Fix Flutter web compilation error (#109)

This PR improves some fill performance issues I found with various Lottie animations.
I think the real issue comes down to the render performance of Path.addPath(). The performance issue happens in the Render thread and seems directly related to how large the animation is on-screen. Flutter might be caching pre-rendered textures and running out of memory.

I've changed how Path.addPath() is called and how the path is rendered for fill_content.dart and gradient_fill_content.dart.

Just as an example, the example/assets/Tests/bm.json animation gets ~60 fps with this fix, compared to 34-52 fps with the lottie-flutter 0.6.0 release. (This is on a Pixel 3 XL)

There are a couple of other changes:

- I fixed a bug with the casing of "weather" in pubspec.yaml. Without this fix, the examples don't build on Ubuntu Linux.
The debugging class MeanCalculator wasn't initializing its fields, causing a null pointer exception when debugging.
- I added antiAliasingSuggested to LottieDrawable to allow fill paints to be anti-aliased. It is off by default. It also provides some minor performance improvements without any noticeable loss in quality. It is only applied to fills right now.
- I added PathFactory to create Paths rather than just new-ing them. path_factory.dart allows you to switch out the normal Path creation with a debug logging implementation so you can see all of the Path calls that are performed during a frame. Just create a DebugPath in the factory rather than Path.

.github/workflows/analyze-and-test.yaml

@@ -10,7 +10,7 @@ jobs:
     name: Flutter analyze
     strategy:
       matrix:
-        flutter: ['stable', 'dev']
+        flutter: ['stable']
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@v2

CHANGELOG.md

@@ -1,3 +1,20 @@
+## [0.7.0+1]
+- Fix Flutter Web compilation error
+
+## [0.7.0]
+- Performance improvement for complex animations.
+
+## [0.6.0]
+- Runs the animation at the frame rate specified in the json file (ie. An animation encoded with a 20 FPS will only
+  be paint 20 times per seconds even though the AnimationController will invalidate the widget 60 times per seconds).  
+  A new property `frameRate` allows to opt-out this behavior and have the widget to repaint at the device frame rate 
+   (`FrameRate.max`).
+- Automatically add a `RepaintBoundary` around the widget. Since `Lottie` animations are generally complex to paint, a
+   `RepaintBoundary` will separate the animation with the rest of the app and improve performance. A new property `addRepaintBoundary`
+   allows to opt-out this behavior.
+- Fix a bug where we would call `markNeedPaint` when the animation was not changing. This removes unnecessary paints in
+  animations with static periods.
+
 ## [0.5.1]
 - Remove direct dependencies on dart:io to support Flutter Web
 

README.md

@@ -8,7 +8,7 @@ animations exported as json with [Bodymovin](https://github.com/airbnb/lottie-we
 
 This repository is a unofficial conversion of the [Lottie-android](https://github.com/airbnb/lottie-android) library in pure Dart. 
 
-It works on Android, iOS and macOS and web.
+It works on Android, iOS, macOS, linux, windows and web.
 
 ## Usage
 

README.template.md

@@ -8,7 +8,7 @@ animations exported as json with [Bodymovin](https://github.com/airbnb/lottie-we
 
 This repository is a unofficial conversion of the [Lottie-android](https://github.com/airbnb/lottie-android) library in pure Dart. 
 
-It works on Android, iOS and macOS and web.
+It works on Android, iOS, macOS, linux, windows and web.
 
 ## Usage
 
@@ -17,7 +17,7 @@ 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.
 
 ```dart
-import 'example/lib/examples/main.dart';
+import 'example/lib/main.dart';
 ```
 
 ### Specify a custom `AnimationController`

example/lib/examples/main.dart

@@ -1,27 +0,0 @@
-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/lottiefiles/angel.zip'),
-          ],
-        ),
-      ),
-    );
-  }
-}

example/lib/main.dart

@@ -1,157 +1,24 @@
-import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
-import 'package:logging/logging.dart';
 import 'package:lottie/lottie.dart';
-import 'src/all_files.g.dart';
 
-void main() {
-  Logger.root
-    ..level = Level.ALL
-    ..onRecord.listen(print);
-  Lottie.traceEnabled = true;
-  runApp(App());
-}
+void main() => runApp(MyApp());
 
-class App extends StatelessWidget {
+class MyApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      //showPerformanceOverlay: true,
       home: Scaffold(
-        appBar: AppBar(
-          title: Text('Lottie Flutter'),
-        ),
-        body: GridView.builder(
-          itemCount: files.length,
-          gridDelegate:
-              SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 4),
-          itemBuilder: (context, index) {
-            var assetName = files[index];
-            return GestureDetector(
-              child: _Item(
-                child: Lottie.asset(
-                  assetName,
-                  frameBuilder: (context, child, composition) {
-                    return AnimatedOpacity(
-                      child: child,
-                      opacity: composition == null ? 0 : 1,
-                      duration: const Duration(seconds: 1),
-                      curve: Curves.easeOut,
-                    );
-                  },
-                ),
-              ),
-              onTap: () {
-                Navigator.of(context).push(MaterialPageRoute<void>(
-                    builder: (context) => Detail(assetName)));
-              },
-            );
-          },
-        ),
-      ),
-    );
-  }
-}
-
-class _Item extends StatelessWidget {
-  final Widget child;
-
-  const _Item({Key key, this.child}) : super(key: key);
-
-  @override
-  Widget build(BuildContext context) {
-    return Padding(
-      padding: const EdgeInsets.all(8.0),
-      child: Container(
-        decoration: BoxDecoration(
-            color: Colors.white,
-            borderRadius: BorderRadius.all(Radius.circular(10)),
-            boxShadow: [
-              BoxShadow(
-                  color: Colors.black.withOpacity(0.1),
-                  offset: Offset(2, 2),
-                  blurRadius: 5)
-            ]),
-        child: child,
-      ),
-    );
-  }
-}
-
-class Detail extends StatefulWidget {
-  final String assetName;
-
-  const Detail(this.assetName, {Key key}) : super(key: key);
-
-  @override
-  _DetailState createState() => _DetailState();
-}
-
-class _DetailState extends State<Detail> 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 Scaffold(
-      appBar: AppBar(
-        title: Text('${widget.assetName}'),
-      ),
-      body: SingleChildScrollView(
-        child: Column(
+        body: ListView(
           children: [
-            Center(
-              child: Lottie.asset(
-                widget.assetName,
-                controller: _controller,
-                onLoaded: (composition) {
-                  _controller.duration = composition.duration;
-                  _controller.repeat();
-                },
-              ),
-            ),
-            AnimatedBuilder(
-              animation: _controller,
-              builder: (context, _) => Row(
-                children: <Widget>[
-                  Expanded(
-                    child: Slider(
-                      value: _controller.value,
-                      onChanged: (newValue) {
-                        _controller.value = newValue;
-                      },
-                    ),
-                  ),
-                  IconButton(
-                    icon: Icon(_controller.isAnimating
-                        ? Icons.stop
-                        : Icons.play_arrow),
-                    onPressed: () {
-                      setState(() {
-                        if (_controller.isAnimating) {
-                          _controller.stop();
-                        } else {
-                          _controller.repeat();
-                        }
-                      });
-                    },
-                  ),
-                ],
-              ),
-            ),
+            // 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/lottiefiles/angel.zip'),
           ],
         ),
       ),

example/lib/main_app.dart

@@ -0,0 +1,160 @@
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:logging/logging.dart';
+import 'package:lottie/lottie.dart';
+import 'src/all_files.g.dart';
+
+void main() {
+  Logger.root
+    ..level = Level.ALL
+    ..onRecord.listen(print);
+  Lottie.traceEnabled = true;
+  runApp(App());
+}
+
+class App extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      //showPerformanceOverlay: true,
+      home: Scaffold(
+        appBar: AppBar(
+          title: Text('Lottie Flutter'),
+        ),
+        body: GridView.builder(
+          itemCount: files.length,
+          gridDelegate:
+              SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 4),
+          itemBuilder: (context, index) {
+            var assetName = files[index];
+            return GestureDetector(
+              child: _Item(
+                child: Lottie.asset(
+                  assetName,
+                  frameBuilder: (context, child, composition) {
+                    return AnimatedOpacity(
+                      child: child,
+                      opacity: composition == null ? 0 : 1,
+                      duration: const Duration(seconds: 1),
+                      curve: Curves.easeOut,
+                    );
+                  },
+                ),
+              ),
+              onTap: () {
+                Navigator.of(context).push(MaterialPageRoute<void>(
+                    builder: (context) => Detail(assetName)));
+              },
+            );
+          },
+        ),
+      ),
+    );
+  }
+}
+
+class _Item extends StatelessWidget {
+  final Widget child;
+
+  const _Item({Key key, this.child}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(8.0),
+      child: Container(
+        decoration: BoxDecoration(
+            color: Colors.white,
+            borderRadius: BorderRadius.all(Radius.circular(10)),
+            boxShadow: [
+              BoxShadow(
+                  color: Colors.black.withOpacity(0.1),
+                  offset: Offset(2, 2),
+                  blurRadius: 5)
+            ]),
+        child: child,
+      ),
+    );
+  }
+}
+
+class Detail extends StatefulWidget {
+  final String assetName;
+
+  const Detail(this.assetName, {Key key}) : super(key: key);
+
+  @override
+  _DetailState createState() => _DetailState();
+}
+
+class _DetailState extends State<Detail> 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 Scaffold(
+      appBar: AppBar(
+        title: Text('${widget.assetName}'),
+      ),
+      body: SingleChildScrollView(
+        child: Column(
+          children: [
+            Center(
+              child: Lottie.asset(
+                widget.assetName,
+                controller: _controller,
+                onLoaded: (composition) {
+                  _controller.duration = composition.duration;
+                  _controller.repeat();
+                },
+              ),
+            ),
+            AnimatedBuilder(
+              animation: _controller,
+              builder: (context, _) => Row(
+                children: <Widget>[
+                  Expanded(
+                    child: Slider(
+                      value: _controller.value,
+                      onChanged: (newValue) {
+                        _controller.value = newValue;
+                      },
+                    ),
+                  ),
+                  IconButton(
+                    icon: Icon(_controller.isAnimating
+                        ? Icons.stop
+                        : Icons.play_arrow),
+                    onPressed: () {
+                      setState(() {
+                        if (_controller.isAnimating) {
+                          _controller.stop();
+                        } else {
+                          _controller.repeat();
+                        }
+                      });
+                    },
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

example/macos/Podfile.lock

@@ -5,13 +5,13 @@ PODS:
     - FlutterMacOS
 
 DEPENDENCIES:
-  - FlutterMacOS (from `Flutter/ephemeral/.symlinks/flutter/darwin-x64`)
+  - FlutterMacOS (from `Flutter/ephemeral/.symlinks/flutter/darwin-x64-profile`)
   - path_provider (from `Flutter/ephemeral/.symlinks/plugins/path_provider/macos`)
   - path_provider_macos (from `Flutter/ephemeral/.symlinks/plugins/path_provider_macos/macos`)
 
 EXTERNAL SOURCES:
   FlutterMacOS:
-    :path: Flutter/ephemeral/.symlinks/flutter/darwin-x64
+    :path: Flutter/ephemeral/.symlinks/flutter/darwin-x64-profile
   path_provider:
     :path: Flutter/ephemeral/.symlinks/plugins/path_provider/macos
   path_provider_macos:

example/pubspec.lock

@@ -21,42 +21,42 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.4.1"
+    version: "2.5.0-nullsafety.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0-nullsafety.1"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.0"
+    version: "1.1.0-nullsafety.3"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.3"
+    version: "1.2.0-nullsafety.1"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.1"
+    version: "1.1.0-nullsafety.1"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.12"
+    version: "1.15.0-nullsafety.3"
   convert:
     dependency: transitive
     description:
@@ -77,7 +77,14 @@ packages:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0-nullsafety.1"
+  ffi:
+    dependency: transitive
+    description:
+      name: ffi
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.1.3"
   file:
     dependency: transitive
     description:
@@ -143,35 +150,35 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.4.1"
+    version: "0.7.0+1"
   matcher:
     dependency: transitive
     description:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.6"
+    version: "0.12.10-nullsafety.1"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.8"
+    version: "1.3.0-nullsafety.3"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.7.0"
+    version: "1.8.0-nullsafety.1"
   path_provider:
     dependency: "direct main"
     description:
       name: path_provider
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.11"
+    version: "1.6.21"
   path_provider_linux:
     dependency: transitive
     description:
@@ -185,21 +192,28 @@ packages:
       name: path_provider_macos
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.0.4+3"
+    version: "0.0.4+4"
   path_provider_platform_interface:
     dependency: transitive
     description:
       name: path_provider_platform_interface
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.2"
+    version: "1.0.3"
+  path_provider_windows:
+    dependency: transitive
+    description:
+      name: path_provider_windows
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.0.4+1"
   pedantic:
     dependency: transitive
     description:
       name: pedantic
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.0"
+    version: "1.9.2"
   platform:
     dependency: transitive
     description:
@@ -213,7 +227,7 @@ packages:
       name: plugin_platform_interface
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.2"
+    version: "1.0.3"
   process:
     dependency: transitive
     description:
@@ -232,63 +246,70 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.7.0"
+    version: "1.8.0-nullsafety.2"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0-nullsafety.1"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0-nullsafety.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.5"
+    version: "1.1.0-nullsafety.1"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0-nullsafety.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.16"
+    version: "0.2.19-nullsafety.2"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0-nullsafety.3"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.1.0-nullsafety.3"
+  win32:
+    dependency: transitive
+    description:
+      name: win32
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.7.3"
   xdg_directories:
     dependency: transitive
     description:
       name: xdg_directories
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.1.0"
+    version: "0.1.2"
 sdks:
-  dart: ">=2.7.0 <3.0.0"
+  dart: ">=2.10.0-110 <2.11.0"
   flutter: ">=1.12.13+hotfix.5 <2.0.0"

example/pubspec.yaml

@@ -8,11 +8,11 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
+  flutter_colorpicker:
+  http:
   lottie:
     path: ../
-  flutter_colorpicker:
   path_provider:
-  http:
 
 dev_dependencies:
   flutter_test:
@@ -34,7 +34,7 @@ flutter:
     - assets/Logo/
     - assets/Images/
     - assets/Images/WeAccept/
-    - assets/Weather/
+    - assets/weather/
     - assets/example_with_images/
     - assets/example_with_images/images/
 

example/test/dynamic_properties_test.dart

@@ -33,6 +33,7 @@ void main() {
           composition: composition,
           controller: animation,
           delegates: LottieDelegates(values: [delegate]),
+          addRepaintBoundary: false,
         ),
       );
       await tester.pump();
@@ -45,6 +46,7 @@ void main() {
             composition: composition,
             controller: animation,
             delegates: LottieDelegates(values: []),
+            addRepaintBoundary: false,
           ),
         );
         await tester.pump();

example/test/utils.dart

@@ -42,7 +42,7 @@ class _CustomerPainter extends CustomPainter {
           thumbSize;
 
       drawable
-        ..setProgress(progress)
+        ..setProgress(progress, frameRate: FrameRate.max)
         ..draw(canvas, rect);
 
       ++index;

example/test/widget_test.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:lottie_example/main.dart';
+import 'package:lottie_example/main_app.dart';
 
 void main() {
   testWidgets('Main sample', (tester) async {

lib/lottie.dart

@@ -1,4 +1,5 @@
 export 'src/composition.dart' show LottieComposition;
+export 'src/frame_rate.dart' show FrameRate;
 export 'src/lottie.dart' show Lottie;
 export 'src/lottie_builder.dart' show LottieBuilder;
 export 'src/lottie_delegates.dart' show LottieDelegates;