(
                        tabs.length,
                        tabCount.value + 1,
                      );
                      tabCount.value = newLength;
                    },
                    child: const Text('Create next tab'),
                  )
                ],
              ),
            ),
          )
          .toList(),
    );
  }
}

 

Folding Iterables in Dart



import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() {
  final values = ['foo', 'bar', 'baz', '1.0'];

  values.fold<int>(0, (pe, e) => pe + e.length); // 12

  values.fold<String>('', (pe, e) => '$pe$e'); // foobarbaz1.0

  values.fold<Map<String, int>>(
    {},
    (pe, e) => pe..addAll(<String, int>{e: e.length}),
  ).log(); // {foo: 3, bar: 3, baz: 3, 1.0: 3}

  values.fold<double>(
    0.0,
    (pe, e) => pe + (double.tryParse(e) ?? 0.0),
  ); // 1.0
}

Custom Iterables in Dart



class Address with IterableMixin {
  final String line1;
  final String line2;
  final String postCode;

  Address({
    required this.line1,
    required this.line2,
    required this.postCode,
  });

  @override
  Iterator<String> get iterator => [line1, line2, postCode].iterator;
}

void testIt() {
  final address = Address(
    line1: 'Foo bar avenue, #10',
    line2: 'Baz street',
    postCode: '123456',
  );
  for (final line in address) {
    devtools.log(line);
  }
}

Class Clusters in Dart



enum AnimalType { dog, cat }

@immutable
abstract class Animal {
  const Animal();
  factory Animal.fromType(AnimalType type) {
    switch (type) {
      case AnimalType.dog:
        return const Dog();
      case AnimalType.cat:
        return const Cat();
    }
  }
  void makeNoise();
}

@immutable
class Dog extends Animal {
  const Dog();
  @override
  void makeNoise() => 'Woof'.log();
}

@immutable
class Cat extends Animal {
  const Cat();
  @override
  void makeNoise() => 'Meow'.log();
}

void testIt() {
  final cat = Animal.fromType(AnimalType.cat);
  cat.makeNoise();
  final dog = Animal.fromType(AnimalType.dog);
  dog.makeNoise();
}

Iterable +/- in Dart



extension AddRemoveItems<T> on Iterable<T> {
  Iterable<T> operator +(T other) => followedBy([other]);
  Iterable<T> operator -(T other) => where((element) => element != other);
}

void testIt() {
  final values = ['foo', 'bar']
    .map((e) => e.toUpperCase()) + 'BAZ';
  values.log(); // (FOO, BAR, BAZ)
  (values - 'BAZ').log(); // (FOO, BAR)
}

Periodic Streams in Dart



import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:convert';
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

@immutable
class Person {
  final String name;
  final int age;

  const Person({
    required this.name,
    required this.age,
  });

  Person.fromJson(Map<String, dynamic> json)
      : name = json["name"] as String,
        age = json["age"] as int;

  @override
  String toString() => 'Person ($name, $age years old)';
}

mixin ListOfThingsAPI<T> {
  Future<Iterable<T>> get(String url) => HttpClient()
      .getUrl(Uri.parse(url))
      .then((req) => req.close())
      .then((resp) => resp.transform(utf8.decoder).join())
      .then((str) => json.decode(str) as List<dynamic>)
      .then((list) => list.cast());
}

class GetPeople with ListOfThingsAPI<Map<String, dynamic>> {
  Future<Iterable<Person>> getPeople(url) => get(url).then(
        (jsons) => jsons.map(
          (json) => Person.fromJson(json),
        ),
      );
}

Stream<dynamic> every(Duration duration) => Stream.periodic(duration);

extension IntToDuration on int {
  Duration get seconds => Duration(seconds: this);
}

void testIt() async {
  await for (final people in every(3.seconds).asyncExpand(
    (_) => GetPeople()
        .getPeople('http://127.0.0.1:5500/apis/people1.json')
        .asStream(),
  )) {
    people.log();
  }
}

/* people1.json
[
    {
        "name": "Foo 1",
        "age": 20
    },
    {
        "name": "Bar 1",
        "age": 30
    }
]
*/

EmptyOnError in Dart



import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:convert';
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

@immutable
class Person {
  final String name;
  final int age;

  const Person({
    required this.name,
    required this.age,
  });

  Person.fromJson(Map<String, dynamic> json)
      : name = json["name"] as String,
        age = json["age"] as int;

  @override
  String toString() => 'Person ($name, $age years old)';
}

const people1Url = 'http://127.0.0.1:5500/apis/people11.json';
const people2Url = 'http://127.0.0.1:5500/apis/people2.json';

extension EmptyOnError<E> on Future<List<Iterable<E>>> {
  Future<List<Iterable<E>>> emptyOnError() => catchError(
        (_, __) => List<Iterable<E>>.empty(),
      );
}

Future<Iterable<Person>> parseJson(String url) => HttpClient()
    .getUrl(Uri.parse(url))
    .then((req) => req.close())
    .then((resp) => resp.transform(utf8.decoder).join())
    .then((str) => json.decode(str) as List<dynamic>)
    .then((json) => json.map((e) => Person.fromJson(e)));

void testIt() async {
  final persons = await Future.wait([
    parseJson(people1Url),
    parseJson(people2Url),
  ]).emptyOnError();
  persons.log();
}

Stream<T> Initial Value in Flutter



import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

const url = 'https://bit.ly/3x7J5Qt';

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    late final StreamController<double> controller;
    controller = useStreamController<double>(onListen: () {
      controller.sink.add(0.0);
    });

    return Scaffold(
      appBar: AppBar(
        title: const Text('Home page'),
      ),
      body: StreamBuilder<double>(
          stream: controller.stream,
          builder: (context, snapshot) {
            if (!snapshot.hasData) {
              return const CircularProgressIndicator();
            } else {
              final rotation = snapshot.data ?? 0.0;
              return GestureDetector(
                onTap: () {
                  controller.sink.add(rotation + 10.0);
                },
                child: RotationTransition(
                  turns: AlwaysStoppedAnimation(rotation / 360.0),
                  child: Center(
                    child: Image.network(url),
                  ),
                ),
              );
            }
          }),
    );
  }
}

Double.normalize in Dart



import 'dart:developer' as devtools show log;

extension Normalize on double {
  double normalized(
    double selfRangeMin,
    double selfRangeMax, [
    double normalizedRangeMin = 0.0,
    double normalizedRangeMax = 1.0,
  ]) =>
      (normalizedRangeMax - normalizedRangeMin) *
          ((this - selfRangeMin) / (selfRangeMax - selfRangeMin)) +
      normalizedRangeMin;
}

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() async {
  2.0.normalized(0, 2.0).log(); // 1.0
  4.0.normalized(0, 8.0).log(); // 0.5
  5.0.normalized(4.0, 6.0, 10.0, 20.0).log(); // 15
}

Hide Sensitive Information in Flutter

 



import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final state = useAppLifecycleState();
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Opacity(
          opacity: state == AppLifecycleState.resumed ? 1.0 : 0.0,
          child: Container(
            decoration: BoxDecoration(
              boxShadow: [
                BoxShadow(
                  blurRadius: 10,
                  color: Colors.black.withAlpha(100),
                  spreadRadius: 10,
                ),
              ],
            ),
            child: Image.asset('assets/card.png'),
          ),
        ),
      ),
    );
  }
}

Iterable.compactMap in Dart



import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension CompactMap<T> on Iterable<T?> {
  Iterable<T> compactMap<E>([
    E? Function(T?)? transform,
  ]) =>
      map(transform ?? (e) => e).where((e) => e != null).cast();
}

const list = ['Hello', null, 'World'];

void testIt() {
  list.log(); // [Hello, null, World]
  list.compactMap().log(); // [Hello, World]
  list.compactMap((e) => e?.toUpperCase()).log(); // [HELLO, WORLD]
}

useEffect in Flutter Hooks



import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final controller = useTextEditingController();
    final text = useState('');
    useEffect(
      () {
        void listener() {
          text.value = controller.text;
        }

        controller.addListener(listener);
        return () => controller.removeListener(listener);
      },
      [controller],
    );
    return Scaffold(
      body: Column(
        children: [
          TextField(
            controller: controller,
          ),
          Text('You typed ${text.value}')
        ],
      ),
    );
  }
}

Merging Streams in Dart



import 'package:async/async.dart' show StreamGroup;
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() async {
  final streams = Iterable.generate(
    3,
    (i) => Stream.periodic(
      const Duration(seconds: 1),
      (_) => 'Stream $i: ${DateTime.now().toIso8601String()}',
    ).take(i + 1),
  );
  await for (final now in StreamGroup.merge(streams)) {
    now.log();
  }
}

Isolate Stream in Dart



Stream<String> getMessages() {
  final rp = ReceivePort();
  return Isolate.spawn(_getMessages, rp.sendPort)
      .asStream()
      .asyncExpand((_) => rp)
      .takeWhile((element) => element is String)
      .cast();
}

void _getMessages(SendPort sp) async {
  await for (final now in Stream.periodic(
    const Duration(seconds: 1),
    (_) => DateTime.now().toIso8601String(),
  ).take(10)) {
    sp.send(now);
  }
  Isolate.exit(sp);
}

void testIt() async {
  await for (final msg in getMessages()) {
    msg.log();
  }
}

Network Image Retry in Flutter



@immutable
class RetryStrategy {
  final bool shouldRetry;
  final Duration waitBeforeRetry;
  const RetryStrategy({
    required this.shouldRetry,
    required this.waitBeforeRetry,
  });
}

typedef Retrier = RetryStrategy Function(String url, Object error);

class NetworkImageWithRetry extends StatelessWidget {
  final Widget loadingWidget;
  final Widget errorWidget;
  final String url;
  final Retrier retrier;

  final _controller = StreamController<Uint8List>.broadcast();

  NetworkImageWithRetry({
    Key? key,
    required this.url,
    required this.retrier,
    required this.loadingWidget,
    required this.errorWidget,
  }) : super(key: key);

  void getData() async {
    while (true == true) {
      try {
        final networkAsset = NetworkAssetBundle(Uri.parse(url));
        final loaded = await networkAsset.load(url);
        final bytes = loaded.buffer.asUint8List();
        _controller.sink.add(bytes);
        break;
      } catch (e) {
        final strategy = retrier(url, e);
        if (strategy.shouldRetry) {
          await Future.delayed(strategy.waitBeforeRetry);
        } else {
          _controller.sink.addError(e);
          break;
        }
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    getData();
    return StreamBuilder(
      stream: _controller.stream,
      builder: (context, AsyncSnapshot<Uint8List> snapshot) {
        if (snapshot.hasError) {
          return errorWidget;
        } else {
          final data = snapshot.data;
          if (snapshot.hasData && data != null) {
            return Image.memory(data);
          } else {
            return loadingWidget;
          }
        }
      },
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Image Retry'),
      ),
      body: NetworkImageWithRetry(
        url: 'https://bit.ly/3qYOtDm',
        errorWidget: const Text('Got an error!'),
        loadingWidget: const Text('Loading...'),
        retrier: (url, error) {
          return RetryStrategy(
            shouldRetry: error is! FlutterError,
            waitBeforeRetry: const Duration(seconds: 1),
          );
        },
      ),
    );
  }
}

Reusable APIs in Flutter

import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:developer' as devtools show log;
import 'dart:convert' show utf8;
import 'package:meta/meta.dart' show useResult;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension GetOnUri on Object {
  Future<HttpClientResponse> getUrl(
    String url,
  ) =>
      HttpClient()
          .getUrl(
            Uri.parse(
              url,
            ),
          )
          .then((req) => req.close());
}

mixin CanMakeGetCall {
  String get url;
  @useResult
  Future<String> getString() => getUrl(url).then(
        (response) => response
            .transform(
              utf8.decoder,
            )
            .join(),
      );
}

@immutable
class GetPeople with CanMakeGetCall {
  const GetPeople();
  @override
  String get url => 'http://127.0.0.1:5500/apis/people.json';
}

void testIt() async {
  final people = await const GetPeople().getString();
  devtools.log(people);
}

ListTile Shadow in Flutter



enum Currency { dollars }

extension Title on Currency {
  String get title {
    switch (this) {
      case Currency.dollars:
        return '\$';
    }
  }
}

@immutable
class Item {
  final IconData icon;
  final String name;
  final double price;
  final Currency currency;

  const Item({
    required this.icon,
    required this.name,
    required this.price,
    required this.currency,
  });

  String get description => '$price${currency.title}';
}

const items = [
  Item(
    icon: Icons.camera_alt,
    name: 'Camera',
    price: 300,
    currency: Currency.dollars,
  ),
  Item(
    icon: Icons.house,
    name: 'House',
    price: 1000000,
    currency: Currency.dollars,
  ),
  Item(
    icon: Icons.watch,
    name: 'Smart Watch',
    price: 200,
    currency: Currency.dollars,
  ),
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: ListView.builder(
        itemCount: items.length,
        itemBuilder: (_, index) {
          return ItemTile(
            item: items[index],
          );
        },
      ),
    );
  }
}

class ItemTile extends StatelessWidget {
  final Item item;
  const ItemTile({Key? key, required this.item}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Stack(
        children: [
          const TileBackground(),
          CustomTile(item: item),
        ],
      ),
    );
  }
}

class CustomTile extends StatelessWidget {
  final Item item;
  const CustomTile({
    Key? key,
    required this.item,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(bottom: 7.0),
      child: Container(
        decoration: customDecoration(),
        child: ListTile(
          leading: Icon(
            item.icon,
            color: Colors.white,
          ),
          title: Text(item.name),
          subtitle: Text(item.description),
        ),
      ),
    );
  }
}

BoxDecoration customDecoration() {
  return BoxDecoration(
    color: const Color.fromARGB(255, 0x7d, 0xcf, 0xff),
    borderRadius: BorderRadius.circular(10.0),
    border: Border.all(
      color: Colors.black,
      width: 2.0,
    ),
  );
}

class TileBackground extends StatelessWidget {
  const TileBackground({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Positioned.fill(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 6.0),
        child: Container(
          decoration: BoxDecoration(
            color: const Color.fromARGB(255, 202, 255, 127),
            borderRadius: BorderRadius.circular(10.0),
            border: Border.all(
              color: Colors.black,
              width: 2.0,
            ),
          ),
        ),
      ),
    );
  }
}

Transparent AppBar in Flutter



const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      extendBodyBehindAppBar: true,
      appBar: AppBar(
        elevation: 0.0,
        backgroundColor: Colors.blueAccent.withAlpha(200),
        title: const Text('Transparent App Bar in Flutter'),
      ),
      body: const ImagesScrollView(),
    );
  }
}

class ImagesScrollView extends StatelessWidget {
  const ImagesScrollView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      padding: const EdgeInsets.only(top: 80.0),
      child: Padding(
        padding: const EdgeInsets.only(
          top: 40.0,
          left: 10.0,
          right: 10.0,
        ),
        child: Column(
          children: images
              .map((url) => ElevatedNetworkImage(url: url))
              .expand(
                (img) => [
                  img,
                  const SizedBox(height: 30.0),
                ],
              )
              .toList(),
        ),
      ),
    );
  }
}

class ElevatedNetworkImage extends StatelessWidget {
  final String url;
  const ElevatedNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return PhysicalShape(
      color: Colors.white,
      clipper: Clipper(),
      elevation: 20.0,
      clipBehavior: Clip.none,
      shadowColor: Colors.white.withAlpha(200),
      child: CutEdges(
        child: Image.network(url),
      ),
    );
  }
}

class Clipper extends CustomClipper<Path> {
  static const variance = 0.2;
  static const reverse = 1.0 - variance;

  @override
  Path getClip(Size size) {
    final path = Path();

    path.moveTo(0.0, size.height * Clipper.variance);
    path.lineTo(size.width * Clipper.variance, 0.0);
    path.lineTo(size.width, 0.0);
    path.lineTo(size.width, size.height * Clipper.reverse);
    path.lineTo(size.width * Clipper.reverse, size.height);
    path.lineTo(0.0, size.height);
    path.lineTo(0.0, size.height * Clipper.variance);
    path.close();
    return path;
  }

  @override
  bool shouldReclip(covariant CustomClipper<Path> oldClipper) => false;
}

class CutEdges extends StatelessWidget {
  final Widget child;

  const CutEdges({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ClipPath(
      clipper: Clipper(),
      child: child,
    );
  }
}

Constructors on Abstract Classes in Dart



import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

enum Type { dog, cat }

abstract class CanRun {
  final Type type;
  const CanRun({required this.type});
}

class Cat extends CanRun {
  const Cat() : super(type: Type.cat);
}

class Dog extends CanRun {
  const Dog() : super(type: Type.dog);
}

@useResult in Dart



import 'package:meta/meta.dart' show useResult;

class Person {
  final String firstName;
  final String lastName;

  const Person({
    required this.firstName,
    required this.lastName,
  });

  @useResult
  String fullName() => '$firstName $lastName';
}

void printFullName() {
  const Person(
    firstName: 'Foo',
    lastName: 'Bar',
  ).fullName();
}

@mustCallSuper in Dart



class Animal {
  @mustCallSuper
  void run() {}
}

class Dog extends Animal {
  @override
  void run() {}
}

Object.hash in Dart



class BreadCrumb {
  final bool isActive;
  final String name;
  BreadCrumb({
    required this.isActive,
    required this.name,
  });
  BreadCrumb activated() => BreadCrumb(
        isActive: true,
        name: name,
      );
  @override
  bool operator ==(covariant BreadCrumb other) =>
      isActive == other.isActive && name == other.name;

  @override
  int get hashCode => Object.hash(isActive, name);
}

Expanded Equally in Flutter



import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

extension ExpandEqually on Iterable<Widget> {
  Iterable<Widget> expandedEqually() => map(
        (w) => Expanded(
          flex: 1,
          child: w,
        ),
      );
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: Column(
        children: [
          Row(
            mainAxisSize: MainAxisSize.max,
            children: [
              Container(
                height: 200,
                color: Colors.yellow,
              ),
              Container(
                height: 200,
                color: Colors.blue,
              ),
            ].expandedEqually().toList(),
          )
        ],
      ),
    );
  }
}

Random Iterable Value in Dart



import 'dart:math' as math show Random;

extension RandomElement<T> on Iterable<T> {
  T getRandomElement() => elementAt(
        math.Random().nextInt(length),
      );
}

final colors = [Colors.blue, Colors.red, Colors.brown];

class HomePage extends StatelessWidget {
  final color = ValueNotifier<MaterialColor>(
    colors.getRandomElement(),
  );
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('List.Random in Flutter'),
      ),
      body: ColorPickerButton(color: color),
    );
  }
}

class ColorPickerButton extends StatelessWidget {
  final ValueNotifier<MaterialColor> color;

  const ColorPickerButton({
    Key? key,
    required this.color,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder<Color>(
      valueListenable: color,
      builder: (context, value, child) {
        return Padding(
          padding: const EdgeInsets.all(8.0),
          child: CenteredTight(
            child: TextButton(
              style: TextButton.styleFrom(backgroundColor: value),
              onPressed: () {
                color.value = colors.getRandomElement();
              },
              child: const Text(
                'Change color',
                style: TextStyle(
                  fontSize: 30,
                  color: Colors.white,
                ),
              ),
            ),
          ),
        );
      },
    );
  }
}

Hardcoded Strings in Flutter



extension Hardcoded on String {
  String get hardcoded => '$this 🧨';
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'My hardcoded string'.hardcoded,
        ),
      ),
      body: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text('String in body'.hardcoded),
        ],
      ),
    );
  }
}

Manually Scroll in List View in Flutter

// Free Flutter Course 💙 https://linktr.ee/vandadnp

import 'package:scrollable_positioned_list/scrollable_positioned_list.dart';

class HomePage extends StatelessWidget {
  final _controller = ItemScrollController();
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Testing'),
      ),
      body: ScrollablePositionedList.builder(
        itemScrollController: _controller,
        itemCount: allImages.length + 1,
        itemBuilder: (context, index) {
          if (index == 0) {
            return IndexSelector(
              count: allImages.length,
              onSelected: (index) {
                _controller.scrollTo(
                  index: index + 1,
                  duration: const Duration(milliseconds: 370),
                );
              },
            );
          } else {
            return ImageWithTitle(index: index);
          }
        },
      ),
    );
  }
}

class ImageWithTitle extends StatelessWidget {
  final int index;
  const ImageWithTitle({
    Key? key,
    required this.index,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text(
          'Image $index',
          style: const TextStyle(fontSize: 30.0),
        ),
        Image.network(allImages.elementAt(index - 1)),
      ],
    );
  }
}

typedef OnIndexSelected = void Function(int index);

class IndexSelector extends StatelessWidget {
  final int count;
  final OnIndexSelected onSelected;
  final String prefix;
  const IndexSelector({
    Key? key,
    required this.count,
    required this.onSelected,
    this.prefix = 'Image',
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: Row(
        children: Iterable.generate(
          count,
          (index) => TextButton(
            onPressed: () {
              onSelected(index);
            },
            child: Text('$prefix ${index + 1}'),
          ),
        ).toList(),
      ),
    );
  }
}

const imageUrls = [
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

AsyncSnapshot to Widget in Flutter



import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const HomePage(),
    ),
  );
}

final future = Future<String>.delayed(
  const Duration(seconds: 3),
  () => 'Hello world',
);

typedef ResolveToWidget<T> = Widget Function(
  ConnectionState connectionState,
  AsyncSnapshot<T> snapshot,
);

extension Materialize on AsyncSnapshot {
  Widget materialize(ResolveToWidget f) => f(
        connectionState,
        this,
      );
}

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Hooks'),
      ),
      body: useFuture(future).materialize((connectionState, snapshot) {
        switch (connectionState) {
          case ConnectionState.done:
            return Text(snapshot.data ?? '');
          default:
            return const CircularProgressIndicator();
        }
      }),
    );
  }
}

Breadcrumbs in Flutter



@immutable
class BreadCrumbPath {
  final String title;
  final bool isActive;
  const BreadCrumbPath({
    required this.title,
    required this.isActive,
  });
  BreadCrumbPath activated() {
    return BreadCrumbPath(
      title: title,
      isActive: true,
    );
  }

  @override
  String toString() => title;
}

class BreatCrumbPathView extends StatelessWidget {
  final BreadCrumbPath path;

  const BreatCrumbPathView({
    Key? key,
    required this.path,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    final title = path.isActive ? '${path.title} →' : path.title;
    return Padding(
      padding: const EdgeInsets.all(2.0),
      child: Text(
        title,
        style: TextStyle(
          height: 1.0,
          fontSize: 20.0,
          color: path.isActive ? Colors.blueAccent : Colors.black,
        ),
      ),
    );
  }
}

typedef OnBreadCrumbPathTapped = void Function(BreadCrumbPath path);

class BreadCrumbView extends StatelessWidget {
  final OnBreadCrumbPathTapped onTapped;
  final Stream<List<BreadCrumbPath>> paths;
  const BreadCrumbView({
    Key? key,
    required this.paths,
    required this.onTapped,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return StreamBuilder<List<BreadCrumbPath>>(
      stream: paths,
      builder: (context, snapshot) {
        final List<Widget> views;
        switch (snapshot.connectionState) {
          case ConnectionState.waiting:
          case ConnectionState.active:
            final paths = snapshot.data ?? [];
            final views = paths
                .map(
                  (path) => GestureDetector(
                    onTap: () => onTapped(path),
                    child: BreatCrumbPathView(path: path),
                  ),
                )
                .toList();
            return Wrap(
              spacing: 4.0,
              children: views,
              alignment: WrapAlignment.start,
              crossAxisAlignment: WrapCrossAlignment.center,
            );
          default:
            return Wrap();
        }
      },
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  List<BreadCrumbPath> _paths = [];
  late final TextEditingController _textController;
  late final StreamController<List<BreadCrumbPath>> _pathsController;

  @override
  void initState() {
    _pathsController = StreamController<List<BreadCrumbPath>>.broadcast(
      onListen: () {
        _pathsController.add(_paths);
      },
    );
    _textController = TextEditingController();
    super.initState();
  }

  @override
  void dispose() {
    _textController.dispose();
    _pathsController.close();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Breadcrumb in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            BreadCrumbView(
              paths: _pathsController.stream,
              onTapped: (path) async {
                await showBreadCrumbPathTappedDialog(
                  context,
                  path,
                );
              },
            ),
            TextField(
              controller: _textController,
              textAlign: TextAlign.center,
              decoration: const InputDecoration(
                hintText: 'Enter a new path here',
              ),
            ),
            TextButton(
              onPressed: () {
                _paths = [
                  ..._paths.map((p) => p.activated()),
                  BreadCrumbPath(
                    title: _textController.text,
                    isActive: false,
                  ),
                ];
                _pathsController.add(_paths);
                _textController.clear();
              },
              child: const Center(
                child: Text('Add new path'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

Future<void> showBreadCrumbPathTappedDialog(
  BuildContext context,
  BreadCrumbPath path,
) {
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: Text('You tapped on $path'),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop();
            },
            child: const Text('OK'),
          ),
        ],
      );
    },
  );
}

Unique Map Values in Dart



import 'dart:developer' as devtools show log;

extension ContainsDuplicateValues on Map {
  bool get containsDuplicateValues => 
    {...values}.length != values.length;
}

extension Log on Object {
  void log() => devtools.log(toString());
}

const people1 = {
  1: 'Foo',
  2: 'Bar',
};
const people2 = {
  1: 'Foo',
  2: 'Foo',
};

void testIt() {
  people1.containsDuplicateValues.log(); // false
  people2.containsDuplicateValues.log(); // true
}

Smart Quotes/Dashes in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Smart Quotes/Dashes in Flutter'),
      ),
      body: const Padding(
        padding: EdgeInsets.all(16.0),
        child: TextField(
          smartQuotesType: SmartQuotesType.disabled,
          smartDashesType: SmartDashesType.disabled,
          maxLines: null,
        ),
      ),
    );
  }
}

Haptic Feedback in Flutter



class CenteredTight extends StatelessWidget {
  final Widget child;
  const CenteredTight({
    Key? key,
    required this.child,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [child],
    );
  }
}

class FullscreenImage extends StatefulWidget {
  final String imageUrl;
  const FullscreenImage({Key? key, required this.imageUrl}) : super(key: key);

  @override
  State<FullscreenImage> createState() => _FullscreenImageState();
}

class _FullscreenImageState extends State<FullscreenImage> {
  var shouldDisplayAppbar = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: shouldDisplayAppbar ? AppBar(title: const Text('Image')) : null,
      body: GestureDetector(
        onTap: () {
          setState(() => shouldDisplayAppbar = !shouldDisplayAppbar);
        },
        child: Image.network(
          widget.imageUrl,
          alignment: Alignment.center,
          width: double.infinity,
          height: double.infinity,
          fit: BoxFit.cover,
        ),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Haptic Feedback in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: CenteredTight(
          child: FractionallySizedBox(
            heightFactor: 0.7,
            child: GestureDetector(
              onLongPress: () async {
                await HapticFeedback.lightImpact();
                Navigator.of(context).push(
                  MaterialPageRoute(
                    builder: (context) {
                      return const FullscreenImage(
                        imageUrl: imageUrl,
                      );
                    },
                  ),
                );
              },
              child: Image.network(imageUrl),
            ),
          ),
        ),
      ),
    );
  }
}

Localization Delegates in Flutter



import 'package:flutter_gen/gen_l10n/app_localizations.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(
    MaterialApp(
      localizationsDelegates: AppLocalizations.localizationsDelegates,
      supportedLocales: AppLocalizations.supportedLocales,
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: BlocProvider<AuthBloc>(
        create: (context) => AuthBloc(FirebaseAuthProvider()),
        child: const HomePage(),
      ),
      routes: {
        createOrUpdateNoteRoute: (context) => const CreateUpdateNoteView(),
      },
    ),
  );
}

Extending Functions in Dart



import 'dart:developer' as devtools show log;

extension ToTextButton on VoidCallback {
  TextButton toTextButton(String title) {
    return TextButton(
      onPressed: this,
      child: Text(title),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Extensions in Flutter'),
      ),
      body: () {
        devtools.log('I am pressed');
      }.toTextButton('Press me'),
    );
  }
}

Paginated ListView in Flutter



@immutable
class Season {
  final String name;
  final String imageUrl;
  const Season({required this.name, required this.imageUrl});
  const Season.spring()
      : name = 'Spring',
        imageUrl = 'https://cnn.it/3xu58Ap';
  const Season.summer()
      : name = 'Summer',
        imageUrl = 'https://bit.ly/2VcCSow';
  const Season.autumn()
      : name = 'Autumn',
        imageUrl = 'https://bit.ly/3A3zStC';
  const Season.winter()
      : name = 'Winter',
        imageUrl = 'https://bit.ly/2TNY7wi';
}

const allSeasons = [
  Season.spring(),
  Season.summer(),
  Season.autumn(),
  Season.winter()
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    final width = MediaQuery.of(context).size.width;
    final height = width / (16.0 / 9.0);
    return Scaffold(
      appBar: AppBar(
        title: const Text('PageScrollPhysics in Flutter'),
      ),
      body: SizedBox(
        width: width,
        height: height,
        child: ListView(
          shrinkWrap: true,
          scrollDirection: Axis.horizontal,
          physics: const PageScrollPhysics(),
          clipBehavior: Clip.antiAlias,
          children: allSeasons.map((season) {
            return SizedBox(
              width: width,
              height: height,
              child: Image.network(
                season.imageUrl,
                height: height,
                fit: BoxFit.cover,
              ),
            );
          }).toList(),
        ),
      ),
    );
  }
}

Immutable Classes in Dart



import 'package:flutter/foundation.dart' show immutable;

@immutable
abstract class Animal {
  final String name;
  const Animal(this.name);
}

class Cat extends Animal {
  const Cat() : super('Cindy Clawford');
}

class Dog extends Animal {
  int age;
  Dog()
      : age = 0,
        super('Bark Twain');
}

Card Widget in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Card in Flutter'),
      ),
      body: Image.network(
        'https://bit.ly/36fNNj9',
        frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
          return Card(
            child: child,
            clipBehavior: Clip.antiAlias,
          );
        },
        loadingBuilder: (context, child, loadingProgress) {
          final totalBytes = loadingProgress?.expectedTotalBytes;
          final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
          if (totalBytes != null && bytesLoaded != null) {
            return Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: const [CircularProgressIndicator()],
            );
          } else {
            return child;
          }
        },
      ),
    );
  }
}

List Equality Ignoring Ordering in Dart



@immutable
class Person {
  final String name;
  const Person(this.name);

  @override
  bool operator ==(covariant Person other) => other.name == name;

  @override
  int get hashCode => name.hashCode;

  @override
  String toString() => name;
}

const people1 = [Person('Foo'), Person('Bar'), Person('Baz')];
const people2 = [Person('Foo'), Person('Bar'), Person('Baz')];
const people3 = [Person('Bar'), Person('Bar'), Person('Baz')];
const people4 = [Person('Bar'), Person('Baz')];

extension IsEqualToIgnoringOrdering<T> on List<T> {
  bool isEqualToIgnoringOrdering(List<T> other) =>
      length == other.length &&
      {...this}.intersection({...other}).length == length;
}

void testIt() {
  assert(people1.isEqualToIgnoringOrdering(people2));
  assert(!people1.isEqualToIgnoringOrdering(people3));
  assert(!people2.isEqualToIgnoringOrdering(people3));
  assert(!people3.isEqualToIgnoringOrdering(people4));
}

Shorten GitHub URLs in Dart

// Want to support my work 🤝? https://buymeacoffee.com/vandad

import 'dart:developer' as devtools show log;
import 'dart:convert' show utf8;

Future<Uri> shortenGitHubUrl(String longUrl) =>
    HttpClient().postUrl(Uri.parse('https://git.io/')).then((req) {
      req.add(utf8.encode('url=$longUrl'));
      return req.close();
    }).then(
      (resp) async {
        try {
          final location = resp.headers[HttpHeaders.locationHeader]?.first;
          if (location != null) {
            return Uri.parse(location);
          } else {
            throw 'No location was specified';
          }
        } catch (e) {
          return Uri.parse(longUrl);
        }
      },
    );

void testIt() async {
  final uri = await shortenGitHubUrl(
      'https://github.com/vandadnp/flutter-tips-and-tricks');
  devtools.log(uri.toString());
  // logs https://git.io/JS5Fm
}

Time Picker in Flutter



class HomePage extends StatelessWidget {
  final timeOfDay = ValueNotifier<TimeOfDay?>(null);
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      valueListenable: timeOfDay,
      builder: (context, value, child) {
        final title = timeOfDay.value?.toString() ?? 'Time Picker in Flutter';
        return Scaffold(
          appBar: AppBar(title: Text(title)),
          body: Center(
            child: TextButton(
              onPressed: () async {
                timeOfDay.value = await showTimePicker(
                  context: context,
                  initialTime: TimeOfDay.now(),
                  initialEntryMode: TimePickerEntryMode.input,
                );
              },
              child: const Text('Please Pick a time'),
            ),
          ),
        );
      },
    );
  }
}

Throttled Print in Flutter



Stream<String> getStream() => Stream.periodic(
      const Duration(milliseconds: 100),
      (e) => DateTime.now().toString(),
    );

void testIt() async {
  await for (final now in getStream()) {
    debugPrintThrottled(now);
  }
}

Map Equality in Dart



typedef Name = String;
typedef Age = int;

const Map<Name, Age> people1 = {
  'foo': 20,
  'bar': 30,
  'baz': 40,
};

const Map<Name, Age> people2 = {
  'baz': 40,
  'foo': 20,
  'bar': 30,
};

void testIt() {
  assert(mapEquals(people1, people2));
}

Unique Maps in Dart



import 'dart:developer' as devtools show log;

typedef Name = String;
typedef Age = int;

const Map<Name, Age> people = {
  'foo': 20,
  'bar': 30,
  'baz': 20,
};

extension Unique<K, V> on Map<K, V> {
  Map<K, V> unique() {
    Map<K, V> result = {};
    for (final value in {...values}) {
      final firstKey = keys.firstWhereOrNull((key) => this[key] == value);
      if (firstKey != null) {
        result[firstKey] = value;
      }
    }
    return result;
  }
}

void testIt() {
  final uniques = people.unique();
  devtools.log(uniques.toString());
  // prints: {foo: 20, bar: 30}
}

Raw Auto Complete in Flutter



const emailProviders = [
  'gmail.com',
  'hotmail.com',
  'yahoo.com',
];

const icons = [
  'https://bit.ly/3HsvvvB',
  'https://bit.ly/3n6GW4L',
  'https://bit.ly/3zf2RLy',
];

class EmailTextField extends StatefulWidget {
  const EmailTextField({Key? key}) : super(key: key);

  @override
  State<EmailTextField> createState() => _EmailTextFieldState();
}

class _EmailTextFieldState extends State<EmailTextField> {
  late final TextEditingController _controller;
  late final FocusNode _focus;

  @override
  Widget build(BuildContext context) {
    return RawAutocomplete<String>(
      textEditingController: _controller,
      focusNode: _focus,
      fieldViewBuilder: (_, controller, focusNode, onSubmitted) {
        return TextFormField(
          controller: controller,
          focusNode: focusNode,
          onFieldSubmitted: (value) {
            onSubmitted();
          },
        );
      },
      optionsBuilder: (textEditingValue) {
        final lastChar = textEditingValue.text.characters.last;
        if (lastChar == '@') {
          return emailProviders;
        } else {
          return [];
        }
      },
      optionsViewBuilder: (context, onSelected, options) {
        return OptionsList(
          onSelected: onSelected,
          options: options,
          controller: _controller,
        );
      },
    );
  }

  @override
  void initState() {
    _controller = TextEditingController();
    _focus = FocusNode();
    super.initState();
  }

  @override
  void dispose() {
    _focus.dispose();
    _controller.dispose();
    super.dispose();
  }
}

class OptionsList extends StatelessWidget {
  final Iterable<String> options;
  final AutocompleteOnSelected<String> onSelected;
  final TextEditingController controller;
  const OptionsList({
    Key? key,
    required this.onSelected,
    required this.options,
    required this.controller,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.topLeft,
      child: Material(
        child: SizedBox(
          height: 150,
          child: ListView.builder(
            padding: const EdgeInsets.all(0.0),
            itemCount: options.length,
            itemBuilder: (context, index) {
              final option = options.elementAt(index);
              return GestureDetector(
                onTap: () => onSelected(controller.text + option),
                child: ListTile(
                  horizontalTitleGap: 2.0,
                  leading: Image.network(
                    icons[index],
                    width: 24,
                    height: 24,
                  ),
                  title: Text(option),
                ),
              );
            },
          ),
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Raw Auto Complete in Flutter'),
      ),
      body: const Padding(
        padding: EdgeInsets.all(16.0),
        child: EmailTextField(),
      ),
    );
  }
}

Title on Object in Dart



import 'dart:developer' as devtools show log;

extension CapTitle on Object {
  String get capitalizedTitle {
    String str;
    if (this is Enum) {
      str = (this as Enum).name;
    } else {
      str = toString();
    }
    return str[0].toUpperCase() + str.substring(1);
  }
}

enum EmailProviders { gmail, yahoo, hotmail }

void testIt() {
  EmailProviders.values.map((p) => p.capitalizedTitle).forEach(devtools.log);
  // prints these:
  // Gmail
  // Yahoo
  // Hotmail
}

Compute in Flutter



import 'dart:developer' as devtools show log;
import 'dart:convert' show utf8, json;

@immutable
class Person {
  final String name;
  final int age;
  const Person(this.name, this.age);
  Person.fromJson(Map<String, dynamic> json)
      : name = json["name"] as String,
        age = json["age"] as int;
}

Future<Iterable<Person>> downloadAndParsePersons(Uri uri) => HttpClient()
    .getUrl(uri)
    .then((req) => req.close())
    .then((response) => response.transform(utf8.decoder).join())
    .then((jsonString) => json.decode(jsonString) as List<dynamic>)
    .then((json) => json.map((map) => Person.fromJson(map)));

void testIt() async {
  final persons = await compute(
    downloadAndParsePersons,
    Uri.parse('https://bit.ly/3Jjcw8R'),
  );
  devtools.log(persons.toString());
}

Filter on Map in Dart



import 'dart:developer' as devtools show log;

typedef Name = String;
typedef Age = int;

extension Filter<K, V> on Map<K, V> {
  Iterable<MapEntry<K, V>> filter(
    bool Function(MapEntry<K, V> entry) f,
  ) sync* {
    for (final entry in entries) {
      if (f(entry)) {
        yield entry;
      }
    }
  }
}

const Map<Name, Age> people = {
  'foo': 20,
  'bar': 31,
  'baz': 25,
  'qux': 32,
};

void testIt() async {
  final peopleOver30 = people.filter((e) => e.value > 30);
  devtools.log(peopleOver30.toString());
  // ☝🏻 prints (MapEntry(bar: 31), MapEntry(qux: 32))
}

Type Alias in Dart



const Map<String, int> people1 = {
  'foo': 20,
  'bar': 30,
  'baz': 25,
};

typedef Age = int;

const Map<String, Age> people2 = {
  'foo': 20,
  'bar': 30,
  'baz': 25,
};

ValueNotifier in Flutter



class DynamicToolTipTextField extends StatelessWidget {
  final TextInputType? keyboardType;
  final ValueNotifier<String?> hint;
  final TextEditingController controller;
  const DynamicToolTipTextField({
    Key? key,
    required this.hint,
    required this.controller,
    this.keyboardType,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      valueListenable: hint,
      builder: (context, value, child) {
        return TextField(
          keyboardType: keyboardType,
          controller: controller,
          decoration: InputDecoration(
            hintText: value as String?,
          ),
        );
      },
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

@immutable
abstract class HasText {
  String get text;
}

enum Hint { pleaseEnterYourEmail, youForgotToEnterYourEmail }

extension GetText on Hint {
  String get text {
    switch (this) {
      case Hint.pleaseEnterYourEmail:
        return 'Please enter your email';
      case Hint.youForgotToEnterYourEmail:
        return 'You forgot to enter your email';
    }
  }
}

class _HomePageState extends State<HomePage> {
  late final ValueNotifier<String?> _hint;
  late final TextEditingController _controller;

  @override
  void initState() {
    _hint = ValueNotifier<String?>(Hint.pleaseEnterYourEmail.text);
    _controller = TextEditingController();
    super.initState();
  }

  @override
  void dispose() {
    _hint.dispose();
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('ValueNotifier in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            DynamicToolTipTextField(
              hint: _hint,
              controller: _controller,
              keyboardType: TextInputType.emailAddress,
            ),
            TextButton(
              onPressed: () async {
                final email = _controller.text;
                if (email.trim().isEmpty) {
                  _hint.value = Hint.youForgotToEnterYourEmail.text;
                  await Future.delayed(const Duration(seconds: 2));
                  _hint.value = Hint.pleaseEnterYourEmail.text;
                }
              },
              child: const Text('Log in'),
            )
          ],
        ),
      ),
    );
  }
}

Object to Integer in Dart



enum ToIntStrategy { round, floor, ceil }

typedef ToIntOnErrorHandler = int Function(Object e);

extension ToInt on Object {
  int toInteger({
    ToIntStrategy strategy = ToIntStrategy.round,
    ToIntOnErrorHandler? onError,
  }) {
    try {
      final doubleValue = double.parse(toString());
      switch (strategy) {
        case ToIntStrategy.round:
          return doubleValue.round();
        case ToIntStrategy.floor:
          return doubleValue.floor();
        case ToIntStrategy.ceil:
          return doubleValue.ceil();
      }
    } catch (e) {
      if (onError != null) {
        return onError(e);
      } else {
        return -1;
      }
    }
  }
}

void testIt() {
  assert('xyz'.toInteger(onError: (_) => 100) == 100);
  assert(1.5.toInteger() == 2);
  assert(1.6.toInteger() == 2);
  assert('1.2'.toInteger(strategy: ToIntStrategy.floor) == 1);
  assert('1.2'.toInteger(strategy: ToIntStrategy.ceil) == 2);
  assert('1.5'.toInteger(strategy: ToIntStrategy.round) == 2);
}

Image Opacity in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _opacity;

  @override
  void initState() {
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 1),
    );
    _opacity = Tween(begin: 0.0, end: 1.0).animate(_controller);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Image.network(
            'https://bit.ly/3ywI8l6',
            opacity: _opacity,
          ),
          Slider(
            value: _controller.value,
            onChanged: (value) {
              setState(() => _controller.value = value);
            },
          ),
        ],
      ),
    );
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }
}

Covariant in Dart

// Want to support my work 🤝? https://buymeacoffee.com/vandad

class Person {
  final String name;
  const Person(this.name);
  @override
  bool operator ==(Object other) {
    if (other is! Person) throw ArgumentError('Was expecting a person');
    return other.name == name;
  }

  @override
  int get hashCode => name.hashCode;
}

class Person {
  final String name;
  const Person(this.name);
  @override
  bool operator ==(covariant Person other) => other.name == name;

  @override
  int get hashCode => name.hashCode;
}

Custom Errors in Streams in Dart



class Either<V, E extends Exception> {
  final V? value;
  final E? error;

  const Either({this.value, this.error}) : assert((value ?? error) != null);

  bool get isError => error != null;
  bool get isValue => value != null;

  @override
  String toString() {
    if (value != null) {
      return "Value: $value";
    } else if (error != null) {
      return "Error: $error";
    } else {
      return 'Unknown state';
    }
  }
}

class DateTimeException implements Exception {
  final String reason;
  const DateTimeException({required this.reason});
}

Stream<Either<DateTime, DateTimeException>> getDateTime() async* {
  var index = 0;
  while (true) {
    if (index % 2 == 0) {
      yield Either(value: DateTime.now());
    } else {
      yield const Either(
        error: DateTimeException(reason: 'Something is wrong!'),
      );
    }
    index += 1;
  }
}

void testIt() async {
  await for (final value in getDateTime()) {
    dev.log(value.toString());
  }
}

Shake Animation in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

const animationWidth = 10.0;

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final TextEditingController _textController;
  late final AnimationController _animationController;
  late final Animation<double> _offsetAnim;
  final defaultHintText = 'Please enter your email here 😊';
  var _hintText = '';

  @override
  void initState() {
    _hintText = defaultHintText;
    _textController = TextEditingController();
    _animationController = AnimationController(
      duration: const Duration(milliseconds: 370),
      vsync: this,
    );
    _offsetAnim = Tween(
      begin: 0.0,
      end: animationWidth,
    ).chain(CurveTween(curve: Curves.elasticIn)).animate(
          _animationController,
        )..addStatusListener(
        (status) {
          if (status == AnimationStatus.completed) {
            _animationController.reverse();
          }
        },
      );
    super.initState();
  }

  @override
  void dispose() {
    _textController.dispose();
    _animationController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Shake Animation in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            AnimatedBuilder(
              animation: _offsetAnim,
              builder: (context, child) {
                return Container(
                  margin: const EdgeInsets.symmetric(
                    horizontal: animationWidth,
                  ),
                  padding: EdgeInsets.only(
                    left: _offsetAnim.value + animationWidth,
                    right: animationWidth - _offsetAnim.value,
                  ),
                  child: TextField(
                    controller: _textController,
                    keyboardType: TextInputType.emailAddress,
                    decoration: InputDecoration(
                      hintText: _hintText,
                    ),
                  ),
                );
              },
            ),
            TextButton(
                onPressed: () async {
                  if (_textController.text.isEmpty) {
                    setState(() {
                      _hintText = 'You forgot to enter your email 🥲';
                      _animationController.forward(from: 0.0);
                    });
                    await Future.delayed(const Duration(seconds: 3));
                    setState(() {
                      _hintText = defaultHintText;
                    });
                  }
                },
                child: const Text('Login'))
          ],
        ),
      ),
    );
  }
}

Throw Enums in Dart



import 'dart:developer' as dev show log;

enum Exceptions { invalidUserName, invalidPassword }

void thisMethodThrows() {
  throw Exceptions.invalidPassword;
}

void testIt() {
  try {
    thisMethodThrows();
  } on Exceptions catch (e) {
    switch (e) {
      case (Exceptions.invalidUserName):
        dev.log("Invalid user name");
        break;
      case (Exceptions.invalidPassword):
        dev.log("Invalid password");
        break;
    }
  }
}

Future Error Test in Flutter



import 'dart:developer' as dev show log;

@immutable
abstract class UserException implements Exception {}

class InvalidUserNameException extends UserException {}

class InvalidUserAgeException extends UserException {}

@immutable
class User {
  final String name;
  final int age;
  User({required this.name, required this.age}) {
    if (!name.contains(RegExp(r'^[a-z ]+$'))) {
      throw InvalidUserNameException();
    } else if (age < 0 || age > 130) {
      throw InvalidUserAgeException();
    }
  }
  const User.anonymous()
      : name = 'Anonymous User',
        age = 0;
}

Future<User> getAsyncUser() => Future.delayed(
      const Duration(seconds: 1),
      () => User(name: 'Foo', age: 20),
    );

void testIt() async {
  final user = await getAsyncUser()
      .catchError(
        handleInvalidUsernameException,
        test: (e) => e is InvalidUserNameException,
      )
      .catchError(
        handleInvalidAgeException,
        test: (e) => e is InvalidUserAgeException,
      );
  dev.log(user.toString());
}

User handleInvalidUsernameException(Object? e) {
  dev.log(e.toString());
  return const User.anonymous();
}

User handleInvalidAgeException(Object? e) {
  dev.log(e.toString());
  return const User.anonymous();
}

Generic URL Retrieval in Dart



import 'dart:developer' as dev show log;

typedef StatusCodeResultBuilder<T> = Future<T> Function(
  int statusCode,
  HttpClientResponse response,
);

extension Get on Uri {
  Future<T?> getBody<T>({
    StatusCodeResultBuilder<T>? statusBuilder,
    T Function(Object error)? onNetworkError,
  }) async {
    try {
      final apiCall = await HttpClient().getUrl(this);
      final response = await apiCall.close();
      final builder = statusBuilder;
      if (builder == null) {
        final data = await response.transform(convert.utf8.decoder).join();
        if (data is T) {
          return data as T?;
        } else {
          return null;
        }
      } else {
        final result = await builder(response.statusCode, response);
        return result;
      }
    } catch (e) {
      if (onNetworkError != null) {
        return onNetworkError(e);
      } else {
        return null;
      }
    }
  }
}

extension ToUri on String {
  Uri toUri() => Uri.parse(this);
}

const url = 'https://bit.ly/3EKWcLa';

void testIt() async {
  final json = await url.toUri().getBody<String>(
    statusBuilder: (statusCode, response) async {
      if (statusCode == 200) {
        return await response.transform(convert.utf8.decoder).join();
      } else {
        return "{'error': 'Unexpected status code $statusCode'}";
      }
    },
    onNetworkError: (error) {
      return "{'error': 'Got network error'}";
    },
  );
  if (json != null) {
    dev.log(json);
  }
}

Custom Error Widget in Flutter



class MyErrorWidget extends StatelessWidget {
  final String text;
  const MyErrorWidget({Key? key, required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SizedBox(
        width: MediaQuery.of(context).size.width,
        child: Padding(
          padding: const EdgeInsets.all(16.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.start,
            children: [
              Image.network('https://bit.ly/3gHlTCU'),
              Text(
                text,
                textAlign: TextAlign.center,
                style: const TextStyle(
                  color: Colors.red,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

void main() {
  ErrorWidget.builder = (FlutterErrorDetails details) {
    bool isInDebugMode = false;
    assert(() {
      isInDebugMode = true;
      return true;
    }());
    final message = details.exception.toString();
    if (isInDebugMode) {
      return MyErrorWidget(text: message);
    } else {
      return Text(
        message,
        textAlign: TextAlign.center,
      );
    }
  };

  runApp(
    const MaterialApp(
      home: HomePage(),
      debugShowCheckedModeBanner: false,
    ),
  );
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Error Widget in Flutter'),
      ),
      body: Builder(
        builder: (context) {
          throw Exception(
              'Here is an exception that is caught by our custom Error Widget in Flutter');
        },
      ),
    );
  }
}

Handle Multiple Future Errors in Dart



import 'dart:developer' as dev show log;

Future<Iterable<T>> waitOn<T>(
  Iterable<Future<T>> futures,
  Function onError,
) async {
  List<T> result = [];
  for (final future in futures) {
    final value = await future.catchError(onError);
    result.add(value);
  }
  return result;
}

void testIt() async {
  final f1 = Future.error('First Error');
  final f2 = Future.delayed(const Duration(seconds: 2), () => 10);
  final f3 = Future.error('Second error');
  final f4 = Future.delayed(const Duration(seconds: 2), () => 'Hello world');
  final result = await waitOn([f1, f2, f3, f4], (error) => -1);
  dev.log(result.toString()); // [-1, 10, -1, Hello world]
}

Future Error Handling in Dart

import 'dart:developer' as dev show log;

extension OnError<T> on Future<T> {
  Future<T> onErrorJustReturn(T value) => catchError((_) => value);
}

Future<bool> isUserRegistered({required String email}) => HttpClient()
    .postUrl(Uri.parse('https://website'))
    .then((req) {
      req.headers.add('email', email);
      return req.close();
    })
    .then((resp) => resp.statusCode == 200)
    .onErrorJustReturn(false);

void testIt() async {
  final isFooRegistered = await isUserRegistered(email: 'foo@flutter.com');
  dev.log(isFooRegistered.toString());
}

String to Toast in Flutter



extension Toast on String {
  Future<void> showAsToast(BuildContext context,
      {required Duration duration}) async {
    final scaffold = ScaffoldMessenger.of(context);
    final controller = scaffold.showSnackBar(
      SnackBar(
        content: Text(this),
        backgroundColor: const Color(0xFF24283b),
        behavior: SnackBarBehavior.floating,
        elevation: 2.0,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10),
        ),
      ),
    );
    await Future.delayed(duration);
    controller.close();
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: TextButton(
          onPressed: () => 'Hello, World!'.showAsToast(
            context,
            duration: const Duration(seconds: 2),
          ),
          child: const Text('Show the snackbar'),
        ),
      ),
    );
  }
}

Waiting in Dart



Future<void> wait(Duration d) async {
  await Future.delayed(d);
}

extension Wait on int {
  Future<void> get seconds => wait(Duration(seconds: this));
  Future<void> get minutes => wait(Duration(minutes: this));
}

void testIt() async {
  await 2.seconds;
  'After 2 seconds'.log();
  await 3.minutes;
  'After 3 minutes'.log();
}

extension Log on Object {
  void log() {
    dev.log(toString());
  }
}

Loading Dialog in Flutter



typedef CloseDialog = void Function();

CloseDialog showLoadingScreen({
  required BuildContext context,
  required String text,
}) {
  final dialog = AlertDialog(
    content: Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        const CircularProgressIndicator(),
        const SizedBox(height: 10),
        Text(text),
      ],
    ),
  );
  showDialog(
    context: context,
    barrierDismissible: false,
    builder: (_) => dialog,
  );

  return () => Navigator.of(context).pop();
}

void testIt(BuildContext context) async {
  final closeDialog = showLoadingScreen(
    context: context,
    text: 'Loading data...',
  );
  await Future.delayed(const Duration(seconds: 2));
  closeDialog();
}

Compact Map on Map<K,V> in Dart



const foo = 'foo';
const bar = 'bar';
const baz = 'baz';

const namesAndAges = {
  foo: 20,
  bar: 25,
  baz: 18,
};

const acceptedNames = [
  foo,
  bar,
];

void testIt() {
  final acceptedAges = namesAndAges.compactMap(
    (e) => acceptedNames.contains(e.key) ? e.value : null,
  );
  acceptedAges.log(); // [20, 25]
}

extension CompactMap<T, E> on Map<T, E> {
  Iterable<V> compactMap<V>(V? Function(MapEntry<T, E>) f) sync* {
    for (final entry in entries) {
      final extracted = f(entry);
      if (extracted != null) {
        yield extracted;
      }
    }
  }
}

Query Parameters in Dart



import 'dart:developer' as devtools show log;

const host = 'freecurrencyapi.net';
const path = '/api/v2/latest';
const apiKey = 'YOUR_API_KEY';
const baseCurrency = 'sek';
const params = {
  'apiKey': apiKey,
  'base_currency': 'sek',
};

void insteadOfThis() {
  const url = 'https://$host$path?apiKey=$apiKey&base_currency=$baseCurrency';
  url.log();
}

void doThis() {
  final url = Uri.https(host, path, params);
  url.log();
}

extension Log on Object {
  void log() {
    devtools.log(toString());
  }
}

Multiple Gradients in Container in Flutter



typedef GradientContainersBuilder = Map<LinearGradient, Widget?> Function();

class GradientContainers extends StatelessWidget {
  final GradientContainersBuilder builder;

  const GradientContainers({
    Key? key,
    required this.builder,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: builder().entries.map((mapEntry) {
        final gradient = mapEntry.key;
        final widget = mapEntry.value;
        return GradientContainer(
          gradient: gradient,
          child: widget,
        );
      }).toList(),
    );
  }
}

class GradientContainer extends StatelessWidget {
  final LinearGradient gradient;
  final Widget? child;

  const GradientContainer({Key? key, required this.gradient, this.child})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Positioned.fill(
      child: Container(
        decoration: BoxDecoration(
          gradient: gradient,
        ),
        child: child,
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GradientContainers(
        builder: () => {
          topLeftToBottomRightGradient: null,
          rightToLeftGradient: null,
          leftToRightGradinet: null,
          bottomRightGradient: Image.network('https://bit.ly/3otHHog'),
        },
      ),
    );
  }
}

const transparent = Color(0x00FFFFFF);

const topLeftToBottomRightGradient = LinearGradient(
  begin: Alignment.topLeft,
  end: Alignment.bottomRight,
  colors: [
    Color(0xff2ac3de),
    transparent,
  ],
);

const bottomRightGradient = LinearGradient(
  begin: Alignment.bottomRight,
  end: Alignment.topLeft,
  colors: [
    Color(0xffbb9af7),
    transparent,
  ],
);

const rightToLeftGradient = LinearGradient(
  begin: Alignment.centerRight,
  end: Alignment.centerLeft,
  colors: [
    Color(0xff9ece6a),
    transparent,
  ],
);

const leftToRightGradinet = LinearGradient(
  begin: Alignment.centerLeft,
  end: Alignment.centerRight,
  colors: [
    Color(0xff7dcfff),
    transparent,
  ],
);

void main() {
  runApp(
    const MaterialApp(
      home: HomePage(),
      debugShowCheckedModeBanner: false,
    ),
  );
}

Filter on Stream<List<T>> in Dart



import 'dart:developer' as devtools show log;

extension Filter<T> on Stream<List<T>> {
  Stream<List<T>> filter(bool Function(T) where) =>
      map((items) => items.where(where).toList());
}

final Stream<List<int>> allNumbers = Stream.periodic(
  const Duration(seconds: 1),
  (value) => [for (var i = 0; i < value; i++) i],
);

bool isEven(num value) => value % 2 == 0;
bool isOdd(num value) => value % 2 != 0;

extension EvenOdd<E extends num> on Stream<List<E>> {
  Stream<List<E>> get evenNumbers => filter(isEven);
  Stream<List<E>> get oddNumbers => filter(isOdd);
}

void readEvenNumbers() async {
  await for (final evenNumber in allNumbers.evenNumbers) {
    devtools.log('All even numbers: $evenNumber');
  }
}

void readOddNumbers() async {
  await for (final oddNumber in allNumbers.oddNumbers) {
    devtools.log('All odd numbers: $oddNumber');
  }
}

Generic Route Arguments in Flutter

extension GetArgument on BuildContext {
  T? getArgument<T>() {
    final modalRoute = ModalRoute.of(this);
    if (modalRoute != null) {
      final args = modalRoute.settings.arguments;
      if (args != null && args is T) {
        return args as T;
      }
    }
    return null;
  }
}

Generic Dialog in Flutter

typedef DialogOptionBuilder<T> = Map<String, T> Function();

Future<T?> showGenericDialog<T>({
  required BuildContext context,
  required String title,
  required String content,
  required DialogOptionBuilder optionsBuilder,
}) {
  final options = optionsBuilder();
  return showDialog<T>(
    context: context,
    builder: (context) {
      return AlertDialog(
        title: Text(title),
        content: Text(content),
        actions: options.keys.map(
          (optionTitle) {
            final T value = options[optionTitle];
            return TextButton(
              onPressed: () {
                Navigator.of(context).pop(value);
              },
              child: Text(optionTitle),
            );
          },
        ).toList(),
      );
    },
  );
}

Future<bool> showLogOutDialog(BuildContext context) {
  return showGenericDialog<bool>(
    context: context,
    title: 'Log out',
    content: 'Are you sure you want to log out?',
    optionsBuilder: () => {
      'Cancel': false,
      'Log out': true,
    },
  ).then(
    (value) => value ?? false,
  );
}

GitHub API in Flutter



import 'dart:io' show HttpHeaders, HttpClient;
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:convert' show utf8, json;

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Future<Iterable<GithubUser>> getGithubFollowers(String accessToken) =>
    HttpClient()
        .getUrl(Uri.parse('https://api.github.com/user/followers'))
        .then((req) {
          req.headers
            ..set(HttpHeaders.authorizationHeader, 'Bearer $accessToken')
            ..set(HttpHeaders.contentTypeHeader, 'application/json');
          return req.close();
        })
        .then((resp) => resp.transform(utf8.decoder).join())
        .then((jsonStr) => json.decode(jsonStr) as List<dynamic>)
        .then(
          (jsonArray) => jsonArray.compactMap((element) {
            if (element is Map<String, dynamic>) {
              return element;
            } else {
              return null;
            }
          }),
        )
        .then(
          (listOfMaps) => listOfMaps.map(
            (map) => GithubUser.fromJson(map),
          ),
        );

class GithubUser {
  final String username;
  final String avatarUrl;

  GithubUser.fromJson(Map<String, dynamic> json)
      : username = json['login'] as String,
        avatarUrl = json['avatar_url'] as String;
}

extension CompactMap<T> on List<T> {
  List<E> compactMap<E>(E? Function(T element) f) {
    Iterable<E> imp(E? Function(T element) f) sync* {
      for (final value in this) {
        final mapped = f(value);
        if (mapped != null) {
          yield mapped;
        }
      }
    }

    return imp(f).toList();
  }
}

const token = 'PUT_YOUR_TOKEN_HERE';

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('GitHub API in Flutter'),
      ),
      body: FutureBuilder(
        future: getGithubFollowers(token),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.done:
              final users = (snapshot.data as Iterable<GithubUser>).toList();
              return ListView.builder(
                itemCount: users.length,
                itemBuilder: (context, index) {
                  final user = users[index];
                  return ListTile(
                    title: Text(user.username),
                    leading: CircularAvatar(url: user.avatarUrl),
                  );
                },
              );
            default:
              return const CircularProgressIndicator();
          }
        },
      ),
    );
  }
}

void main() {
  runApp(
    const MaterialApp(
      home: HomePage(),
      debugShowCheckedModeBanner: false,
    ),
  );
}

ChangeNotifier in Flutter



import 'package:provider/provider.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const allImages = [
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class ImageData {
  final Uint8List imageData;
  const ImageData(this.imageData);
}

class Images extends ChangeNotifier {
  final List<ImageData> _items = [];

  var _isLoading = false;
  bool get isLoading => _isLoading;

  UnmodifiableListView<ImageData> get items => UnmodifiableListView(_items);

  void loadNextImage() async {
    if (_items.length < allImages.length) {
      // time to load more
      _isLoading = true;
      notifyListeners();
      final imageUrl = allImages[_items.length];
      final networkAsset = NetworkAssetBundle(Uri.parse(imageUrl));
      final loaded = await networkAsset.load(imageUrl);
      final bytes = loaded.buffer.asUint8List();
      final imageData = ImageData(bytes);
      _items.insert(0, imageData);
      _isLoading = false;
      notifyListeners();
    } else {
      if (isLoading) {
        _isLoading = false;
        notifyListeners();
      }
    }
  }
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('ChangeNotifier in Flutter'),
        actions: [
          Consumer<Images>(
            builder: (context, value, child) {
              return IconButton(
                onPressed: () {
                  value.loadNextImage();
                },
                icon: const Icon(Icons.add_box_outlined),
              );
            },
          )
        ],
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Consumer<Images>(
          builder: (context, value, child) {
            final images = value.items;
            final isLoading = value.isLoading;
            return ListView.builder(
              itemBuilder: (context, index) {
                if (index == 0 && isLoading) {
                  return Center(
                    child: Column(
                      children: const [
                        CircularProgressIndicator(),
                        SizedBox(height: 16.0),
                      ],
                    ),
                  );
                } else {
                  final imageIndex = isLoading ? index - 1 : index;
                  final imageData = images[imageIndex].imageData;
                  return Column(
                    children: [
                      RoundedImageWithShadow(imageData: imageData),
                      const SizedBox(height: 16.0),
                    ],
                  );
                }
              },
              itemCount: isLoading ? images.length + 1 : images.length,
            );
          },
        ),
      ),
    );
  }
}

class RoundedImageWithShadow extends StatelessWidget {
  final Uint8List imageData;
  const RoundedImageWithShadow({Key? key, required this.imageData})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            blurRadius: 2,
            color: Colors.black.withAlpha(40),
            spreadRadius: 2,
          ),
        ],
      ),
      child: Image.memory(
        imageData,
        fit: BoxFit.cover,
      ),
    );
  }
}

void main() {
  runApp(
    MaterialApp(
      home: ChangeNotifierProvider(
        create: (_) => Images(),
        child: const HomePage(),
      ),
      debugShowCheckedModeBanner: false,
    ),
  );
}

Refresh Indicator in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const allImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final _images = [allImages.first];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Refresh Indicator in Flutter'),
      ),
      body: RefreshIndicator(
        onRefresh: () async {
          final nextIndex = _images.length + 1;
          if (nextIndex < allImages.length) {
            setState(() {
              _images.insert(0, allImages[nextIndex]);
            });
          }
        },
        child: ListView.builder(
          physics: const AlwaysScrollableScrollPhysics(),
          padding: const EdgeInsets.all(16),
          itemCount: _images.length,
          itemBuilder: (context, index) {
            final imageUrl = _images[index];
            return Column(
              children: [
                RoundedImageWithShadow(url: imageUrl),
                const SizedBox(height: 16),
              ],
            );
          },
        ),
      ),
    );
  }
}

class RoundedImageWithShadow extends StatelessWidget {
  final String url;
  const RoundedImageWithShadow({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            blurRadius: 2,
            color: Colors.black.withAlpha(40),
            spreadRadius: 2,
          ),
        ],
      ),
      child: Image.network(url),
    );
  }
}

FlatMap in Dart



extension FlatMap<T> on T? {
  E? flatMap<E>(E? Function(T) f) => this != null ? f(this!) : null;
}

AuthUser? get insteadOfThis {
  final user = FirebaseAuth.instance.currentUser;
  if (user != null) {
    return AuthUser.fromFirebase(user);
  } else {
    return null;
  }
}

AuthUser? get doThis =>
    FirebaseAuth.instance.currentUser.flatMap((u) => AuthUser.fromFirebase(u));

OrientationBuilder in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class RoundedImageWithShadow extends StatelessWidget {
  final String url;
  const RoundedImageWithShadow({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            blurRadius: 2,
            color: Colors.black.withAlpha(40),
            spreadRadius: 2,
          ),
        ],
      ),
      child: Image.network(url),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: OrientationBuilder(
          builder: (context, orientation) {
            final int count;
            switch (orientation) {
              case Orientation.portrait:
                count = 2;
                break;
              case Orientation.landscape:
                count = 4;
                break;
            }
            return GridView.count(
              padding: const EdgeInsets.all(8.0),
              crossAxisCount: count,
              mainAxisSpacing: 8.0,
              crossAxisSpacing: 8.0,
              children: images
                  .map((url) => RoundedImageWithShadow(url: url))
                  .toList(),
            );
          },
        ),
      ),
    );
  }
}

final images = [
  'https://bit.ly/3qJ2FCf',
  'https://bit.ly/3Hs9JsV',
  'https://bit.ly/3cfT6Cv',
  'https://bit.ly/30wGnIE',
  'https://bit.ly/3kJYsum',
  'https://bit.ly/3oDoMaJ',
  'https://bit.ly/3FndXQM',
  'https://bit.ly/3ci4i1f',
];

Linear Gradient in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Linear Gradient in Flutter'),
      ),
      body: const ImageWithShadow(url: 'https://bit.ly/3otHHog'),
    );
  }
}

class ImageWithShadow extends StatelessWidget {
  final String url;

  const ImageWithShadow({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: Stack(
        children: [
          Positioned.fill(
            child: Container(
              decoration: BoxDecoration(
                boxShadow: [
                  BoxShadow(
                    blurRadius: 10.0,
                    color: Colors.black.withOpacity(0.5),
                    offset: const Offset(0.0, 3.0),
                  )
                ],
                borderRadius: const BorderRadius.all(Radius.circular(20)),
                gradient: const LinearGradient(
                  begin: Alignment.topCenter,
                  end: Alignment.bottomCenter,
                  colors: [
                    Color.fromARGB(255, 176, 229, 251),
                    Color.fromARGB(255, 235, 202, 250)
                  ],
                ),
              ),
            ),
          ),
          Image.network(url),
        ],
      ),
    );
  }
}

Bloc Text Editing Controller in Flutter

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:bloc/bloc.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

abstract class Event {
  const Event();
}

class SearchEvent extends Event {
  final String searchString;
  const SearchEvent(this.searchString);
}

class ClearSearch extends Event {}

class SearchBloc extends Bloc<Event, List<String>> {
  static const names = ['foo', 'bar', 'baz'];

  SearchBloc() : super(names) {
    on<Event>((event, emit) {
      if (event is SearchEvent) {
        emit(names
            .where((element) => element.contains(event.searchString))
            .toList());
      } else if (event is ClearSearch) {
        emit(names);
      }
    });
  }
}

class BlocTextEditingController extends TextEditingController {
  SearchBloc? bloc;
  BlocTextEditingController() {
    addListener(() {
      if (text.isEmpty) {
        bloc?.add(ClearSearch());
      } else {
        bloc?.add(SearchEvent(text));
      }
    });
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

const largeStyle = TextStyle(fontSize: 30);

class _HomePageState extends State<HomePage> {
  late final BlocTextEditingController _controller;

  @override
  void initState() {
    _controller = BlocTextEditingController();
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.bloc = BlocProvider.of<SearchBloc>(context);
    return Scaffold(
      appBar: AppBar(
        title: Text('Bloc Search in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: BlocBuilder<SearchBloc, List<String>>(
          builder: (context, state) {
            return ListView.builder(
              itemBuilder: (context, index) {
                if (index == 0) {
                  // search field
                  return TextField(
                    decoration: InputDecoration(
                      hintText: 'Enter search term here...',
                      hintStyle: largeStyle,
                    ),
                    style: largeStyle,
                    controller: _controller,
                  );
                } else {
                  final name = state[index - 1];
                  return ListTile(
                    title: Text(
                      name,
                      style: largeStyle,
                    ),
                  );
                }
              },
              itemCount: state.length + 1, // +1 for search
            );
          },
        ),
      ),
    );
  }
}

Blurred TabBar in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class CustomTabBar extends StatelessWidget {
  final List<IconButton> buttons;

  const CustomTabBar({Key? key, required this.buttons}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.bottomCenter,
      child: ClipRect(
        child: Container(
          height: 80,
          color: Colors.white.withOpacity(0.4),
          child: BackdropFilter(
            filter: ImageFilter.blur(sigmaX: 4.0, sigmaY: 4.0),
            child: Container(
              width: double.infinity,
              decoration: BoxDecoration(
                color: Colors.white.withOpacity(0.5),
              ),
              child: Padding(
                padding: const EdgeInsets.only(bottom: 15),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: buttons,
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

const summerIcon = Icon(
  Icons.surfing,
  size: 40.0,
  color: Colors.teal,
);

const autumnIcon = Icon(
  Icons.nature_outlined,
  size: 40.0,
  color: Colors.black45,
);

const winterIcon = Icon(
  Icons.snowboarding,
  size: 40.0,
  color: Colors.black45,
);

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Blurred Tab Bar'),
      ),
      body: Stack(
        children: [
          ListView.builder(
            itemCount: images.length,
            itemBuilder: (context, index) {
              final url = images[index];
              return Image.network(url);
            },
          ),
          CustomTabBar(
            buttons: [
              IconButton(
                icon: summerIcon,
                onPressed: () {
                  // implement me
                },
              ),
              IconButton(
                icon: autumnIcon,
                onPressed: () {
                  // implement me
                },
              ),
              IconButton(
                icon: winterIcon,
                onPressed: () {
                  // implement me
                },
              )
            ],
          )
        ],
      ),
    );
  }
}

Play YouTube in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

const videoIds = [
  'BHACKCNDMW8',
  '26h9hBZFl7w',
  'glENND73k4Q',
  'd0tU18Ybcvk',
];

class VideoView extends StatelessWidget {
  final String videoId;
  final _key = UniqueKey();

  VideoView({required this.videoId});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Watch a Video'),
      ),
      body: Center(
        child: Container(
          height: 232.0,
          child: WebView(
            key: _key,
            initialUrl: 'https://www.youtube.com/embed/$videoId',
            javascriptMode: JavascriptMode.unrestricted,
          ),
        ),
      ),
    );
  }
}

class YouTubeVideoThumbnail extends StatelessWidget {
  final String videoId;
  final String thumbnailUrl;

  const YouTubeVideoThumbnail({Key? key, required this.videoId})
      : thumbnailUrl = 'https://img.youtube.com/vi/$videoId/maxresdefault.jpg',
        super(key: key);

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () {
        Navigator.of(context).push(
          MaterialPageRoute(
            builder: (_) => VideoView(videoId: videoId),
          ),
        );
      },
      child: Container(
        height: 256.0,
        clipBehavior: Clip.antiAlias,
        decoration: BoxDecoration(
          boxShadow: [
            BoxShadow(
              blurRadius: 10.0,
              color: Colors.black.withAlpha(50),
              spreadRadius: 10.0,
            ),
          ],
          borderRadius: BorderRadius.circular(20),
          image: DecorationImage(
            fit: BoxFit.fitHeight,
            image: NetworkImage(thumbnailUrl),
          ),
        ),
        child: Center(
          child: Icon(
            Icons.play_arrow,
            color: Colors.white,
            size: 100.0,
          ),
        ),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('YouTube Videos in Flutter')),
      body: ListView.builder(
        itemCount: videoIds.length,
        itemBuilder: (context, index) {
          final videoId = videoIds[index];
          return Padding(
            padding: const EdgeInsets.all(8.0),
            child: YouTubeVideoThumbnail(videoId: videoId),
          );
        },
      ),
    );
  }
}

ListView Background in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class ListItem {
  const ListItem();
  factory ListItem.emptyTile() => EmptyTile();
  factory ListItem.tile(
    String title,
    String subTitle,
  ) =>
      Tile(
        title,
        subTitle,
      );
}

class Tile extends ListItem {
  final String title;
  final String subTitle;
  const Tile(this.title, this.subTitle) : super();
}

class EmptyTile extends ListItem {}

final items = [
  for (var i = 1; i <= 6; i++) ListItem.tile('Title $i', 'Sub title $i'),
  ListItem.emptyTile(),
  for (var i = 7; i <= 12; i++) ListItem.tile('Title $i', 'Sub title $i'),
];

class Background extends StatelessWidget {
  final Widget child;
  const Background({Key? key, required this.child}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        image: DecorationImage(
          fit: BoxFit.fitHeight,
          image: NetworkImage('https://bit.ly/3jXSDto'),
        ),
      ),
      child: child,
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Background(
        child: ListView.builder(
          padding: EdgeInsets.zero,
          itemCount: items.length,
          itemBuilder: (context, index) {
            final item = items[index];
            if (item is Tile) {
              return Container(
                color: Colors.grey[200],
                child: ListTile(
                  title: Text(item.title),
                  subtitle: Text(item.subTitle),
                ),
              );
            } else if (item is EmptyTile) {
              return SizedBox(
                height: 450,
              );
            } else {
              throw 'unexpcted item';
            }
          },
        ),
      ),
    );
  }
}

Integer to Binary in Dart

extension ToBinary on int {
  String toBinary(
    int len, {
    int separateAtLength = 4,
    String separator = ',',
  }) =>
      toRadixString(2)
          .padLeft(len, '0')
          .splitByLength(separateAtLength)
          .join(separator);
}

void testIt() {
  assert(1.toBinary(8) == '0000,0001');
  assert(2.toBinary(4) == '0010');
  assert(3.toBinary(16) == '0000,0000,0000,0011');
  assert(255.toBinary(8, separateAtLength: 8) == '11111111');
  assert(255.toBinary(8, separateAtLength: 4) == '1111,1111');
}

extension SplitByLength on String {
  Iterable<String> splitByLength(int len, {String filler = '0'}) sync* {
    final missingFromLength =
        length % len == 0 ? 0 : len - (characters.length % len);
    final expectedLength = length + missingFromLength;
    final src = padLeft(expectedLength, filler);
    final chars = src.characters;
    for (var i = 0; i < chars.length; i += len) {
      yield chars.getRange(i, i + len).toString();
    }
  }
}

Split String by Length in Dart



void testIt() {
  assert('dartlang'
      .splitByLength(5, filler: '💙')
      .isEqualTo(['💙💙dar', 'tlang']));

  assert('0100010'.splitByLength(4).isEqualTo(['0010', '0010']));
  assert('foobar'.splitByLength(3).isEqualTo(['foo', 'bar']));
  assert('flutter'.splitByLength(4, filler: 'X').isEqualTo(['Xflu', 'tter']));
  assert('dart'.splitByLength(5, filler: '').isEqualTo(['dart']));
}

extension SplitByLength on String {
  Iterable<String> splitByLength(int len, {String filler = '0'}) sync* {
    final missingFromLength =
        length % len == 0 ? 0 : len - (characters.length % len);
    final expectedLength = length + missingFromLength;
    final src = padLeft(expectedLength, filler);
    final chars = src.characters;
    for (var i = 0; i < chars.length; i += len) {
      yield chars.getRange(i, i + len).toString();
    }
  }
}

Image Tint in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

enum OverlayColor { brown, orange, yellow, green, blue }

extension Color on OverlayColor {
  MaterialColor get color {
    switch (this) {
      case OverlayColor.blue:
        return Colors.blue;
      case OverlayColor.brown:
        return Colors.brown;
      case OverlayColor.green:
        return Colors.green;
      case OverlayColor.orange:
        return Colors.orange;
      case OverlayColor.yellow:
        return Colors.yellow;
    }
  }
}

extension Title on OverlayColor {
  String get title => toString().split('.').last;
}

extension ToTextButtonWithValue on OverlayColor {
  TextButtonWithValue<OverlayColor> toTextButtonWithValue(
      OnTextButtonWithValuePressed onPressed) {
    return TextButtonWithValue(
      value: this,
      onPressed: onPressed,
      child: Text(title),
    );
  }
}

typedef OnTextButtonWithValuePressed<T> = void Function(T value);

class TextButtonWithValue<T> extends StatelessWidget {
  final T value;
  final OnTextButtonWithValuePressed onPressed;
  final Widget child;
  const TextButtonWithValue({
    Key? key,
    required this.value,
    required this.onPressed,
    required this.child,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        onPressed(value);
      },
      child: child,
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  OverlayColor? _overlayColor;

  ColorFilter? getcolorFilter() {
    final overlayColor = _overlayColor;
    if (overlayColor == null) {
      return null;
    }
    return ColorFilter.mode(
      overlayColor.color,
      BlendMode.colorBurn,
    );
  }

  Iterable<Widget> overlayColorButtons() {
    return OverlayColor.values.map((overlayColor) {
      return Expanded(
        flex: 1,
        child: Container(
          child: overlayColor.toTextButtonWithValue(
            (value) {
              setState(() {
                _overlayColor = value;
              });
            },
          ),
        ),
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Tinting Images in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: [
            Container(
              height: 250.0,
              clipBehavior: Clip.antiAlias,
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(20),
                image: DecorationImage(
                  colorFilter: getcolorFilter(),
                  fit: BoxFit.fitHeight,
                  image: NetworkImage('https://bit.ly/3jOueGG'),
                ),
              ),
            ),
            SizedBox(height: 16.0),
            Row(
              children: overlayColorButtons().toList(),
            )
          ],
        ),
      ),
    );
  }
}

SlideTransition in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/gestures.dart';

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final _controller = AnimationController(
    duration: Duration(milliseconds: 500),
    vsync: this,
  );

  late final _animation = Tween<Offset>(
    begin: Offset(0.0, 0.0),
    end: Offset(-0.83, 0.0),
  ).animate(
    CurvedAnimation(
      parent: _controller,
      curve: Curves.easeInQuint,
    ),
  );

  var _isExpanded = false;

  @override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.forward();
    return Scaffold(
      body: SizedBox.expand(
        child: Stack(
          fit: StackFit.passthrough,
          children: [
            Image.network(
              'https://bit.ly/3BWYDbz',
              fit: BoxFit.fitHeight,
            ),
            Positioned(
              top: 200.0,
              child: SlideTransition(
                position: _animation,
                child: GestureDetector(
                  onTap: () {
                    _isExpanded = !_isExpanded;
                    if (_isExpanded) {
                      _controller.reverse();
                    } else {
                      _controller.forward();
                    }
                  },
                  child: Box(),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class Box extends StatelessWidget {
  const Box({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        color: Colors.blue[200]?.withAlpha(200),
        border: Border.all(
          color: Colors.blue,
          style: BorderStyle.solid,
          width: 1.0,
        ),
        borderRadius: BorderRadius.only(
          topRight: Radius.circular(10),
          bottomRight: Radius.circular(10),
        ),
      ),
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Row(
          children: [
            Text(
              'By: Jesper Anhede',
              style: TextStyle(
                fontSize: 18.0,
              ),
            ),
            SizedBox(width: 10.0),
            Icon(
              Icons.info,
              color: Colors.pink[400],
            ),
          ],
        ),
      ),
    );
  }
}

Expansion Panels and Lists in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class Event {
  final String title;
  final String details;
  final String imageUrl;
  bool isExpanded = false;

  Event({
    required this.title,
    required this.details,
    required this.imageUrl,
  });

  @override
  bool operator ==(covariant Event other) => title == other.title;
}

const diwaliDetails =
    '''Diwali, or Dipawali, is India's biggest and most important holiday of the year. The festival gets its name from the row (avali) of clay lamps (deepa) that Indians light outside their homes to symbolize the inner light that protects from spiritual darkness. This festival is as important to Hindus as the Christmas holiday is to Christians.''';

const halloweenDetails =
    '''Halloween or Hallowe'en, less commonly known as Allhalloween, All Hallows' Eve, or All Saints' Eve, is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Hallows' Day.''';

final events = [
  Event(
    title: 'Diwali',
    details: diwaliDetails,
    imageUrl: 'https://bit.ly/3mGg8YW',
  ),
  Event(
    title: 'Halloween',
    details: halloweenDetails,
    imageUrl: 'https://bit.ly/3wb1w7j',
  ),
];

extension ToPanel on Event {
  ExpansionPanel toPanel() {
    return ExpansionPanel(
      headerBuilder: (context, isExpanded) {
        return Padding(
          padding: const EdgeInsets.all(8.0),
          child: Text(
            title,
            style: TextStyle(fontSize: 30.0),
          ),
        );
      },
      isExpanded: isExpanded,
      body: Container(
        height: 250,
        width: double.infinity,
        decoration: BoxDecoration(
          image: DecorationImage(
            fit: BoxFit.fitWidth,
            colorFilter: ColorFilter.mode(
              Colors.black.withOpacity(0.5),
              BlendMode.luminosity,
            ),
            image: NetworkImage(imageUrl),
          ),
        ),
        child: SingleChildScrollView(
          child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: Text(
              details,
              textAlign: TextAlign.center,
              style: TextStyle(fontSize: 20, color: Colors.white, shadows: [
                Shadow(
                  blurRadius: 1.0,
                  offset: Offset.zero,
                  color: Colors.black,
                )
              ]),
            ),
          ),
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Expansion Panels in Flutter'),
      ),
      body: SingleChildScrollView(
        child: ExpansionPanelList(
          children: events.map((e) => e.toPanel()).toList(),
          expansionCallback: (panelIndex, isExpanded) {
            setState(() {
              events[panelIndex].isExpanded = !isExpanded;
            });
          },
        ),
      ),
    );
  }
}

Complete CRUD App in Flutter

//Want to support my work 🤝? https://buymeacoffee.com/vandad

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart'
    show getApplicationDocumentsDirectory;

class Person implements Comparable {
  final int id;
  final String firstName;
  final String lastName;
  const Person(this.id, this.firstName, this.lastName);

  String get fullName => '$firstName $lastName';

  Person.fromData(Map<String, Object?> data)
      : id = data['ID'] as int,
        firstName = data['FIRST_NAME'] as String,
        lastName = data['LAST_NAME'] as String;

  @override
  int compareTo(covariant Person other) => other.id.compareTo(id);

  @override
  bool operator ==(covariant Person other) => id == other.id;

  @override
  String toString() =>
      'Person, ID = $id, firstName = $firstName, lastName = $lastName';
}

class PersonDB {
  final _controller = StreamController<List<Person>>.broadcast();
  List<Person> _persons = [];
  Database? _db;
  final String dbName;
  PersonDB({required this.dbName});

  Future<bool> close() async {
    final db = _db;
    if (db == null) {
      return false;
    }
    await db.close();
    return true;
  }

  Future<bool> open() async {
    if (_db != null) {
      return true;
    }
    final directory = await getApplicationDocumentsDirectory();
    final path = '${directory.path}/$dbName';
    try {
      final db = await openDatabase(path);
      _db = db;

      // create the table if it doesn't exist

      final create = '''CREATE TABLE IF NOT EXISTS PEOPLE (
          ID INTEGER PRIMARY KEY AUTOINCREMENT,
          FIRST_NAME STRING NOT NULL,
          LAST_NAME STRING NOT NULL
        )''';

      await db.execute(create);

      // if everything went fine, we then read all the objects
      // and populate the stream

      _persons = await _fetchPeople();
      _controller.add(_persons);
      return true;
    } catch (e) {
      print('error = $e');
      return false;
    }
  }

  Future<List<Person>> _fetchPeople() async {
    final db = _db;
    if (db == null) {
      return [];
    }

    try {
      // read the existing data if any
      final readResult = await db.query(
        'PEOPLE',
        distinct: true,
        columns: ['ID', 'FIRST_NAME', 'LAST_NAME'],
        orderBy: 'ID',
      );

      final people = readResult.map((row) => Person.fromData(row)).toList();
      return people;
    } catch (e) {
      print('error = $e');
      return [];
    }
  }

  Future<bool> delete(Person person) async {
    final db = _db;
    if (db == null) {
      return false;
    }
    try {
      final deletedCount = await db.delete(
        'PEOPLE',
        where: 'ID = ?',
        whereArgs: [person.id],
      );

      // delete it locally as well

      if (deletedCount == 1) {
        _persons.remove(person);
        _controller.add(_persons);
        return true;
      } else {
        return false;
      }
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  Future<bool> create(String firstName, String lastName) async {
    final db = _db;
    if (db == null) {
      return false;
    }
    try {
      final id = await db.insert(
        'PEOPLE',
        {
          'FIRST_NAME': firstName,
          'LAST_NAME': lastName,
        },
      );

      final person = Person(id, firstName, lastName);
      _persons.add(person);
      _controller.add(_persons);

      return true;
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  // uses the person's id to update its first name and last name
  Future<bool> update(Person person) async {
    final db = _db;
    if (db == null) {
      return false;
    }
    try {
      final updatedCount = await db.update(
        'PEOPLE',
        {
          'FIRST_NAME': person.firstName,
          'LAST_NAME': person.lastName,
        },
        where: 'ID = ?',
        whereArgs: [person.id],
      );

      if (updatedCount == 1) {
        _persons.removeWhere((p) => p.id == person.id);
        _persons.add(person);
        _controller.add(_persons);
        return true;
      } else {
        return false;
      }
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  Stream<List<Person>> all() =>
      _controller.stream.map((event) => event..sort());
}

typedef OnCompose = void Function(String firstName, String lastName);

class ComposeWidget extends StatefulWidget {
  final OnCompose onCompose;

  const ComposeWidget({Key? key, required this.onCompose}) : super(key: key);

  @override
  State<ComposeWidget> createState() => _ComposeWidgetState();
}

class _ComposeWidgetState extends State<ComposeWidget> {
  final firstNameController = TextEditingController();
  final lastNameController = TextEditingController();

  @override
  void dispose() {
    firstNameController.dispose();
    lastNameController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Column(children: [
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter first name',
          ),
          controller: firstNameController,
        ),
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter last name',
          ),
          controller: lastNameController,
        ),
        TextButton(
          onPressed: () {
            final firstName = firstNameController.text;
            final lastName = lastNameController.text;
            widget.onCompose(firstName, lastName);
          },
          child: Text(
            'Add to list',
            style: TextStyle(fontSize: 24),
          ),
        ),
      ]),
    );
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  late final PersonDB _crudStorage;

  @override
  void initState() {
    _crudStorage = PersonDB(dbName: 'db.sqlite');
    _crudStorage.open();
    super.initState();
  }

  @override
  void dispose() {
    _crudStorage.close();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SQLite in Flutter'),
      ),
      body: StreamBuilder(
        stream: _crudStorage.all(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.active:
            case ConnectionState.waiting:
              if (snapshot.data == null) {
                return Center(child: CircularProgressIndicator());
              }
              final people = snapshot.data as List<Person>;
              return Column(
                children: [
                  ComposeWidget(
                    onCompose: (firstName, lastName) async {
                      await _crudStorage.create(firstName, lastName);
                    },
                  ),
                  Expanded(
                    child: ListView.builder(
                      itemCount: people.length,
                      itemBuilder: (context, index) {
                        final person = people[index];
                        return ListTile(
                          onTap: () async {
                            final update =
                                await showUpdateDialog(context, person);
                            if (update == null) {
                              return;
                            }
                            await _crudStorage.update(update);
                          },
                          title: Text(
                            person.fullName,
                            style: TextStyle(fontSize: 24),
                          ),
                          subtitle: Text(
                            'ID: ${person.id}',
                            style: TextStyle(fontSize: 18),
                          ),
                          trailing: TextButton(
                            onPressed: () async {
                              final shouldDelete =
                                  await showDeleteDialog(context);
                              if (shouldDelete) {
                                await _crudStorage.delete(person);
                              }
                            },
                            child: Icon(
                              Icons.disabled_by_default_rounded,
                              color: Colors.red,
                            ),
                          ),
                        );
                      },
                    ),
                  ),
                ],
              );
            default:
              return Center(child: CircularProgressIndicator());
          }
        },
      ),
    );
  }
}

final firstNameController = TextEditingController();
final lastNameController = TextEditingController();

Future<Person?> showUpdateDialog(BuildContext context, Person person) {
  firstNameController.text = person.firstName;
  lastNameController.text = person.lastName;
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text('Enter your udpated values here:'),
            TextField(controller: firstNameController),
            TextField(controller: lastNameController),
          ],
        ),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop(null);
            },
            child: Text('Cancel'),
          ),
          TextButton(
            onPressed: () {
              final newPerson = Person(
                person.id,
                firstNameController.text,
                lastNameController.text,
              );
              Navigator.of(context).pop(newPerson);
            },
            child: Text('Save'),
          ),
        ],
      );
    },
  ).then((value) {
    if (value is Person) {
      return value;
    } else {
      return null;
    }
  });
}

Future<bool> showDeleteDialog(BuildContext context) {
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: Text('Are you sure you want to delete this item?'),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop(false);
            },
            child: Text('No'),
          ),
          TextButton(
            onPressed: () {
              Navigator.of(context).pop(true);
            },
            child: Text('Delete'),
          )
        ],
      );
    },
  ).then(
    (value) {
      if (value is bool) {
        return value;
      } else {
        return false;
      }
    },
  );
}

SQLite Storage in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart'
    show getApplicationDocumentsDirectory;

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class Person implements Comparable {
  final int id;
  final String firstName;
  final String lastName;
  const Person(this.id, this.firstName, this.lastName);

  String get fullName => '$firstName $lastName';

  Person.fromData(Map<String, Object?> data)
      : id = data['ID'] as int,
        firstName = data['FIRST_NAME'] as String,
        lastName = data['LAST_NAME'] as String;

  @override
  int compareTo(covariant Person other) => other.id.compareTo(id);
}

typedef OnCompose = void Function(String firstName, String lastName);

class ComposeWidget extends StatefulWidget {
  final OnCompose onCompose;

  const ComposeWidget({Key? key, required this.onCompose}) : super(key: key);

  @override
  State<ComposeWidget> createState() => _ComposeWidgetState();
}

class _ComposeWidgetState extends State<ComposeWidget> {
  final firstNameController = TextEditingController();
  final lastNameController = TextEditingController();

  @override
  void dispose() {
    firstNameController.dispose();
    lastNameController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Column(children: [
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter first name',
          ),
          controller: firstNameController,
        ),
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter last name',
          ),
          controller: lastNameController,
        ),
        TextButton(
          onPressed: () {
            final firstName = firstNameController.text;
            final lastName = lastNameController.text;
            widget.onCompose(firstName, lastName);
          },
          child: Text(
            'Add to list',
            style: TextStyle(fontSize: 24),
          ),
        ),
      ]),
    );
  }
}

class _HomePageState extends State<HomePage> {
  late final Database db;
  bool hasSetUpAlready = false;

  Future<bool> setupDatabase() async {
    if (hasSetUpAlready == false) {
      final directory = await getApplicationDocumentsDirectory();
      final path = '${directory.path}/db.sqlite';
      try {
        db = await openDatabase(path);

        // create the table if it doesn't exist

        final create = '''CREATE TABLE IF NOT EXISTS PEOPLE (
          ID INTEGER PRIMARY KEY AUTOINCREMENT,
          FIRST_NAME STRING NOT NULL,
          LAST_NAME STRING NOT NULL
        )''';

        await db.execute(create);
        hasSetUpAlready = true;
        return true;
      } catch (e) {
        print('error = $e');
        hasSetUpAlready = false;
        return false;
      }
    } else {
      return true;
    }
  }

  Future<List<Person>> fetchPersons() async {
    if (!await setupDatabase()) {
      return [];
    }

    try {
      // read the existing data if any
      final readResult = await db.query(
        'PEOPLE',
        distinct: true,
        columns: ['ID', 'FIRST_NAME', 'LAST_NAME'],
        orderBy: 'ID',
      );

      final people = readResult.map((row) => Person.fromData(row)).toList()
        ..sort();
      return people;
    } catch (e) {
      print('error = $e');
      return [];
    }
  }

  Future<bool> addPerson(String firstName, String lastName) async {
    try {
      await db.insert(
        'PEOPLE',
        {
          'FIRST_NAME': firstName,
          'LAST_NAME': lastName,
        },
      );
      return true;
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SQLite in Flutter'),
      ),
      body: FutureBuilder(
        future: fetchPersons(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.done:
              final people = snapshot.data as List<Person>;
              return Column(
                children: [
                  ComposeWidget(
                    onCompose: (firstName, lastName) async {
                      await addPerson(firstName, lastName);
                      setState(() {});
                    },
                  ),
                  Expanded(
                    child: ListView.builder(
                      itemCount: people.length,
                      itemBuilder: (context, index) {
                        final person = people[index];
                        return ListTile(
                          title: Text(
                            person.fullName,
                            style: TextStyle(fontSize: 24),
                          ),
                          subtitle: Text(
                            'ID: ${person.id}',
                            style: TextStyle(fontSize: 18),
                          ),
                        );
                      },
                    ),
                  ),
                ],
              );
            default:
              return CircularProgressIndicator();
          }
        },
      ),
    );
  }
}

Circular Progress with Percentage in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class SizedCircularProgressIndicator extends StatelessWidget {
  final double progress;
  final double width;
  final double height;
  final TextStyle? textStyle;
  const SizedCircularProgressIndicator({
    Key? key,
    this.textStyle,
    required this.progress,
    required this.width,
    required this.height,
  }) : super(key: key);

  TextStyle get style => textStyle ?? TextStyle(fontSize: 30.0);
  int get _progress => (progress * 100.0).toInt();

  @override
  Widget build(BuildContext context) {
    return Stack(
      alignment: Alignment.center,
      children: [
        Text('$_progress%', style: style),
        SizedBox(
          width: width,
          height: height,
          child: CircularProgressIndicator(
            backgroundColor: Colors.white70,
            value: progress,
            color: Colors.blueAccent,
            strokeWidth: 3.0,
          ),
        ),
      ],
    );
  }
}

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView.builder(
        scrollDirection: Axis.horizontal,
        itemCount: images.length,
        itemBuilder: (context, index) {
          return WithBlurredBackground(imageUrl: images[index]);
        },
      ),
    );
  }
}

class WithBlurredBackground extends StatelessWidget {
  final String imageUrl;

  const WithBlurredBackground({Key? key, required this.imageUrl})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox.expand(
      child: Stack(
        alignment: Alignment.center,
        fit: StackFit.passthrough,
        children: [
          SizedBox.expand(
            child: ClipRect(
              child: ImageFiltered(
                imageFilter: ImageFilter.blur(
                  sigmaX: 10.0,
                  sigmaY: 10.0,
                ),
                child: Image.network(
                  imageUrl,
                  fit: BoxFit.fitHeight,
                ),
              ),
            ),
          ),
          NetworkImageWithProgress(url: imageUrl),
        ],
      ),
    );
  }
}

class NetworkImageWithProgress extends StatelessWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Image.network(
      url,
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return SizedCircularProgressIndicator(
            height: 100,
            width: 100,
            progress: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

Opening URLs in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

class Person {
  final String profileUrl;
  final String name;
  final String email;
  final String phoneNumber;
  final String websiteUrl;

  const Person({
    Key? key,
    required this.profileUrl,
    required this.name,
    required this.email,
    required this.phoneNumber,
    required this.websiteUrl,
  });

  Person.vandad()
      : profileUrl = 'https://bit.ly/3jwusS0',
        name = 'Vandad Nahavandipoor',
        email = 'vandad.np@gmail.com',
        phoneNumber = '071234567',
        websiteUrl = 'https://pixolity.se';
}

void open(String url) async {
  if (await canLaunch(url)) {
    await launch(url);
  }
}

class PersonNameView extends StatelessWidget {
  final Person person;
  const PersonNameView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      person.name,
      style: TextStyle(
        fontSize: 20,
        fontWeight: FontWeight.bold,
        color: Colors.black,
      ),
    );
  }
}

class PersonEmailView extends StatelessWidget {
  final Person person;
  const PersonEmailView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        open('mailto:${person.email}');
      },
      child: Text(
        '💌 Email me',
        style: TextStyle(fontSize: 20.0),
      ),
    );
  }
}

class PersonPhoneView extends StatelessWidget {
  final Person person;
  const PersonPhoneView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        open('tel://${person.phoneNumber}');
      },
      child: Text(
        '🤙🏻 Call me',
        style: TextStyle(fontSize: 20.0),
      ),
    );
  }
}

class PersonWebsiteView extends StatelessWidget {
  final Person person;
  const PersonWebsiteView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        open(person.websiteUrl);
      },
      child: Text(
        '🌍 Visit my website',
        style: TextStyle(fontSize: 20.0),
      ),
    );
  }
}

const bigText = TextStyle(fontSize: 20.0);

class PersonView extends StatelessWidget {
  final Person person;
  const PersonView({Key? key, required this.person}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
          color: Colors.blue[50],
          borderRadius: BorderRadius.circular(16.0),
          border: Border.all(color: Colors.white, width: 3.0),
          boxShadow: [
            BoxShadow(
              blurRadius: 30.0,
              color: Colors.black.withAlpha(50),
              spreadRadius: 20.0,
            ),
          ]),
      child: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            CircleAvatar(
              radius: 100.0,
              backgroundImage: NetworkImage(person.profileUrl),
            ),
            SizedBox(height: 10),
            PersonNameView(person),
            PersonEmailView(person),
            PersonPhoneView(person),
            PersonWebsiteView(person)
          ],
        ),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SingleChildScrollView(
          child: PersonView(
            person: Person.vandad(),
          ),
        ),
      ),
    );
  }
}

Commodore 64 Screen in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const textColor = Color.fromRGBO(156, 156, 247, 1);

class BoxPainter extends CustomPainter {
  final bool isBlinking;
  BoxPainter({required this.isBlinking});

  @override
  void paint(Canvas canvas, Size size) {
    if (isBlinking) {
      final rect = Rect.fromLTWH(
        size.width / 20.0,
        size.height / 2.8,
        size.width / 24.0,
        size.height / 13.0,
      );
      final paint = Paint()..color = textColor;
      canvas.drawRect(rect, paint);
    }
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => true;
}

class ReadyPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final textStyle = TextStyle(
      color: textColor,
      fontSize: size.width / 45.0,
      fontFamily: 'C64',
    );
    final span = TextSpan(
      text: 'READY',
      style: textStyle,
    );
    final painter = TextPainter(
      text: span,
      textDirection: TextDirection.ltr,
    );

    painter.layout(
      minWidth: 0,
      maxWidth: size.width,
    );
    final offset = Offset(
      painter.width / 2.0,
      painter.height * 8.0,
    );
    painter.paint(canvas, offset);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class SubTitlePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final textStyle = TextStyle(
      color: textColor,
      fontSize: size.width / 45.0,
      fontFamily: 'C64',
    );
    final span = TextSpan(
      text: '64K RAM SYSTEM 38911 BASIC BYTES FREE',
      style: textStyle,
    );
    final painter = TextPainter(
      text: span,
      textDirection: TextDirection.ltr,
    );

    painter.layout(
      minWidth: 0,
      maxWidth: size.width,
    );
    final offset = Offset(
      size.width - painter.width - (size.width / 11),
      painter.height * 6.0,
    );
    painter.paint(canvas, offset);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class TitlePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final textStyle = TextStyle(
      color: textColor,
      fontSize: size.width / 40.0,
      fontFamily: 'C64',
    );
    final span = TextSpan(
      text: '**** COMMODORE 64 BASIC V2 ****',
      style: textStyle,
    );
    final painter = TextPainter(
      text: span,
      textDirection: TextDirection.ltr,
    );

    painter.layout(
      minWidth: 0,
      maxWidth: size.width,
    );
    final offset = Offset(
      size.width - painter.width - (size.width / 9),
      size.height / 6,
    );
    painter.paint(canvas, offset);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class BackgroundPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final border = size.width / 20.0;

    final color = Color.fromRGBO(
      58,
      57,
      213,
      1,
    );

    final paint = Paint()..color = color;

    final rect = Rect.fromLTWH(
      border,
      border,
      size.width - (border * 2.0),
      size.height - (border * 2.0),
    );

    canvas.drawRect(rect, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class BorderPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()..color = textColor;
    final rect = Rect.fromLTWH(
      0.0,
      0.0,
      size.width,
      size.height,
    );

    canvas.drawRect(rect, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class Commodore64Painter extends CustomPainter {
  final bool isBlinking;

  late final List<CustomPainter> painters;

  Commodore64Painter({required this.isBlinking}) {
    painters = [
      BorderPainter(),
      BackgroundPainter(),
      TitlePainter(),
      SubTitlePainter(),
      ReadyPainter(),
      BoxPainter(isBlinking: isBlinking)
    ];
  }

  @override
  void paint(Canvas canvas, Size size) {
    painters.forEach(
      (p) => p.paint(
        canvas,
        size,
      ),
    );
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => painters
      .map((p) => p.shouldRepaint(oldDelegate))
      .reduce((p1, p2) => p1 || p2);
}

class Commodore64 extends StatefulWidget {
  const Commodore64({Key? key}) : super(key: key);

  @override
  State<Commodore64> createState() => _Commodore64State();
}

class _Commodore64State extends State<Commodore64> {
  bool _isBlinking = false;

  final timer = Stream.periodic(Duration(seconds: 1), (value) => value);

  void _triggerRedraw() async {
    await for (final _ in timer) {
      setState(() {
        _isBlinking = !_isBlinking;
      });
    }
  }

  @override
  void initState() {
    super.initState();
    _triggerRedraw();
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(builder: (context, constraints) {
      return Container(
        width: constraints.maxWidth,
        height: constraints.maxWidth / (16.0 / 9.0),
        child: CustomPaint(
          painter: Commodore64Painter(isBlinking: _isBlinking),
        ),
      );
    });
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Commodore64(),
      ),
    );
  }
}

Animated Lists in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class NetworkImage extends StatelessWidget {
  final String url;
  const NetworkImage({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Image.network(
      url,
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return LinearProgressIndicator(
            value: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

class NetworkImageCard extends StatelessWidget {
  final String url;
  const NetworkImageCard({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        clipBehavior: Clip.antiAlias,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(20.0),
        ),
        child: NetworkImage(
          url: url,
        ),
      ),
    );
  }
}

const imageUrls = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

Stream<String> images() => Stream.periodic(
      Duration(seconds: 3),
      (index) => index % imageUrls.length,
    ).map((index) => imageUrls[index]);

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final GlobalKey<AnimatedListState> _key = GlobalKey();

  List<String> imageUrls = [];

  void populateList() async {
    await for (final url in images()) {
      imageUrls.insert(0, url);
      _key.currentState?.insertItem(
        0,
        duration: Duration(milliseconds: 400),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    populateList();
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Lists in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: AnimatedList(
          key: _key,
          initialItemCount: imageUrls.length,
          itemBuilder: (context, index, animation) {
            final imageUrl = imageUrls[index];
            return SizeTransition(
              sizeFactor: animation.drive(
                CurveTween(curve: Curves.elasticInOut),
              ),
              child: Column(
                children: [
                  NetworkImageCard(url: imageUrl),
                  SizedBox(height: 10.0),
                ],
              ),
            );
          },
        ),
      ),
    );
  }
}

CheckboxListTile in Flutter

import 'package:flutter/material.dart';



enum Item { umbrella, coat, boots }

extension Info on Item {
  String get title {
    switch (this) {
      case Item.umbrella:
        return 'Umbrella';
      case Item.boots:
        return 'Boots';
      case Item.coat:
        return 'Jacket';
    }
  }

  String get icon {
    switch (this) {
      case Item.umbrella:
        return '☂️';
      case Item.boots:
        return '🥾';
      case Item.coat:
        return '🧥';
    }
  }
}

typedef OnChecked = void Function(bool);

class Tile extends StatelessWidget {
  final Item item;
  final bool isChecked;
  final OnChecked onChecked;
  const Tile({
    Key? key,
    required this.item,
    required this.isChecked,
    required this.onChecked,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
      constraints: BoxConstraints(minHeight: 100.0),
      child: Center(
        child: CheckboxListTile(
          shape: ContinuousRectangleBorder(),
          value: isChecked,
          secondary: Text(
            item.icon,
            style: TextStyle(fontSize: 30.0),
          ),
          title: Text(
            item.title,
            style: TextStyle(fontSize: 40.0),
          ),
          onChanged: (value) {
            onChecked(value ?? false);
          },
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final Set<Item> _enabledItems = {};

  Widget get listView {
    return ListView.builder(
      shrinkWrap: true,
      itemBuilder: (context, index) {
        final item = Item.values[index];
        final isChecked = _enabledItems.contains(item);
        return Tile(
          isChecked: isChecked,
          item: item,
          onChecked: (isChecked) {
            setState(() {
              if (isChecked) {
                _enabledItems.add(item);
              } else {
                _enabledItems.remove(item);
              }
            });
          },
        );
      },
      itemCount: Item.values.length,
    );
  }

  Widget get title {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Text(
        "Remember to pick all items! It's going to be rainy today!",
        textAlign: TextAlign.center,
        style: TextStyle(fontSize: 40),
      ),
    );
  }

  Widget get readyButton {
    final onPressed = () async {
      // program this
      await showDialog(
        context: context,
        builder: (context) {
          return AlertDialog(
            content: Text('You seem to be ready for a rainy day! ✅'),
            actions: [
              TextButton(
                onPressed: () {
                  Navigator.of(context).pop();
                },
                child: Text('OK'),
              )
            ],
          );
        },
      );
    };

    final isEnabled = _enabledItems.containsAll(Item.values);

    return FractionallySizedBox(
      widthFactor: 0.8,
      child: ElevatedButton(
        onPressed: isEnabled ? onPressed : null,
        child: Text('Ready!'),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Checkbox List Tile in Flutter'),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: [
            title,
            listView,
            SizedBox(height: 50.0),
            readyButton,
          ],
        ),
      ),
    );
  }
}

- Operator on String in Dart



extension Minus on String {
  String operator -(String rhs) => replaceAll(rhs, '');
}

void testIt() {
  assert('foo bar' - 'foo ' == 'bar');
  assert('foo bar foo' - 'foo' == ' bar ');
  assert('bar' - 'foo' == 'bar');
  assert('BAR' - 'bar' == 'BAR');
  assert('foo' - 'FOO' == 'foo');
  assert('foobarbaz' - 'bar' == 'foobaz');
}

Dart Progress for Future<T>



import 'dart:io' show stdout;
import 'dart:async' show Future, Stream;

const loadingSequence = ['⢿', '⣻', '⣽', '⣾', '⣷', '⣯', '⣟', '⡿'];
const escape = '\x1B[38;5;';
const color = '${escape}1m';
const textColor = '${escape}6m';

String progress({required int value, required String text}) {
  final progress = '$color${loadingSequence[value % loadingSequence.length]}';
  final coloredText = '$textColor$text';
  return '$progress\t$coloredText';
}

Future<T> performWithProgress<T>({
  required Future<T> task,
  required String progressText,
}) {
  final stream = Stream<String>.periodic(
    Duration(milliseconds: 100),
    (value) => progress(
      value: value,
      text: progressText,
    ),
  );

  final subscription = stream.listen(
    (event) {
      stdout.write('\r $event');
    },
  );

  task.whenComplete(() {
    stdout.write('\r ✅\t$progressText');
    stdout.write('\n');
    subscription.cancel();
  });

  return task;
}

final task1 = Future.delayed(Duration(seconds: 1), () => 'Result 1');
final task2 = Future.delayed(Duration(seconds: 2), () => 'Result 2');
final task3 = Future.delayed(Duration(seconds: 3), () => 'Result 3');

void main(List<String> args) async {
  var result = await performWithProgress(
    task: task1,
    progressText: 'Loading task 1',
  );
  print('\tTask 1 result: $result');
  result = await performWithProgress(
    task: task2,
    progressText: 'Loading task 2',
  );
  print('\tTask 2 result: $result');
  result = await performWithProgress(
    task: task3,
    progressText: 'Loading task 3',
  );
  print('\tTask 3 result: $result');
}

Move Widget Shadows with Animation



import 'package:flutter/material.dart';

class ImageTransition extends AnimatedWidget {
  final String imageUrl;

  Animation<double> get shadowXOffset => listenable as Animation<double>;

  const ImageTransition(this.imageUrl, {shadowXOffset})
      : super(listenable: shadowXOffset);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20.0),
        boxShadow: [
          BoxShadow(
            blurRadius: 10,
            offset: Offset(shadowXOffset.value, 20.0),
            color: Colors.black.withAlpha(100),
            spreadRadius: -10,
          )
        ],
      ),
      child: Image.network(imageUrl),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class CustomCurve extends CurveTween {
  CustomCurve() : super(curve: Curves.easeInOutSine);
  @override
  double transform(double t) {
    return (super.transform(t) - 0.5) * 25.0;
  }
}

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );
    _animation = CustomCurve().animate(_controller);
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.repeat(reverse: true);
    return Scaffold(
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Center(
          child: ImageTransition(
            'https://bit.ly/3x7J5Qt',
            shadowXOffset: _animation,
          ),
        ),
      ),
    );
  }
}

Gallery with Blurred Backgrounds in Flutter


import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView.builder(
        scrollDirection: Axis.horizontal,
        itemCount: images.length,
        itemBuilder: (context, index) {
          return WithBlurredBackground(imageUrl: images[index]);
        },
      ),
    );
  }
}

class WithBlurredBackground extends StatelessWidget {
  final String imageUrl;

  const WithBlurredBackground({Key? key, required this.imageUrl})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox.expand(
      child: Stack(
        alignment: Alignment.center,
        fit: StackFit.passthrough,
        children: [
          SizedBox.expand(
            child: ClipRect(
              child: ImageFiltered(
                imageFilter: ImageFilter.blur(
                  sigmaX: 10.0,
                  sigmaY: 10.0,
                ),
                child: Image.network(
                  imageUrl,
                  fit: BoxFit.fitHeight,
                ),
              ),
            ),
          ),
          Image.network(imageUrl),
        ],
      ),
    );
  }
}

Custom Path Clippers in Flutter



import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Padding(
          padding: const EdgeInsets.only(
            top: 40.0,
            left: 10.0,
            right: 10.0,
          ),
          child: Column(
            children: images
                .map((url) => ElevatedNetworkImage(url: url))
                .expand(
                  (img) => [
                    img,
                    SizedBox(height: 30.0),
                  ],
                )
                .toList(),
          ),
        ),
      ),
    );
  }
}

class ElevatedNetworkImage extends StatelessWidget {
  final String url;
  const ElevatedNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return PhysicalShape(
      color: Colors.white,
      clipper: Clipper(),
      elevation: 20.0,
      clipBehavior: Clip.none,
      shadowColor: Colors.white.withAlpha(200),
      child: CutEdges(
        child: Image.network(url),
      ),
    );
  }
}

class Clipper extends CustomClipper<Path> {
  static const variance = 0.2;
  static const reverse = 1.0 - variance;

  @override
  Path getClip(Size size) {
    final path = Path();

    path.moveTo(0.0, size.height * Clipper.variance);
    path.lineTo(size.width * Clipper.variance, 0.0);
    path.lineTo(size.width, 0.0);
    path.lineTo(size.width, size.height * Clipper.reverse);
    path.lineTo(size.width * Clipper.reverse, size.height);
    path.lineTo(0.0, size.height);
    path.lineTo(0.0, size.height * Clipper.variance);
    path.close;
    return path;
  }

  @override
  bool shouldReclip(covariant CustomClipper<Path> oldClipper) => false;
}

class CutEdges extends StatelessWidget {
  final Widget child;

  const CutEdges({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ClipPath(
      clipper: Clipper(),
      child: child,
    );
  }
}

Frost Effect on Images in Flutter



import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

final loremIpsum =
    'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.';

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(
            8.0,
            0.0,
            8.0,
            0.0,
          ),
          child: SingleChildScrollView(
            child: Column(
              children: images
                  .map(
                    (url) => GlossyNetworkImageWithProgress(
                      url: url,
                      title: 'Image title',
                      description: loremIpsum,
                    ),
                  )
                  .expand(
                    (image) => [
                      image,
                      SizedBox(height: 16.0),
                    ],
                  )
                  .toList(),
            ),
          ),
        ),
      ),
    );
  }
}

class GlossyNetworkImageWithProgress extends StatefulWidget {
  final String url;
  final String title;
  final String description;

  const GlossyNetworkImageWithProgress(
      {Key? key,
      required this.url,
      required this.title,
      required this.description})
      : super(key: key);

  @override
  _GlossyNetworkImageWithProgressState createState() =>
      _GlossyNetworkImageWithProgressState();
}

class _GlossyNetworkImageWithProgressState
    extends State<GlossyNetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final networkImage = Image.network(
      widget.url,
      fit: BoxFit.fitHeight,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );

    return BottomGloss(
      networkImage: networkImage,
      title: widget.title,
      description: widget.description,
    );
  }
}

class BottomGloss extends StatelessWidget {
  final String title;
  final String description;

  const BottomGloss(
      {Key? key,
      required this.networkImage,
      required this.title,
      required this.description})
      : super(key: key);

  final Image networkImage;

  @override
  Widget build(BuildContext context) {
    return ClipRRect(
      borderRadius: BorderRadius.all(Radius.circular(8.0)),
      child: Stack(
        fit: StackFit.passthrough,
        children: [
          networkImage,
          Container(
            height: 300.0,
            alignment: Alignment.bottomCenter,
            child: ClipRect(
              child: FractionallySizedBox(
                heightFactor: 0.5,
                child: BackdropFilter(
                  filter: ImageFilter.blur(
                    sigmaX: 10.0,
                    sigmaY: 10.0,
                  ),
                  child: BottomContents(
                    title: title,
                    description: description,
                  ),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class BottomContents extends StatelessWidget {
  final String title;
  final String description;

  const BottomContents({
    Key? key,
    required this.title,
    required this.description,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.white.withOpacity(0.4),
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: SingleChildScrollView(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              TitleText(text: title),
              SizedBox(height: 8.0),
              SubTitleText(text: description),
            ],
          ),
        ),
      ),
    );
  }
}

class SubTitleText extends StatelessWidget {
  final String text;
  const SubTitleText({Key? key, required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      text,
      style: TextStyle(
        color: Colors.black,
        fontSize: 20.0,
      ),
    );
  }
}

class TitleText extends StatelessWidget {
  final String text;
  const TitleText({Key? key, required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      text,
      style: TextStyle(
        color: Colors.white,
        fontSize: 30.0,
      ),
    );
  }
}

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 300.0,
      width: MediaQuery.of(context).size.width,
      child: child is ProgressIndicator ? Center(child: child) : child,
    );
  }
}

Custom Clippers in Flutter

import 'package:flutter/material.dart';
import 'dart:math' show min;

const gridImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GridView.count(
        padding: const EdgeInsets.fromLTRB(8.0, 48.0, 8.0, 48.0),
        crossAxisCount: 2,
        mainAxisSpacing: 8.0,
        crossAxisSpacing: 8.0,
        children: gridImages
            .map((url) => NetworkImageWithProgress(url: url))
            .toList(),
      ),
    );
  }
}

class CircularClipper extends CustomClipper<Rect> {
  @override
  Rect getClip(Size size) {
    final center = Offset(
      size.width / 2.0,
      size.height / 2.0,
    );
    final minWidthorHeight = min(size.width, size.height);
    return Rect.fromCenter(
      center: center,
      width: minWidthorHeight,
      height: minWidthorHeight,
    );
  }

  @override
  bool shouldReclip(covariant CustomClipper<Rect> oldClipper) => false;
}

class Circular extends StatelessWidget {
  final Widget child;
  const Circular({Key? key, required this.child}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return ClipOval(
      clipper: CircularClipper(),
      child: child,
    );
  }
}

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 220.0,
      width: MediaQuery.of(context).size.width,
      child: child is ProgressIndicator
          ? Center(child: child)
          : Circular(child: child),
    );
  }
}

class NetworkImageWithProgress extends StatefulWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  _NetworkImageWithProgressState createState() =>
      _NetworkImageWithProgressState();
}

class _NetworkImageWithProgressState extends State<NetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      fit: BoxFit.fitHeight,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

Check if Website is Up or Down in Dart



class UpStatus {
  final bool isUp;
  final DateTime timestamp;
  const UpStatus(this.isUp, this.timestamp);
}

class Pling {
  final String url;
  final Duration interval;
  const Pling({
    required this.url,
    required this.interval,
  });
  Stream<UpStatus> checkIfUp() =>
      Stream.periodic(interval, (_) => DateTime.now()).asyncExpand(
        (now) => HttpClient()
            .headUrl(Uri.parse(url))
            .then((req) => req..followRedirects = false)
            .then((req) => req.close())
            .then((resp) => resp.statusCode)
            .then((statusCode) => statusCode == 200)
            .onError((error, stackTrace) => false)
            .then((isUp) => UpStatus(isUp, now))
            .asStream(),
      );
}

const oneSecond = Duration(seconds: 1);
const url = 'https://dart.dev';

extension IsOrIsNot on bool {
  String get isOrIsNot => this ? 'is' : 'is not';
}

void testIt() async {
  final pling = Pling(
    url: url,
    interval: oneSecond,
  );
  await for (final upStatus in pling.checkIfUp()) {
    final timestamp = upStatus.timestamp;
    final isUpStr = upStatus.isUp.isOrIsNot;
    print('$url $isUpStr up at $timestamp');
  }
}

Section Titles on ListView in Flutter

import 'package:flutter/material.dart';

final List<Section> allSections = [
  Section(
    'Spring',
    [
      'https://cnn.it/3xu58Ap',
      'https://bit.ly/3ueqqC1',
    ],
  ),
  Section(
    'Summer',
    [
      'https://bit.ly/3ojNhLc',
      'https://bit.ly/2VcCSow',
    ],
  ),
  Section(
    'Autumn',
    [
      'https://bit.ly/3ib1TJk',
      'https://bit.ly/2XSpjvq',
    ],
  ),
  Section(
    'Winter',
    [
      'https://bit.ly/3iaQNE7',
      'https://bit.ly/3AY8YE4',
    ],
  ),
];

class Section {
  final String title;
  final List<String> urls;
  const Section(this.title, this.urls);
}

extension ToWidgets on Section {
  Iterable<Widget> toNetworkImageCards() {
    return [
      Padding(
        padding: const EdgeInsets.all(8.0),
        child: Text(
          title,
          style: TextStyle(
            fontSize: 40,
          ),
        ),
      ),
      ...urls.expand(
        (url) => [
          NetworkImageCard(url: url),
          SizedBox(height: 10),
        ],
      ),
    ];
  }
}

class NetworkImageCard extends StatelessWidget {
  final String url;
  const NetworkImageCard({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        child: NetworkImageWithProgress(
          url: url,
        ),
      ),
    );
  }
}

class NetworkImageWithProgress extends StatefulWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  _NetworkImageWithProgressState createState() =>
      _NetworkImageWithProgressState();
}

class _NetworkImageWithProgressState extends State<NetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      fit: BoxFit.fitWidth,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 220.0,
      width: MediaQuery.of(context).size.width,
      child: child is ProgressIndicator ? Center(child: child) : child,
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListView.builder(
        itemBuilder: (context, index) {
          final section = allSections[index];
          return Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: section.toNetworkImageCards().toList(),
          );
        },
        itemCount: allSections.length,
      ),
    );
  }
}

Circular Progress in Flutter



import 'package:flutter/material.dart';

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 220.0,
      width: MediaQuery.of(context).size.width,
      child: Center(child: child),
    );
  }
}

class NetworkImageWithProgress extends StatefulWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  _NetworkImageWithProgressState createState() =>
      _NetworkImageWithProgressState();
}

class _NetworkImageWithProgressState extends State<NetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      fit: BoxFit.fitWidth,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

final images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3ywzOla',
].map((url) => NetworkImageWithProgress(url: url)).expand(
      (element) => [
        element,
        SizedBox(
          height: 10.0,
        )
      ],
    );

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Column(
          children: images.toList(),
        ),
      ),
    );
  }
}

Displaying Scroll Wheels in Flutter



import 'package:flutter/material.dart';

class FadingNetworkImage extends StatefulWidget {
  final String url;

  const FadingNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  _FadingNetworkImageState createState() => _FadingNetworkImageState();
}

class _FadingNetworkImageState extends State<FadingNetworkImage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller =
        AnimationController(vsync: this, duration: Duration(seconds: 1));

    _animation = Tween(begin: 0.0, end: 1.0).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: child,
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return LinearProgressIndicator(
            value: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

final images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3ywzOla',
].map((i) => NetworkImageCard(url: i));

class NetworkImageCard extends StatelessWidget {
  final String url;
  const NetworkImageCard({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        clipBehavior: Clip.antiAlias,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(20.0),
          boxShadow: [
            BoxShadow(
              blurRadius: 5,
              offset: Offset(0, 0),
              color: Colors.black.withAlpha(40),
              spreadRadius: 5,
            )
          ],
        ),
        child: FadingNetworkImage(
          url: url,
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListWheelScrollView(
        itemExtent: 164.0,
        squeeze: 0.9,
        perspective: 0.003,
        children: images.toList(),
      ),
    );
  }
}

Post Messages to Slack with Dart



import 'dart:convert' show utf8;
import 'dart:convert' show json;

class SlackMessage {
  final String? inChannel;
  final String? userName;
  final String message;
  final String? iconEmoji;

  const SlackMessage({
    required this.inChannel,
    required this.userName,
    required this.message,
    required this.iconEmoji,
  });

  Future<bool> send(String webhookUrl) async {
    final payload = {
      'text': message,
      if (inChannel != null) 'channel': inChannel!,
      if (userName != null) 'username': userName!,
      if (iconEmoji != null) 'icon_emoji': iconEmoji!
    };

    final request = await HttpClient().postUrl(Uri.parse(webhookUrl));
    final payloadData = utf8.encode(json.encode(payload));
    request.add(payloadData);
    final response = await request.close();
    return response.statusCode == 200;
  }
}

const webhookUrl = 'put your webhook url here';

void testIt() async {
  final message = SlackMessage(
    inChannel: 'dart',
    userName: 'Flutter',
    message: 'Hello from Dart in Terminal',
    iconEmoji: 'blue_heart:',
  );
  if (await message.send(webhookUrl)) {
    print('Successfully sent the message');
  } else {
    print('Could not send the message');
  }
}

Unwrap List<T?>? in Dart



extension Unwrap<T> on List<T?>? {
  List<T> unwrap() => (this ?? []).whereType<T>().toList();
}

void testOptionalListOfOptionals() {
  final List<int?>? optionalListOfOptionals = [1, 2, null, 3, null];
  final unwrapped = optionalListOfOptionals.unwrap(); // List<int>
  print(unwrapped); // prints [1, 2, 3]
}

void testListOfOptionals() {
  final listOfOptionals = [20, 30, null, 40]; // List<int?>
  final unwrapped = listOfOptionals.unwrap(); // List<int>
  print(unwrapped); // prints [20, 30, 40]
}

void testNormalList() {
  final list = [50, 60, 70]; // List<int>
  final unwrapped = list.unwrap(); // List<int>
  print(unwrapped); // prints [50, 60, 70]
}

Avoiding UI Jitters When Switching Widgets in Flutter



const imageUrls = [
  'https://cnn.it/3xu58Ap', // spring
  'https://bit.ly/2VcCSow', // summer
  'https://bit.ly/3A3zStC', // autumn
  'https://bit.ly/2TNY7wi' // winter
];

extension ToNetworkImage<T extends String> on List<T> {
  List<Widget> toNetworkImages() => map((s) => Image.network(s)).toList();
}

class HomePage extends StatefulWidget {
  @override
  State createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _currentIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Indexed Stack')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            IndexedStack(
              index: _currentIndex,
              children: imageUrls.toNetworkImages(),
            ),
            TextButton(
              onPressed: () {
                setState(
                  () {
                    _currentIndex++;
                    if (_currentIndex >= imageUrls.length) {
                      _currentIndex = 0;
                    }
                  },
                );
              },
              child: Text('Go to next season'),
            )
          ],
        ),
      ),
    );
  }
}

Detect Redirects in Dart



Future<bool> doesRedirect(String url) => HttpClient()
    .headUrl(Uri.parse(url))
    .then((req) => req..followRedirects = false)
    .then((req) => req.close())
    .then((resp) => resp.statusCode)
    .then((statusCode) => [301, 302, 303, 307, 308].contains(statusCode));

void testIt() async {
  final test1 = await doesRedirect('https://cnn.it/3xu58Ap');
  assert(test1 == true);

  final test2 = await doesRedirect('https://dart.dev');
  assert(test2 == false);

  final test3 = await doesRedirect('https://bit.ly/2VcCSow');
  assert(test3 == true);
}

Proportional Constraints in Flutter



class ProportionalWidthNetworkImage extends StatelessWidget {
  final String url;
  final double widthProportion;

  const ProportionalWidthNetworkImage(
      {Key? key, required this.url, required this.widthProportion})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        return Image.network(
          url,
          loadingBuilder: (context, child, loadingProgress) {
            final widget =
                loadingProgress == null ? child : LinearProgressIndicator();
            return Container(
              width: constraints.maxWidth * widthProportion,
              child: widget,
            );
          },
        );
      },
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ProportionalWidthNetworkImage(
          url: 'https://cnn.it/3xu58Ap',
          widthProportion: 0.8,
        ),
      ),
    );
  }
}

Displaying Cupertino Action Sheets in Flutter



import 'package:flutter/cupertino.dart';

enum Season { spring, summer, autumn, winter }

extension Title on Season {
  String get title => describeEnum(this).capitalized;
}

extension Caps on String {
  String get capitalized => this[0].toUpperCase() + substring(1);
}

extension ToWidget on Season {
  Widget toWidget() {
    switch (this) {
      case Season.spring:
        return Image.network('https://cnn.it/3xu58Ap');
      case Season.summer:
        return Image.network('https://bit.ly/2VcCSow');
      case Season.autumn:
        return Image.network('https://bit.ly/3A3zStC');
      case Season.winter:
        return Image.network('https://bit.ly/2TNY7wi');
    }
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Future<Season> _chooseSeason(
  BuildContext context,
  Season currentSeason,
) async {
  CupertinoActionSheet actionSheet(BuildContext context) {
    return CupertinoActionSheet(
      title: Text('Choose your favorite season:'),
      actions: Season.values
          .map(
            (season) => CupertinoActionSheetAction(
              onPressed: () {
                Navigator.of(context).pop(season);
              },
              child: Text(season.title),
            ),
          )
          .toList(),
      cancelButton: CupertinoActionSheetAction(
        onPressed: () {
          Navigator.of(context).pop(currentSeason);
        },
        child: Text('Cancel'),
      ),
    );
  }

  return await showCupertinoModalPopup(
    context: context,
    builder: (context) => actionSheet(context),
  );
}

class _HomePageState extends State<HomePage> {
  var _season = Season.spring;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_season.title),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          _season.toWidget(),
          TextButton(
            onPressed: () async {
              _season = await _chooseSeason(
                context,
                _season,
              );
              setState(() {});
            },
            child: Text('Choose a season'),
          ),
        ],
      ),
    );
  }
}

Rotating List<T> in Dart



extension Rotate<T> on List<T> {
  int _rotationTimes(int places) {
    if (isEmpty) {
      return 0;
    }
    if (places == 0) {
      throw ArgumentError('places should be more than 0');
    }
    return places % length;
  }

  List<T> rotatedRight(int places) {
    final times = _rotationTimes(places);
    if (times == 0) {
      return this;
    } else {
      final cutOff = length - times;
      return sublist(cutOff)..addAll(sublist(0, cutOff));
    }
  }

  List<T> rotatedLeft(int places) {
    final times = _rotationTimes(places);
    if (times == 0) {
      return this;
    } else {
      return sublist(times)..addAll(sublist(0, times));
    }
  }
}

extension Equality<T extends Comparable> on List<T> {
  bool isEqualTo(List<T> other) {
    if (other.length != length) {
      return false;
    }
    for (var i = 0; i < length; i++) {
      if (other[i] != this[i]) {
        return false;
      }
    }
    return true;
  }
}

const arr = [1, 2, 3];

void testIt() {
  assert(arr.rotatedRight(1).isEqualTo([3, 1, 2]));
  assert(arr.rotatedRight(2).isEqualTo([2, 3, 1]));
  assert(arr.rotatedRight(3).isEqualTo([1, 2, 3]));
  assert(arr.rotatedRight(4).isEqualTo([3, 1, 2]));
  assert(arr.rotatedLeft(1).isEqualTo([2, 3, 1]));
  assert(arr.rotatedLeft(2).isEqualTo([3, 1, 2]));
  assert(arr.rotatedLeft(3).isEqualTo([1, 2, 3]));
  assert(arr.rotatedLeft(4).isEqualTo([2, 3, 1]));
}

Displaying SnackBars in Flutter



class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Hello world'),
      ),
      body: Center(
        child: TextButton(
          onPressed: () {
            final now = DateFormat('kk:mm:ss').format(DateTime.now());
            ScaffoldMessenger.of(context).removeCurrentSnackBar();
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                behavior: SnackBarBehavior.floating,
                elevation: 5.0,
                backgroundColor:
                    Colors.blue[600]!.withOpacity(0.8).withAlpha(200),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(10),
                  side: BorderSide(
                    color: Colors.black.withOpacity(0.4),
                    width: 3.0,
                  ),
                ),
                content: Text('Some text $now'),
              ),
            );
          },
          child: Text('Show toast'),
        ),
      ),
    );
  }
}

Custom Tab Bar Using ToggleButtons in Flutter



class TabBarButton extends StatelessWidget {
  final IconData icon;
  final double size;

  const TabBarButton({Key? key, required this.icon, this.size = 60.0})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Icon(
        icon,
        size: size,
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Toggle Buttons'),
      ),
      body: Column(
        children: [
          CustomTabBar(),
        ],
      ),
    );
  }
}

class CustomTabBar extends StatefulWidget {
  const CustomTabBar({Key? key}) : super(key: key);

  @override
  _CustomTabBarState createState() => _CustomTabBarState();
}

class _CustomTabBarState extends State<CustomTabBar> {
  var _selection = [false, false, false];

  @override
  Widget build(BuildContext context) {
    return Expanded(
      child: Align(
        alignment: FractionalOffset.bottomCenter,
        child: SafeArea(
          child: ToggleButtons(
            isSelected: _selection,
            onPressed: (index) {
              setState(() {
                _selection = List.generate(
                  _selection.length,
                  (i) => index == i ? true : false,
                );
              });
            },
            selectedColor: Colors.white,
            fillColor: Colors.blue,
            borderRadius: BorderRadius.circular(10.0),
            borderWidth: 4.0,
            borderColor: Colors.blue[400],
            selectedBorderColor: Colors.blue,
            highlightColor: Colors.blue.withOpacity(0.2),
            children: [
              TabBarButton(icon: Icons.settings),
              TabBarButton(icon: Icons.add),
              TabBarButton(icon: Icons.settings_remote)
            ],
          ),
        ),
      ),
    );
  }
}

Hashable Mixins in Dart



enum PetType { cat, dog }

mixin Pet {
  String get name;
  int get age;
  PetType get type;
  @override
  String toString() => 'Pet ($type), name = $name, age = $age';
  @override
  int get hashCode => hashValues(name, age, type);
  @override
  bool operator ==(covariant Pet o) => o.hashCode == hashCode;
}

class Cat with Pet {
  @override
  final String name;
  @override
  final int age;
  @override
  final PetType type;
  const Cat({required this.name, required this.age}) : type = PetType.cat;
}

void testIt() {
  final cats = <Cat>{
    Cat(name: 'Kitty 1', age: 2),
    Cat(name: 'Kitty 2', age: 3),
    Cat(name: 'Kitty 1', age: 2),
  };
  cats.forEach(print);
  /* 👆🏻 prints the following:
  Pet (PetType.cat), name = Kitty 1, age = 2
  Pet (PetType.cat), name = Kitty 2, age = 3
  */
}

Flutter Tips and Tricks in Terminal



import 'dart:convert' show utf8;
import 'dart:io' show HttpClient, exit, Process, stderr;
import 'dart:math' show Random;

const rawBlobRoot =
    'https://raw.githubusercontent.com/vandadnp/flutter-tips-and-tricks/main/';

void main(List<String> args) async {
  final url = Uri.https('bit.ly', '/2V1GKsC');
  try {
    final client = HttpClient();
    final images = await client
        .getUrl(url)
        .then((req) => req.close())
        .then((resp) => resp.transform(utf8.decoder).join())
        .then((body) => body.split('\n').map((e) => e.trim()))
        .then((iter) => iter.toList())
        .then((list) => list..retainWhere((s) => s.endsWith('.jpg)')))
        .then((imageList) => imageList.map((e) => e.replaceAll('![](', '')))
        .then((imageList) => imageList.map((e) => e.replaceAll(')', '')))
        .then((iter) => iter.toList());

    final found = images[Random().nextInt(images.length)];
    final result = '$rawBlobRoot$found';
    await Process.run('open', [result]);
    exit(0);
  } catch (e) {
    stderr.writeln('Could not proceed due to $e');
    exit(1);
  }
}

Searching List<List<T>> in Dart



const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const arr3 = [7, 8, 9];
const arr = [arr1, arr2, arr3];

extension FlattenFind<T extends Comparable> on Iterable<Iterable<T>> {
  bool containsElement(T value) {
    for (final arr in this) {
      if (arr.contains(value)) {
        return true;
      }
    }
    return false;
  }
}

void testIt() {
  assert(arr.containsElement(2));
  assert(arr.containsElement(8));
  assert(!arr.containsElement(10));
  assert(!arr.containsElement(10));
}

Cloning Objects in Dart



class Person {
  final Map<String, Object> _values;
  static const FIRST_NAME_KEY = 'FIRST_NAME';
  static const LAST_NAME_KEY = 'LAST_NAME';

  Person.from(Map<String, Object> props) : _values = props;

  Person({
    required String firstName,
    required String lastName,
    Map<String, Object>? props,
  }) : _values = {
          FIRST_NAME_KEY: firstName,
          LAST_NAME_KEY: lastName,
        };

  @override
  bool operator ==(covariant Person other) =>
      other.firstName == firstName && other.lastName == lastName;

  @override
  String toString() => _values.toString();
}

extension Properties on Person {
  String get firstName => _values[Person.FIRST_NAME_KEY].toString();
  set firstName(String newValue) => _values[Person.FIRST_NAME_KEY] = newValue;

  String get lastName => _values[Person.LAST_NAME_KEY].toString();
  set lastName(String newValue) => _values[Person.LAST_NAME_KEY] = newValue;
}

extension Clone on Person {
  Person clone([Map<String, Object>? additionalProps]) =>
      Person.from(Map.from(_values)..addAll(additionalProps ?? {}));
}

extension Subscripts on Person {
  Object? operator [](String key) => _values[key];
  operator []=(String key, Object value) => _values[key] = value;
}

void testIt() {
  final foo = Person(
    firstName: 'Foo Firstname',
    lastName: 'Foo Lastname',
  );
  print(foo); // {FIRST_NAME: Foo Firstname, LAST_NAME: Foo Lastname}
  final copyOfFoo = foo.clone();
  print(copyOfFoo); // {FIRST_NAME: Foo Firstname, LAST_NAME: Foo Lastname}
  final bar = foo.clone({'age': 30});
  print(bar); // {FIRST_NAME: Foo Firstname, LAST_NAME: Foo Lastname, age: 30}
  assert(foo == copyOfFoo);
  assert(foo == bar);
  assert(foo['age'] == null);
  assert(copyOfFoo['age'] == null);
  assert(bar['age'] == 30);
}

Color Filters in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var sliderValue = 0.0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Color Filters in Flutter!'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          ColorFiltered(
            colorFilter: ColorFilter.mode(
              Colors.orange.withOpacity(sliderValue),
              BlendMode.colorBurn,
            ),
            child: Image.network('https://tinyurl.com/4vtvh35h'),
          ),
          Slider(
            value: sliderValue,
            onChanged: (value) {
              setState(() {
                sliderValue = value;
              });
            },
          )
        ],
      ),
    );
  }
}

Flattening Lists in Dart



class Person {
  final String name;
  const Person(this.name);
  @override
  String toString() => 'Person: $name';
}

class House {
  final List<Person>? tennants;
  final List<Person> builders;
  const House({
    required this.tennants,
    required this.builders,
  });
}

const houses = [
  House(tennants: null, builders: [
    Person('Builder 1'),
  ]),
  House(tennants: [
    Person('Tennant 1'),
    Person('Tennant 2'),
  ], builders: [
    Person('Builder 3')
  ]),
];

extension OptionalFlattend<T> on Iterable<List<T>?> {
  Iterable<T> flattened() => expand((e) => e ?? []);
}

void testOptionalFlatten() {
  final allTennants = houses.map((h) => h.tennants).flattened();
  print(allTennants); // Person: Tennant 1, Person: Tennant 2
}

extension Flattend<T> on Iterable<List<T>> {
  Iterable<T> flattened() => expand((e) => e);
}

void testNonOptionalFlatten() {
  final allBuilders = houses.map((h) => h.builders).flattened();
  print(allBuilders); // Person: Builder 1, Person: Builder 2
}

void testIt() {
  testOptionalFlatten();
  testNonOptionalFlatten();
}

Managing Duplicates in List<T> in Dart



extension Duplicates<T> on List<T> {
  void addAllByAvoidingDuplicates(Iterable<T> values) =>
      replaceRange(0, length, {
        ...([...this] + [...values])
      });

  int get numberOfDuplicates => length - {...this}.length;

  bool get containsDuplicates => numberOfDuplicates > 0;

  List<T> get uniques => [
        ...{...this}
      ];

  void removeDuplicates() => replaceRange(
        0,
        length,
        uniques,
      );

  List<T> get duplicates => [
        for (var i = 0; i < length; i++)
          [...this].skip(i + 1).contains(this[i]) ? this[i] : null
      ].whereType<T>().toList();
}

void testIt() {
  final values = [3, 2, 10, 30, 40, 30, 100, 10];

  assert(values.numberOfDuplicates == 2);
  assert(values.containsDuplicates == true);

  assert(values.uniques.length == values.length - 2);
  print(values.uniques); // [3, 2, 10, 30, 40, 100]

  values.removeDuplicates();
  print(values); // [3, 2, 10, 30, 40, 100]

  assert(values.numberOfDuplicates == 0);
  assert(!values.containsDuplicates);
  assert(values.duplicates.isEmpty);

  values.addAllByAvoidingDuplicates([3, 2, 10, 200]);
  print(values); // [3, 2, 10, 30, 40, 100, 200]
  assert(values.containsDuplicates == false);
}

FlatMap and CompactMap in Dart



extension CompactMap<T> on List<T> {
  List<E> compactMap<E>(E? Function(T element) f) {
    Iterable<E> imp(E? Function(T element) f) sync* {
      for (final value in this) {
        final mapped = f(value);
        if (mapped != null) {
          yield mapped;
        }
      }
    }

    return imp(f).toList();
  }
}

extension FlatMap<T> on T? {
  E? flatMap<E>(E? Function(T value) f) {
    if (this != null) {
      return f(this!);
    } else {
      return null;
    }
  }
}

void testIt() {
  final foo = [1, 2, null, 3, null, 4];
  final bar = foo.compactMap((element) => element.flatMap((e) => e * 2));
  print(bar); // prints 2, 4, 6, 8
}

Equality of List<T> in Dart



extension Equality<T extends Comparable> on List<T> {
  bool isEqualTo(List<T> other) {
    if (other.length != length) {
      return false;
    }
    for (var i = 0; i < length; i++) {
      if (other[i] != this[i]) {
        return false;
      }
    }
    return true;
  }
}

int ascendingComparator<T extends Comparable>(T lhs, T rhs) =>
    lhs.compareTo(rhs);
int descendingComparator<T extends Comparable>(T lhs, T rhs) =>
    rhs.compareTo(lhs);

extension Sorted<T extends Comparable> on List<T> {
  List<T> sorted({bool descending = false}) => descending
      ? ([...this]..sort(descendingComparator))
      : ([...this]..sort(ascendingComparator));
}

void testIt() {
  assert([1, 2, 3].isEqualTo([1, 2, 3]));
  assert(![1, 2, 3].isEqualTo([1, 2, 2]));
  assert([3, 1, 2].sorted().isEqualTo([1, 2, 3]));
  assert(![3, 1, 2].sorted().isEqualTo([3, 1, 2]));
  assert(['Foo', 'Bar', 'Baz'].isEqualTo(['Foo', 'Bar', 'Baz']));
  assert(!['Foo', 'Bar', 'Baz'].isEqualTo(['foo', 'Bar', 'Baz']));
}

Constants in Dart




class Person {
  final String name;
  final int age;
  const Person({required this.name, required this.age});
}

const foo = Person(name: 'Foo', age: 20);
const foo2 = Person(name: 'Foo', age: 20);
const bar = Person(name: 'Bar', age: 20);

void assert_eq(Object lhs, Object rhs) {
  assert(lhs == rhs);
}

void assert_ne(Object lhs, Object rhs) {
  assert(lhs != rhs);
}

void testIt() {
  assert_eq(foo, foo2);
  assert_ne(foo, bar);
  assert_ne(foo2, bar);
}

Displaying Scrollable Bottom Sheets in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Scrollable Sheet')),
      body: DraggableScrollableSheet(
        initialChildSize: 0.2,
        minChildSize: 0.2,
        maxChildSize: 0.8,
        builder: (context, scrollController) {
          return Container(
            decoration: decoration(),
            clipBehavior: Clip.antiAlias,
            child: SingleChildScrollView(
              controller: scrollController,
              child: column(),
            ),
          );
        },
      ),
    );
  }
}

const urls = [
  'https://tinyurl.com/4vtvh35h',
  'https://tinyurl.com/pujhs55w',
  'https://tinyurl.com/u5k7zueh',
];

List<Widget> imageWithLoremIpsum(String uri) => [
      Image.network(uri),
      SizedBox(height: 10),
      loremIpsum(),
      SizedBox(height: 10),
    ];

Column column() => Column(
      children: imageWithLoremIpsum(urls[0]) +
          imageWithLoremIpsum(urls[1]) +
          imageWithLoremIpsum(urls[2]),
    );

Text loremIpsum() => Text(
      'Lorem ipsum ' * 10,
      textAlign: TextAlign.center,
    );

BoxDecoration decoration() => BoxDecoration(
      border: Border.all(color: Colors.white),
      borderRadius: BorderRadius.only(
        topLeft: Radius.circular(10),
        topRight: Radius.circular(10),
      ),
      color: Colors.white70,
    );

YouTube Ad Remover in Dart



import 'dart:io' show stdout, stderr, exitCode;
import 'package:collection/collection.dart' show IterableExtension;

// example argument: https://www.youtube.com/watch?v=mtETXtSP0pA
void main(List<String> args) async {
  if (args.isEmpty) {
    stdout.writeln('usage: dart youtube.dart "https://..."');
    return;
  }

  final link =
      args.firstWhereOrNull((element) => Uri.tryParse(element) != null);

  if (link == null) {
    stderr.writeln('No YouTube url found');
    exitCode = 1;
    return;
  }

  try {
    final uri = Uri.parse(link);
    if (uri.scheme.toLowerCase() != 'https' ||
        uri.host.toLowerCase() != 'www.youtube.com' ||
        uri.queryParameters['v'] == null) {
      throw FormatException();
    } else {
      final videoId = uri.queryParameters['v'];
      final embedUri = Uri.parse('${uri.scheme}://${uri.host}/embed/$videoId');
      stdout.writeln(embedUri);
      exitCode = 0;
    }
  } on FormatException catch (e) {
    stderr.writeln('Invalid Uri, try again! err = $e');
    exitCode = 1;
    return;
  }
}

Fade Between Widgets in Flutter



const urls = [
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var isShowingFirstImage = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('AnimatedCrossFade in Flutter'),
      ),
      body: Center(
        child: AnimatedCrossFade(
          layoutBuilder: (topChild, topChildKey, bottomChild, bottomChildKey) {
            return GestureDetector(
              onTap: () {
                setState(() {
                  isShowingFirstImage = !isShowingFirstImage;
                });
              },
              child: AnimatedCrossFade.defaultLayoutBuilder(
                  topChild, topChildKey, bottomChild, bottomChildKey),
            );
          },
          firstChild: Image.network(urls[0]),
          secondChild: Image.network(urls[1]),
          crossFadeState: isShowingFirstImage
              ? CrossFadeState.showFirst
              : CrossFadeState.showSecond,
          duration: Duration(milliseconds: 400),
        ),
      ),
    );
  }
}

Sort Descriptors in Dart



int ascendingComparator<T extends Comparable>(T lhs, T rhs) =>
    lhs.compareTo(rhs);
int descendingComparator<T extends Comparable>(T lhs, T rhs) =>
    rhs.compareTo(lhs);

extension Sorted<T extends Comparable> on List<T> {
  List<T> sorted({bool descending = false}) => descending
      ? (this..sort(descendingComparator))
      : (this..sort(ascendingComparator));
}

class Person implements Comparable {
  final int age;
  final String name;
  const Person({required this.age, required this.name});
  @override
  int compareTo(covariant Person other) => age.compareTo(other.age);
  @override
  String toString() => 'Person, name = $name ($age)';
}

void testIt() {
  final people = [
    Person(age: 39, name: 'Father Foo'),
    Person(age: 40, name: 'Mother Bar'),
    Person(age: 13, name: 'Son Baz'),
  ];

  print('ascending sort');
  people.sorted().forEach(print);
  // prints Son Baz (13), Father Foo (39), Mother Bar (40)
  print('descending sort');
  people.sorted(descending: true).forEach(print);
  // prints Mother Bar (40), Father Foo (39), Son Baz (13)
}

User Sortable Columns and Tables in Flutter



class Language {
  final String name;
  final Image image;
  const Language(this.name, this.image);
  Language.dart()
      : name = 'Dart',
        image = Image.network('https://bit.ly/3yH1Ivj');
  Language.rust()
      : name = 'Rust',
        image = Image.network('https://bit.ly/3lPTqhb');
  Language.python()
      : name = 'Python',
        image = Image.network('https://bit.ly/3iCFCEP');

  Language.java()
      : name = 'Java',
        image = Image.network('https://bit.ly/3CCapJH');
  static List<Language> all = [
    Language.dart(),
    Language.rust(),
    Language.python(),
    Language.java(),
  ];
}

extension Sort on List<Language> {
  void sortByName(bool ascending) => sort((lhs, rhs) =>
      ascending ? lhs.name.compareTo(rhs.name) : rhs.name.compareTo(lhs.name));
}

List<DataRow> rows(List<Language> langs) => langs
    .map(
      (l) => DataRow(
        cells: [
          DataCell(
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: l.image,
            ),
          ),
          DataCell(Text(l.name)),
        ],
      ),
    )
    .toList();

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final List<Language> _langs = Language.all..sortByName(true);
  int sortedColumnIndex = 1;
  var isSortedAscending = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('WhatsApp')),
      body: DataTable(
        sortAscending: isSortedAscending,
        sortColumnIndex: sortedColumnIndex,
        columns: [
          DataColumn(label: Text('Image')),
          DataColumn(
            label: Text('Name'),
            onSort: (columnIndex, ascending) {
              setState(() {
                sortedColumnIndex = columnIndex;
                isSortedAscending = ascending;
                _langs.sortByName(ascending);
              });
            },
          ),
        ],
        rows: rows(_langs),
      ),
    );
  }
}

Content-Length of List<Uri> in Dart

Recursive Dot Notation on Maps in Dart




final person = {
  'firstName': 'Foo',
  'lastName': 'Bar',
  'age': 30,
  'address': {
    'street': {
      'name': 'Baz street',
      'numberOfHouses': 20,
    },
    'houseNumber': '#20',
    'city': 'Stockholm',
    'country': 'Sweden'
  },
};

extension KeyPath on Map {
  Object? valueFor({required String keyPath}) {
    final keysSplit = keyPath.split('.');
    final thisKey = keysSplit.removeAt(0);
    final thisValue = this[thisKey];
    if (keysSplit.isEmpty) {
      return thisValue;
    } else if (thisValue is Map) {
      return thisValue.valueFor(keyPath: keysSplit.join('.'));
    }
  }
}

void testIt() {
  assert(person.valueFor(keyPath: 'firstName') == 'Foo');
  assert(person.valueFor(keyPath: 'age') == 30);
  assert(person.valueFor(keyPath: 'address.street.name') == 'Baz street');
  assert(person.valueFor(keyPath: 'address.houseNumber') == '#20');
}

Allow User Selection of Text in Flutter



const text = 'Flutter is an open-source UI software development'
    ' kit created by Google. It is used to develop cross platform applications'
    ' for Android, iOS, Linux, Mac, Windows, Google Fuchsia, '
    'and the web from a single codebase.';

const imageUrl = 'https://bit.ly/3gT5Qk2';

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Selectable Text in Flutter'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Image.network(imageUrl),
          SizedBox(height: 10.0),
          Padding(
            padding: const EdgeInsets.all(8.0),
            child: SelectableText(
              text,
              textAlign: TextAlign.center,
              showCursor: true,
              cursorColor: Colors.blue,
              toolbarOptions: ToolbarOptions(
                copy: true,
                selectAll: true,
              ),
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.w300,
              ),
            ),
          ),
        ],
      ),
    );
  }
}

Placing Constraints on Widgets in Flutter



const dashes = [
  'https://bit.ly/3gHlTCU',
  'https://bit.ly/3wOLO1c',
  'https://bit.ly/3cXWD9j',
  'https://bit.ly/3gT5Qk2',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('ConstrainedBox in Flutter'),
      ),
      body: InteractiveViewer(
        minScale: 1.0,
        maxScale: 2.0,
        child: SingleChildScrollView(
          scrollDirection: Axis.vertical,
          child: Table(
            defaultVerticalAlignment: TableCellVerticalAlignment.middle,
            children: dashes
                .map(
                  (dash) => TableRow(
                    children: [
                      ConstrainedBox(
                        constraints: BoxConstraints(
                          minHeight: 300,
                        ),
                        child: Image.network(dash),
                      ),
                    ],
                  ),
                )
                .toList(),
          ),
        ),
      ),
    );
  }
}

Animating Position Changes in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var isMovedUp = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('AnimatedPositioned in Flutter')),
      body: Center(
        child: GestureDetector(
          onTap: () => setState(() => isMovedUp = !isMovedUp),
          child: Stack(
            clipBehavior: Clip.none,
            alignment: Alignment.center,
            children: [
              Image.network('https://bit.ly/2VcCSow'),
              Text(
                'Summer 😎',
                style: TextStyle(
                  fontSize: 30,
                  color: Colors.black,
                ),
              ),
              AnimatedPositioned(
                duration: Duration(seconds: 1),
                bottom: isMovedUp ? 140 : 10.0,
                curve: Curves.elasticInOut,
                child: CircleAvatar(
                  radius: 100,
                  backgroundImage: NetworkImage('https://bit.ly/3cXWD9j'),
                  backgroundColor: Colors.orange[300],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Transitioning Between Widgets in Flutter



enum Season { spring, summer, autumn, winter }

extension Caps on String {
  String get capitalized => this[0].toUpperCase() + substring(1);
}

extension Title on Season {
  String get title => describeEnum(this).capitalized;
}

class TitledImage {
  final String title;
  final Uri uri;
  final ValueKey key;
  const TitledImage(this.title, this.uri, this.key);

  TitledImage.spring()
      : title = Season.spring.title,
        uri = Uri.https('cnn.it', '/3xu58Ap'),
        key = ValueKey(1);

  TitledImage.summer()
      : title = Season.summer.title,
        uri = Uri.https('bit.ly', '/2VcCSow'),
        key = ValueKey(2);

  TitledImage.autumn()
      : title = Season.autumn.title,
        uri = Uri.https('bit.ly', '/3A3zStC'),
        key = ValueKey(3);

  TitledImage.winter()
      : title = Season.winter.title,
        uri = Uri.https('bit.ly', '/2TNY7wi'),
        key = ValueKey(4);
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _img = TitledImage.summer();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(_img.title)),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          AnimatedSwitcher(
            switchInCurve: Curves.easeIn,
            switchOutCurve: Curves.easeOut,
            duration: Duration(milliseconds: 300),
            transitionBuilder: (child, animation) {
              return FadeTransition(opacity: animation, child: child);
            },
            child: Image.network(
              _img.uri.toString(),
              key: _img.key,
            ),
          ),
          getButtons(),
        ],
      ),
    );
  }

  Widget getButtons() {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.spring()),
          child: Text(Season.spring.title),
        ),
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.summer()),
          child: Text(Season.summer.title),
        ),
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.autumn()),
          child: Text(Season.autumn.title),
        ),
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.winter()),
          child: Text(Season.winter.title),
        ),
      ],
    );
  }
}

Doubly Linked Lists in Dart



class Person extends LinkedListEntry<Person> {
  final String name;
  final int age;
  Person({
    required this.name,
    required this.age,
  });

  @override
  String toString() => 'Person name = $name, age = $age';
}

void testIt() {
  final persons = LinkedList<Person>();
  final dad = Person(name: 'Father Foo', age: 47);
  final mom = Person(name: 'Mother Bar', age: 47);
  final daughter = Person(name: 'Daughter Baz', age: 22);
  persons.addAll([dad, mom, daughter]);

  print(persons.first.previous); // null
  print(persons.first); // Person name = Father Foo, age = 47
  print(persons.first.next); // Person name = Mother Bar, age = 47
  print(persons.last.previous); // Person name = Mother Bar, age = 47
  print(persons.first.next?.next); // Person name = Daughter Baz, age = 22
  print(persons.last.next); // null
}

Reordering Items Inside List Views in Flutter



class Item {
  final Color color;
  final String text;
  final UniqueKey uniqueKey;
  Item(this.color, this.text) : uniqueKey = UniqueKey();
}

extension ToListItem on Item {
  Widget toListItem() => LimitedBox(
        key: uniqueKey,
        maxHeight: 200,
        child: Container(
          color: color,
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Text(
              text,
              style: TextStyle(
                color: Colors.white,
                fontSize: 100,
              ),
            ),
          ),
        ),
      );
}

class _HomePageState extends State<HomePage> {
  var items = [
    Item(Colors.deepPurple, 'Foo'),
    Item(Colors.blueGrey, 'Bar'),
    Item(Colors.lightGreen, 'Baz')
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Reordered List View in Flutter'),
      ),
      body: ReorderableListView(
        onReorder: (oldIndex, newIndex) {
          setState(() {
            final item = items.removeAt(oldIndex);
            items.insert(newIndex, item);
          });
        },
        children: items.map((i) => i.toListItem()).toList(),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Custom Stream Transformers in Dart



in this example we have created our own string transformer that
can trim a Stream<String> by trimming whitespace from both
beginning and end of the string
*/

import 'dart:convert' show utf8;

class StringTrimmer extends StreamTransformerBase<String, String> {
  const StringTrimmer();
  @override
  Stream<String> bind(Stream<String> stream) =>
      Stream.fromFuture(stream.join(' ')).map((str) => str.trim());
}

final string =
    '''   A long line of text with spaces in the beginning and the end, 
    divided into three lines just for the purpose of this demonstration    ''';

void testIt() async {
  final bytes = utf8.encode(string);
  final result = await Stream.value(bytes)
      .transform(utf8.decoder)
      .transform(LineSplitter())
      .transform(StringTrimmer())
      .join();
  print(result);
}

Expanding Stream Elements in Dart

/*


in this example we expand every element inside our Stream<int> to
a stream that in turn contains n+1 elements where n is the index generated
by our main stream, that's to say, 0, 1, 2, 3, 4, etc

*/
Stream<int> nestedEvents(int count) {
  return Stream.periodic(
    Duration(seconds: 1),
    (e) => e,
  ).take(count).asyncExpand(
        (i) => Stream.fromIterable(
          Iterable.generate(i + 1),
        ),
      );
}

void testIt() async {
  /* 
  prints the followings in this order
  0, 1
  0, 1, 2
  0, 1, 2, 3
  0, 1, 2, 3, 4
  */
  await for (final value in nestedEvents(5)) {
    print('Value is $value');
  }
}

Consume Streams for a Duration in Dart

extension TakeFor<T> on Stream<T> {
  Stream<T> takeFor(Duration duration) {
    final upTo = DateTime.now().add(duration);
    return takeWhile((_) {
      final now = DateTime.now();
      return now.isBefore(upTo) | now.isAtSameMomentAs(upTo);
    });
  }
}

Stream<DateTime> source() => Stream.periodic(
      Duration(milliseconds: 500),
      (_) => DateTime.now(),
    );

void testIt() async {
  await for (final dateTime in source().takeFor(
    Duration(seconds: 4),
  )) {
    print('date time is $dateTime');
  }
}

Shortening URLs in Dart

import 'dart:convert' show json;

Future<Uri> shortenUri(Uri uri, String bitlyToken) async {
  final client = HttpClient();

  final endpoint = Uri.https('api-ssl.bitly.com', '/v4/shorten');

  final response = await client.postUrl(endpoint).then(
    (req) {

      req.headers
        ..set(HttpHeaders.contentTypeHeader, 'application/json')
        ..set(HttpHeaders.authorizationHeader, 'Bearer $bitlyToken');

      final body = {
        'long_url': uri.toString(),
        'domain': 'bit.ly',
      };
      final bodyBytes = utf8.encode(json.encode(body));
      req.add(bodyBytes);

      return req.close();
    },
  );

  final responseBody = await response.transform(utf8.decoder).join();
  final responseJson = json.decode(responseBody) as Map<String, dynamic>;
  return Uri.parse(responseJson['link']);
}

void testIt() async {
  print(await shortenUri(
    Uri.parse('https://pixolity.se'),
    'XXX',
  ));
}

LimitedBox Widget as ListView Items in Flutter

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

extension ToListItemImage on String {
  Widget toListItemImage() {
    return LimitedBox(
      maxHeight: 150.0,
      child: Image.network(
        this,
        fit: BoxFit.fitWidth,
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Limited Box in Flutter')),
      body: ListView(
        children: images.map((str) => str.toListItemImage()).toList(),
      ),
    );
  }
}

Generically Convert Anything to Int in Dart

extension ToInt on Object {
  int toInt() {
    final list = [
      if (this is Iterable<Object>)
        ...(List.of(this as Iterable<Object>))
      else if (this is int)
        [this as int]
      else
        (double.tryParse(toString()) ?? 0.0).round()
    ];
    return list
        .map((e) => (double.tryParse(e.toString()) ?? 0.0).round())
        .reduce((lhs, rhs) => lhs + rhs);
  }
}

void testIt() {
  assert(1.toInt() == 1);
  assert((2.2).toInt() == 2);
  assert((2.0).toInt() == 2);
  assert('3'.toInt() == 3);
  assert(['4', '5'].toInt() == 9);
  assert([4, 5].toInt() == 9);
  assert(['2.4', '3.5'].toInt() == 6);
  assert(['2', '3.5'].toInt() == 6);
  assert({'2', 3, '4.2'}.toInt() == 9);
  assert(['2', 3, '4.2', 5.3].toInt() == 14);
}

Validating URL Certificates in Dart

import 'dart:io' show HttpClient;

Future<bool> isSecuredWithValidCert(String uriString) async {
  final uri = Uri.parse(uriString);
  final client = HttpClient();
  try {
    await client.headUrl(uri).then((r) => r.close());
    return true;
  } on HandshakeException {
    return false;
  }
}

void testIt() async {
  await isSecuredWithValidCert('https://expired.badssl.com');
  await isSecuredWithValidCert('https://wrong.host.badssl.com');
  await isSecuredWithValidCert('https://self-signed.badssl.com');
  await isSecuredWithValidCert('https://untrusted-root.badssl.com');
  await isSecuredWithValidCert('https://revoked.badssl.com');
}

Displaying Popup Menus in Flutter

enum ImageAction { copy }

PopupMenuItem<ImageAction> copyButton({VoidCallback? onPressed}) =>
    PopupMenuItem<ImageAction>(
      value: ImageAction.copy,
      child: TextButton.icon(
        icon: Icon(Icons.copy),
        label: Text('Copy'),
        onPressed: onPressed,
      ),
    );

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter'),
      ),
      body: Center(
        child: PopupMenuButton<ImageAction>(
          elevation: 10,
          offset: Offset(0, 50),
          itemBuilder: (_) => [
            copyButton(
              onPressed: () {
                print('Copy the image...');
              },
            ),
          ],
          child: Image.network('https://bit.ly/3ywI8l6'),
        ),
      ),
    );
  }
}

Implementing Drag and Drop in Flutter

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  String? _imageUrl;

  bool shouldAccept(String? value) => Uri.tryParse(value ?? '') != null;

  Widget dragTargetBuilder(
    BuildContext context,
    List<String?> incoming,
    dynamic rejected,
  ) {
    final emptyContainer = Container(
      color: Colors.grey[200],
      height: 200,
      child: Center(
        child: Text('Drag an image here'),
      ),
    );

    if (incoming.isNotEmpty) {
      _imageUrl = incoming.first;
    }

    if (_imageUrl == null) {
      return emptyContainer;
    }

    try {
      final uri = Uri.parse(_imageUrl ?? '');
      return Container(
        color: Colors.grey[200],
        height: 200,
        child: Center(
          child: Image.network(uri.toString()),
        ),
      );
    } on FormatException {
      return emptyContainer;
    }
  }

  static final firstImageUrl = 'https://bit.ly/3xnoJTm';
  static final secondImageUrl = 'https://bit.ly/3hIuC78';
  final firstImage = Image.network(firstImageUrl);
  final secondImage = Image.network(secondImageUrl);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Tooltips in Flutter')),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            DragTarget<String>(
              onWillAccept: shouldAccept,
              builder: dragTargetBuilder,
            ),
            SizedBox(height: 10.0),
            DraggableImage(
              imageWidget: firstImage,
              imageUrl: firstImageUrl,
            ),
            SizedBox(height: 10.0),
            DraggableImage(
              imageWidget: secondImage,
              imageUrl: secondImageUrl,
            ),
          ],
        ),
      ),
    );
  }
}

class DraggableImage extends StatelessWidget {
  const DraggableImage({
    Key? key,
    required this.imageWidget,
    required this.imageUrl,
  }) : super(key: key);

  final Image imageWidget;
  final String imageUrl;

  @override
  Widget build(BuildContext context) {
    return Draggable<String>(
      data: imageUrl,
      feedback: Container(
        width: MediaQuery.of(context).size.width,
        decoration: BoxDecoration(
          boxShadow: [
            BoxShadow(
              blurRadius: 30,
              color: Colors.black,
              spreadRadius: 10,
            ),
          ],
        ),
        child: imageWidget,
      ),
      child: imageWidget,
    );
  }
}

Dismissing List Items in Flutter

const gridImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3dLJNeD',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        slivers: [
          CustomAppBar(),
          CustomGridView(),
          CustomListView(
            imageUrls: gridImages,
          ),
        ],
      ),
    );
  }
}

class _CustomListViewState extends State<CustomListView> {
  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverList(
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            final url = widget.imageUrls[index];
            return Dismissible(
              key: ValueKey(url),
              onDismissed: (_) {
                widget.imageUrls.remove(url);
              },
              background: Container(
                color: Colors.red,
                child: FittedBox(
                  alignment: Alignment.centerRight,
                  fit: BoxFit.fitHeight,
                  child: Icon(Icons.delete, color: Colors.white),
                ),
              ),
              child: Padding(
                padding: const EdgeInsets.only(bottom: 8.0),
                child: Image.network(url),
              ),
            );
          },
          childCount: widget.imageUrls.length,
        ),
      ),
    );
  }
}

class CustomListView extends StatefulWidget {
  final List<String> imageUrls;

  const CustomListView({
    Key? key,
    required this.imageUrls,
  }) : super(key: key);

  @override
  _CustomListViewState createState() => _CustomListViewState();
}

class CustomGridView extends StatelessWidget {
  const CustomGridView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverGrid(
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 3,
          mainAxisSpacing: 10,
          crossAxisSpacing: 10,
          childAspectRatio: 1.0,
        ),
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            return Container(
              width: 100,
              height: 100,
              child: Image.network(gridImages[index]),
            );
          },
          childCount: gridImages.length,
        ),
      ),
    );
  }
}

class CustomAppBar extends StatelessWidget {
  const CustomAppBar({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverAppBar(
      backgroundColor: Colors.orange[300],
      forceElevated: true,
      pinned: false,
      snap: false,
      floating: true,
      expandedHeight: 172,
      flexibleSpace: FlexibleSpaceBar(
        title: Text(
          'Flutter',
          style: TextStyle(
            fontSize: 30,
            color: Colors.white,
            decoration: TextDecoration.underline,
          ),
        ),
        collapseMode: CollapseMode.parallax,
        background: Image.network('https://bit.ly/3x7J5Qt'),
      ),
    );
  }
}

Animating Widgets with Ease in Flutter

class Ball extends StatefulWidget {
  const Ball({Key? key}) : super(key: key);

  @override
  _BallState createState() => _BallState();
}

class _BallState extends State<Ball> with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 4),
      reverseDuration: Duration(seconds: 4),
    );
    _animation = Tween(begin: 0.0, end: 2 * pi).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.repeat();
    return AnimatedBuilder(
      animation: _animation,
      builder: (context, image) {
        return Transform.rotate(
          angle: _animation.value,
          child: image,
        );
      },
      child: Image.network('https://bit.ly/3xspdrp'),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Builder in Flutter'),
      ),
      body: Center(
        child: Ball(),
      ),
    );
  }
}

Displaying Tool Tips in Flutter

const imagesAndInfo = [
  ['https://bit.ly/3xnoJTm', 'Stockholm, Sweden'],
  ['https://bit.ly/3hIuC78', 'Dalarna, Sweden'],
  ['https://bit.ly/3wi9mdG', 'Brighton, UK'],
  ['https://bit.ly/3dSSMuy', 'Hove, UK'],
  ['https://bit.ly/3xoWCmV', 'Kerala, India'],
  ['https://bit.ly/3hGmjZC', 'Salvador da Bahia, Brazil']
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Tooltips in Flutter')),
      body: ListView.builder(
        itemCount: imagesAndInfo.length,
        itemBuilder: (_, index) {
          return Padding(
            padding: const EdgeInsets.only(top: 8.0, left: 8.0, right: 8.0),
            child: Tooltip(
              decoration: BoxDecoration(
                color: Colors.black,
                boxShadow: [
                  BoxShadow(
                    color: Colors.white.withAlpha(180),
                    offset: Offset.zero,
                    spreadRadius: 30.0,
                    blurRadius: 30.0,
                  ),
                ],
                borderRadius: BorderRadius.all(Radius.circular(8.0)),
              ),
              textStyle: TextStyle(fontSize: 20, color: Colors.white),
              message: imagesAndInfo[index][1],
              child: Image.network(
                imagesAndInfo[index][0],
              ),
            ),
          );
        },
      ),
    );
  }
}

Displaying Assorted Widgets Inside TableView in Flutter

const natureUrls = [
  'https://bit.ly/3dAtFwy',
  'https://bit.ly/36cHehe',
  'https://bit.ly/365uqt1',
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3jBvJYU',
  'https://bit.ly/3yhbHHi'
];

extension ToImage on String {
  Widget toPaddedNetworkImage() => Padding(
        padding: const EdgeInsets.all(8.0),
        child: Image.network(this),
      );
}

extension ToImages on List<String> {
  List<Widget> toPaddedNetworkImages() =>
      map((str) => str.toPaddedNetworkImage()).toList();
}

extension ToTableRow on List<Widget> {
  TableRow toTableRow() => TableRow(children: this);
}

class ListPaginator<T> extends Iterable {
  final List<List<T>> list;
  ListPaginator({required List<T> input, required int itemsPerPage})
      : list = [
          for (var i = 0; i < input.length; i += itemsPerPage)
            input.getRange(i, min(input.length, i + itemsPerPage)).toList(),
        ];

  @override
  Iterator get iterator => list.iterator;
}

class HomePage extends StatelessWidget {
  final provider = ListPaginator<String>(
    input: natureUrls,
    itemsPerPage: 3,
  );
  HomePage({Key? key}) : super(key: key);

  Iterable<TableRow> getRows() sync* {
    for (final List<String> urlBatch in provider) {
      final networkImages = urlBatch.toPaddedNetworkImages();
      yield TableRow(children: networkImages);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('TableView in Flutter'),
      ),
      body: SingleChildScrollView(
        child: Table(
          defaultVerticalAlignment: TableCellVerticalAlignment.bottom,
          children: getRows().toList(),
        ),
      ),
    );
  }
}

Page Indicator with Page View in Flutter

const dashes = [
  'https://bit.ly/3gHlTCU',
  'https://bit.ly/3wOLO1c',
  'https://bit.ly/3cXWD9j',
  'https://bit.ly/3gT5Qk2',
];

class PageText extends StatelessWidget {
  final int current;
  final int total;

  const PageText({
    Key? key,
    required this.current,
    required this.total,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      'Page ${current + 1} of $total',
      style: TextStyle(fontSize: 30.0, shadows: [
        Shadow(
          offset: Offset(0.0, 1.0),
          blurRadius: 20.0,
          color: Colors.black.withAlpha(140),
        )
      ]),
    );
  }
}

class _HomePageState extends State<HomePage> {
  var _index = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Page Indicator')),
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: PageView.builder(
                onPageChanged: (pageIndex) {
                  setState(() => _index = pageIndex);
                },
                scrollDirection: Axis.horizontal,
                itemCount: dashes.length,
                itemBuilder: (context, index) {
                  return Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Image.network(dashes[index]),
                      Text('Dash #${index + 1}'),
                    ],
                  );
                },
              ),
            ),
            PageText(current: _index, total: dashes.length)
          ],
        ),
      ),
    );
  }
}

Animating and Moving a Floating Action Button in Flutter

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

const List<FloatingActionButtonLocation> locations = [
  FloatingActionButtonLocation.centerDocked,
  FloatingActionButtonLocation.startDocked,
  FloatingActionButtonLocation.startFloat,
  FloatingActionButtonLocation.centerFloat,
  FloatingActionButtonLocation.endFloat,
  FloatingActionButtonLocation.endDocked
];

extension GoAround<T> on List<T> {
  T elementByGoingAround(int index) {
    final finalIndex = index >= length ? index.remainder(length) : index;
    return this[finalIndex];
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _locationIndex = 0;

  FloatingActionButtonLocation get location =>
      locations.elementByGoingAround(_locationIndex);

  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(
        title: Text('Floating Action Button'),
      ),
      floatingActionButtonLocation: location,
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(() => _locationIndex += 1);
        },
        child: Icon(Icons.add),
      ),
      bottomNavigationBar: BottomNavigationBar(
        backgroundColor: Colors.yellow[600],
        selectedItemColor: Colors.black,
        items: [
          BottomNavigationBarItem(
            icon: Icon(Icons.bedtime),
            label: 'Item 1',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.access_alarms),
            label: 'Item 2',
          )
        ],
        currentIndex: 0,
      ),
    );
  }
}

Fading Network Image Widget in Flutter

class FadingNetworkImage extends StatefulWidget {
  final String url;

  const FadingNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  _FadingNetworkImageState createState() => _FadingNetworkImageState();
}

class _FadingNetworkImageState extends State<FadingNetworkImage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller =
        AnimationController(vsync: this, duration: Duration(seconds: 1));

    _animation = Tween(begin: 0.0, end: 1.0).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(opacity: _animation, child: child);
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return LinearProgressIndicator(
            value: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

const dashes = [
  'https://bit.ly/3gHlTCU',
  'https://bit.ly/3wOLO1c',
  'https://bit.ly/3cXWD9j',
  'https://bit.ly/3gT5Qk2',
];

extension GoAround<T> on List<T> {
  T elementByGoingAround(int index) {
    final finalIndex = index >= length ? index.remainder(length) : index;
    return this[finalIndex];
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int _index = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Faded Image'),
      ),
      body: Center(
          child: Column(
        children: [
          FadingNetworkImage(
            url: dashes.elementByGoingAround(_index),
          ),
          TextButton(
            onPressed: () {
              setState(() => _index += 1);
            },
            child: Text('Load next Dash'),
          ),
        ],
      )),
    );
  }
}

Transparent Alert Dialogs in Flutter

TextStyle get whiteTextStyle => TextStyle(color: Colors.white);

Future<void> showTextDialog({
  required BuildContext context,
  required String text,
}) {
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.all(
            Radius.circular(10),
          ),
          side: BorderSide(
            color: Colors.white,
            style: BorderStyle.solid,
            width: 2,
          ),
        ),
        backgroundColor: Colors.black.withAlpha(150),
        titleTextStyle: whiteTextStyle,
        contentTextStyle: whiteTextStyle,
        content: Text(text),
        actions: [
          TextButton(
            style: TextButton.styleFrom(primary: Colors.white),
            onPressed: () {
              Navigator.of(context).pop();
            },
            child: Text('OK'),
          )
        ],
      );
    },
  );
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Rounded Corder Dialog',
        ),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Image.network('https://bit.ly/3ywI8l6'),
          TextButton(
            onPressed: () async {
              await showTextDialog(
                context: context,
                text: 'Hello world',
              );
            },
            child: Text('Show dialog'),
          ),
        ],
      ),
    );
  }
}

Network Image Size in Dart

import 'dart:ui' as ui;

Future<Size> getImageSize(String uri) {
  final image = Image.network('https://bit.ly/3dAtFwy');
  final comp = Completer<ui.Image>();
  image.image
      .resolve(
        ImageConfiguration.empty,
      )
      .addListener(
        ImageStreamListener(
          (ImageInfo info, _) => comp.complete(info.image),
        ),
      );
  return comp.future.then(
    (image) => Size(
      image.width.toDouble(),
      image.height.toDouble(),
    ),
  );
}

void testIt() async {
  final imageSize = await getImageSize('https://bit.ly/3dAtFwy');
  print(imageSize);
  assert(imageSize.width == 2048.0);
  assert(imageSize.height == 1365.0);
  print(imageSize.aspectRatio);
}

Animated Icons in Flutter

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final Animation<double> _animation;
  late final AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );
    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.repeat(reverse: true);
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Icons in Fluter'),
      ),
      body: Center(
        child: AnimatedIcon(
          color: Colors.green[300],
          size: MediaQuery.of(context).size.width,
          icon: AnimatedIcons.search_ellipsis,
          progress: _animation,
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Custom Scroll Views in Flutter

const gridImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3dLJNeD',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        slivers: [
          CustomAppBar(),
          CustomGridView(),
          CustomListView(),
        ],
      ),
    );
  }
}

class CustomListView extends StatelessWidget {
  const CustomListView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverList(
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            return Padding(
              padding: const EdgeInsets.only(bottom: 8.0),
              child: Image.network(gridImages[index]),
            );
          },
          childCount: gridImages.length,
        ),
      ),
    );
  }
}

class CustomGridView extends StatelessWidget {
  const CustomGridView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverGrid(
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 3,
          mainAxisSpacing: 10,
          crossAxisSpacing: 10,
          childAspectRatio: 1.0,
        ),
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            return Container(
              width: 100,
              height: 100,
              child: Image.network(gridImages[index]),
            );
          },
          childCount: gridImages.length,
        ),
      ),
    );
  }
}

class CustomAppBar extends StatelessWidget {
  const CustomAppBar({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverAppBar(
      backgroundColor: Colors.orange[300],
      forceElevated: true,
      pinned: false,
      snap: false,
      floating: true,
      expandedHeight: 172,
      flexibleSpace: FlexibleSpaceBar(
        title: Text(
          'Flutter',
          style: TextStyle(
            fontSize: 30,
            color: Colors.white,
            decoration: TextDecoration.underline,
          ),
        ),
        collapseMode: CollapseMode.parallax,
        background: Image.network('https://bit.ly/3x7J5Qt'),
      ),
    );
  }
}

Parallax App Bar in Flutter

JSON HTTP Requests in Dart

URL Timeouts in Dart

Detecting URL File Types in Dart

Paginated Lists in Dart

Requesting DELETE on APIs in Dart

Animated Containers in Flutter

Hiding Widgets in Flutter

Simple Opacity Animation in Flutter

Vignette Widget in Flutter

Drop Down Button Configuration and Usage in Flutter

Expandable List Items in Flutter

Infinite Scrolling in Flutter

Infinite Arrays in Dart

Custom Color Picker Component in Flutter

Displaying and Reacting to Switches in Flutter

Displaying Bottom Bars in Flutter

Displaying Buttons on AppBar in Flutter

Displaying Bottom Sheets in Flutter

Converting Enums to Radio Buttons in Flutter

Check Existence of Websites in Flutter

Images inside AlertDialog in Flutter

Returning Values from AlertDialog in Flutter

Simple Grid View in Flutter

Rendering Bullet Points in Flutter

Retrying Futures in Flutter

Containers as ClipOvals in Flutter

Rich Texts in Flutter

Wrapping Widgets in Flutter

Sweep Gradients in Flutter

Stream and StreamBuilder in Flutter

Blur Effect in Flutter

Convert Enums to Strings in Dart

Replacing Text in TextField in Flutter

Aspect Ratio in Flutter

Zoom and Pan in Flutter

Resizing Images in Flutter to Fit Screen Height

Validating URLs in Flutter

FrameBuilder for Network Images in Flutter

Adding Shadow to Icons in Flutter

Calculating Median of Lists in Dart

Generic Functions with Reduce in Dart

Passing Back Data From a Screen to the Previous One in Flutter

Flinging an Animation in Flutter

Fade Animations in Flutter

Throttling User Input in Flutter

Censoring TextFields in Flutter

Customizing TextButton in Flutter

Multiline TextFields in Flutter

Filtering TextField Input in Flutter

Focusing Manually on TextFields in Flutter

Data Streams Over HTTP/HTTPs in Dart

Catching Nonexistent Accessors or Methods in Dart

Using Expando in Dart

Implementing Custom Maps in Dart

Dynamically Calling Functions in Dart

Factory Constructors in Dart

Calculating the Sum of List Items in Dart

Removing Duplicate Strings in Lists in Dart (Case-Insensitive)

Implementing Range in Dart

Converting Lists to Maps in Dart

Implementing Hashable in Dart

Random Name Generator in Dart

Capturing Stack Traces in Dart Exceptions

Removing Duplicates from Lists in Dart

Optional Spread Operator in Dart

Calling Optional Functions in Dart

Odd-Even Sort in Dart

Implementing Zip and Tuples in Dart

Swapping Values in Lists with XOR in Dart

Waiting for Multiple Futures in Dart

Using Queues as Stacks in Dart

Custom Iterators in Dart

Iterables as Ranges and Transform in Dart

Errors vs Exceptions in Dart

Custom Annotations in Dart

Classes as Enums in Dart

Spread Operator in Collection Literals in Dart

StreamBuilder and StreamController in Dart

Almost Equal in Dart

Enum Associated Values in Dart

Implementing Comparable in Dart

Implementing Custom Integer Types in Dart

Custom Subscripts in Dart

Dart List Enumeration with Index

Applying Mixins to Other Mixins in Dart

Parameter Types in Dart

Custom Exceptions in Dart

rethrowing Exceptions in Dart

mixins and JSON Parsing in Dart

mixins vs abstract classes in Dart

Drawing Shapes in Flutter with LayoutBuilder, CustomPaint and CustomPainter

Generic Type Aliases in Dart

Callable Classes in Dart

Synchronous Generators in Dart

Implicit Interfaces in Dart

Did you know that in #Dart, every #class implicitly exports an #interface that can be #implemented (as opposed to #extended) by other classes? This is called "implicit interface".

Do you know how "const" constructors work in #Dart?

Did you know that in #Dart, it is actually preferred to use #async and #await over using raw #Futures?

In #Dart, you can use a combination of #Initializer #List plus default values for your class #member #fields to create elegant and handy convenience initializers

Did you know that in #Dart, you can extract elements of a certain type from your Lists using the #whereType #generic #function instead of calculating the #equality yourselves?

Do you know about #Type #Promotion in Dart?

"address" is an optional field of the "Person" class. If you look at the "doThis()" function you see that I'm saving the value of address in a local variable and then comparing it with null and then returning if it's null. The Dart compiler is intelligent enough to understand that after the if-statement, "address" is NOT null anymore since you've already compared it with null and returned from the function.

If you look at the "insteadOfThis" function, the first one, the Dart compiler cannot make the same assumption if you don't first store the value of address in a local variable. In that first function the Dart compiler, even after the if-statement, needs you to refer to address as an optional, using "address?" syntax.

The mechanism the Dart compiler uses in the "doThis()" function is called Type Promotion.

4 lines of #Dart code that include the #spread operator, #cascade #operator, #generics, #extensions, #private prefix and #getters

Functions as First Class Citizens in Dart

Download Details: 
Author: vandadnp
Source Code: https://github.com/vandadnp/flutter-tips-and-tricks

#flutter #dart #programming #developer 

Veronica  Roob

Veronica Roob

1648869960

LaravelS: An Out-Of-The-Box Adapter Between Swoole and Laravel/Lumen

 _                               _  _____ 
| |                             | |/ ____|
| |     __ _ _ __ __ ___   _____| | (___  
| |    / _` | '__/ _` \ \ / / _ \ |\___ \ 
| |___| (_| | | | (_| |\ V /  __/ |____) |
|______\__,_|_|  \__,_| \_/ \___|_|_____/ 
                                           

🚀 LaravelS is an out-of-the-box adapter between Swoole and Laravel/Lumen.

Please Watch this repository to get the latest updates.

中文文档

Features

Built-in Http/WebSocket server

Multi-port mixed protocol

Custom process

Memory resident

Asynchronous event listening

Asynchronous task queue

Millisecond cron job

Common Components

Gracefully reload

Automatically reload after modifying code

Support Laravel/Lumen both, good compatibility

Simple & Out of the box

Benchmark

Which is the fastest web framework?

TechEmpower Framework Benchmarks

Requirements

DependencyRequirement
PHP>= 5.5.9 Recommend PHP7+
Swoole>= 1.7.19 No longer support PHP5 since 2.0.12 Recommend 4.5.0+
Laravel/Lumen>= 5.1 Recommend 8.0+

Install

1.Require package via Composer(packagist).

composer require "hhxsv5/laravel-s:~3.7.0" -vvv
# Make sure that your composer.lock file is under the VCS

2.Register service provider(pick one of two).

Laravel: in config/app.php file, Laravel 5.5+ supports package discovery automatically, you should skip this step

'providers' => [
    //...
    Hhxsv5\LaravelS\Illuminate\LaravelSServiceProvider::class,
],

Lumen: in bootstrap/app.php file

$app->register(Hhxsv5\LaravelS\Illuminate\LaravelSServiceProvider::class);

3.Publish configuration and binaries.

After upgrading LaravelS, you need to republish; click here to see the change notes of each version.

php artisan laravels publish
# Configuration: config/laravels.php
# Binary: bin/laravels bin/fswatch bin/inotify

4.Change config/laravels.php: listen_ip, listen_port, refer Settings.

5.Performance tuning

Adjust kernel parameters

Number of Workers: LaravelS uses Swoole's Synchronous IO mode, the larger the worker_num setting, the better the concurrency performance, but it will cause more memory usage and process switching overhead. If one request takes 100ms, in order to provide 1000QPS concurrency, at least 100 Worker processes need to be configured. The calculation method is: worker_num = 1000QPS/(1s/1ms) = 100, so incremental pressure testing is needed to calculate the best worker_num.

Number of Task Workers

Run

Please read the notices carefully before running, Important notices(IMPORTANT).

  • Commands: php bin/laravels {start|stop|restart|reload|info|help}.
CommandDescription
startStart LaravelS, list the processes by "ps -ef|grep laravels"
stopStop LaravelS, and trigger the method onStop of Custom process
restartRestart LaravelS: Stop gracefully before starting; The service is unavailable until startup is complete
reloadReload all Task/Worker/Timer processes which contain your business codes, and trigger the method onReload of Custom process, CANNOT reload Master/Manger processes. After modifying config/laravels.php, you only have to call restart to restart
infoDisplay component version information
helpDisplay help information
  • Boot options for the commands start and restart.
OptionDescription
-d|--daemonizeRun as a daemon, this option will override the swoole.daemonize setting in laravels.php
-e|--envThe environment the command should run under, such as --env=testing will use the configuration file .env.testing firstly, this feature requires Laravel 5.2+
-i|--ignoreIgnore checking PID file of Master process
-x|--x-versionThe version(branch) of the current project, stored in $_ENV/$_SERVER, access via $_ENV['X_VERSION'] $_SERVER['X_VERSION'] $request->server->get('X_VERSION')
  • Runtime files: start will automatically execute php artisan laravels config and generate these files, developers generally don't need to pay attention to them, it's recommended to add them to .gitignore.
FileDescription
storage/laravels.confLaravelS's runtime configuration file
storage/laravels.pidPID file of Master process
storage/laravels-timer-process.pidPID file of the Timer process
storage/laravels-custom-processes.pidPID file of all custom processes

Deploy

It is recommended to supervise the main process through Supervisord, the premise is without option -d and to set swoole.daemonize to false.

[program:laravel-s-test]
directory=/var/www/laravel-s-test
command=/usr/local/bin/php bin/laravels start -i
numprocs=1
autostart=true
autorestart=true
startretries=3
user=www-data
redirect_stderr=true
stdout_logfile=/var/log/supervisor/%(program_name)s.log

Cooperate with Nginx (Recommended)

Demo.

gzip on;
gzip_min_length 1024;
gzip_comp_level 2;
gzip_types text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml application/x-httpd-php image/jpeg image/gif image/png font/ttf font/otf image/svg+xml;
gzip_vary on;
gzip_disable "msie6";
upstream swoole {
    # Connect IP:Port
    server 127.0.0.1:5200 weight=5 max_fails=3 fail_timeout=30s;
    # Connect UnixSocket Stream file, tips: put the socket file in the /dev/shm directory to get better performance
    #server unix:/yourpath/laravel-s-test/storage/laravels.sock weight=5 max_fails=3 fail_timeout=30s;
    #server 192.168.1.1:5200 weight=3 max_fails=3 fail_timeout=30s;
    #server 192.168.1.2:5200 backup;
    keepalive 16;
}
server {
    listen 80;
    # Don't forget to bind the host
    server_name laravels.com;
    root /yourpath/laravel-s-test/public;
    access_log /yourpath/log/nginx/$server_name.access.log  main;
    autoindex off;
    index index.html index.htm;
    # Nginx handles the static resources(recommend enabling gzip), LaravelS handles the dynamic resource.
    location / {
        try_files $uri @laravels;
    }
    # Response 404 directly when request the PHP file, to avoid exposing public/*.php
    #location ~* \.php$ {
    #    return 404;
    #}
    location @laravels {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout 120s;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        # "swoole" is the upstream
        proxy_pass http://swoole;
    }
}

Cooperate with Apache

LoadModule proxy_module /yourpath/modules/mod_proxy.so
LoadModule proxy_balancer_module /yourpath/modules/mod_proxy_balancer.so
LoadModule lbmethod_byrequests_module /yourpath/modules/mod_lbmethod_byrequests.so
LoadModule proxy_http_module /yourpath/modules/mod_proxy_http.so
LoadModule slotmem_shm_module /yourpath/modules/mod_slotmem_shm.so
LoadModule rewrite_module /yourpath/modules/mod_rewrite.so
LoadModule remoteip_module /yourpath/modules/mod_remoteip.so
LoadModule deflate_module /yourpath/modules/mod_deflate.so

<IfModule deflate_module>
    SetOutputFilter DEFLATE
    DeflateCompressionLevel 2
    AddOutputFilterByType DEFLATE text/html text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml application/x-httpd-php image/jpeg image/gif image/png font/ttf font/otf image/svg+xml
</IfModule>

<VirtualHost *:80>
    # Don't forget to bind the host
    ServerName www.laravels.com
    ServerAdmin hhxsv5@sina.com

    DocumentRoot /yourpath/laravel-s-test/public;
    DirectoryIndex index.html index.htm
    <Directory "/">
        AllowOverride None
        Require all granted
    </Directory>

    RemoteIPHeader X-Forwarded-For

    ProxyRequests Off
    ProxyPreserveHost On
    <Proxy balancer://laravels>  
        BalancerMember http://192.168.1.1:5200 loadfactor=7
        #BalancerMember http://192.168.1.2:5200 loadfactor=3
        #BalancerMember http://192.168.1.3:5200 loadfactor=1 status=+H
        ProxySet lbmethod=byrequests
    </Proxy>
    #ProxyPass / balancer://laravels/
    #ProxyPassReverse / balancer://laravels/

    # Apache handles the static resources, LaravelS handles the dynamic resource.
    RewriteEngine On
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} !-d
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} !-f
    RewriteRule ^/(.*)$ balancer://laravels%{REQUEST_URI} [P,L]

    ErrorLog ${APACHE_LOG_DIR}/www.laravels.com.error.log
    CustomLog ${APACHE_LOG_DIR}/www.laravels.com.access.log combined
</VirtualHost>

Enable WebSocket server

The Listening address of WebSocket Sever is the same as Http Server.

1.Create WebSocket Handler class, and implement interface WebSocketHandlerInterface.The instant is automatically instantiated when start, you do not need to manually create it.

namespace App\Services;
use Hhxsv5\LaravelS\Swoole\WebSocketHandlerInterface;
use Swoole\Http\Request;
use Swoole\Http\Response;
use Swoole\WebSocket\Frame;
use Swoole\WebSocket\Server;
/**
 * @see https://www.swoole.co.uk/docs/modules/swoole-websocket-server
 */
class WebSocketService implements WebSocketHandlerInterface
{
    // Declare constructor without parameters
    public function __construct()
    {
    }
    // public function onHandShake(Request $request, Response $response)
    // {
           // Custom handshake: https://www.swoole.co.uk/docs/modules/swoole-websocket-server-on-handshake
           // The onOpen event will be triggered automatically after a successful handshake
    // }
    public function onOpen(Server $server, Request $request)
    {
        // Before the onOpen event is triggered, the HTTP request to establish the WebSocket has passed the Laravel route,
        // so Laravel's Request, Auth information are readable, Session is readable and writable, but only in the onOpen event.
        // \Log::info('New WebSocket connection', [$request->fd, request()->all(), session()->getId(), session('xxx'), session(['yyy' => time()])]);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $server->push($request->fd, 'Welcome to LaravelS');
    }
    public function onMessage(Server $server, Frame $frame)
    {
        // \Log::info('Received message', [$frame->fd, $frame->data, $frame->opcode, $frame->finish]);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $server->push($frame->fd, date('Y-m-d H:i:s'));
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

2.Modify config/laravels.php.

// ...
'websocket'      => [
    'enable'  => true, // Note: set enable to true
    'handler' => \App\Services\WebSocketService::class,
],
'swoole'         => [
    //...
    // Must set dispatch_mode in (2, 4, 5), see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
    'dispatch_mode' => 2,
    //...
],
// ...

3.Use SwooleTable to bind FD & UserId, optional, Swoole Table Demo. Also you can use the other global storage services, like Redis/Memcached/MySQL, but be careful that FD will be possible conflicting between multiple Swoole Servers.

4.Cooperate with Nginx (Recommended)

Refer WebSocket Proxy

map $http_upgrade $connection_upgrade {
    default upgrade;
    ''      close;
}
upstream swoole {
    # Connect IP:Port
    server 127.0.0.1:5200 weight=5 max_fails=3 fail_timeout=30s;
    # Connect UnixSocket Stream file, tips: put the socket file in the /dev/shm directory to get better performance
    #server unix:/yourpath/laravel-s-test/storage/laravels.sock weight=5 max_fails=3 fail_timeout=30s;
    #server 192.168.1.1:5200 weight=3 max_fails=3 fail_timeout=30s;
    #server 192.168.1.2:5200 backup;
    keepalive 16;
}
server {
    listen 80;
    # Don't forget to bind the host
    server_name laravels.com;
    root /yourpath/laravel-s-test/public;
    access_log /yourpath/log/nginx/$server_name.access.log  main;
    autoindex off;
    index index.html index.htm;
    # Nginx handles the static resources(recommend enabling gzip), LaravelS handles the dynamic resource.
    location / {
        try_files $uri @laravels;
    }
    # Response 404 directly when request the PHP file, to avoid exposing public/*.php
    #location ~* \.php$ {
    #    return 404;
    #}
    # Http and WebSocket are concomitant, Nginx identifies them by "location"
    # !!! The location of WebSocket is "/ws"
    # Javascript: var ws = new WebSocket("ws://laravels.com/ws");
    location =/ws {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout: Nginx will close the connection if the proxied server does not send data to Nginx in 60 seconds; At the same time, this close behavior is also affected by heartbeat setting of Swoole.
        # proxy_read_timeout 60s;
        proxy_http_version 1.1;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
        proxy_pass http://swoole;
    }
    location @laravels {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout 60s;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        proxy_pass http://swoole;
    }
}

5.Heartbeat setting

Heartbeat setting of Swoole

// config/laravels.php
'swoole' => [
    //...
    // All connections are traversed every 60 seconds. If a connection does not send any data to the server within 600 seconds, the connection will be forced to close.
    'heartbeat_idle_time'      => 600,
    'heartbeat_check_interval' => 60,
    //...
],

Proxy read timeout of Nginx

# Nginx will close the connection if the proxied server does not send data to Nginx in 60 seconds
proxy_read_timeout 60s;

6.Push data in controller

namespace App\Http\Controllers;
class TestController extends Controller
{
    public function push()
    {
        $fd = 1; // Find fd by userId from a map [userId=>fd].
        /**@var \Swoole\WebSocket\Server $swoole */
        $swoole = app('swoole');
        $success = $swoole->push($fd, 'Push data to fd#1 in Controller');
        var_dump($success);
    }
}

Listen events

System events

Usually, you can reset/destroy some global/static variables, or change the current Request/Response object.

laravels.received_request After LaravelS parsed Swoole\Http\Request to Illuminate\Http\Request, before Laravel's Kernel handles this request.

// Edit file `app/Providers/EventServiceProvider.php`, add the following code into method `boot`
// If no variable $events, you can also call Facade \Event::listen(). 
$events->listen('laravels.received_request', function (\Illuminate\Http\Request $req, $app) {
    $req->query->set('get_key', 'hhxsv5');// Change query of request
    $req->request->set('post_key', 'hhxsv5'); // Change post of request
});

laravels.generated_response After Laravel's Kernel handled the request, before LaravelS parses Illuminate\Http\Response to Swoole\Http\Response.

// Edit file `app/Providers/EventServiceProvider.php`, add the following code into method `boot`
// If no variable $events, you can also call Facade \Event::listen(). 
$events->listen('laravels.generated_response', function (\Illuminate\Http\Request $req, \Symfony\Component\HttpFoundation\Response $rsp, $app) {
    $rsp->headers->set('header-key', 'hhxsv5');// Change header of response
});

Customized asynchronous events

This feature depends on AsyncTask of Swoole, your need to set swoole.task_worker_num in config/laravels.php firstly. The performance of asynchronous event processing is influenced by number of Swoole task process, you need to set task_worker_num appropriately.

1.Create event class.

use Hhxsv5\LaravelS\Swoole\Task\Event;
class TestEvent extends Event
{
    protected $listeners = [
        // Listener list
        TestListener1::class,
        // TestListener2::class,
    ];
    private $data;
    public function __construct($data)
    {
        $this->data = $data;
    }
    public function getData()
    {
        return $this->data;
    }
}

2.Create listener class.

use Hhxsv5\LaravelS\Swoole\Task\Task;
use Hhxsv5\LaravelS\Swoole\Task\Listener;
class TestListener1 extends Listener
{
    /**
     * @var TestEvent
     */
    protected $event;
    
    public function handle()
    {
        \Log::info(__CLASS__ . ':handle start', [$this->event->getData()]);
        sleep(2);// Simulate the slow codes
        // Deliver task in CronJob, but NOT support callback finish() of task.
        // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
        $ret = Task::deliver(new TestTask('task data'));
        var_dump($ret);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

3.Fire event.

// Create instance of event and fire it, "fire" is asynchronous.
use Hhxsv5\LaravelS\Swoole\Task\Event;
$event = new TestEvent('event data');
// $event->delay(10); // Delay 10 seconds to fire event
// $event->setTries(3); // When an error occurs, try 3 times in total
$success = Event::fire($event);
var_dump($success);// Return true if sucess, otherwise false

Asynchronous task queue

This feature depends on AsyncTask of Swoole, your need to set swoole.task_worker_num in config/laravels.php firstly. The performance of task processing is influenced by number of Swoole task process, you need to set task_worker_num appropriately.

1.Create task class.

use Hhxsv5\LaravelS\Swoole\Task\Task;
class TestTask extends Task
{
    private $data;
    private $result;
    public function __construct($data)
    {
        $this->data = $data;
    }
    // The logic of task handling, run in task process, CAN NOT deliver task
    public function handle()
    {
        \Log::info(__CLASS__ . ':handle start', [$this->data]);
        sleep(2);// Simulate the slow codes
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $this->result = 'the result of ' . $this->data;
    }
    // Optional, finish event, the logic of after task handling, run in worker process, CAN deliver task 
    public function finish()
    {
        \Log::info(__CLASS__ . ':finish start', [$this->result]);
        Task::deliver(new TestTask2('task2 data')); // Deliver the other task
    }
}

2.Deliver task.

// Create instance of TestTask and deliver it, "deliver" is asynchronous.
use Hhxsv5\LaravelS\Swoole\Task\Task;
$task = new TestTask('task data');
// $task->delay(3);// delay 3 seconds to deliver task
// $task->setTries(3); // When an error occurs, try 3 times in total
$ret = Task::deliver($task);
var_dump($ret);// Return true if sucess, otherwise false

Millisecond cron job

Wrapper cron job base on Swoole's Millisecond Timer, replace Linux Crontab.

1.Create cron job class.

namespace App\Jobs\Timer;
use App\Tasks\TestTask;
use Swoole\Coroutine;
use Hhxsv5\LaravelS\Swoole\Task\Task;
use Hhxsv5\LaravelS\Swoole\Timer\CronJob;
class TestCronJob extends CronJob
{
    protected $i = 0;
    // !!! The `interval` and `isImmediate` of cron job can be configured in two ways(pick one of two): one is to overload the corresponding method, and the other is to pass parameters when registering cron job.
    // --- Override the corresponding method to return the configuration: begin
    public function interval()
    {
        return 1000;// Run every 1000ms
    }
    public function isImmediate()
    {
        return false;// Whether to trigger `run` immediately after setting up
    }
    // --- Override the corresponding method to return the configuration: end
    public function run()
    {
        \Log::info(__METHOD__, ['start', $this->i, microtime(true)]);
        // do something
        // sleep(1); // Swoole < 2.1
        Coroutine::sleep(1); // Swoole>=2.1 Coroutine will be automatically created for run().
        $this->i++;
        \Log::info(__METHOD__, ['end', $this->i, microtime(true)]);

        if ($this->i >= 10) { // Run 10 times only
            \Log::info(__METHOD__, ['stop', $this->i, microtime(true)]);
            $this->stop(); // Stop this cron job, but it will run again after restart/reload.
            // Deliver task in CronJob, but NOT support callback finish() of task.
            // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
            $ret = Task::deliver(new TestTask('task data'));
            var_dump($ret);
        }
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

2.Register cron job.

// Register cron jobs in file "config/laravels.php"
[
    // ...
    'timer'          => [
        'enable' => true, // Enable Timer
        'jobs'   => [ // The list of cron job
            // Enable LaravelScheduleJob to run `php artisan schedule:run` every 1 minute, replace Linux Crontab
            // \Hhxsv5\LaravelS\Illuminate\LaravelScheduleJob::class,
            // Two ways to configure parameters:
            // [\App\Jobs\Timer\TestCronJob::class, [1000, true]], // Pass in parameters when registering
            \App\Jobs\Timer\TestCronJob::class, // Override the corresponding method to return the configuration
        ],
        'max_wait_time' => 5, // Max waiting time of reloading
        // Enable the global lock to ensure that only one instance starts the timer when deploying multiple instances. This feature depends on Redis, please see https://laravel.com/docs/7.x/redis
        'global_lock'     => false,
        'global_lock_key' => config('app.name', 'Laravel'),
    ],
    // ...
];

3.Note: it will launch multiple timers when build the server cluster, so you need to make sure that launch one timer only to avoid running repetitive task.

4.LaravelS v3.4.0 starts to support the hot restart [Reload] Timer process. After LaravelS receives the SIGUSR1 signal, it waits for max_wait_time(default 5) seconds to end the process, then the Manager process will pull up the Timer process again.

5.If you only need to use minute-level scheduled tasks, it is recommended to enable Hhxsv5\LaravelS\Illuminate\LaravelScheduleJob instead of Linux Crontab, so that you can follow the coding habits of Laravel task scheduling and configure Kernel.

// app/Console/Kernel.php
protected function schedule(Schedule $schedule)
{
    // runInBackground() will start a new child process to execute the task. This is asynchronous and will not affect the execution timing of other tasks.
    $schedule->command(TestCommand::class)->runInBackground()->everyMinute();
}

Automatically reload after modifying code

Via inotify, support Linux only.

1.Install inotify extension.

2.Turn on the switch in Settings.

3.Notice: Modify the file only in Linux to receive the file change events. It's recommended to use the latest Docker. Vagrant Solution.

Via fswatch, support OS X/Linux/Windows.

1.Install fswatch.

2.Run command in your project root directory.

# Watch current directory
./bin/fswatch
# Watch app directory
./bin/fswatch ./app

Via inotifywait, support Linux.

1.Install inotify-tools.

2.Run command in your project root directory.

# Watch current directory
./bin/inotify
# Watch app directory
./bin/inotify ./app

When the above methods does not work, the ultimate solution: set max_request=1,worker_num=1, so that Worker process will restart after processing a request. The performance of this method is very poor, so only development environment use.

Get the instance of SwooleServer in your project

/**
 * $swoole is the instance of `Swoole\WebSocket\Server` if enable WebSocket server, otherwise `Swoole\Http\Server`
 * @var \Swoole\WebSocket\Server|\Swoole\Http\Server $swoole
 */
$swoole = app('swoole');
var_dump($swoole->stats());
$swoole->push($fd, 'Push WebSocket message');

Use SwooleTable

1.Define Table, support multiple.

All defined tables will be created before Swoole starting.

// in file "config/laravels.php"
[
    // ...
    'swoole_tables'  => [
        // Scene:bind UserId & FD in WebSocket
        'ws' => [// The Key is table name, will add suffix "Table" to avoid naming conflicts. Here defined a table named "wsTable"
            'size'   => 102400,// The max size
            'column' => [// Define the columns
                ['name' => 'value', 'type' => \Swoole\Table::TYPE_INT, 'size' => 8],
            ],
        ],
        //...Define the other tables
    ],
    // ...
];

2.Access Table: all table instances will be bound on SwooleServer, access by app('swoole')->xxxTable.

namespace App\Services;
use Hhxsv5\LaravelS\Swoole\WebSocketHandlerInterface;
use Swoole\Http\Request;
use Swoole\WebSocket\Frame;
use Swoole\WebSocket\Server;
class WebSocketService implements WebSocketHandlerInterface
{
    /**@var \Swoole\Table $wsTable */
    private $wsTable;
    public function __construct()
    {
        $this->wsTable = app('swoole')->wsTable;
    }
    // Scene:bind UserId & FD in WebSocket
    public function onOpen(Server $server, Request $request)
    {
        // var_dump(app('swoole') === $server);// The same instance
        /**
         * Get the currently logged in user
         * This feature requires that the path to establish a WebSocket connection go through middleware such as Authenticate.
         * E.g:
         * Browser side: var ws = new WebSocket("ws://127.0.0.1:5200/ws");
         * Then the /ws route in Laravel needs to add the middleware like Authenticate.
         * Route::get('/ws', function () {
         *     // Respond any content with status code 200
         *     return 'websocket';
         * })->middleware(['auth']);
         */
        // $user = Auth::user();
        // $userId = $user ? $user->id : 0; // 0 means a guest user who is not logged in
        $userId = mt_rand(1000, 10000);
        // if (!$userId) {
        //     // Disconnect the connections of unlogged users
        //     $server->disconnect($request->fd);
        //     return;
        // }
        $this->wsTable->set('uid:' . $userId, ['value' => $request->fd]);// Bind map uid to fd
        $this->wsTable->set('fd:' . $request->fd, ['value' => $userId]);// Bind map fd to uid
        $server->push($request->fd, "Welcome to LaravelS #{$request->fd}");
    }
    public function onMessage(Server $server, Frame $frame)
    {
        // Broadcast
        foreach ($this->wsTable as $key => $row) {
            if (strpos($key, 'uid:') === 0 && $server->isEstablished($row['value'])) {
                $content = sprintf('Broadcast: new message "%s" from #%d', $frame->data, $frame->fd);
                $server->push($row['value'], $content);
            }
        }
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        $uid = $this->wsTable->get('fd:' . $fd);
        if ($uid !== false) {
            $this->wsTable->del('uid:' . $uid['value']); // Unbind uid map
        }
        $this->wsTable->del('fd:' . $fd);// Unbind fd map
        $server->push($fd, "Goodbye #{$fd}");
    }
}

Multi-port mixed protocol

For more information, please refer to Swoole Server AddListener

To make our main server support more protocols not just Http and WebSocket, we bring the feature multi-port mixed protocol of Swoole in LaravelS and name it Socket. Now, you can build TCP/UDP applications easily on top of Laravel.

Create Socket handler class, and extend Hhxsv5\LaravelS\Swoole\Socket\{TcpSocket|UdpSocket|Http|WebSocket}.

namespace App\Sockets;
use Hhxsv5\LaravelS\Swoole\Socket\TcpSocket;
use Swoole\Server;
class TestTcpSocket extends TcpSocket
{
    public function onConnect(Server $server, $fd, $reactorId)
    {
        \Log::info('New TCP connection', [$fd]);
        $server->send($fd, 'Welcome to LaravelS.');
    }
    public function onReceive(Server $server, $fd, $reactorId, $data)
    {
        \Log::info('Received data', [$fd, $data]);
        $server->send($fd, 'LaravelS: ' . $data);
        if ($data === "quit\r\n") {
            $server->send($fd, 'LaravelS: bye' . PHP_EOL);
            $server->close($fd);
        }
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        \Log::info('Close TCP connection', [$fd]);
        $server->send($fd, 'Goodbye');
    }
}

These Socket connections share the same worker processes with your HTTP/WebSocket connections. So it won't be a problem at all if you want to deliver tasks, use SwooleTable, even Laravel components such as DB, Eloquent and so on. At the same time, you can access Swoole\Server\Port object directly by member property swoolePort.

public function onReceive(Server $server, $fd, $reactorId, $data)
{
    $port = $this->swoolePort; // Get the `Swoole\Server\Port` object
}
namespace App\Http\Controllers;
class TestController extends Controller
{
    public function test()
    {
        /**@var \Swoole\Http\Server|\Swoole\WebSocket\Server $swoole */
        $swoole = app('swoole');
        // $swoole->ports: Traverse all Port objects, https://www.swoole.co.uk/docs/modules/swoole-server/multiple-ports
        $port = $swoole->ports[0]; // Get the `Swoole\Server\Port` object, $port[0] is the port of the main server
        foreach ($port->connections as $fd) { // Traverse all connections
            // $swoole->send($fd, 'Send tcp message');
            // if($swoole->isEstablished($fd)) {
            //     $swoole->push($fd, 'Send websocket message');
            // }
        }
    }
}

Register Sockets.

// Edit `config/laravels.php`
//...
'sockets' => [
    [
        'host'     => '127.0.0.1',
        'port'     => 5291,
        'type'     => SWOOLE_SOCK_TCP,// Socket type: SWOOLE_SOCK_TCP/SWOOLE_SOCK_TCP6/SWOOLE_SOCK_UDP/SWOOLE_SOCK_UDP6/SWOOLE_UNIX_DGRAM/SWOOLE_UNIX_STREAM
        'settings' => [// Swoole settings:https://www.swoole.co.uk/docs/modules/swoole-server-methods#swoole_server-addlistener
            'open_eof_check' => true,
            'package_eof'    => "\r\n",
        ],
        'handler'  => \App\Sockets\TestTcpSocket::class,
        'enable'   => true, // whether to enable, default true
    ],
],

About the heartbeat configuration, it can only be set on the main server and cannot be configured on Socket, but the Socket inherits the heartbeat configuration of the main server.

For TCP socket, onConnect and onClose events will be blocked when dispatch_mode of Swoole is 1/3, so if you want to unblock these two events please set dispatch_mode to 2/4/5.

'swoole' => [
    //...
    'dispatch_mode' => 2,
    //...
];

Test.

TCP: telnet 127.0.0.1 5291

UDP: [Linux] echo "Hello LaravelS" > /dev/udp/127.0.0.1/5292

Register example of other protocols.

  • UDP
  • Http
  • WebSocket: The main server must turn on WebSocket, that is, set websocket.enable to true.

Coroutine

Swoole Coroutine

Warning: The order of code execution in the coroutine is out of order. The data of the request level should be isolated by the coroutine ID. However, there are many singleton and static attributes in Laravel/Lumen, the data between different requests will affect each other, it's Unsafe. For example, the database connection is a singleton, the same database connection shares the same PDO resource. This is fine in the synchronous blocking mode, but it does not work in the asynchronous coroutine mode. Each query needs to create different connections and maintain IO state of different connections, which requires a connection pool.

DO NOT enable the coroutine, only the custom process can use the coroutine.

Custom process

Support developers to create special work processes for monitoring, reporting, or other special tasks. Refer addProcess.

Create Proccess class, implements CustomProcessInterface.

namespace App\Processes;
use App\Tasks\TestTask;
use Hhxsv5\LaravelS\Swoole\Process\CustomProcessInterface;
use Hhxsv5\LaravelS\Swoole\Task\Task;
use Swoole\Coroutine;
use Swoole\Http\Server;
use Swoole\Process;
class TestProcess implements CustomProcessInterface
{
    /**
     * @var bool Quit tag for Reload updates
     */
    private static $quit = false;

    public static function callback(Server $swoole, Process $process)
    {
        // The callback method cannot exit. Once exited, Manager process will automatically create the process 
        while (!self::$quit) {
            \Log::info('Test process: running');
            // sleep(1); // Swoole < 2.1
            Coroutine::sleep(1); // Swoole>=2.1: Coroutine & Runtime will be automatically enabled for callback().
             // Deliver task in custom process, but NOT support callback finish() of task.
            // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
            $ret = Task::deliver(new TestTask('task data'));
            var_dump($ret);
            // The upper layer will catch the exception thrown in the callback and record it in the Swoole log, and then this process will exit. The Manager process will re-create the process after 3 seconds, so developers need to try/catch to catch the exception by themselves to avoid frequent process creation.
            // throw new \Exception('an exception');
        }
    }
    // Requirements: LaravelS >= v3.4.0 & callback() must be async non-blocking program.
    public static function onReload(Server $swoole, Process $process)
    {
        // Stop the process...
        // Then end process
        \Log::info('Test process: reloading');
        self::$quit = true;
        // $process->exit(0); // Force exit process
    }
    // Requirements: LaravelS >= v3.7.4 & callback() must be async non-blocking program.
    public static function onStop(Server $swoole, Process $process)
    {
        // Stop the process...
        // Then end process
        \Log::info('Test process: stopping');
        self::$quit = true;
        // $process->exit(0); // Force exit process
    }
}

Register TestProcess.

// Edit `config/laravels.php`
// ...
'processes' => [
    'test' => [ // Key name is process name
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false, // Whether redirect stdin/stdout, true or false
        'pipe'     => 0,     // The type of pipeline, 0: no pipeline 1: SOCK_STREAM 2: SOCK_DGRAM
        'enable'   => true,  // Whether to enable, default true
        //'num'    => 3   // To create multiple processes of this class, default is 1
        //'queue'    => [ // Enable message queue as inter-process communication, configure empty array means use default parameters
        //    'msg_key'  => 0,    // The key of the message queue. Default: ftok(__FILE__, 1).
        //    'mode'     => 2,    // Communication mode, default is 2, which means contention mode
        //    'capacity' => 8192, // The length of a single message, is limited by the operating system kernel parameters. The default is 8192, and the maximum is 65536
        //],
        //'restart_interval' => 5, // After the process exits abnormally, how many seconds to wait before restarting the process, default 5 seconds
    ],
],

Note: The callback() cannot quit. If quit, the Manager process will re-create the process.

Example: Write data to a custom process.

// config/laravels.php
'processes' => [
    'test' => [
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false,
        'pipe'     => 1,
    ],
],
// app/Processes/TestProcess.php
public static function callback(Server $swoole, Process $process)
{
    while ($data = $process->read()) {
        \Log::info('TestProcess: read data', [$data]);
        $process->write('TestProcess: ' . $data);
    }
}
// app/Http/Controllers/TestController.php
public function testProcessWrite()
{
    /**@var \Swoole\Process $process */
    $process = app('swoole')->customProcesses['test'];
    $process->write('TestController: write data' . time());
    var_dump($process->read());
}

Common components

Apollo

LaravelS will pull the Apollo configuration and write it to the .env file when starting. At the same time, LaravelS will start the custom process apollo to monitor the configuration and automatically reload when the configuration changes.

Enable Apollo: add --enable-apollo and Apollo parameters to the startup parameters.

php bin/laravels start --enable-apollo --apollo-server=http://127.0.0.1:8080 --apollo-app-id=LARAVEL-S-TEST

Support hot updates(optional).

// Edit `config/laravels.php`
'processes' => Hhxsv5\LaravelS\Components\Apollo\Process::getDefinition(),
// When there are other custom process configurations
'processes' => [
    'test' => [
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false,
        'pipe'     => 1,
    ],
    // ...
] + Hhxsv5\LaravelS\Components\Apollo\Process::getDefinition(),

List of available parameters.

ParameterDescriptionDefaultDemo
apollo-serverApollo server URL---apollo-server=http://127.0.0.1:8080
apollo-app-idApollo APP ID---apollo-app-id=LARAVEL-S-TEST
apollo-namespacesThe namespace to which the APP belongs, support specify the multipleapplication--apollo-namespaces=application --apollo-namespaces=env
apollo-clusterThe cluster to which the APP belongsdefault--apollo-cluster=default
apollo-client-ipIP of current instance, can also be used for grayscale publishingLocal intranet IP--apollo-client-ip=10.2.1.83
apollo-pull-timeoutTimeout time(seconds) when pulling configuration5--apollo-pull-timeout=5
apollo-backup-old-envWhether to backup the old configuration file when updating the configuration file .envfalse--apollo-backup-old-env

Prometheus

Support Prometheus monitoring and alarm, Grafana visually view monitoring metrics. Please refer to Docker Compose for the environment construction of Prometheus and Grafana.

Require extension APCu >= 5.0.0, please install it by pecl install apcu.

Copy the configuration file prometheus.php to the config directory of your project. Modify the configuration as appropriate.

# Execute commands in the project root directory
cp vendor/hhxsv5/laravel-s/config/prometheus.php config/

If your project is Lumen, you also need to manually load the configuration $app->configure('prometheus'); in bootstrap/app.php.

Configure global middleware: Hhxsv5\LaravelS\Components\Prometheus\RequestMiddleware::class. In order to count the request time consumption as accurately as possible, RequestMiddleware must be the first global middleware, which needs to be placed in front of other middleware.

Register ServiceProvider: Hhxsv5\LaravelS\Components\Prometheus\ServiceProvider::class.

Configure the CollectorProcess in config/laravels.php to collect the metrics of Swoole Worker/Task/Timer processes regularly.

'processes' => Hhxsv5\LaravelS\Components\Prometheus\CollectorProcess::getDefinition(),

Create the route to output metrics.

use Hhxsv5\LaravelS\Components\Prometheus\Exporter;

Route::get('/actuator/prometheus', function () {
    $result = app(Exporter::class)->render();
    return response($result, 200, ['Content-Type' => Exporter::REDNER_MIME_TYPE]);
});

Complete the configuration of Prometheus and start it.

global:
  scrape_interval: 5s
  scrape_timeout: 5s
  evaluation_interval: 30s
scrape_configs:
- job_name: laravel-s-test
  honor_timestamps: true
  metrics_path: /actuator/prometheus
  scheme: http
  follow_redirects: true
  static_configs:
  - targets:
    - 127.0.0.1:5200 # The ip and port of the monitored service
# Dynamically discovered using one of the supported service-discovery mechanisms
# https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config
# - job_name: laravels-eureka
#   honor_timestamps: true
#   scrape_interval: 5s
#   metrics_path: /actuator/prometheus
#   scheme: http
#   follow_redirects: true
  # eureka_sd_configs:
  # - server: http://127.0.0.1:8080/eureka
  #   follow_redirects: true
  #   refresh_interval: 5s

Start Grafana, then import panel json.

Grafana Dashboard

Other features

Configure Swoole events

Supported events:

EventInterfaceWhen happened
ServerStartHhxsv5\LaravelS\Swoole\Events\ServerStartInterfaceOccurs when the Master process is starting, this event should not handle complex business logic, and can only do some simple work of initialization.
ServerStopHhxsv5\LaravelS\Swoole\Events\ServerStopInterfaceOccurs when the server exits normally, CANNOT use async or coroutine related APIs in this event.
WorkerStartHhxsv5\LaravelS\Swoole\Events\WorkerStartInterfaceOccurs after the Worker/Task process is started, and the Laravel initialization has been completed.
WorkerStopHhxsv5\LaravelS\Swoole\Events\WorkerStopInterfaceOccurs after the Worker/Task process exits normally
WorkerErrorHhxsv5\LaravelS\Swoole\Events\WorkerErrorInterfaceOccurs when an exception or fatal error occurs in the Worker/Task process

1.Create an event class to implement the corresponding interface.

namespace App\Events;
use Hhxsv5\LaravelS\Swoole\Events\ServerStartInterface;
use Swoole\Atomic;
use Swoole\Http\Server;
class ServerStartEvent implements ServerStartInterface
{
    public function __construct()
    {
    }
    public function handle(Server $server)
    {
        // Initialize a global counter (available across processes)
        $server->atomicCount = new Atomic(2233);

        // Invoked in controller: app('swoole')->atomicCount->get();
    }
}
namespace App\Events;
use Hhxsv5\LaravelS\Swoole\Events\WorkerStartInterface;
use Swoole\Http\Server;
class WorkerStartEvent implements WorkerStartInterface
{
    public function __construct()
    {
    }
    public function handle(Server $server, $workerId)
    {
        // Initialize a database connection pool
        // DatabaseConnectionPool::init();
    }
}

2.Configuration.

// Edit `config/laravels.php`
'event_handlers' => [
    'ServerStart' => [\App\Events\ServerStartEvent::class], // Trigger events in array order
    'WorkerStart' => [\App\Events\WorkerStartEvent::class],
],

Serverless

Alibaba Cloud Function Compute

Function Compute.

1.Modify bootstrap/app.php and set the storage directory. Because the project directory is read-only, the /tmp directory can only be read and written.

$app->useStoragePath(env('APP_STORAGE_PATH', '/tmp/storage'));

2.Create a shell script laravels_bootstrap and grant executable permission.

#!/usr/bin/env bash
set +e

# Create storage-related directories
mkdir -p /tmp/storage/app/public
mkdir -p /tmp/storage/framework/cache
mkdir -p /tmp/storage/framework/sessions
mkdir -p /tmp/storage/framework/testing
mkdir -p /tmp/storage/framework/views
mkdir -p /tmp/storage/logs

# Set the environment variable APP_STORAGE_PATH, please make sure it's the same as APP_STORAGE_PATH in .env
export APP_STORAGE_PATH=/tmp/storage

# Start LaravelS
php bin/laravels start

3.Configure template.xml.

ROSTemplateFormatVersion: '2015-09-01'
Transform: 'Aliyun::Serverless-2018-04-03'
Resources:
  laravel-s-demo:
    Type: 'Aliyun::Serverless::Service'
    Properties:
      Description: 'LaravelS Demo for Serverless'
    fc-laravel-s:
      Type: 'Aliyun::Serverless::Function'
      Properties:
        Handler: laravels.handler
        Runtime: custom
        MemorySize: 512
        Timeout: 30
        CodeUri: ./
        InstanceConcurrency: 10
        EnvironmentVariables:
          BOOTSTRAP_FILE: laravels_bootstrap

Important notices

Singleton Issue

Under FPM mode, singleton instances will be instantiated and recycled in every request, request start=>instantiate instance=>request end=>recycled instance.

Under Swoole Server, All singleton instances will be held in memory, different lifetime from FPM, request start=>instantiate instance=>request end=>do not recycle singleton instance. So need developer to maintain status of singleton instances in every request.

Common solutions:

Write a XxxCleaner class to clean up the singleton object state. This class implements the interface Hhxsv5\LaravelS\Illuminate\Cleaners\CleanerInterface and then registers it in cleaners of laravels.php.

Reset status of singleton instances by Middleware.

Re-register ServiceProvider, add XxxServiceProvider into register_providers of file laravels.php. So that reinitialize singleton instances in every request Refer.

Cleaners

Configuration cleaners.

Known issues

Known issues: a package of known issues and solutions.

Debugging method

Logging; if you want to output to the console, you can use stderr, Log::channel('stderr')->debug('debug message').

Laravel Dump Server(Laravel 5.7 has been integrated by default).

Read request

Read request by Illuminate\Http\Request Object, $_ENV is readable, $_SERVER is partially readable, CANNOT USE $_GET/$_POST/$_FILES/$_COOKIE/$_REQUEST/$_SESSION/$GLOBALS.

public function form(\Illuminate\Http\Request $request)
{
    $name = $request->input('name');
    $all = $request->all();
    $sessionId = $request->cookie('sessionId');
    $photo = $request->file('photo');
    // Call getContent() to get the raw POST body, instead of file_get_contents('php://input')
    $rawContent = $request->getContent();
    //...
}

Output response

Respond by Illuminate\Http\Response Object, compatible with echo/vardump()/print_r(),CANNOT USE functions dd()/exit()/die()/header()/setcookie()/http_response_code().

public function json()
{
    return response()->json(['time' => time()])->header('header1', 'value1')->withCookie('c1', 'v1');
}

Persistent connection

Singleton connection will be resident in memory, it is recommended to turn on persistent connection for better performance.

Database connection, it will reconnect automatically immediately after disconnect.

// config/database.php
'connections' => [
    'my_conn' => [
        'driver'    => 'mysql',
        'host'      => env('DB_MY_CONN_HOST', 'localhost'),
        'port'      => env('DB_MY_CONN_PORT', 3306),
        'database'  => env('DB_MY_CONN_DATABASE', 'forge'),
        'username'  => env('DB_MY_CONN_USERNAME', 'forge'),
        'password'  => env('DB_MY_CONN_PASSWORD', ''),
        'charset'   => 'utf8mb4',
        'collation' => 'utf8mb4_unicode_ci',
        'prefix'    => '',
        'strict'    => false,
        'options'   => [
            // Enable persistent connection
            \PDO::ATTR_PERSISTENT => true,
        ],
    ],
],

Redis connection, it won't reconnect automatically immediately after disconnect, and will throw an exception about lost connection, reconnect next time. You need to make sure that SELECT DB correctly before operating Redis every time.

// config/database.php
'redis' => [
    'client' => env('REDIS_CLIENT', 'phpredis'), // It is recommended to use phpredis for better performance.
    'default' => [
        'host'       => env('REDIS_HOST', 'localhost'),
        'password'   => env('REDIS_PASSWORD', null),
        'port'       => env('REDIS_PORT', 6379),
        'database'   => 0,
        'persistent' => true, // Enable persistent connection
    ],
],

About memory leaks

Avoid using global variables. If necessary, please clean or reset them manually.

Infinitely appending element into static/global variable will lead to OOM(Out of Memory).

class Test
{
    public static $array = [];
    public static $string = '';
}

// Controller
public function test(Request $req)
{
    // Out of Memory
    Test::$array[] = $req->input('param1');
    Test::$string .= $req->input('param2');
}

Memory leak detection method

Modify config/laravels.php: worker_num=1, max_request=1000000, remember to change it back after test;

Add routing /debug-memory-leak without route middleware to observe the memory changes of the Worker process;

Start LaravelS and request /debug-memory-leak until diff_mem is less than or equal to zero; if diff_mem is always greater than zero, it means that there may be a memory leak in Global Middleware or Laravel Framework;

After completing Step 3, alternately request the business routes and /debug-memory-leak (It is recommended to use ab/wrk to make a large number of requests for business routes), the initial increase in memory is normal. After a large number of requests for the business routes, if diff_mem is always greater than zero and curr_mem continues to increase, there is a high probability of memory leak; If curr_mem always changes within a certain range and does not continue to increase, there is a low probability of memory leak.

If you still can't solve it, max_request is the last guarantee.

Linux kernel parameter adjustment

Linux kernel parameter adjustment

Pressure test

Pressure test

Alternatives

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License

MIT

Author: hhxsv5
Source Code: https://github.com/hhxsv5/laravel-s
License: MIT License

#php #laravel 

Daniel  Hughes

Daniel Hughes

1649214000

LaravelS: Glue for using Swoole in Laravel Or Lumen.

🚀 LaravelS is an out-of-the-box adapter between Swoole and Laravel/Lumen.

Please Watch this repository to get the latest updates.

中文文档

Table of Contents

Features

Built-in Http/WebSocket server

Multi-port mixed protocol

Custom process

Memory resident

Asynchronous event listening

Asynchronous task queue

Millisecond cron job

Common Components

Gracefully reload

Automatically reload after modifying code

Support Laravel/Lumen both, good compatibility

Simple & Out of the box

Benchmark

Which is the fastest web framework?

TechEmpower Framework Benchmarks

Requirements

DependencyRequirement
PHP>= 5.5.9 Recommend PHP7+
Swoole>= 1.7.19 No longer support PHP5 since 2.0.12 Recommend 4.5.0+
Laravel/Lumen>= 5.1 Recommend 8.0+

Install

1.Require package via Composer(packagist).

composer require "hhxsv5/laravel-s:~3.7.0" -vvv
# Make sure that your composer.lock file is under the VCS

2.Register service provider(pick one of two).

Laravel: in config/app.php file, Laravel 5.5+ supports package discovery automatically, you should skip this step

'providers' => [
    //...
    Hhxsv5\LaravelS\Illuminate\LaravelSServiceProvider::class,
],

Lumen: in bootstrap/app.php file

$app->register(Hhxsv5\LaravelS\Illuminate\LaravelSServiceProvider::class);

3.Publish configuration and binaries.

After upgrading LaravelS, you need to republish; click here to see the change notes of each version.

php artisan laravels publish
# Configuration: config/laravels.php
# Binary: bin/laravels bin/fswatch bin/inotify

4.Change config/laravels.php: listen_ip, listen_port, refer Settings.

5.Performance tuning

Adjust kernel parameters

Number of Workers: LaravelS uses Swoole's Synchronous IO mode, the larger the worker_num setting, the better the concurrency performance, but it will cause more memory usage and process switching overhead. If one request takes 100ms, in order to provide 1000QPS concurrency, at least 100 Worker processes need to be configured. The calculation method is: worker_num = 1000QPS/(1s/1ms) = 100, so incremental pressure testing is needed to calculate the best worker_num.

Number of Task Workers

Run

Please read the notices carefully before running, Important notices(IMPORTANT).

  • Commands: php bin/laravels {start|stop|restart|reload|info|help}.
CommandDescription
startStart LaravelS, list the processes by "ps -ef|grep laravels"
stopStop LaravelS, and trigger the method onStop of Custom process
restartRestart LaravelS: Stop gracefully before starting; The service is unavailable until startup is complete
reloadReload all Task/Worker/Timer processes which contain your business codes, and trigger the method onReload of Custom process, CANNOT reload Master/Manger processes. After modifying config/laravels.php, you only have to call restart to restart
infoDisplay component version information
helpDisplay help information
  • Boot options for the commands start and restart.
OptionDescription
-d|--daemonizeRun as a daemon, this option will override the swoole.daemonize setting in laravels.php
-e|--envThe environment the command should run under, such as --env=testing will use the configuration file .env.testing firstly, this feature requires Laravel 5.2+
-i|--ignoreIgnore checking PID file of Master process
-x|--x-versionThe version(branch) of the current project, stored in $_ENV/$_SERVER, access via $_ENV['X_VERSION'] $_SERVER['X_VERSION'] $request->server->get('X_VERSION')
  • Runtime files: start will automatically execute php artisan laravels config and generate these files, developers generally don't need to pay attention to them, it's recommended to add them to .gitignore.
FileDescription
storage/laravels.confLaravelS's runtime configuration file
storage/laravels.pidPID file of Master process
storage/laravels-timer-process.pidPID file of the Timer process
storage/laravels-custom-processes.pidPID file of all custom processes

Deploy

It is recommended to supervise the main process through Supervisord, the premise is without option -d and to set swoole.daemonize to false.

[program:laravel-s-test]
directory=/var/www/laravel-s-test
command=/usr/local/bin/php bin/laravels start -i
numprocs=1
autostart=true
autorestart=true
startretries=3
user=www-data
redirect_stderr=true
stdout_logfile=/var/log/supervisor/%(program_name)s.log

Cooperate with Nginx (Recommended)

Demo.

gzip on;
gzip_min_length 1024;
gzip_comp_level 2;
gzip_types text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml application/x-httpd-php image/jpeg image/gif image/png font/ttf font/otf image/svg+xml;
gzip_vary on;
gzip_disable "msie6";
upstream swoole {
    # Connect IP:Port
    server 127.0.0.1:5200 weight=5 max_fails=3 fail_timeout=30s;
    # Connect UnixSocket Stream file, tips: put the socket file in the /dev/shm directory to get better performance
    #server unix:/yourpath/laravel-s-test/storage/laravels.sock weight=5 max_fails=3 fail_timeout=30s;
    #server 192.168.1.1:5200 weight=3 max_fails=3 fail_timeout=30s;
    #server 192.168.1.2:5200 backup;
    keepalive 16;
}
server {
    listen 80;
    # Don't forget to bind the host
    server_name laravels.com;
    root /yourpath/laravel-s-test/public;
    access_log /yourpath/log/nginx/$server_name.access.log  main;
    autoindex off;
    index index.html index.htm;
    # Nginx handles the static resources(recommend enabling gzip), LaravelS handles the dynamic resource.
    location / {
        try_files $uri @laravels;
    }
    # Response 404 directly when request the PHP file, to avoid exposing public/*.php
    #location ~* \.php$ {
    #    return 404;
    #}
    location @laravels {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout 120s;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        # "swoole" is the upstream
        proxy_pass http://swoole;
    }
}

Cooperate with Apache

LoadModule proxy_module /yourpath/modules/mod_proxy.so
LoadModule proxy_balancer_module /yourpath/modules/mod_proxy_balancer.so
LoadModule lbmethod_byrequests_module /yourpath/modules/mod_lbmethod_byrequests.so
LoadModule proxy_http_module /yourpath/modules/mod_proxy_http.so
LoadModule slotmem_shm_module /yourpath/modules/mod_slotmem_shm.so
LoadModule rewrite_module /yourpath/modules/mod_rewrite.so
LoadModule remoteip_module /yourpath/modules/mod_remoteip.so
LoadModule deflate_module /yourpath/modules/mod_deflate.so

<IfModule deflate_module>
    SetOutputFilter DEFLATE
    DeflateCompressionLevel 2
    AddOutputFilterByType DEFLATE text/html text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml application/x-httpd-php image/jpeg image/gif image/png font/ttf font/otf image/svg+xml
</IfModule>

<VirtualHost *:80>
    # Don't forget to bind the host
    ServerName www.laravels.com
    ServerAdmin hhxsv5@sina.com

    DocumentRoot /yourpath/laravel-s-test/public;
    DirectoryIndex index.html index.htm
    <Directory "/">
        AllowOverride None
        Require all granted
    </Directory>

    RemoteIPHeader X-Forwarded-For

    ProxyRequests Off
    ProxyPreserveHost On
    <Proxy balancer://laravels>  
        BalancerMember http://192.168.1.1:5200 loadfactor=7
        #BalancerMember http://192.168.1.2:5200 loadfactor=3
        #BalancerMember http://192.168.1.3:5200 loadfactor=1 status=+H
        ProxySet lbmethod=byrequests
    </Proxy>
    #ProxyPass / balancer://laravels/
    #ProxyPassReverse / balancer://laravels/

    # Apache handles the static resources, LaravelS handles the dynamic resource.
    RewriteEngine On
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} !-d
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} !-f
    RewriteRule ^/(.*)$ balancer://laravels%{REQUEST_URI} [P,L]

    ErrorLog ${APACHE_LOG_DIR}/www.laravels.com.error.log
    CustomLog ${APACHE_LOG_DIR}/www.laravels.com.access.log combined
</VirtualHost>

Enable WebSocket server

The Listening address of WebSocket Sever is the same as Http Server.

1.Create WebSocket Handler class, and implement interface WebSocketHandlerInterface.The instant is automatically instantiated when start, you do not need to manually create it.

namespace App\Services;
use Hhxsv5\LaravelS\Swoole\WebSocketHandlerInterface;
use Swoole\Http\Request;
use Swoole\Http\Response;
use Swoole\WebSocket\Frame;
use Swoole\WebSocket\Server;
/**
 * @see https://www.swoole.co.uk/docs/modules/swoole-websocket-server
 */
class WebSocketService implements WebSocketHandlerInterface
{
    // Declare constructor without parameters
    public function __construct()
    {
    }
    // public function onHandShake(Request $request, Response $response)
    // {
           // Custom handshake: https://www.swoole.co.uk/docs/modules/swoole-websocket-server-on-handshake
           // The onOpen event will be triggered automatically after a successful handshake
    // }
    public function onOpen(Server $server, Request $request)
    {
        // Before the onOpen event is triggered, the HTTP request to establish the WebSocket has passed the Laravel route,
        // so Laravel's Request, Auth information are readable, Session is readable and writable, but only in the onOpen event.
        // \Log::info('New WebSocket connection', [$request->fd, request()->all(), session()->getId(), session('xxx'), session(['yyy' => time()])]);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $server->push($request->fd, 'Welcome to LaravelS');
    }
    public function onMessage(Server $server, Frame $frame)
    {
        // \Log::info('Received message', [$frame->fd, $frame->data, $frame->opcode, $frame->finish]);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $server->push($frame->fd, date('Y-m-d H:i:s'));
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

2.Modify config/laravels.php.

// ...
'websocket'      => [
    'enable'  => true, // Note: set enable to true
    'handler' => \App\Services\WebSocketService::class,
],
'swoole'         => [
    //...
    // Must set dispatch_mode in (2, 4, 5), see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
    'dispatch_mode' => 2,
    //...
],
// ...

3.Use SwooleTable to bind FD & UserId, optional, Swoole Table Demo. Also you can use the other global storage services, like Redis/Memcached/MySQL, but be careful that FD will be possible conflicting between multiple Swoole Servers.

4.Cooperate with Nginx (Recommended)

Refer WebSocket Proxy

map $http_upgrade $connection_upgrade {
    default upgrade;
    ''      close;
}
upstream swoole {
    # Connect IP:Port
    server 127.0.0.1:5200 weight=5 max_fails=3 fail_timeout=30s;
    # Connect UnixSocket Stream file, tips: put the socket file in the /dev/shm directory to get better performance
    #server unix:/yourpath/laravel-s-test/storage/laravels.sock weight=5 max_fails=3 fail_timeout=30s;
    #server 192.168.1.1:5200 weight=3 max_fails=3 fail_timeout=30s;
    #server 192.168.1.2:5200 backup;
    keepalive 16;
}
server {
    listen 80;
    # Don't forget to bind the host
    server_name laravels.com;
    root /yourpath/laravel-s-test/public;
    access_log /yourpath/log/nginx/$server_name.access.log  main;
    autoindex off;
    index index.html index.htm;
    # Nginx handles the static resources(recommend enabling gzip), LaravelS handles the dynamic resource.
    location / {
        try_files $uri @laravels;
    }
    # Response 404 directly when request the PHP file, to avoid exposing public/*.php
    #location ~* \.php$ {
    #    return 404;
    #}
    # Http and WebSocket are concomitant, Nginx identifies them by "location"
    # !!! The location of WebSocket is "/ws"
    # Javascript: var ws = new WebSocket("ws://laravels.com/ws");
    location =/ws {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout: Nginx will close the connection if the proxied server does not send data to Nginx in 60 seconds; At the same time, this close behavior is also affected by heartbeat setting of Swoole.
        # proxy_read_timeout 60s;
        proxy_http_version 1.1;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
        proxy_pass http://swoole;
    }
    location @laravels {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout 60s;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        proxy_pass http://swoole;
    }
}

5.Heartbeat setting

Heartbeat setting of Swoole

// config/laravels.php
'swoole' => [
    //...
    // All connections are traversed every 60 seconds. If a connection does not send any data to the server within 600 seconds, the connection will be forced to close.
    'heartbeat_idle_time'      => 600,
    'heartbeat_check_interval' => 60,
    //...
],

Proxy read timeout of Nginx

# Nginx will close the connection if the proxied server does not send data to Nginx in 60 seconds
proxy_read_timeout 60s;

6.Push data in controller

namespace App\Http\Controllers;
class TestController extends Controller
{
    public function push()
    {
        $fd = 1; // Find fd by userId from a map [userId=>fd].
        /**@var \Swoole\WebSocket\Server $swoole */
        $swoole = app('swoole');
        $success = $swoole->push($fd, 'Push data to fd#1 in Controller');
        var_dump($success);
    }
}

Listen events

System events

Usually, you can reset/destroy some global/static variables, or change the current Request/Response object.

laravels.received_request After LaravelS parsed Swoole\Http\Request to Illuminate\Http\Request, before Laravel's Kernel handles this request.

// Edit file `app/Providers/EventServiceProvider.php`, add the following code into method `boot`
// If no variable $events, you can also call Facade \Event::listen(). 
$events->listen('laravels.received_request', function (\Illuminate\Http\Request $req, $app) {
    $req->query->set('get_key', 'hhxsv5');// Change query of request
    $req->request->set('post_key', 'hhxsv5'); // Change post of request
});

laravels.generated_response After Laravel's Kernel handled the request, before LaravelS parses Illuminate\Http\Response to Swoole\Http\Response.

// Edit file `app/Providers/EventServiceProvider.php`, add the following code into method `boot`
// If no variable $events, you can also call Facade \Event::listen(). 
$events->listen('laravels.generated_response', function (\Illuminate\Http\Request $req, \Symfony\Component\HttpFoundation\Response $rsp, $app) {
    $rsp->headers->set('header-key', 'hhxsv5');// Change header of response
});

Customized asynchronous events

This feature depends on AsyncTask of Swoole, your need to set swoole.task_worker_num in config/laravels.php firstly. The performance of asynchronous event processing is influenced by number of Swoole task process, you need to set task_worker_num appropriately.

1.Create event class.

use Hhxsv5\LaravelS\Swoole\Task\Event;
class TestEvent extends Event
{
    protected $listeners = [
        // Listener list
        TestListener1::class,
        // TestListener2::class,
    ];
    private $data;
    public function __construct($data)
    {
        $this->data = $data;
    }
    public function getData()
    {
        return $this->data;
    }
}

2.Create listener class.

use Hhxsv5\LaravelS\Swoole\Task\Task;
use Hhxsv5\LaravelS\Swoole\Task\Listener;
class TestListener1 extends Listener
{
    /**
     * @var TestEvent
     */
    protected $event;
    
    public function handle()
    {
        \Log::info(__CLASS__ . ':handle start', [$this->event->getData()]);
        sleep(2);// Simulate the slow codes
        // Deliver task in CronJob, but NOT support callback finish() of task.
        // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
        $ret = Task::deliver(new TestTask('task data'));
        var_dump($ret);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

3.Fire event.

// Create instance of event and fire it, "fire" is asynchronous.
use Hhxsv5\LaravelS\Swoole\Task\Event;
$event = new TestEvent('event data');
// $event->delay(10); // Delay 10 seconds to fire event
// $event->setTries(3); // When an error occurs, try 3 times in total
$success = Event::fire($event);
var_dump($success);// Return true if sucess, otherwise false

Asynchronous task queue

This feature depends on AsyncTask of Swoole, your need to set swoole.task_worker_num in config/laravels.php firstly. The performance of task processing is influenced by number of Swoole task process, you need to set task_worker_num appropriately.

1.Create task class.

use Hhxsv5\LaravelS\Swoole\Task\Task;
class TestTask extends Task
{
    private $data;
    private $result;
    public function __construct($data)
    {
        $this->data = $data;
    }
    // The logic of task handling, run in task process, CAN NOT deliver task
    public function handle()
    {
        \Log::info(__CLASS__ . ':handle start', [$this->data]);
        sleep(2);// Simulate the slow codes
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $this->result = 'the result of ' . $this->data;
    }
    // Optional, finish event, the logic of after task handling, run in worker process, CAN deliver task 
    public function finish()
    {
        \Log::info(__CLASS__ . ':finish start', [$this->result]);
        Task::deliver(new TestTask2('task2 data')); // Deliver the other task
    }
}

2.Deliver task.

// Create instance of TestTask and deliver it, "deliver" is asynchronous.
use Hhxsv5\LaravelS\Swoole\Task\Task;
$task = new TestTask('task data');
// $task->delay(3);// delay 3 seconds to deliver task
// $task->setTries(3); // When an error occurs, try 3 times in total
$ret = Task::deliver($task);
var_dump($ret);// Return true if sucess, otherwise false

Millisecond cron job

Wrapper cron job base on Swoole's Millisecond Timer, replace Linux Crontab.

1.Create cron job class.

namespace App\Jobs\Timer;
use App\Tasks\TestTask;
use Swoole\Coroutine;
use Hhxsv5\LaravelS\Swoole\Task\Task;
use Hhxsv5\LaravelS\Swoole\Timer\CronJob;
class TestCronJob extends CronJob
{
    protected $i = 0;
    // !!! The `interval` and `isImmediate` of cron job can be configured in two ways(pick one of two): one is to overload the corresponding method, and the other is to pass parameters when registering cron job.
    // --- Override the corresponding method to return the configuration: begin
    public function interval()
    {
        return 1000;// Run every 1000ms
    }
    public function isImmediate()
    {
        return false;// Whether to trigger `run` immediately after setting up
    }
    // --- Override the corresponding method to return the configuration: end
    public function run()
    {
        \Log::info(__METHOD__, ['start', $this->i, microtime(true)]);
        // do something
        // sleep(1); // Swoole < 2.1
        Coroutine::sleep(1); // Swoole>=2.1 Coroutine will be automatically created for run().
        $this->i++;
        \Log::info(__METHOD__, ['end', $this->i, microtime(true)]);

        if ($this->i >= 10) { // Run 10 times only
            \Log::info(__METHOD__, ['stop', $this->i, microtime(true)]);
            $this->stop(); // Stop this cron job, but it will run again after restart/reload.
            // Deliver task in CronJob, but NOT support callback finish() of task.
            // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
            $ret = Task::deliver(new TestTask('task data'));
            var_dump($ret);
        }
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

2.Register cron job.

// Register cron jobs in file "config/laravels.php"
[
    // ...
    'timer'          => [
        'enable' => true, // Enable Timer
        'jobs'   => [ // The list of cron job
            // Enable LaravelScheduleJob to run `php artisan schedule:run` every 1 minute, replace Linux Crontab
            // \Hhxsv5\LaravelS\Illuminate\LaravelScheduleJob::class,
            // Two ways to configure parameters:
            // [\App\Jobs\Timer\TestCronJob::class, [1000, true]], // Pass in parameters when registering
            \App\Jobs\Timer\TestCronJob::class, // Override the corresponding method to return the configuration
        ],
        'max_wait_time' => 5, // Max waiting time of reloading
        // Enable the global lock to ensure that only one instance starts the timer when deploying multiple instances. This feature depends on Redis, please see https://laravel.com/docs/7.x/redis
        'global_lock'     => false,
        'global_lock_key' => config('app.name', 'Laravel'),
    ],
    // ...
];

3.Note: it will launch multiple timers when build the server cluster, so you need to make sure that launch one timer only to avoid running repetitive task.

4.LaravelS v3.4.0 starts to support the hot restart [Reload] Timer process. After LaravelS receives the SIGUSR1 signal, it waits for max_wait_time(default 5) seconds to end the process, then the Manager process will pull up the Timer process again.

5.If you only need to use minute-level scheduled tasks, it is recommended to enable Hhxsv5\LaravelS\Illuminate\LaravelScheduleJob instead of Linux Crontab, so that you can follow the coding habits of Laravel task scheduling and configure Kernel.

// app/Console/Kernel.php
protected function schedule(Schedule $schedule)
{
    // runInBackground() will start a new child process to execute the task. This is asynchronous and will not affect the execution timing of other tasks.
    $schedule->command(TestCommand::class)->runInBackground()->everyMinute();
}

Automatically reload after modifying code

Via inotify, support Linux only.

1.Install inotify extension.

2.Turn on the switch in Settings.

3.Notice: Modify the file only in Linux to receive the file change events. It's recommended to use the latest Docker. Vagrant Solution.

Via fswatch, support OS X/Linux/Windows.

1.Install fswatch.

2.Run command in your project root directory.

# Watch current directory
./bin/fswatch
# Watch app directory
./bin/fswatch ./app

Via inotifywait, support Linux.

1.Install inotify-tools.

2.Run command in your project root directory.

# Watch current directory
./bin/inotify
# Watch app directory
./bin/inotify ./app

When the above methods does not work, the ultimate solution: set max_request=1,worker_num=1, so that Worker process will restart after processing a request. The performance of this method is very poor, so only development environment use.

Get the instance of SwooleServer in your project

/**
 * $swoole is the instance of `Swoole\WebSocket\Server` if enable WebSocket server, otherwise `Swoole\Http\Server`
 * @var \Swoole\WebSocket\Server|\Swoole\Http\Server $swoole
 */
$swoole = app('swoole');
var_dump($swoole->stats());
$swoole->push($fd, 'Push WebSocket message');

Use SwooleTable

1.Define Table, support multiple.

All defined tables will be created before Swoole starting.

// in file "config/laravels.php"
[
    // ...
    'swoole_tables'  => [
        // Scene:bind UserId & FD in WebSocket
        'ws' => [// The Key is table name, will add suffix "Table" to avoid naming conflicts. Here defined a table named "wsTable"
            'size'   => 102400,// The max size
            'column' => [// Define the columns
                ['name' => 'value', 'type' => \Swoole\Table::TYPE_INT, 'size' => 8],
            ],
        ],
        //...Define the other tables
    ],
    // ...
];

2.Access Table: all table instances will be bound on SwooleServer, access by app('swoole')->xxxTable.

namespace App\Services;
use Hhxsv5\LaravelS\Swoole\WebSocketHandlerInterface;
use Swoole\Http\Request;
use Swoole\WebSocket\Frame;
use Swoole\WebSocket\Server;
class WebSocketService implements WebSocketHandlerInterface
{
    /**@var \Swoole\Table $wsTable */
    private $wsTable;
    public function __construct()
    {
        $this->wsTable = app('swoole')->wsTable;
    }
    // Scene:bind UserId & FD in WebSocket
    public function onOpen(Server $server, Request $request)
    {
        // var_dump(app('swoole') === $server);// The same instance
        /**
         * Get the currently logged in user
         * This feature requires that the path to establish a WebSocket connection go through middleware such as Authenticate.
         * E.g:
         * Browser side: var ws = new WebSocket("ws://127.0.0.1:5200/ws");
         * Then the /ws route in Laravel needs to add the middleware like Authenticate.
         * Route::get('/ws', function () {
         *     // Respond any content with status code 200
         *     return 'websocket';
         * })->middleware(['auth']);
         */
        // $user = Auth::user();
        // $userId = $user ? $user->id : 0; // 0 means a guest user who is not logged in
        $userId = mt_rand(1000, 10000);
        // if (!$userId) {
        //     // Disconnect the connections of unlogged users
        //     $server->disconnect($request->fd);
        //     return;
        // }
        $this->wsTable->set('uid:' . $userId, ['value' => $request->fd]);// Bind map uid to fd
        $this->wsTable->set('fd:' . $request->fd, ['value' => $userId]);// Bind map fd to uid
        $server->push($request->fd, "Welcome to LaravelS #{$request->fd}");
    }
    public function onMessage(Server $server, Frame $frame)
    {
        // Broadcast
        foreach ($this->wsTable as $key => $row) {
            if (strpos($key, 'uid:') === 0 && $server->isEstablished($row['value'])) {
                $content = sprintf('Broadcast: new message "%s" from #%d', $frame->data, $frame->fd);
                $server->push($row['value'], $content);
            }
        }
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        $uid = $this->wsTable->get('fd:' . $fd);
        if ($uid !== false) {
            $this->wsTable->del('uid:' . $uid['value']); // Unbind uid map
        }
        $this->wsTable->del('fd:' . $fd);// Unbind fd map
        $server->push($fd, "Goodbye #{$fd}");
    }
}

Multi-port mixed protocol

For more information, please refer to Swoole Server AddListener

To make our main server support more protocols not just Http and WebSocket, we bring the feature multi-port mixed protocol of Swoole in LaravelS and name it Socket. Now, you can build TCP/UDP applications easily on top of Laravel.

Create Socket handler class, and extend Hhxsv5\LaravelS\Swoole\Socket\{TcpSocket|UdpSocket|Http|WebSocket}.

namespace App\Sockets;
use Hhxsv5\LaravelS\Swoole\Socket\TcpSocket;
use Swoole\Server;
class TestTcpSocket extends TcpSocket
{
    public function onConnect(Server $server, $fd, $reactorId)
    {
        \Log::info('New TCP connection', [$fd]);
        $server->send($fd, 'Welcome to LaravelS.');
    }
    public function onReceive(Server $server, $fd, $reactorId, $data)
    {
        \Log::info('Received data', [$fd, $data]);
        $server->send($fd, 'LaravelS: ' . $data);
        if ($data === "quit\r\n") {
            $server->send($fd, 'LaravelS: bye' . PHP_EOL);
            $server->close($fd);
        }
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        \Log::info('Close TCP connection', [$fd]);
        $server->send($fd, 'Goodbye');
    }
}

These Socket connections share the same worker processes with your HTTP/WebSocket connections. So it won't be a problem at all if you want to deliver tasks, use SwooleTable, even Laravel components such as DB, Eloquent and so on. At the same time, you can access Swoole\Server\Port object directly by member property swoolePort.

public function onReceive(Server $server, $fd, $reactorId, $data)
{
    $port = $this->swoolePort; // Get the `Swoole\Server\Port` object
}
namespace App\Http\Controllers;
class TestController extends Controller
{
    public function test()
    {
        /**@var \Swoole\Http\Server|\Swoole\WebSocket\Server $swoole */
        $swoole = app('swoole');
        // $swoole->ports: Traverse all Port objects, https://www.swoole.co.uk/docs/modules/swoole-server/multiple-ports
        $port = $swoole->ports[0]; // Get the `Swoole\Server\Port` object, $port[0] is the port of the main server
        foreach ($port->connections as $fd) { // Traverse all connections
            // $swoole->send($fd, 'Send tcp message');
            // if($swoole->isEstablished($fd)) {
            //     $swoole->push($fd, 'Send websocket message');
            // }
        }
    }
}

Register Sockets.

// Edit `config/laravels.php`
//...
'sockets' => [
    [
        'host'     => '127.0.0.1',
        'port'     => 5291,
        'type'     => SWOOLE_SOCK_TCP,// Socket type: SWOOLE_SOCK_TCP/SWOOLE_SOCK_TCP6/SWOOLE_SOCK_UDP/SWOOLE_SOCK_UDP6/SWOOLE_UNIX_DGRAM/SWOOLE_UNIX_STREAM
        'settings' => [// Swoole settings:https://www.swoole.co.uk/docs/modules/swoole-server-methods#swoole_server-addlistener
            'open_eof_check' => true,
            'package_eof'    => "\r\n",
        ],
        'handler'  => \App\Sockets\TestTcpSocket::class,
        'enable'   => true, // whether to enable, default true
    ],
],

About the heartbeat configuration, it can only be set on the main server and cannot be configured on Socket, but the Socket inherits the heartbeat configuration of the main server.

For TCP socket, onConnect and onClose events will be blocked when dispatch_mode of Swoole is 1/3, so if you want to unblock these two events please set dispatch_mode to 2/4/5.

'swoole' => [
    //...
    'dispatch_mode' => 2,
    //...
];

Test.

TCP: telnet 127.0.0.1 5291

UDP: [Linux] echo "Hello LaravelS" > /dev/udp/127.0.0.1/5292

Register example of other protocols.

  • UDP
'sockets' => [
    [
        'host'     => '0.0.0.0',
        'port'     => 5292,
        'type'     => SWOOLE_SOCK_UDP,
        'settings' => [
            'open_eof_check' => true,
            'package_eof'    => "\r\n",
        ],
        'handler'  => \App\Sockets\TestUdpSocket::class,
    ],
],
  • Http
'sockets' => [
    [
        'host'     => '0.0.0.0',
        'port'     => 5293,
        'type'     => SWOOLE_SOCK_TCP,
        'settings' => [
            'open_http_protocol' => true,
        ],
        'handler'  => \App\Sockets\TestHttp::class,
    ],
],
  • WebSocket: The main server must turn on WebSocket, that is, set websocket.enable to true.
'sockets' => [
    [
        'host'     => '0.0.0.0',
        'port'     => 5294,
        'type'     => SWOOLE_SOCK_TCP,
        'settings' => [
            'open_http_protocol'      => true,
            'open_websocket_protocol' => true,
        ],
        'handler'  => \App\Sockets\TestWebSocket::class,
    ],
],

Coroutine

Swoole Coroutine

Warning: The order of code execution in the coroutine is out of order. The data of the request level should be isolated by the coroutine ID. However, there are many singleton and static attributes in Laravel/Lumen, the data between different requests will affect each other, it's Unsafe. For example, the database connection is a singleton, the same database connection shares the same PDO resource. This is fine in the synchronous blocking mode, but it does not work in the asynchronous coroutine mode. Each query needs to create different connections and maintain IO state of different connections, which requires a connection pool.

DO NOT enable the coroutine, only the custom process can use the coroutine.

Custom process

Support developers to create special work processes for monitoring, reporting, or other special tasks. Refer addProcess.

Create Proccess class, implements CustomProcessInterface.

namespace App\Processes;
use App\Tasks\TestTask;
use Hhxsv5\LaravelS\Swoole\Process\CustomProcessInterface;
use Hhxsv5\LaravelS\Swoole\Task\Task;
use Swoole\Coroutine;
use Swoole\Http\Server;
use Swoole\Process;
class TestProcess implements CustomProcessInterface
{
    /**
     * @var bool Quit tag for Reload updates
     */
    private static $quit = false;

    public static function callback(Server $swoole, Process $process)
    {
        // The callback method cannot exit. Once exited, Manager process will automatically create the process 
        while (!self::$quit) {
            \Log::info('Test process: running');
            // sleep(1); // Swoole < 2.1
            Coroutine::sleep(1); // Swoole>=2.1: Coroutine & Runtime will be automatically enabled for callback().
             // Deliver task in custom process, but NOT support callback finish() of task.
            // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
            $ret = Task::deliver(new TestTask('task data'));
            var_dump($ret);
            // The upper layer will catch the exception thrown in the callback and record it in the Swoole log, and then this process will exit. The Manager process will re-create the process after 3 seconds, so developers need to try/catch to catch the exception by themselves to avoid frequent process creation.
            // throw new \Exception('an exception');
        }
    }
    // Requirements: LaravelS >= v3.4.0 & callback() must be async non-blocking program.
    public static function onReload(Server $swoole, Process $process)
    {
        // Stop the process...
        // Then end process
        \Log::info('Test process: reloading');
        self::$quit = true;
        // $process->exit(0); // Force exit process
    }
    // Requirements: LaravelS >= v3.7.4 & callback() must be async non-blocking program.
    public static function onStop(Server $swoole, Process $process)
    {
        // Stop the process...
        // Then end process
        \Log::info('Test process: stopping');
        self::$quit = true;
        // $process->exit(0); // Force exit process
    }
}

Register TestProcess.

// Edit `config/laravels.php`
// ...
'processes' => [
    'test' => [ // Key name is process name
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false, // Whether redirect stdin/stdout, true or false
        'pipe'     => 0,     // The type of pipeline, 0: no pipeline 1: SOCK_STREAM 2: SOCK_DGRAM
        'enable'   => true,  // Whether to enable, default true
        //'num'    => 3   // To create multiple processes of this class, default is 1
        //'queue'    => [ // Enable message queue as inter-process communication, configure empty array means use default parameters
        //    'msg_key'  => 0,    // The key of the message queue. Default: ftok(__FILE__, 1).
        //    'mode'     => 2,    // Communication mode, default is 2, which means contention mode
        //    'capacity' => 8192, // The length of a single message, is limited by the operating system kernel parameters. The default is 8192, and the maximum is 65536
        //],
        //'restart_interval' => 5, // After the process exits abnormally, how many seconds to wait before restarting the process, default 5 seconds
    ],
],

Note: The callback() cannot quit. If quit, the Manager process will re-create the process.

Example: Write data to a custom process.

// config/laravels.php
'processes' => [
    'test' => [
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false,
        'pipe'     => 1,
    ],
],
// app/Processes/TestProcess.php
public static function callback(Server $swoole, Process $process)
{
    while ($data = $process->read()) {
        \Log::info('TestProcess: read data', [$data]);
        $process->write('TestProcess: ' . $data);
    }
}
// app/Http/Controllers/TestController.php
public function testProcessWrite()
{
    /**@var \Swoole\Process $process */
    $process = app('swoole')->customProcesses['test'];
    $process->write('TestController: write data' . time());
    var_dump($process->read());
}

Common components

Apollo

LaravelS will pull the Apollo configuration and write it to the .env file when starting. At the same time, LaravelS will start the custom process apollo to monitor the configuration and automatically reload when the configuration changes.

Enable Apollo: add --enable-apollo and Apollo parameters to the startup parameters.

php bin/laravels start --enable-apollo --apollo-server=http://127.0.0.1:8080 --apollo-app-id=LARAVEL-S-TEST

Support hot updates(optional).

// Edit `config/laravels.php`
'processes' => Hhxsv5\LaravelS\Components\Apollo\Process::getDefinition(),
// When there are other custom process configurations
'processes' => [
    'test' => [
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false,
        'pipe'     => 1,
    ],
    // ...
] + Hhxsv5\LaravelS\Components\Apollo\Process::getDefinition(),

List of available parameters.

ParameterDescriptionDefaultDemo
apollo-serverApollo server URL---apollo-server=http://127.0.0.1:8080
apollo-app-idApollo APP ID---apollo-app-id=LARAVEL-S-TEST
apollo-namespacesThe namespace to which the APP belongs, support specify the multipleapplication--apollo-namespaces=application --apollo-namespaces=env
apollo-clusterThe cluster to which the APP belongsdefault--apollo-cluster=default
apollo-client-ipIP of current instance, can also be used for grayscale publishingLocal intranet IP--apollo-client-ip=10.2.1.83
apollo-pull-timeoutTimeout time(seconds) when pulling configuration5--apollo-pull-timeout=5
apollo-backup-old-envWhether to backup the old configuration file when updating the configuration file .envfalse--apollo-backup-old-env

Prometheus

Support Prometheus monitoring and alarm, Grafana visually view monitoring metrics. Please refer to Docker Compose for the environment construction of Prometheus and Grafana.

Require extension APCu >= 5.0.0, please install it by pecl install apcu.

Copy the configuration file prometheus.php to the config directory of your project. Modify the configuration as appropriate.

# Execute commands in the project root directory
cp vendor/hhxsv5/laravel-s/config/prometheus.php config/

If your project is Lumen, you also need to manually load the configuration $app->configure('prometheus'); in bootstrap/app.php.

Configure global middleware: Hhxsv5\LaravelS\Components\Prometheus\RequestMiddleware::class. In order to count the request time consumption as accurately as possible, RequestMiddleware must be the first global middleware, which needs to be placed in front of other middleware.

Register ServiceProvider: Hhxsv5\LaravelS\Components\Prometheus\ServiceProvider::class.

Configure the CollectorProcess in config/laravels.php to collect the metrics of Swoole Worker/Task/Timer processes regularly.

'processes' => Hhxsv5\LaravelS\Components\Prometheus\CollectorProcess::getDefinition(),

Create the route to output metrics.

use Hhxsv5\LaravelS\Components\Prometheus\Exporter;

Route::get('/actuator/prometheus', function () {
    $result = app(Exporter::class)->render();
    return response($result, 200, ['Content-Type' => Exporter::REDNER_MIME_TYPE]);
});

Complete the configuration of Prometheus and start it.

global:
  scrape_interval: 5s
  scrape_timeout: 5s
  evaluation_interval: 30s
scrape_configs:
- job_name: laravel-s-test
  honor_timestamps: true
  metrics_path: /actuator/prometheus
  scheme: http
  follow_redirects: true
  static_configs:
  - targets:
    - 127.0.0.1:5200 # The ip and port of the monitored service
# Dynamically discovered using one of the supported service-discovery mechanisms
# https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config
# - job_name: laravels-eureka
#   honor_timestamps: true
#   scrape_interval: 5s
#   metrics_path: /actuator/prometheus
#   scheme: http
#   follow_redirects: true
  # eureka_sd_configs:
  # - server: http://127.0.0.1:8080/eureka
  #   follow_redirects: true
  #   refresh_interval: 5s

Start Grafana, then import panel json.

Grafana Dashboard

Other features

Configure Swoole events

Supported events:

EventInterfaceWhen happened
ServerStartHhxsv5\LaravelS\Swoole\Events\ServerStartInterfaceOccurs when the Master process is starting, this event should not handle complex business logic, and can only do some simple work of initialization.
ServerStopHhxsv5\LaravelS\Swoole\Events\ServerStopInterfaceOccurs when the server exits normally, CANNOT use async or coroutine related APIs in this event.
WorkerStartHhxsv5\LaravelS\Swoole\Events\WorkerStartInterfaceOccurs after the Worker/Task process is started, and the Laravel initialization has been completed.
WorkerStopHhxsv5\LaravelS\Swoole\Events\WorkerStopInterfaceOccurs after the Worker/Task process exits normally
WorkerErrorHhxsv5\LaravelS\Swoole\Events\WorkerErrorInterfaceOccurs when an exception or fatal error occurs in the Worker/Task process

1.Create an event class to implement the corresponding interface.

namespace App\Events;
use Hhxsv5\LaravelS\Swoole\Events\ServerStartInterface;
use Swoole\Atomic;
use Swoole\Http\Server;
class ServerStartEvent implements ServerStartInterface
{
    public function __construct()
    {
    }
    public function handle(Server $server)
    {
        // Initialize a global counter (available across processes)
        $server->atomicCount = new Atomic(2233);

        // Invoked in controller: app('swoole')->atomicCount->get();
    }
}
namespace App\Events;
use Hhxsv5\LaravelS\Swoole\Events\WorkerStartInterface;
use Swoole\Http\Server;
class WorkerStartEvent implements WorkerStartInterface
{
    public function __construct()
    {
    }
    public function handle(Server $server, $workerId)
    {
        // Initialize a database connection pool
        // DatabaseConnectionPool::init();
    }
}

2.Configuration.

// Edit `config/laravels.php`
'event_handlers' => [
    'ServerStart' => [\App\Events\ServerStartEvent::class], // Trigger events in array order
    'WorkerStart' => [\App\Events\WorkerStartEvent::class],
],

Serverless

Alibaba Cloud Function Compute

Function Compute.

1.Modify bootstrap/app.php and set the storage directory. Because the project directory is read-only, the /tmp directory can only be read and written.

$app->useStoragePath(env('APP_STORAGE_PATH', '/tmp/storage'));

2.Create a shell script laravels_bootstrap and grant executable permission.

#!/usr/bin/env bash
set +e

# Create storage-related directories
mkdir -p /tmp/storage/app/public
mkdir -p /tmp/storage/framework/cache
mkdir -p /tmp/storage/framework/sessions
mkdir -p /tmp/storage/framework/testing
mkdir -p /tmp/storage/framework/views
mkdir -p /tmp/storage/logs

# Set the environment variable APP_STORAGE_PATH, please make sure it's the same as APP_STORAGE_PATH in .env
export APP_STORAGE_PATH=/tmp/storage

# Start LaravelS
php bin/laravels start

3.Configure template.xml.

ROSTemplateFormatVersion: '2015-09-01'
Transform: 'Aliyun::Serverless-2018-04-03'
Resources:
  laravel-s-demo:
    Type: 'Aliyun::Serverless::Service'
    Properties:
      Description: 'LaravelS Demo for Serverless'
    fc-laravel-s:
      Type: 'Aliyun::Serverless::Function'
      Properties:
        Handler: laravels.handler
        Runtime: custom
        MemorySize: 512
        Timeout: 30
        CodeUri: ./
        InstanceConcurrency: 10
        EnvironmentVariables:
          BOOTSTRAP_FILE: laravels_bootstrap

Important notices

Singleton Issue

Under FPM mode, singleton instances will be instantiated and recycled in every request, request start=>instantiate instance=>request end=>recycled instance.

Under Swoole Server, All singleton instances will be held in memory, different lifetime from FPM, request start=>instantiate instance=>request end=>do not recycle singleton instance. So need developer to maintain status of singleton instances in every request.

Common solutions:

Write a XxxCleaner class to clean up the singleton object state. This class implements the interface Hhxsv5\LaravelS\Illuminate\Cleaners\CleanerInterface and then registers it in cleaners of laravels.php.

Reset status of singleton instances by Middleware.

Re-register ServiceProvider, add XxxServiceProvider into register_providers of file laravels.php. So that reinitialize singleton instances in every request Refer.

Cleaners

Configuration cleaners.

Known issues

Known issues: a package of known issues and solutions.

Debugging method

Logging; if you want to output to the console, you can use stderr, Log::channel('stderr')->debug('debug message').

Laravel Dump Server(Laravel 5.7 has been integrated by default).

Read request

Read request by Illuminate\Http\Request Object, $_ENV is readable, $_SERVER is partially readable, CANNOT USE $_GET/$_POST/$_FILES/$_COOKIE/$_REQUEST/$_SESSION/$GLOBALS.

public function form(\Illuminate\Http\Request $request)
{
    $name = $request->input('name');
    $all = $request->all();
    $sessionId = $request->cookie('sessionId');
    $photo = $request->file('photo');
    // Call getContent() to get the raw POST body, instead of file_get_contents('php://input')
    $rawContent = $request->getContent();
    //...
}

Output response

Respond by Illuminate\Http\Response Object, compatible with echo/vardump()/print_r(),CANNOT USE functions dd()/exit()/die()/header()/setcookie()/http_response_code().

public function json()
{
    return response()->json(['time' => time()])->header('header1', 'value1')->withCookie('c1', 'v1');
}

Persistent connection

Singleton connection will be resident in memory, it is recommended to turn on persistent connection for better performance.

  1. Database connection, it will reconnect automatically immediately after disconnect.
// config/database.php
'connections' => [
    'my_conn' => [
        'driver'    => 'mysql',
        'host'      => env('DB_MY_CONN_HOST', 'localhost'),
        'port'      => env('DB_MY_CONN_PORT', 3306),
        'database'  => env('DB_MY_CONN_DATABASE', 'forge'),
        'username'  => env('DB_MY_CONN_USERNAME', 'forge'),
        'password'  => env('DB_MY_CONN_PASSWORD', ''),
        'charset'   => 'utf8mb4',
        'collation' => 'utf8mb4_unicode_ci',
        'prefix'    => '',
        'strict'    => false,
        'options'   => [
            // Enable persistent connection
            \PDO::ATTR_PERSISTENT => true,
        ],
    ],
],
  1. Redis connection, it won't reconnect automatically immediately after disconnect, and will throw an exception about lost connection, reconnect next time. You need to make sure that SELECT DB correctly before operating Redis every time.
// config/database.php
'redis' => [
    'client' => env('REDIS_CLIENT', 'phpredis'), // It is recommended to use phpredis for better performance.
    'default' => [
        'host'       => env('REDIS_HOST', 'localhost'),
        'password'   => env('REDIS_PASSWORD', null),
        'port'       => env('REDIS_PORT', 6379),
        'database'   => 0,
        'persistent' => true, // Enable persistent connection
    ],
],

About memory leaks

Avoid using global variables. If necessary, please clean or reset them manually.

Infinitely appending element into static/global variable will lead to OOM(Out of Memory).

class Test
{
    public static $array = [];
    public static $string = '';
}

// Controller
public function test(Request $req)
{
    // Out of Memory
    Test::$array[] = $req->input('param1');
    Test::$string .= $req->input('param2');
}

Memory leak detection method

Modify config/laravels.php: worker_num=1, max_request=1000000, remember to change it back after test;

Add routing /debug-memory-leak without route middleware to observe the memory changes of the Worker process;

Route::get('/debug-memory-leak', function () {
    global $previous;
    $current = memory_get_usage();
    $stats = [
        'prev_mem' => $previous,
        'curr_mem' => $current,
        'diff_mem' => $current - $previous,
    ];
    $previous = $current;
    return $stats;
});

Start LaravelS and request /debug-memory-leak until diff_mem is less than or equal to zero; if diff_mem is always greater than zero, it means that there may be a memory leak in Global Middleware or Laravel Framework;

After completing Step 3, alternately request the business routes and /debug-memory-leak (It is recommended to use ab/wrk to make a large number of requests for business routes), the initial increase in memory is normal. After a large number of requests for the business routes, if diff_mem is always greater than zero and curr_mem continues to increase, there is a high probability of memory leak; If curr_mem always changes within a certain range and does not continue to increase, there is a low probability of memory leak.

If you still can't solve it, max_request is the last guarantee.

Linux kernel parameter adjustment

Linux kernel parameter adjustment

Pressure test

Pressure test


Author: hhxsv5
Source Code: https://github.com/hhxsv5/laravel-s
License: MIT License

#laravel #php 

LaravelS: Glue for using Swoole in Laravel Or Lumen

🚀 LaravelS is an out-of-the-box adapter between Swoole and Laravel/Lumen.

Please Watch this repository to get the latest updates.

 _                               _  _____ 
| |                             | |/ ____|
| |     __ _ _ __ __ ___   _____| | (___  
| |    / _` | '__/ _` \ \ / / _ \ |\___ \ 
| |___| (_| | | | (_| |\ V /  __/ |____) |
|______\__,_|_|  \__,_| \_/ \___|_|_____/ 

中文文档

Features

Built-in Http/WebSocket server

Multi-port mixed protocol

Custom process

Memory resident

Asynchronous event listening

Asynchronous task queue

Millisecond cron job

Common Components

Gracefully reload

Automatically reload after modifying code

Support Laravel/Lumen both, good compatibility

Simple & Out of the box

Benchmark

Which is the fastest web framework?

TechEmpower Framework Benchmarks

Requirements

DependencyRequirement
PHP>= 5.5.9 Recommend PHP7+
Swoole>= 1.7.19 No longer support PHP5 since 2.0.12 Recommend 4.5.0+
Laravel/Lumen>= 5.1 Recommend 8.0+

Install

1.Require package via Composer(packagist).

composer require "hhxsv5/laravel-s:~3.7.0" -vvv
# Make sure that your composer.lock file is under the VCS

2.Register service provider(pick one of two).

Laravel: in config/app.php file, Laravel 5.5+ supports package discovery automatically, you should skip this step

'providers' => [
    //...
    Hhxsv5\LaravelS\Illuminate\LaravelSServiceProvider::class,
],

Lumen: in bootstrap/app.php file

$app->register(Hhxsv5\LaravelS\Illuminate\LaravelSServiceProvider::class);

3.Publish configuration and binaries.

After upgrading LaravelS, you need to republish; click here to see the change notes of each version.

php artisan laravels publish
# Configuration: config/laravels.php
# Binary: bin/laravels bin/fswatch bin/inotify

4.Change config/laravels.php: listen_ip, listen_port, refer Settings.

5.Performance tuning

Adjust kernel parameters

Number of Workers: LaravelS uses Swoole's Synchronous IO mode, the larger the worker_num setting, the better the concurrency performance, but it will cause more memory usage and process switching overhead. If one request takes 100ms, in order to provide 1000QPS concurrency, at least 100 Worker processes need to be configured. The calculation method is: worker_num = 1000QPS/(1s/1ms) = 100, so incremental pressure testing is needed to calculate the best worker_num.

Number of Task Workers

Run

Please read the notices carefully before running, Important notices(IMPORTANT).

  • Commands: php bin/laravels {start|stop|restart|reload|info|help}.
CommandDescription
startStart LaravelS, list the processes by "ps -ef|grep laravels"
stopStop LaravelS, and trigger the method onStop of Custom process
restartRestart LaravelS: Stop gracefully before starting; The service is unavailable until startup is complete
reloadReload all Task/Worker/Timer processes which contain your business codes, and trigger the method onReload of Custom process, CANNOT reload Master/Manger processes. After modifying config/laravels.php, you only have to call restart to restart
infoDisplay component version information
helpDisplay help information
  • Boot options for the commands start and restart.
OptionDescription
-d|--daemonizeRun as a daemon, this option will override the swoole.daemonize setting in laravels.php
-e|--envThe environment the command should run under, such as --env=testing will use the configuration file .env.testing firstly, this feature requires Laravel 5.2+
-i|--ignoreIgnore checking PID file of Master process
-x|--x-versionThe version(branch) of the current project, stored in $_ENV/$_SERVER, access via $_ENV['X_VERSION'] $_SERVER['X_VERSION'] $request->server->get('X_VERSION')
  • Runtime files: start will automatically execute php artisan laravels config and generate these files, developers generally don't need to pay attention to them, it's recommended to add them to .gitignore.
FileDescription
storage/laravels.confLaravelS's runtime configuration file
storage/laravels.pidPID file of Master process
storage/laravels-timer-process.pidPID file of the Timer process
storage/laravels-custom-processes.pidPID file of all custom processes

Deploy

It is recommended to supervise the main process through Supervisord, the premise is without option -d and to set swoole.daemonize to false.

[program:laravel-s-test]
directory=/var/www/laravel-s-test
command=/usr/local/bin/php bin/laravels start -i
numprocs=1
autostart=true
autorestart=true
startretries=3
user=www-data
redirect_stderr=true
stdout_logfile=/var/log/supervisor/%(program_name)s.log

Cooperate with Nginx (Recommended)

Demo.

gzip on;
gzip_min_length 1024;
gzip_comp_level 2;
gzip_types text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml application/x-httpd-php image/jpeg image/gif image/png font/ttf font/otf image/svg+xml;
gzip_vary on;
gzip_disable "msie6";
upstream swoole {
    # Connect IP:Port
    server 127.0.0.1:5200 weight=5 max_fails=3 fail_timeout=30s;
    # Connect UnixSocket Stream file, tips: put the socket file in the /dev/shm directory to get better performance
    #server unix:/yourpath/laravel-s-test/storage/laravels.sock weight=5 max_fails=3 fail_timeout=30s;
    #server 192.168.1.1:5200 weight=3 max_fails=3 fail_timeout=30s;
    #server 192.168.1.2:5200 backup;
    keepalive 16;
}
server {
    listen 80;
    # Don't forget to bind the host
    server_name laravels.com;
    root /yourpath/laravel-s-test/public;
    access_log /yourpath/log/nginx/$server_name.access.log  main;
    autoindex off;
    index index.html index.htm;
    # Nginx handles the static resources(recommend enabling gzip), LaravelS handles the dynamic resource.
    location / {
        try_files $uri @laravels;
    }
    # Response 404 directly when request the PHP file, to avoid exposing public/*.php
    #location ~* \.php$ {
    #    return 404;
    #}
    location @laravels {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout 120s;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        # "swoole" is the upstream
        proxy_pass http://swoole;
    }
}

Cooperate with Apache

LoadModule proxy_module /yourpath/modules/mod_proxy.so
LoadModule proxy_balancer_module /yourpath/modules/mod_proxy_balancer.so
LoadModule lbmethod_byrequests_module /yourpath/modules/mod_lbmethod_byrequests.so
LoadModule proxy_http_module /yourpath/modules/mod_proxy_http.so
LoadModule slotmem_shm_module /yourpath/modules/mod_slotmem_shm.so
LoadModule rewrite_module /yourpath/modules/mod_rewrite.so
LoadModule remoteip_module /yourpath/modules/mod_remoteip.so
LoadModule deflate_module /yourpath/modules/mod_deflate.so

<IfModule deflate_module>
    SetOutputFilter DEFLATE
    DeflateCompressionLevel 2
    AddOutputFilterByType DEFLATE text/html text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml application/x-httpd-php image/jpeg image/gif image/png font/ttf font/otf image/svg+xml
</IfModule>

<VirtualHost *:80>
    # Don't forget to bind the host
    ServerName www.laravels.com
    ServerAdmin hhxsv5@sina.com

    DocumentRoot /yourpath/laravel-s-test/public;
    DirectoryIndex index.html index.htm
    <Directory "/">
        AllowOverride None
        Require all granted
    </Directory>

    RemoteIPHeader X-Forwarded-For

    ProxyRequests Off
    ProxyPreserveHost On
    <Proxy balancer://laravels>  
        BalancerMember http://192.168.1.1:5200 loadfactor=7
        #BalancerMember http://192.168.1.2:5200 loadfactor=3
        #BalancerMember http://192.168.1.3:5200 loadfactor=1 status=+H
        ProxySet lbmethod=byrequests
    </Proxy>
    #ProxyPass / balancer://laravels/
    #ProxyPassReverse / balancer://laravels/

    # Apache handles the static resources, LaravelS handles the dynamic resource.
    RewriteEngine On
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} !-d
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} !-f
    RewriteRule ^/(.*)$ balancer://laravels%{REQUEST_URI} [P,L]

    ErrorLog ${APACHE_LOG_DIR}/www.laravels.com.error.log
    CustomLog ${APACHE_LOG_DIR}/www.laravels.com.access.log combined
</VirtualHost>

Enable WebSocket server

The Listening address of WebSocket Sever is the same as Http Server.

1.Create WebSocket Handler class, and implement interface WebSocketHandlerInterface.The instant is automatically instantiated when start, you do not need to manually create it.

namespace App\Services;
use Hhxsv5\LaravelS\Swoole\WebSocketHandlerInterface;
use Swoole\Http\Request;
use Swoole\Http\Response;
use Swoole\WebSocket\Frame;
use Swoole\WebSocket\Server;
/**
 * @see https://www.swoole.co.uk/docs/modules/swoole-websocket-server
 */
class WebSocketService implements WebSocketHandlerInterface
{
    // Declare constructor without parameters
    public function __construct()
    {
    }
    // public function onHandShake(Request $request, Response $response)
    // {
           // Custom handshake: https://www.swoole.co.uk/docs/modules/swoole-websocket-server-on-handshake
           // The onOpen event will be triggered automatically after a successful handshake
    // }
    public function onOpen(Server $server, Request $request)
    {
        // Before the onOpen event is triggered, the HTTP request to establish the WebSocket has passed the Laravel route,
        // so Laravel's Request, Auth information are readable, Session is readable and writable, but only in the onOpen event.
        // \Log::info('New WebSocket connection', [$request->fd, request()->all(), session()->getId(), session('xxx'), session(['yyy' => time()])]);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $server->push($request->fd, 'Welcome to LaravelS');
    }
    public function onMessage(Server $server, Frame $frame)
    {
        // \Log::info('Received message', [$frame->fd, $frame->data, $frame->opcode, $frame->finish]);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $server->push($frame->fd, date('Y-m-d H:i:s'));
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

2.Modify config/laravels.php.

// ...
'websocket'      => [
    'enable'  => true, // Note: set enable to true
    'handler' => \App\Services\WebSocketService::class,
],
'swoole'         => [
    //...
    // Must set dispatch_mode in (2, 4, 5), see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
    'dispatch_mode' => 2,
    //...
],
// ...

3.Use SwooleTable to bind FD & UserId, optional, Swoole Table Demo. Also you can use the other global storage services, like Redis/Memcached/MySQL, but be careful that FD will be possible conflicting between multiple Swoole Servers.

4.Cooperate with Nginx (Recommended)

Refer WebSocket Proxy

map $http_upgrade $connection_upgrade {
    default upgrade;
    ''      close;
}
upstream swoole {
    # Connect IP:Port
    server 127.0.0.1:5200 weight=5 max_fails=3 fail_timeout=30s;
    # Connect UnixSocket Stream file, tips: put the socket file in the /dev/shm directory to get better performance
    #server unix:/yourpath/laravel-s-test/storage/laravels.sock weight=5 max_fails=3 fail_timeout=30s;
    #server 192.168.1.1:5200 weight=3 max_fails=3 fail_timeout=30s;
    #server 192.168.1.2:5200 backup;
    keepalive 16;
}
server {
    listen 80;
    # Don't forget to bind the host
    server_name laravels.com;
    root /yourpath/laravel-s-test/public;
    access_log /yourpath/log/nginx/$server_name.access.log  main;
    autoindex off;
    index index.html index.htm;
    # Nginx handles the static resources(recommend enabling gzip), LaravelS handles the dynamic resource.
    location / {
        try_files $uri @laravels;
    }
    # Response 404 directly when request the PHP file, to avoid exposing public/*.php
    #location ~* \.php$ {
    #    return 404;
    #}
    # Http and WebSocket are concomitant, Nginx identifies them by "location"
    # !!! The location of WebSocket is "/ws"
    # Javascript: var ws = new WebSocket("ws://laravels.com/ws");
    location =/ws {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout: Nginx will close the connection if the proxied server does not send data to Nginx in 60 seconds; At the same time, this close behavior is also affected by heartbeat setting of Swoole.
        # proxy_read_timeout 60s;
        proxy_http_version 1.1;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
        proxy_pass http://swoole;
    }
    location @laravels {
        # proxy_connect_timeout 60s;
        # proxy_send_timeout 60s;
        # proxy_read_timeout 60s;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Real-PORT $remote_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header Scheme $scheme;
        proxy_set_header Server-Protocol $server_protocol;
        proxy_set_header Server-Name $server_name;
        proxy_set_header Server-Addr $server_addr;
        proxy_set_header Server-Port $server_port;
        proxy_pass http://swoole;
    }
}

5.Heartbeat setting

Heartbeat setting of Swoole

// config/laravels.php
'swoole' => [
    //...
    // All connections are traversed every 60 seconds. If a connection does not send any data to the server within 600 seconds, the connection will be forced to close.
    'heartbeat_idle_time'      => 600,
    'heartbeat_check_interval' => 60,
    //...
],

Proxy read timeout of Nginx

# Nginx will close the connection if the proxied server does not send data to Nginx in 60 seconds
proxy_read_timeout 60s;

6.Push data in controller

namespace App\Http\Controllers;
class TestController extends Controller
{
    public function push()
    {
        $fd = 1; // Find fd by userId from a map [userId=>fd].
        /**@var \Swoole\WebSocket\Server $swoole */
        $swoole = app('swoole');
        $success = $swoole->push($fd, 'Push data to fd#1 in Controller');
        var_dump($success);
    }
}

Listen events

System events

Usually, you can reset/destroy some global/static variables, or change the current Request/Response object.

laravels.received_request After LaravelS parsed Swoole\Http\Request to Illuminate\Http\Request, before Laravel's Kernel handles this request.

// Edit file `app/Providers/EventServiceProvider.php`, add the following code into method `boot`
// If no variable $events, you can also call Facade \Event::listen(). 
$events->listen('laravels.received_request', function (\Illuminate\Http\Request $req, $app) {
    $req->query->set('get_key', 'hhxsv5');// Change query of request
    $req->request->set('post_key', 'hhxsv5'); // Change post of request
});

laravels.generated_response After Laravel's Kernel handled the request, before LaravelS parses Illuminate\Http\Response to Swoole\Http\Response.

// Edit file `app/Providers/EventServiceProvider.php`, add the following code into method `boot`
// If no variable $events, you can also call Facade \Event::listen(). 
$events->listen('laravels.generated_response', function (\Illuminate\Http\Request $req, \Symfony\Component\HttpFoundation\Response $rsp, $app) {
    $rsp->headers->set('header-key', 'hhxsv5');// Change header of response
});

Customized asynchronous events

This feature depends on AsyncTask of Swoole, your need to set swoole.task_worker_num in config/laravels.php firstly. The performance of asynchronous event processing is influenced by number of Swoole task process, you need to set task_worker_num appropriately.

1.Create event class.

use Hhxsv5\LaravelS\Swoole\Task\Event;
class TestEvent extends Event
{
    protected $listeners = [
        // Listener list
        TestListener1::class,
        // TestListener2::class,
    ];
    private $data;
    public function __construct($data)
    {
        $this->data = $data;
    }
    public function getData()
    {
        return $this->data;
    }
}

2.Create listener class.

use Hhxsv5\LaravelS\Swoole\Task\Task;
use Hhxsv5\LaravelS\Swoole\Task\Listener;
class TestListener1 extends Listener
{
    /**
     * @var TestEvent
     */
    protected $event;
    
    public function handle()
    {
        \Log::info(__CLASS__ . ':handle start', [$this->event->getData()]);
        sleep(2);// Simulate the slow codes
        // Deliver task in CronJob, but NOT support callback finish() of task.
        // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
        $ret = Task::deliver(new TestTask('task data'));
        var_dump($ret);
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

3.Fire event.

// Create instance of event and fire it, "fire" is asynchronous.
use Hhxsv5\LaravelS\Swoole\Task\Event;
$event = new TestEvent('event data');
// $event->delay(10); // Delay 10 seconds to fire event
// $event->setTries(3); // When an error occurs, try 3 times in total
$success = Event::fire($event);
var_dump($success);// Return true if sucess, otherwise false

Asynchronous task queue

This feature depends on AsyncTask of Swoole, your need to set swoole.task_worker_num in config/laravels.php firstly. The performance of task processing is influenced by number of Swoole task process, you need to set task_worker_num appropriately.

1.Create task class.

use Hhxsv5\LaravelS\Swoole\Task\Task;
class TestTask extends Task
{
    private $data;
    private $result;
    public function __construct($data)
    {
        $this->data = $data;
    }
    // The logic of task handling, run in task process, CAN NOT deliver task
    public function handle()
    {
        \Log::info(__CLASS__ . ':handle start', [$this->data]);
        sleep(2);// Simulate the slow codes
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
        $this->result = 'the result of ' . $this->data;
    }
    // Optional, finish event, the logic of after task handling, run in worker process, CAN deliver task 
    public function finish()
    {
        \Log::info(__CLASS__ . ':finish start', [$this->result]);
        Task::deliver(new TestTask2('task2 data')); // Deliver the other task
    }
}

2.Deliver task.

// Create instance of TestTask and deliver it, "deliver" is asynchronous.
use Hhxsv5\LaravelS\Swoole\Task\Task;
$task = new TestTask('task data');
// $task->delay(3);// delay 3 seconds to deliver task
// $task->setTries(3); // When an error occurs, try 3 times in total
$ret = Task::deliver($task);
var_dump($ret);// Return true if sucess, otherwise false

Millisecond cron job

Wrapper cron job base on Swoole's Millisecond Timer, replace Linux Crontab.

1.Create cron job class.

namespace App\Jobs\Timer;
use App\Tasks\TestTask;
use Swoole\Coroutine;
use Hhxsv5\LaravelS\Swoole\Task\Task;
use Hhxsv5\LaravelS\Swoole\Timer\CronJob;
class TestCronJob extends CronJob
{
    protected $i = 0;
    // !!! The `interval` and `isImmediate` of cron job can be configured in two ways(pick one of two): one is to overload the corresponding method, and the other is to pass parameters when registering cron job.
    // --- Override the corresponding method to return the configuration: begin
    public function interval()
    {
        return 1000;// Run every 1000ms
    }
    public function isImmediate()
    {
        return false;// Whether to trigger `run` immediately after setting up
    }
    // --- Override the corresponding method to return the configuration: end
    public function run()
    {
        \Log::info(__METHOD__, ['start', $this->i, microtime(true)]);
        // do something
        // sleep(1); // Swoole < 2.1
        Coroutine::sleep(1); // Swoole>=2.1 Coroutine will be automatically created for run().
        $this->i++;
        \Log::info(__METHOD__, ['end', $this->i, microtime(true)]);

        if ($this->i >= 10) { // Run 10 times only
            \Log::info(__METHOD__, ['stop', $this->i, microtime(true)]);
            $this->stop(); // Stop this cron job, but it will run again after restart/reload.
            // Deliver task in CronJob, but NOT support callback finish() of task.
            // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
            $ret = Task::deliver(new TestTask('task data'));
            var_dump($ret);
        }
        // The exceptions thrown here will be caught by the upper layer and recorded in the Swoole log. Developers need to try/catch manually.
    }
}

2.Register cron job.

// Register cron jobs in file "config/laravels.php"
[
    // ...
    'timer'          => [
        'enable' => true, // Enable Timer
        'jobs'   => [ // The list of cron job
            // Enable LaravelScheduleJob to run `php artisan schedule:run` every 1 minute, replace Linux Crontab
            // \Hhxsv5\LaravelS\Illuminate\LaravelScheduleJob::class,
            // Two ways to configure parameters:
            // [\App\Jobs\Timer\TestCronJob::class, [1000, true]], // Pass in parameters when registering
            \App\Jobs\Timer\TestCronJob::class, // Override the corresponding method to return the configuration
        ],
        'max_wait_time' => 5, // Max waiting time of reloading
        // Enable the global lock to ensure that only one instance starts the timer when deploying multiple instances. This feature depends on Redis, please see https://laravel.com/docs/7.x/redis
        'global_lock'     => false,
        'global_lock_key' => config('app.name', 'Laravel'),
    ],
    // ...
];

3.Note: it will launch multiple timers when build the server cluster, so you need to make sure that launch one timer only to avoid running repetitive task.

4.LaravelS v3.4.0 starts to support the hot restart [Reload] Timer process. After LaravelS receives the SIGUSR1 signal, it waits for max_wait_time(default 5) seconds to end the process, then the Manager process will pull up the Timer process again.

5.If you only need to use minute-level scheduled tasks, it is recommended to enable Hhxsv5\LaravelS\Illuminate\LaravelScheduleJob instead of Linux Crontab, so that you can follow the coding habits of Laravel task scheduling and configure Kernel.

// app/Console/Kernel.php
protected function schedule(Schedule $schedule)
{
    // runInBackground() will start a new child process to execute the task. This is asynchronous and will not affect the execution timing of other tasks.
    $schedule->command(TestCommand::class)->runInBackground()->everyMinute();
}

Automatically reload after modifying code

Via inotify, support Linux only.

1.Install inotify extension.

2.Turn on the switch in Settings.

3.Notice: Modify the file only in Linux to receive the file change events. It's recommended to use the latest Docker. Vagrant Solution.

Via fswatch, support OS X/Linux/Windows.

1.Install fswatch.

2.Run command in your project root directory.

# Watch current directory
./bin/fswatch
# Watch app directory
./bin/fswatch ./app

Via inotifywait, support Linux.

1.Install inotify-tools.

2.Run command in your project root directory.

# Watch current directory
./bin/inotify
# Watch app directory
./bin/inotify ./app

When the above methods does not work, the ultimate solution: set max_request=1,worker_num=1, so that Worker process will restart after processing a request. The performance of this method is very poor, so only development environment use.

Get the instance of SwooleServer in your project

/**
 * $swoole is the instance of `Swoole\WebSocket\Server` if enable WebSocket server, otherwise `Swoole\Http\Server`
 * @var \Swoole\WebSocket\Server|\Swoole\Http\Server $swoole
 */
$swoole = app('swoole');
var_dump($swoole->stats());
$swoole->push($fd, 'Push WebSocket message');

Use SwooleTable

1.Define Table, support multiple.

All defined tables will be created before Swoole starting.

// in file "config/laravels.php"
[
    // ...
    'swoole_tables'  => [
        // Scene:bind UserId & FD in WebSocket
        'ws' => [// The Key is table name, will add suffix "Table" to avoid naming conflicts. Here defined a table named "wsTable"
            'size'   => 102400,// The max size
            'column' => [// Define the columns
                ['name' => 'value', 'type' => \Swoole\Table::TYPE_INT, 'size' => 8],
            ],
        ],
        //...Define the other tables
    ],
    // ...
];

2.Access Table: all table instances will be bound on SwooleServer, access by app('swoole')->xxxTable.

namespace App\Services;
use Hhxsv5\LaravelS\Swoole\WebSocketHandlerInterface;
use Swoole\Http\Request;
use Swoole\WebSocket\Frame;
use Swoole\WebSocket\Server;
class WebSocketService implements WebSocketHandlerInterface
{
    /**@var \Swoole\Table $wsTable */
    private $wsTable;
    public function __construct()
    {
        $this->wsTable = app('swoole')->wsTable;
    }
    // Scene:bind UserId & FD in WebSocket
    public function onOpen(Server $server, Request $request)
    {
        // var_dump(app('swoole') === $server);// The same instance
        /**
         * Get the currently logged in user
         * This feature requires that the path to establish a WebSocket connection go through middleware such as Authenticate.
         * E.g:
         * Browser side: var ws = new WebSocket("ws://127.0.0.1:5200/ws");
         * Then the /ws route in Laravel needs to add the middleware like Authenticate.
         * Route::get('/ws', function () {
         *     // Respond any content with status code 200
         *     return 'websocket';
         * })->middleware(['auth']);
         */
        // $user = Auth::user();
        // $userId = $user ? $user->id : 0; // 0 means a guest user who is not logged in
        $userId = mt_rand(1000, 10000);
        // if (!$userId) {
        //     // Disconnect the connections of unlogged users
        //     $server->disconnect($request->fd);
        //     return;
        // }
        $this->wsTable->set('uid:' . $userId, ['value' => $request->fd]);// Bind map uid to fd
        $this->wsTable->set('fd:' . $request->fd, ['value' => $userId]);// Bind map fd to uid
        $server->push($request->fd, "Welcome to LaravelS #{$request->fd}");
    }
    public function onMessage(Server $server, Frame $frame)
    {
        // Broadcast
        foreach ($this->wsTable as $key => $row) {
            if (strpos($key, 'uid:') === 0 && $server->isEstablished($row['value'])) {
                $content = sprintf('Broadcast: new message "%s" from #%d', $frame->data, $frame->fd);
                $server->push($row['value'], $content);
            }
        }
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        $uid = $this->wsTable->get('fd:' . $fd);
        if ($uid !== false) {
            $this->wsTable->del('uid:' . $uid['value']); // Unbind uid map
        }
        $this->wsTable->del('fd:' . $fd);// Unbind fd map
        $server->push($fd, "Goodbye #{$fd}");
    }
}

Multi-port mixed protocol

For more information, please refer to Swoole Server AddListener

To make our main server support more protocols not just Http and WebSocket, we bring the feature multi-port mixed protocol of Swoole in LaravelS and name it Socket. Now, you can build TCP/UDP applications easily on top of Laravel.

Create Socket handler class, and extend Hhxsv5\LaravelS\Swoole\Socket\{TcpSocket|UdpSocket|Http|WebSocket}.

namespace App\Sockets;
use Hhxsv5\LaravelS\Swoole\Socket\TcpSocket;
use Swoole\Server;
class TestTcpSocket extends TcpSocket
{
    public function onConnect(Server $server, $fd, $reactorId)
    {
        \Log::info('New TCP connection', [$fd]);
        $server->send($fd, 'Welcome to LaravelS.');
    }
    public function onReceive(Server $server, $fd, $reactorId, $data)
    {
        \Log::info('Received data', [$fd, $data]);
        $server->send($fd, 'LaravelS: ' . $data);
        if ($data === "quit\r\n") {
            $server->send($fd, 'LaravelS: bye' . PHP_EOL);
            $server->close($fd);
        }
    }
    public function onClose(Server $server, $fd, $reactorId)
    {
        \Log::info('Close TCP connection', [$fd]);
        $server->send($fd, 'Goodbye');
    }
}

These Socket connections share the same worker processes with your HTTP/WebSocket connections. So it won't be a problem at all if you want to deliver tasks, use SwooleTable, even Laravel components such as DB, Eloquent and so on. At the same time, you can access Swoole\Server\Port object directly by member property swoolePort.

public function onReceive(Server $server, $fd, $reactorId, $data)
{
    $port = $this->swoolePort; // Get the `Swoole\Server\Port` object
}
namespace App\Http\Controllers;
class TestController extends Controller
{
    public function test()
    {
        /**@var \Swoole\Http\Server|\Swoole\WebSocket\Server $swoole */
        $swoole = app('swoole');
        // $swoole->ports: Traverse all Port objects, https://www.swoole.co.uk/docs/modules/swoole-server/multiple-ports
        $port = $swoole->ports[0]; // Get the `Swoole\Server\Port` object, $port[0] is the port of the main server
        foreach ($port->connections as $fd) { // Traverse all connections
            // $swoole->send($fd, 'Send tcp message');
            // if($swoole->isEstablished($fd)) {
            //     $swoole->push($fd, 'Send websocket message');
            // }
        }
    }
}

Register Sockets.

// Edit `config/laravels.php`
//...
'sockets' => [
    [
        'host'     => '127.0.0.1',
        'port'     => 5291,
        'type'     => SWOOLE_SOCK_TCP,// Socket type: SWOOLE_SOCK_TCP/SWOOLE_SOCK_TCP6/SWOOLE_SOCK_UDP/SWOOLE_SOCK_UDP6/SWOOLE_UNIX_DGRAM/SWOOLE_UNIX_STREAM
        'settings' => [// Swoole settings:https://www.swoole.co.uk/docs/modules/swoole-server-methods#swoole_server-addlistener
            'open_eof_check' => true,
            'package_eof'    => "\r\n",
        ],
        'handler'  => \App\Sockets\TestTcpSocket::class,
        'enable'   => true, // whether to enable, default true
    ],
],

About the heartbeat configuration, it can only be set on the main server and cannot be configured on Socket, but the Socket inherits the heartbeat configuration of the main server.

For TCP socket, onConnect and onClose events will be blocked when dispatch_mode of Swoole is 1/3, so if you want to unblock these two events please set dispatch_mode to 2/4/5.

'swoole' => [
    //...
    'dispatch_mode' => 2,
    //...
];

Test.

TCP: telnet 127.0.0.1 5291

UDP: [Linux] echo "Hello LaravelS" > /dev/udp/127.0.0.1/5292

Register example of other protocols.

  • UDP
  • Http
  • WebSocket: The main server must turn on WebSocket, that is, set websocket.enable to true.

Coroutine

Swoole Coroutine

Warning: The order of code execution in the coroutine is out of order. The data of the request level should be isolated by the coroutine ID. However, there are many singleton and static attributes in Laravel/Lumen, the data between different requests will affect each other, it's Unsafe. For example, the database connection is a singleton, the same database connection shares the same PDO resource. This is fine in the synchronous blocking mode, but it does not work in the asynchronous coroutine mode. Each query needs to create different connections and maintain IO state of different connections, which requires a connection pool.

DO NOT enable the coroutine, only the custom process can use the coroutine.

Custom process

Support developers to create special work processes for monitoring, reporting, or other special tasks. Refer addProcess.

Create Proccess class, implements CustomProcessInterface.

namespace App\Processes;
use App\Tasks\TestTask;
use Hhxsv5\LaravelS\Swoole\Process\CustomProcessInterface;
use Hhxsv5\LaravelS\Swoole\Task\Task;
use Swoole\Coroutine;
use Swoole\Http\Server;
use Swoole\Process;
class TestProcess implements CustomProcessInterface
{
    /**
     * @var bool Quit tag for Reload updates
     */
    private static $quit = false;

    public static function callback(Server $swoole, Process $process)
    {
        // The callback method cannot exit. Once exited, Manager process will automatically create the process 
        while (!self::$quit) {
            \Log::info('Test process: running');
            // sleep(1); // Swoole < 2.1
            Coroutine::sleep(1); // Swoole>=2.1: Coroutine & Runtime will be automatically enabled for callback().
             // Deliver task in custom process, but NOT support callback finish() of task.
            // Note: Modify task_ipc_mode to 1 or 2 in config/laravels.php, see https://www.swoole.co.uk/docs/modules/swoole-server/configuration
            $ret = Task::deliver(new TestTask('task data'));
            var_dump($ret);
            // The upper layer will catch the exception thrown in the callback and record it in the Swoole log, and then this process will exit. The Manager process will re-create the process after 3 seconds, so developers need to try/catch to catch the exception by themselves to avoid frequent process creation.
            // throw new \Exception('an exception');
        }
    }
    // Requirements: LaravelS >= v3.4.0 & callback() must be async non-blocking program.
    public static function onReload(Server $swoole, Process $process)
    {
        // Stop the process...
        // Then end process
        \Log::info('Test process: reloading');
        self::$quit = true;
        // $process->exit(0); // Force exit process
    }
    // Requirements: LaravelS >= v3.7.4 & callback() must be async non-blocking program.
    public static function onStop(Server $swoole, Process $process)
    {
        // Stop the process...
        // Then end process
        \Log::info('Test process: stopping');
        self::$quit = true;
        // $process->exit(0); // Force exit process
    }
}

Register TestProcess.

// Edit `config/laravels.php`
// ...
'processes' => [
    'test' => [ // Key name is process name
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false, // Whether redirect stdin/stdout, true or false
        'pipe'     => 0,     // The type of pipeline, 0: no pipeline 1: SOCK_STREAM 2: SOCK_DGRAM
        'enable'   => true,  // Whether to enable, default true
        //'num'    => 3   // To create multiple processes of this class, default is 1
        //'queue'    => [ // Enable message queue as inter-process communication, configure empty array means use default parameters
        //    'msg_key'  => 0,    // The key of the message queue. Default: ftok(__FILE__, 1).
        //    'mode'     => 2,    // Communication mode, default is 2, which means contention mode
        //    'capacity' => 8192, // The length of a single message, is limited by the operating system kernel parameters. The default is 8192, and the maximum is 65536
        //],
        //'restart_interval' => 5, // After the process exits abnormally, how many seconds to wait before restarting the process, default 5 seconds
    ],
],

Note: The callback() cannot quit. If quit, the Manager process will re-create the process.

Example: Write data to a custom process.

// config/laravels.php
'processes' => [
    'test' => [
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false,
        'pipe'     => 1,
    ],
],
// app/Processes/TestProcess.php
public static function callback(Server $swoole, Process $process)
{
    while ($data = $process->read()) {
        \Log::info('TestProcess: read data', [$data]);
        $process->write('TestProcess: ' . $data);
    }
}
// app/Http/Controllers/TestController.php
public function testProcessWrite()
{
    /**@var \Swoole\Process $process */
    $process = app('swoole')->customProcesses['test'];
    $process->write('TestController: write data' . time());
    var_dump($process->read());
}

Common components

Apollo

LaravelS will pull the Apollo configuration and write it to the .env file when starting. At the same time, LaravelS will start the custom process apollo to monitor the configuration and automatically reload when the configuration changes.

Enable Apollo: add --enable-apollo and Apollo parameters to the startup parameters.

php bin/laravels start --enable-apollo --apollo-server=http://127.0.0.1:8080 --apollo-app-id=LARAVEL-S-TEST

Support hot updates(optional).

// Edit `config/laravels.php`
'processes' => Hhxsv5\LaravelS\Components\Apollo\Process::getDefinition(),
// When there are other custom process configurations
'processes' => [
    'test' => [
        'class'    => \App\Processes\TestProcess::class,
        'redirect' => false,
        'pipe'     => 1,
    ],
    // ...
] + Hhxsv5\LaravelS\Components\Apollo\Process::getDefinition(),

List of available parameters.

ParameterDescriptionDefaultDemo
apollo-serverApollo server URL---apollo-server=http://127.0.0.1:8080
apollo-app-idApollo APP ID---apollo-app-id=LARAVEL-S-TEST
apollo-namespacesThe namespace to which the APP belongs, support specify the multipleapplication--apollo-namespaces=application --apollo-namespaces=env
apollo-clusterThe cluster to which the APP belongsdefault--apollo-cluster=default
apollo-client-ipIP of current instance, can also be used for grayscale publishingLocal intranet IP--apollo-client-ip=10.2.1.83
apollo-pull-timeoutTimeout time(seconds) when pulling configuration5--apollo-pull-timeout=5
apollo-backup-old-envWhether to backup the old configuration file when updating the configuration file .envfalse--apollo-backup-old-env

Prometheus

Support Prometheus monitoring and alarm, Grafana visually view monitoring metrics. Please refer to Docker Compose for the environment construction of Prometheus and Grafana.

Require extension APCu >= 5.0.0, please install it by pecl install apcu.

Copy the configuration file prometheus.php to the config directory of your project. Modify the configuration as appropriate.

# Execute commands in the project root directory
cp vendor/hhxsv5/laravel-s/config/prometheus.php config/

If your project is Lumen, you also need to manually load the configuration $app->configure('prometheus'); in bootstrap/app.php.

Configure global middleware: Hhxsv5\LaravelS\Components\Prometheus\RequestMiddleware::class. In order to count the request time consumption as accurately as possible, RequestMiddleware must be the first global middleware, which needs to be placed in front of other middleware.

Register ServiceProvider: Hhxsv5\LaravelS\Components\Prometheus\ServiceProvider::class.

Configure the CollectorProcess in config/laravels.php to collect the metrics of Swoole Worker/Task/Timer processes regularly.

'processes' => Hhxsv5\LaravelS\Components\Prometheus\CollectorProcess::getDefinition(),

Create the route to output metrics.

use Hhxsv5\LaravelS\Components\Prometheus\Exporter;

Route::get('/actuator/prometheus', function () {
    $result = app(Exporter::class)->render();
    return response($result, 200, ['Content-Type' => Exporter::REDNER_MIME_TYPE]);
});

Complete the configuration of Prometheus and start it.

global:
  scrape_interval: 5s
  scrape_timeout: 5s
  evaluation_interval: 30s
scrape_configs:
- job_name: laravel-s-test
  honor_timestamps: true
  metrics_path: /actuator/prometheus
  scheme: http
  follow_redirects: true
  static_configs:
  - targets:
    - 127.0.0.1:5200 # The ip and port of the monitored service
# Dynamically discovered using one of the supported service-discovery mechanisms
# https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config
# - job_name: laravels-eureka
#   honor_timestamps: true
#   scrape_interval: 5s
#   metrics_path: /actuator/prometheus
#   scheme: http
#   follow_redirects: true
  # eureka_sd_configs:
  # - server: http://127.0.0.1:8080/eureka
  #   follow_redirects: true
  #   refresh_interval: 5s

Start Grafana, then import panel json.

Grafana Dashboard

Other features

Configure Swoole events

Supported events:

EventInterfaceWhen happened
ServerStartHhxsv5\LaravelS\Swoole\Events\ServerStartInterfaceOccurs when the Master process is starting, this event should not handle complex business logic, and can only do some simple work of initialization.
ServerStopHhxsv5\LaravelS\Swoole\Events\ServerStopInterfaceOccurs when the server exits normally, CANNOT use async or coroutine related APIs in this event.
WorkerStartHhxsv5\LaravelS\Swoole\Events\WorkerStartInterfaceOccurs after the Worker/Task process is started, and the Laravel initialization has been completed.
WorkerStopHhxsv5\LaravelS\Swoole\Events\WorkerStopInterfaceOccurs after the Worker/Task process exits normally
WorkerErrorHhxsv5\LaravelS\Swoole\Events\WorkerErrorInterfaceOccurs when an exception or fatal error occurs in the Worker/Task process

1.Create an event class to implement the corresponding interface.

namespace App\Events;
use Hhxsv5\LaravelS\Swoole\Events\ServerStartInterface;
use Swoole\Atomic;
use Swoole\Http\Server;
class ServerStartEvent implements ServerStartInterface
{
    public function __construct()
    {
    }
    public function handle(Server $server)
    {
        // Initialize a global counter (available across processes)
        $server->atomicCount = new Atomic(2233);

        // Invoked in controller: app('swoole')->atomicCount->get();
    }
}
namespace App\Events;
use Hhxsv5\LaravelS\Swoole\Events\WorkerStartInterface;
use Swoole\Http\Server;
class WorkerStartEvent implements WorkerStartInterface
{
    public function __construct()
    {
    }
    public function handle(Server $server, $workerId)
    {
        // Initialize a database connection pool
        // DatabaseConnectionPool::init();
    }
}

2.Configuration.

// Edit `config/laravels.php`
'event_handlers' => [
    'ServerStart' => [\App\Events\ServerStartEvent::class], // Trigger events in array order
    'WorkerStart' => [\App\Events\WorkerStartEvent::class],
],

Serverless

Alibaba Cloud Function Compute

Function Compute.

1.Modify bootstrap/app.php and set the storage directory. Because the project directory is read-only, the /tmp directory can only be read and written.

$app->useStoragePath(env('APP_STORAGE_PATH', '/tmp/storage'));

2.Create a shell script laravels_bootstrap and grant executable permission.

#!/usr/bin/env bash
set +e

# Create storage-related directories
mkdir -p /tmp/storage/app/public
mkdir -p /tmp/storage/framework/cache
mkdir -p /tmp/storage/framework/sessions
mkdir -p /tmp/storage/framework/testing
mkdir -p /tmp/storage/framework/views
mkdir -p /tmp/storage/logs

# Set the environment variable APP_STORAGE_PATH, please make sure it's the same as APP_STORAGE_PATH in .env
export APP_STORAGE_PATH=/tmp/storage

# Start LaravelS
php bin/laravels start

3.Configure template.xml.

ROSTemplateFormatVersion: '2015-09-01'
Transform: 'Aliyun::Serverless-2018-04-03'
Resources:
  laravel-s-demo:
    Type: 'Aliyun::Serverless::Service'
    Properties:
      Description: 'LaravelS Demo for Serverless'
    fc-laravel-s:
      Type: 'Aliyun::Serverless::Function'
      Properties:
        Handler: laravels.handler
        Runtime: custom
        MemorySize: 512
        Timeout: 30
        CodeUri: ./
        InstanceConcurrency: 10
        EnvironmentVariables:
          BOOTSTRAP_FILE: laravels_bootstrap

Important notices

Singleton Issue

Under FPM mode, singleton instances will be instantiated and recycled in every request, request start=>instantiate instance=>request end=>recycled instance.

Under Swoole Server, All singleton instances will be held in memory, different lifetime from FPM, request start=>instantiate instance=>request end=>do not recycle singleton instance. So need developer to maintain status of singleton instances in every request.

Common solutions:

Write a XxxCleaner class to clean up the singleton object state. This class implements the interface Hhxsv5\LaravelS\Illuminate\Cleaners\CleanerInterface and then registers it in cleaners of laravels.php.

Reset status of singleton instances by Middleware.

Re-register ServiceProvider, add XxxServiceProvider into register_providers of file laravels.php. So that reinitialize singleton instances in every request Refer.

Cleaners

Configuration cleaners.

Known issues

Known issues: a package of known issues and solutions.

Debugging method

Logging; if you want to output to the console, you can use stderr, Log::channel('stderr')->debug('debug message').

Laravel Dump Server(Laravel 5.7 has been integrated by default).

Read request

Read request by Illuminate\Http\Request Object, $_ENV is readable, $_SERVER is partially readable, CANNOT USE $_GET/$_POST/$_FILES/$_COOKIE/$_REQUEST/$_SESSION/$GLOBALS.

public function form(\Illuminate\Http\Request $request)
{
    $name = $request->input('name');
    $all = $request->all();
    $sessionId = $request->cookie('sessionId');
    $photo = $request->file('photo');
    // Call getContent() to get the raw POST body, instead of file_get_contents('php://input')
    $rawContent = $request->getContent();
    //...
}

Output response

Respond by Illuminate\Http\Response Object, compatible with echo/vardump()/print_r(),CANNOT USE functions dd()/exit()/die()/header()/setcookie()/http_response_code().

public function json()
{
    return response()->json(['time' => time()])->header('header1', 'value1')->withCookie('c1', 'v1');
}

Persistent connection

Singleton connection will be resident in memory, it is recommended to turn on persistent connection for better performance.

  1. Database connection, it will reconnect automatically immediately after disconnect.
// config/database.php
'connections' => [
    'my_conn' => [
        'driver'    => 'mysql',
        'host'      => env('DB_MY_CONN_HOST', 'localhost'),
        'port'      => env('DB_MY_CONN_PORT', 3306),
        'database'  => env('DB_MY_CONN_DATABASE', 'forge'),
        'username'  => env('DB_MY_CONN_USERNAME', 'forge'),
        'password'  => env('DB_MY_CONN_PASSWORD', ''),
        'charset'   => 'utf8mb4',
        'collation' => 'utf8mb4_unicode_ci',
        'prefix'    => '',
        'strict'    => false,
        'options'   => [
            // Enable persistent connection
            \PDO::ATTR_PERSISTENT => true,
        ],
    ],
],
  1. Redis connection, it won't reconnect automatically immediately after disconnect, and will throw an exception about lost connection, reconnect next time. You need to make sure that SELECT DB correctly before operating Redis every time.
// config/database.php
'redis' => [
    'client' => env('REDIS_CLIENT', 'phpredis'), // It is recommended to use phpredis for better performance.
    'default' => [
        'host'       => env('REDIS_HOST', 'localhost'),
        'password'   => env('REDIS_PASSWORD', null),
        'port'       => env('REDIS_PORT', 6379),
        'database'   => 0,
        'persistent' => true, // Enable persistent connection
    ],
],

About memory leaks

Avoid using global variables. If necessary, please clean or reset them manually.

Infinitely appending element into static/global variable will lead to OOM(Out of Memory).

class Test
{
    public static $array = [];
    public static $string = '';
}

// Controller
public function test(Request $req)
{
    // Out of Memory
    Test::$array[] = $req->input('param1');
    Test::$string .= $req->input('param2');
}

Memory leak detection method

Modify config/laravels.php: worker_num=1, max_request=1000000, remember to change it back after test;

Add routing /debug-memory-leak without route middleware to observe the memory changes of the Worker process;

Start LaravelS and request /debug-memory-leak until diff_mem is less than or equal to zero; if diff_mem is always greater than zero, it means that there may be a memory leak in Global Middleware or Laravel Framework;

After completing Step 3, alternately request the business routes and /debug-memory-leak (It is recommended to use ab/wrk to make a large number of requests for business routes), the initial increase in memory is normal. After a large number of requests for the business routes, if diff_mem is always greater than zero and curr_mem continues to increase, there is a high probability of memory leak; If curr_mem always changes within a certain range and does not continue to increase, there is a low probability of memory leak.

If you still can't solve it, max_request is the last guarantee.

Linux kernel parameter adjustment

Linux kernel parameter adjustment

Pressure test

Pressure test

Alternatives

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Author: hhxsv5
Source Code: https://github.com/hhxsv5/laravel-s 
License: MIT License

#php #laravel #http 

Zachary Palmer

Zachary Palmer

1555901576

CSS Flexbox Tutorial | Build a Chat Application

Creating the conversation sidebar and main chat section

In this article we are going to focus on building a basic sidebar, and the main chat window inside our chat shell. See below.

Chat shell with a fixed width sidebar and expanded chat window

This is the second article in this series. You can check out the previous article for setting up the shell OR you can just check out the chat-shell branch from the following repository.

https://github.com/lyraddigital/flexbox-chat-app.git

Open up the chat.html file. You should have the following HTML.

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title>Chat App</title>
    <link rel="stylesheet" type="text/css" media="screen" href="css/chat.css" />
</head>
<body>
    <div id="chat-container">
    </div>
</body>
</html>

Now inside of the chat-container div add the following HTML.

<div id="side-bar">
</div>
<div id="chat-window">
</div>

Now let’s also add the following CSS under the #chat-container selector in the chat.css file.

#side-bar {
    background: #0048AA;
    border-radius: 10px 0 0 10px;
}
#chat-window {
    background: #999;
    border-radius: 0 10px 10px 0;
}

Now reload the page. You should see the following:-

So what happened? Where is our sidebar and where is our chat window? I expected to see a blue side bar and a grey chat window, but it’s no where to be found. Well it’s all good. This is because we have no content inside of either element, so it can be 0 pixels wide.

Sizing Flex Items

So now that we know that our items are 0 pixels wide, let’s attempt to size them. We’ll attempt to try this first using explicit widths.

Add the following width property to the #side-bar rule, then reload the page.

width: 275px;

Hmm. Same result. It’s still a blank shell. Oh wait I have to make sure the height is 100% too. So we better do that too. Once again add the following property to the #side-bar rule, then reload the page.

height: 100%;

So now we have our sidebar that has grown to be exactly 275 pixels wide, and is 100% high. So that’s it. We’re done right? Wrong. Let me ask you a question. How big is the chat window? Let’s test that by adding some text to it. Try this yourself just add some text. You should see something similar to this.

So as you can see the chat window is only as big as the text that’s inside of it, and it is not next to the side bar. And this makes sense because up until now the chat shell is not a flex container, and just a regular block level element.

So let’s make our chat shell a flex container. Set the following display property for the #chat-window selector. Then reload the page.

display: flex;

So as you can see by the above illustration, we can see it’s now next to the side bar, and not below it. But as you can see currently it’s only as wide as the text that’s inside of it.

But we want it to take up the remaining space of the chat shell. Well we know how to do this, as we did it in the previous article. Set the flex-grow property to 1 on the #chat-window selector. Basically copy and paste the property below and reload the page.

flex-grow: 1;

So now we have the chat window taking up the remaining space of the chat shell. Next, let’s remove the background property, and also remove all text inside the chat-window div if any still exists. You should now see the result below.

But are we done? Technically yes, but before we move on, let’s improve things a little bit.

Understanding the default alignment

If you remember, before we had defined our chat shell to be a flex container, we had to make sure we set the height of the side bar to be 100%. Otherwise it was 0 pixels high, and as a result nothing was displayed. With that said, try removing the height property from the #side-bar selector and see what happens when you reload the page. Yes that’s right, it still works. The height of the sidebar is still 100% high.

So what happened here? Why do we no longer have to worry about setting the height to 100%? Well this is one of the cool things Flexbox gives you for free. By default every flex item will stretch vertically to fill in the entire height of the flex container. We can in fact change this behaviour, and we will see how this is done in a future article.

Setting the size of the side bar properly

So another feature of Flexbox is being able to set the size of a flex item by using the flex-basis property. The flex-basis property allows you to specify an initial size of a flex item, before any growing or shrinking takes place. We’ll understand more about this in an upcoming article.

For now I just want you to understand one important thing. And that is using width to specify the size of the sidebar is not a good idea. Let’s see why.

Say that potentially, if the screen is mobile we want the side bar to now appear across the top of the chat shell, acting like a top bar instead. We can do this by changing the direction flex items can flex inside a flex container. For example, add the following CSS to the #chat-container selector. Then reload the page.

flex-direction: column;

So as you can see we are back to a blank shell. So firstly let’s understand what we actually did here. By setting the flex-direction property to column, we changed the direction of how the flex items flex. By default flex items will flex from left to right. However when we set flex-direction to column, it changes this behaviour forcing flex items to flex from top to bottom instead. On top of this, when the direction of flex changes, the sizing and alignment of flex items changes as well.

When flexing from left to right, we get a height of 100% for free as already mentioned, and then we made sure the side bar was set to be 275 pixels wide, by setting the width property.

However now that we a flexing from top to bottom, the width of the flex item by default would be 100% wide, and you would need to specify the height instead. So try this. Add the following property to the #side-bar selector to set the height of the side bar. Then reload the page.

height: 275px;

Now we are seeing the side bar again, as we gave it a fixed height too. But we still have that fixed width. That’s not what we wanted. We want the side bar (ie our new top bar) here to now be 100% wide. Comment out the width for a moment and reload the page again.

So now we were able to move our side bar so it appears on top instead, acting like a top bar. Which as previously mentioned might be suited for mobile device widths. But to do this we had to swap the value of width to be the value of height. Wouldn’t it be great if this size was preserved regardless of which direction our items are flexing.

Try this, remove all widths and height properties from the #side-bar selector and write the following instead. Then reload the page.

flex-basis: 275px;

As you can see we get the same result. Now remove the flex-direction property from the #chat-container selector. Then once again reload the page.

Once again we are back to our final output. But now we also have the flexibility to easily change the side bar to be a top bar if we need to, by just changing the direction items can flow. Regardless of the direction of flex, the size of our side bar / top bar is preserved.

Conclusion

Ok so once again we didn’t build much, but we did cover a lot of concepts about Flexbox around sizing. 

#css #programming #webdev