tchigher / lottie-flutter

Render After Effects animations natively on Flutter. This package is a pure Dart implementation of a Lottie player.

Lottie for Flutter

Lottie is a mobile library for Android and iOS that parses Adobe After Effects animations exported as json with Bodymovin and renders them natively on mobile!

This repository is a unofficial conversion of the Lottie-android library in pure Dart.

It works on Android, iOS and macOS. (Web support is coming)

Usage

Simple animation

This example shows how to display a Lottie animation in the simplest way.
The Lottie widget will load the json file and run the animation indefinitely.

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: ListView(
          children: [
            // Load a Lottie file from your assets
            Lottie.asset('assets/LottieLogo1.json'),

            // Load a Lottie file from a remote url
            Lottie.network(
                'https://raw.githubusercontent.com/xvrh/lottie-flutter/master/example/assets/Mobilo/A.json'),

            // Load an animation and its images from a zip file
            Lottie.asset('assets/lottiesfiles/angel.zip'),
          ],
        ),
      ),
    );
  }
}

To load an animation from the assets folder, we need to add an assets section in the pubspec.yaml:

flutter:
  assets:
    - assets/

Specify a custom AnimationController

This example shows how to have full control over the animation by providing your own AnimationController.

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

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> with TickerProviderStateMixin {
  AnimationController _controller;

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

    _controller = AnimationController(vsync: this);
  }

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: ListView(
          children: [
            Lottie.network(
              'https://raw.githubusercontent.com/xvrh/lottie-flutter/master/sample_app/assets/Mobilo/C.json',
              controller: _controller,
              onLoaded: (composition) {
                // Configure the AnimationController with the duration of the
                // Lottie file and start the animation.
                _controller
                  ..duration = composition.duration
                  ..forward();
              },
            ),
          ],
        ),
      ),
    );
  }
}

Control the size of the Widget

The Lottie widget takes the same arguments and have the same behavior as the Image widget in term of controlling its size.

Lottie.asset(
  'assets/LottieLogo1.json',
  width: 200,
  height: 200,
  fit: BoxFit.fill,
)

width and height are optionals and fallback on the size imposed by the parent or on the intrinsic size of the lottie animation.

Custom loading

This example shows how to load and parse a Lottie composition from a json file.

The Lottie widget has several convenient constructors (Lottie.asset, Lottie.network, Lottie.memory) to load, parse and cache automatically the json file.

Sometime you may prefer to have full control over the loading of the file. Use LottieComposition.fromByteData to parse the file from a list of bytes.

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  Future<LottieComposition> _composition;

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

    _composition = _loadComposition();
  }

  Future<LottieComposition> _loadComposition() async {
    var assetData = await rootBundle.load('assets/LottieLogo1.json');
    return await LottieComposition.fromByteData(assetData);
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<LottieComposition>(
      future: _composition,
      builder: (context, snapshot) {
        var composition = snapshot.data;
        if (composition != null) {
          return Lottie(composition: composition);
        } else {
          return Center(child: CircularProgressIndicator());
        }
      },
    );
  }
}

Custom drawing

This example goes low level and shows you how to draw a LottieComposition on a custom Canvas at a specific frame in a specific position and size.

class CustomDrawer extends StatelessWidget {
  final LottieComposition composition;

  const CustomDrawer(this.composition, {Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: _Painter(composition),
      size: Size(400, 400),
    );
  }
}

class _Painter extends CustomPainter {
  final LottieComposition composition;

  _Painter(this.composition);

  @override
  void paint(Canvas canvas, Size size) {
    var drawable = LottieDrawable(composition);

    var frameCount = 40;
    var columns = 10;
    for (var i = 0; i < frameCount; i++) {
      var destRect = Offset(i % columns * 50.0, i ~/ 10 * 80.0) & (size / 5);
      drawable.draw(canvas, destRect, progress: i / frameCount);
    }
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}

Limitations

This is a new library so usability, documentation and performance are still work in progress.

The following features are not yet implemented:

• Dash path effects
• Transforms on gradients (stroke and fills)
• Expose Value callback to modify dynamically some properties of the animation
• Text in animations has very basic support (unoptimized and buggy)

Flutter Web

Run the app with flutter run -d Chrome --dart-define=FLUTTER_WEB_USE_SKIA=true --release

The performance are not great and some features are missing.

See a preview here: https://xvrh.github.io/lottie-flutter/index.html

Complete example

See the Sample app (in the example folder) for a complete example of the various possibilities.