Edward Jackson

Edward Jackson

1560835976

Paths in Flutter: A Visual Guide

In this article, we will go through each function which in Path class and see how they behave.

Flutter gives us a lot of standard views to use in our projects, but from time to time we need to create custom views. We will go through each function which in Path class and see how they behave.

One of the most common way to do this is, using paths.

But first, let’s quickly go over our base playground.

p.s. I wanted to pick Totoro as a the header because of my latest trip to Japan and also it is cute :) Also there is a path in the gif :)

import 'package:flutter/material.dart';

void main() => runApp(
      MaterialApp(
        home: PathExample(),
      ),
    );

class PathExample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: PathPainter(),
    );
  }
}

class PathPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    // TODO: do operations here
    path.close();
    canvas.drawPath(path, paint);
  }

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

Basically what we have here is a StatelessWidgetwith CustomPaintas a child and it gets our CustomPainteras a painter. CustomPaint is a widget that provides us a canvas to be used by the CustomPainter to paint what we provided in the paint method.

For painting options, we created a Paint object and decided to draw everything stroke style with a width of 8 in color red.

Next, we have our Path in our code to be used for drawing. Path is basically a collection of drawn elements. These elements are drawn according to its starting point. The initial starting point for a Path is (0,0).

Lastly, we have our canvas . We use canvas for drawing our path on it with the paint that we created.

Now that we are done with the playground, let’s talk about the screen coordinate system in case it is not familiar to some people.

For the screen, the start point (0,0) is the screen’s top left corner. X coordinate direction is the horizontal axis and the right edge of the screen is the positive visible limit and its value is the width of the screen. Y coordinate direction is the vertical axis and bottom edge of the screen is the positive visible limit and its value is the height of the screen.

Now we are ready to start.

moveTo

moveTo method helps us to move the starting point of the sub-path to the point provided within the method.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    // Moves starting point to the center of the screen
    path.moveTo(size.width / 2, size.height / 2);
    canvas.drawPath(path, paint);
}

Moves starting point to center

lineTo

lineTo is the method to draw a line from the current point of the path to the point provided within the method.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    // Draws a line from left top corner to right bottom
    path.lineTo(size.width, size.height);
    canvas.drawPath(path, paint);
}

Draws a line from top left to bottom right

lineTo example

quadraticBezierTo

quadraticBezierTo method was for me the most complicated one to understand. It draws a Bezier Curves and as we learn from Mathematics, it does this with the control point provided.

Disclaimer: Since it’s a complicated concept, I wanted to keep this as visual as possible, you can see how bezier curves are calculated.

From the left center of the screen, we draw a bezier curve to the right center of the screen.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.moveTo(0, size.height / 2);
    path.quadraticBezierTo(size.width / 2, size.height, size.width, size.height / 2);
    canvas.drawPath(path, paint);
}

cubicTo

cubicTo method adds a Bezier curve in cubic style.

Unlike to quadraticBezierTo, we assign two different control points for . This way you can have the bezier calculations for two control points to have cool views like a wave.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;
    
    Path path = Path();
    path.cubicTo(size.width / 4, 3 * size.height / 4, 3 * size.width / 4, size.height / 4, size.width, size.height);
    canvas.drawPath(path, paint);
}

conicTo

conicTo is also basically acting like a quadraticBeizerTo wit the only difference being the weight variable. If the weight is bigger than 1, the drawn shape is a hyperbola. If the weight is 1 then drawn shape is parabola and if it’s smaller than 1, the drawn shape would be an ellipse.

One important thing to note is, as the weight increases, the curve is pulled more to control point.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.conicTo(size.width / 4, 3 * size.height / 4, size.width, size.height, 20);
    canvas.drawPath(path, paint);
}

arcTo

arcTo is accepting an oval then, gets a start angle and sweep angle as a radian. It starts drawing the oval from the start angle and adds the sweep angle to the start angle.

e.g. For drawing an arc starting from left middle edge to top edge of an oval, we will start from 0 which is the radian value for 0 and add 1.57 which is the radian value for 90.

The example below shows the arc of an oval drawn from the center of the screen.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    // Method to convert degree to radians
    num degToRad(num deg) => deg * (Math.pi / 180.0);

    Path path = Path();
    path.arcTo(Rect.fromLTWH(size.width / 2, size.height / 2, size.width / 4, size.height / 4), degToRad(0), degToRad(90), true);
    canvas.drawPath(path, paint);
}

addRect

addRect adds a rectangle as a new sub-path.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    // Adds a rectangle
    path.addRect(Rect.fromLTWH(size.width / 2, size.height / 2, size.width / 4, size.height / 4));
    canvas.drawPath(path, paint);
}

addOval

addOval adds an oval as a sub-path. From the example above, we will only change the method call.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    // Adds an oval
    path.addOval(Rect.fromLTWH(size.width / 2, size.height / 2, size.width / 4, size.height / 4));
    canvas.drawPath(path, paint);
}

addArc

addArcis acting as arcTo.

e.g. For drawing an arc starting from left middle edge to top edge of an oval, we will start from 3.14 which is the radian value for 180 and add 1.57 which is the radian value for 90.

For making things easier, I added a function to calculate the radian from degree.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    // Method to convert degree to radians
    num degToRad(num deg) => deg * (Math.pi / 180.0);

    Path path = Path();
    // Adds a quarter arc
    path.addArc(Rect.fromLTWH(0, 0, size.width, size.height), degToRad(180), degToRad(90));
    canvas.drawPath(path, paint);
}

addPolygon

addPolygon method draws polygon from sets of points. It gets a set of Offset values which will be the positions for the polygon. Lastly it accepts a boolean, true acts like path.close() and draws a straight line between the last and first point and false does nothing.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    // Adds a polygon from the starting point to quarter point of the screen and lastly
    // it will be in the bottom middle. Close method will draw a line between start and end.
    path.addPolygon([
      Offset.zero,
      Offset(size.width / 4, size.height / 4),
      Offset(size.width / 2, size.height)
    ], true);
    canvas.drawPath(path, paint);
}

close = false

close = true

addRRect

addRRect is a method to create a rounded cornered rectangle. We will use the rectangle above and corners with radius of 16.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.addRRect(
      RRect.fromRectAndRadius(Rect.fromLTWH(size.width / 2, size.height / 2, size.width / 4, size.height / 4), Radius.circular(16))
    );
    canvas.drawPath(path, paint);
}

addPath

addPath is the method to add one path to another one with an offset. We will add one path with line to the rounded corner rectangle above.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.addRRect(
        RRect.fromRectAndRadius(Rect.fromLTWH(size.width / 2, size.height / 2, size.width / 4, size.height / 4), Radius.circular(16))
    );
    Path secondPath = Path();
    secondPath.lineTo(size.width / 2, size.height / 2);
    path.addPath(secondPath, Offset(16, 16));
    canvas.drawPath(path, paint);
}

relativeLineTo

relativeLineTo is basically behaving like lineTo but only offsets the drawn shape to the current point. Width the same code lineTo would have the half of the length.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.moveTo(size.width / 4, size.height / 4);
    path.relativeLineTo(size.width / 2, size.height / 2);
    canvas.drawPath(path, paint);
}

relativeQuadraticBezierTo

relativeQuadraticBezierTo method acts like quadraticBezierTo method. Current point is calculated relative to the current position of the path.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.moveTo(size.width / 4, size.height / 4);
    path.relativeQuadraticBezierTo(size.width / 2, size.height, size.width, size.height / 2);
    canvas.drawPath(path, paint);
}

relativeConicTo

relativeConicTo behaves exactly like conicto method. It calculates the current point relative to the path’s current position.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.moveTo(size.width / 4, size.height / 4);
    path.relativeConicTo(size.width / 4, 3 * size.height / 4, size.width, size.height, 20);
    canvas.drawPath(path, paint);
}

relativeCubicTo

relativeCubicTo method behaves exactly like cubicTo. Only difference is, it’s current position will be calculated relative to the current position of the path.

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 8.0;

    Path path = Path();
    path.moveTo(size.width / 4, size.height / 4);
    path.relativeCubicTo(size.width / 4, 3 * size.height / 4, 3 * size.width / 4, size.height / 4, size.width, size.height);
    canvas.drawPath(path, paint);
}

Conclusion

Drawing custom shapes with canvas are really important and it’s helpful for us to use our creativity in our application development. These operations can be used to create a cool background, graphics and so on.

So, go ahead and play around with it, if you have any questions either leave a comment below.

Thank you!

Learn More

Getting started with Flutter

Android Studio for beginners

Flutter Tutorial - Flight List UI Example In Flutter

Let’s Develop a Mobile App in Flutter

Mastering styled text in Flutter

A Design Pattern for Flutter

Weather App with “flutter_bloc”

An introduction to Dart and Flutter

Learn Flutter & Dart to Build iOS & Android Apps

Flutter & Dart - The Complete Flutter App Development Course

Dart and Flutter: The Complete Developer’s Guide

Flutter - Advanced Course

#flutter #mobile-apps #ios #android

What is GEEK

Buddha Community

Paths in Flutter: A Visual Guide

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.

sksl_warm-up

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.

flutter_autofill

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 RangeSliderDatePicker with support for date range and time picker with the new style.

flutter_DatePicker

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:

#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

Terry  Tremblay

Terry Tremblay

1598396940

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-mobile-desktop-web-embedded_min

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.

humming_bird_dart_flutter

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

Dream11

NuBank

NuBank

Reflectly app

Reflectly app

Abbey Road Studios

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.

Flutter as a service

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

Brain  Crist

Brain Crist

1602147600

Flutter App Development Trends 2020

As the new decade dawns upon us, a slew of technologies has been making a lot of noise to grab the developers’ attention. While native app development is going strong, the trade winds are now blowing towards going cross-platform.

Adobe PhoneGap, React Native, Xamarin and Ionic are all leaving no stone unturned to be the undefeated champion of cross-platform development. Still, Google’s Flutter is all set to take them all on at once.

There are a tonne of resources available online to learn about Flutter, and you can start with this step by step flutter guide.

With reduced code development time, increased time-to-market speed, near-native performance, and a bevy of advantages under its hood, Flutter is set to dominate the market this decade.

Before we take a look at trends making the Flutter race ahead in 2020, let us do a quick recap of what Flutter is, for those who have been living under a rock.

#flutter #flutter-for-mobile-app #flutter-app-development #mobile-app-development #flutter-trends #software-development #advantages-of-flutter-mobile #pros-and-cons-of-flutter

Juned Ghanchi

1621572917

Flutter App Development Company India, Flutter App Developers for Hire

We build the best-in-class flutter apps that let your business work with great capacity and with a lower operating cost. And businesses can perform well and achieve higher productivity with minimal efforts.

Using app built by our developers eliminates the need to hire separate programmers for native platforms. The apps developed with the Flutter SDK package are heavily optimized for native style platforms and API integrations.

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