A Beginners Guide to Dynamic Theme in Flutter using BLoC

Flutter ecosystem is really good for building high-quality apps with a lot of features. State management is one of the important aspect of high-quality and it is always a challenging task for every software developer irrespective of the type of application he/she is building. State management becomes more complex as the complexity of the application increases. In Flutter, we have an option of BLoC(Business Logic Component) for clean and elegant state management.

BLoC pattern is a very robust technique for state management as it uses Streams as it’s core and it is not at all a difficult task to implement BLoC in any application. Dynamic Theme refers to changing the theme of the app based on the user’s preference at runtime. This technique is used for good user experience as user always has a choice to switch the theme. When we talk about BLoC pattern in Flutter, 3 things come in our mind:

1. StreamController
2. Stream
3. Sink

If you are not familiar with Streams and BLoC pattern, then I would recommend you to learn those from this resource.

First of all we will be creating a new file in lib folder for BLoC logic. This file will contain the logic part(main core of the BLoC pattern logic) required for our application.

import 'dart:async';

class ThemeBloc {
  final _themeStreamController = StreamController<bool>();
  get changeTheTheme => _themeStreamController.sink.add;
  get darkThemeIsEnabled => _themeStreamController.stream;
}

Here, we are creating StreamController of bool because we want to pass the boolean data in our stream. After that, we are implementing the changeTheTheme() and darkThemeIsEnabled() functions using the sink and stream respectively.

import 'package:flutter/material.dart';
import 'theme.bloc.dart';

class HomePage extends StatelessWidget {

  final bool isDarkThemeEnabled;
  final ThemeBloc bloc;

  HomePage(this.isDarkThemeEnabled, this.bloc);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Robo World"),
        centerTitle: true,
      ),
      body: ListView.builder(
        itemCount: 20,
        itemBuilder: (BuildContext context, index) {
          return ListTile(
            title: Text("User ${index+1}"),
            leading: Image.network('https://robohash.org/user$index}'),
            trailing: Icon(Icons.edit),
          );
        },
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            ListTile(
              title: Text("Dark Theme"),
              trailing: Switch(
                value: isDarkThemeEnabled,
                onChanged: bloc.changeTheTheme
              ),
            )
          ],
        ),
      ),
    );
  }
}

In the home_page.dart file, we are just creating a scaffold and inside that scaffold, we are just rendering a list with random images in the list tile. The data is rendered for demo purpose. A drawer is created and a switch is given in order to switch between the light and the dark theme.

Now, after all these files in place, we are required to setup the main.dart filefor starting the app accordingly. Here’s the main.dart file.

import 'package:dynamic_theme/home_page.dart';
import 'package:dynamic_theme/theme.bloc.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder(
      initialData: false,
      stream: bloc.darkThemeIsEnabled,
      builder: (context, snapshot) {
        return MaterialApp(
          theme: snapshot.data ? ThemeData.dark() : ThemeData.light(),
          home: new HomePage(snapshot.data, bloc)
        );
      }
    );
  }
}

final bloc = ThemeBloc();

In the main.dart file, we are using a StreamBuilder widget to deal with the Streams which are introduced due to BLoC pattern.

Here are the screenshots of the app which we have built.

This app is a demo app which can be implemented for performing dynamic theme behaviour in your app using BLoC pattern for State Management. The dynamic theme functionality gives a good User Experience as the user has it’s own choice to switch between the different colour themes.

The Final Words

Dynamic Theme is always a good experience for the user and because of this, it is really awesome to implement dynamic theme in apps. BLoC Pattern is a very robust technique for state management in flutter which can be used to scale any app at any level. So, we can use BLoC Pattern for state management as well as for implementing dynamic themes.

Good Bye!!!

#flutter #dart #mobile-apps #ios

What is GEEK

Buddha Community

Google's Flutter 1.20 stable announced with new features - Navoki

Flutter Google cross-platform UI framework has released a new version 1.20 stable.

Flutter is Google’s UI framework to make apps for Android, iOS, Web, Windows, Mac, Linux, and Fuchsia OS. Since the last 2 years, the flutter Framework has already achieved popularity among mobile developers to develop Android and iOS apps. In the last few releases, Flutter also added the support of making web applications and desktop applications.

Last month they introduced the support of the Linux desktop app that can be distributed through Canonical Snap Store(Snapcraft), this enables the developers to publish there Linux desktop app for their users and publish on Snap Store.  If you want to learn how to Publish Flutter Desktop app in Snap Store that here is the tutorial.

Flutter 1.20 Framework is built on Google’s made Dart programming language that is a cross-platform language providing native performance, new UI widgets, and other more features for the developer usage.

Here are the few key points of this release:

Performance improvements for Flutter and Dart

In this release, they have got multiple performance improvements in the Dart language itself. A new improvement is to reduce the app size in the release versions of the app. Another performance improvement is to reduce junk in the display of app animation by using the warm-up phase.

If your app is junk information during the first run then the Skia Shading Language shader provides for pre-compilation as part of your app’s build. This can speed it up by more than 2x.

Added a better support of mouse cursors for web and desktop flutter app,. Now many widgets will show cursor on top of them or you can specify the type of supported cursor you want.

Autofill for mobile text fields

Autofill was already supported in native applications now its been added to the Flutter SDK. Now prefilled information stored by your OS can be used for autofill in the application. This feature will be available soon on the flutter web.

A new widget for interaction

InteractiveViewer is a new widget design for common interactions in your app like pan, zoom drag and drop for resizing the widget. Informations on this you can check more on this API documentation where you can try this widget on the DartPad. In this release, drag-drop has more features added like you can know precisely where the drop happened and get the position.

Updated Material Slider, RangeSlider, TimePicker, and DatePicker

In this new release, there are many pre-existing widgets that were updated to match the latest material guidelines, these updates include better interaction with Slider and RangeSlider, DatePicker with support for date range and time picker with the new style.

New pubspec.yaml format

Other than these widget updates there is some update within the project also like in pubspec.yaml file format. If you are a flutter plugin publisher then your old pubspec.yaml  is no longer supported to publish a plugin as the older format does not specify for which platform plugin you are making. All existing plugin will continue to work with flutter apps but you should make a plugin update as soon as possible.

Preview of embedded Dart DevTools in Visual Studio Code

Visual Studio code flutter extension got an update in this release. You get a preview of new features where you can analyze that Dev tools in your coding workspace. Enable this feature in your vs code by _dart.previewEmbeddedDevTools_setting. Dart DevTools menu you can choose your favorite page embed on your code workspace.

Network tracking

The updated the Dev tools comes with the network page that enables network profiling. You can track the timings and other information like status and content type of your** network calls** within your app. You can also monitor gRPC traffic.

Generate type-safe platform channels for platform interop

Pigeon is a command-line tool that will generate types of safe platform channels without adding additional dependencies. With this instead of manually matching method strings on platform channel and serializing arguments, you can invoke native class and pass nonprimitive data objects by directly calling the Dartmethod.

There is still a long list of updates in the new version of Flutter 1.2 that we cannot cover in this blog. You can get more details you can visit the official site to know more. Also, you can subscribe to the Navoki newsletter to get updates on these features and upcoming new updates and lessons. In upcoming new versions, we might see more new features and improvements.

You can get more free Flutter tutorials you can follow these courses:

• Setup Flutter Desktop on Windows, Linux, MacOS using VSCode and Build – Flutter Tutorial
• Flutter Desktop Linux app | Build and Publish on Snapcraft Store
• Firebase Local Emulator Suite in Flutter

#dart #developers #flutter #app developed #dart devtools in visual studio code #firebase local emulator suite in flutter #flutter autofill #flutter date picker #flutter desktop linux app build and publish on snapcraft store #flutter pigeon #flutter range slider #flutter slider #flutter time picker #flutter tutorial #flutter widget #google flutter #linux #navoki #pubspec format #setup flutter desktop on windows

What is Flutter and why you should learn it?

Flutter is an open-source UI toolkit for mobile developers, so they can use it to build native-looking** Android and iOS** applications from the same code base for both platforms. Flutter is also working to make Flutter apps for Web, PWA (progressive Web-App) and Desktop platform (Windows,macOS,Linux).

Flutter was officially released in December 2018. Since then, it has gone a much stronger flutter community.

There has been much increase in flutter developers, flutter packages, youtube tutorials, blogs, flutter examples apps, official and private events, and more. Flutter is now on top software repos based and trending on GitHub.

Flutter meaning?

What is Flutter? this question comes to many new developer’s mind.

Flutter means flying wings quickly, and lightly but obviously, this doesn’t apply in our SDK.

So Flutter was one of the companies that were acquired by **Google **for around $40 million. That company was based on providing gesture detection and recognition from a standard webcam. But later when the Flutter was going to release in alpha version for developer it’s name was Sky, but since Google already owned Flutter name, so they rename it to Flutter.

Where Flutter is used?

Flutter is used in many startup companies nowadays, and even some MNCs are also adopting Flutter as a mobile development framework. Many top famous companies are using their apps in Flutter. Some of them here are

Dream11

NuBank

Reflectly app

Abbey Road Studios

and many more other apps. Mobile development companies also adopted Flutter as a service for their clients. Even I was one of them who developed flutter apps as a freelancer and later as an IT company for mobile apps.

#dart #flutter #uncategorized #flutter framework #flutter jobs #flutter language #flutter meaning #flutter meaning in hindi #google flutter #how does flutter work #what is flutter

Flutter Bloc State Management

A flutter bloc state management series that will walk you through from all the basics of streams to advance state management tools like flutter_bloc/bloc package

Let’s start by understanding what we mean by state management and why should we care about it in the first place.

What Exactly Is State management ?

In simple words, state means data or the current information the user can see or manipulate.

For eg: Interface controls such as text fields, OK buttons, radio buttons, etc. To maintain these state of data like weather a button is pressed or not what is the current text in the text field or is a toggle button on or off, These data which user generally see or interacts with or generates on some event is called the state and the term used for maintaining all these information(state) is called state management.

The problem :

State management can become very messy when the application grows, simple tools like setState in flutter can’t be the solution for managing large changes at once and tools like inherited widget can create a lot of boilerplate code.

The Solution :

To overcome the above problem we can simply use tools like flutter_bloc/bloc these packages are created by the community are pretty useful for reducing boilerplate code and can be very easy to implement.

Before going deep into the flutter_bloc package we need to make our basics clear these basics includes :

_:: _streams

:: cubit

:: bloc

Streams :

A stream is a sequence of asynchronous data. Streams are just like water hose which have a sink and a drain, Which we can use to provide and retrieve data from streams. To fully understand the concept of bloc we will first need to understand the core features and basic application of streams in Dart.

As we know the basic definition of streams lets generate our own stream using the yield keyword.

using yield to generate stream’s

In the above example, we have a function getRandomNumberStream this function is present in “lib\streamGenerators.dart” (It’s better to clone the repo and take a look at the structure of the program) which output streams we have specified that by using *async. **Then we have a Future.delayed() which delays our execution for the first run for 1000 ms and then 500 ms for every other subsequent execution. Then we output(yield) the value.

What** yield **does it basically output the data in the form of a stream, So this function is going to be our go-to for all our need for streams in this first series.

Now let me brief about all the basic functions that are available with streams.

• .map: .map helps us to map the event that we are getting from the stream by passing them to a function. ex

StreamGenerators.getRandomNumberStream(10).map((event) => "This event --$event-- is mapped");

op:
This event --$0-- is mapped
This event --$1-- is mapped
This event --$2-- is mapped
This event --$3-- is mapped
This event --$4-- is mapped

• .take: .take will only take the first N values and drain the rest of the values. ex

#bloc #flutter-widget #flutter-state-management #flutter-bloc #flutter

Adobe XD plugin for Flutter with CodePen Tutorial

Recently Adobe XD releases a new version of the plugin that you can use to export designs directly into flutter widgets or screens. Yes, you read it right, now you can make and export your favorite design in Adobe XD and export all the design in the widget form or as a full-screen design, this can save you a lot of time required in designing.

What we will do?
I will make a simple design of a dialogue box with a card design with text over it as shown below. After you complete this exercise you can experiment with the UI. You can make your own components or import UI kits available with the Adobe XD.

#developers #flutter #adobe xd design export to flutter #adobe xd flutter code #adobe xd flutter code generator - plugin #adobe xd flutter plugin #adobe xd flutter plugin tutorial #adobe xd plugins #adobe xd to flutter #adobe xd tutorial #codepen for flutter.

Themes in Flutter: Part 3

In the 1st part, we saw 15 parameters of ThemeData class. Those were brightness, visualDensity, primaryColor, primaryColorBrightness, primaryColorLight, primaryColorDark, canvasColor, ascentColor, ascentColorBrightness, scaffoldNBackgroundColor, bottomAppBarColor, cardColor, dividerColor, focusColor.
In the 2nd part, we saw 27 parameters of ThemeData class. Those were hoverColor, hightlightColor, splashColor, splashFactory, selectedRowColor, unselectedWidgetColor, disabledColor, buttonTheme, toggleButtonsTheme, buttonColor, secondaryHeaderColor, textSelectionColor, cursorColor, textSelectionHandleColor, backgroundColor, dialogBackgroundColor, indicatorColor, hintColor, errorColor, toggleableActiveColor, textTheme, primaryTextTheme, accentTextTheme, inputDecorationTheme, iconTheme, primaryIconTheme, accentIconTheme.
Let’s start with 3rd set fo ThemeData parameters.

#flutter #flutter-color #flutter-widget #flutter-theme #flutter-ui