README.template.md

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 an unofficial conversion of the Lottie-android library in pure Dart.

It works on Android, iOS, macOS, linux, windows and web.

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 'example/lib/main.dart';

Specify a custom AnimationController

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

With a custom AnimationController you have a rich API to play the animation in various ways: start and stop the animation when you want, play forward or backward, loop between specifics points...

import 'example/lib/examples/animation_controller.dart';

See this file for a more comprehensive example.

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

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 AssetLottie (or NetworkLottie, MemoryLottie) to load a lottie composition from a json file.

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

import 'example/lib/examples/custom_load.dart#example';

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.

import 'example/lib/examples/custom_draw.dart#example';

Modify properties at runtime

This example shows how to modify some properties of the animation at runtime. Here we change the text, the color, the opacity and the position of some layers. For each ValueDelegate we can either provide a static value or a callback to compute a value for a each frame.

import 'example/lib/examples/simple_dynamic_properties.dart#example';

Frame rate

By default, the animation is played at the frame rate exported by AfterEffect. This is the most power-friendly as generally the animation is exported at 10 or 30 FPS compared to the phone's 60 or 120 FPS. If the result is not good, you can change the frame rate

Lottie.asset('anim.json',
  // Use the device frame rate (up to 120FPS)
  frameRate: FrameRate.max,
  // Use the exported frame rate (default)
  frameRate: FrameRate.composition,
  // Specific frame rate
  frameRate: FrameRate(10),
)

Telegram Stickers (.tgs) and DotLottie (.lottie)

TGS file can be loaded by providing a special decoder

import 'example/lib/examples/telegram_stickers.dart#example';

You can select the correct .json file from a dotlottie (.lottie) archive by providing a custom decoder

import 'example/lib/examples/dotlottie.dart#example';

Performance or excessive CPU/GPU usage

Version v3.0 introduced the renderCache parameter to help reduce an excessive energy consumption.

In this mode, the frames of the animation are rendered lazily in an offscreen cache. Subsequent runs of the animation are cheaper to render. It helps reduce the power usage of the application at the cost of an increased memory usage.

Limitations

This port supports the same feature set as Lottie Android.

Flutter Web

Run the app with flutter run -d chrome --web-renderer canvaskit

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

More examples

See the example folder for more code samples of the various possibilities.