[Impeller] Jittery glyphs when animating text transformation #149652
Description
Steps to reproduce
-
Run the sample code (wraps a Text widget within an animation-controlled Transform widget).
-
Tap the text to trigger the scale animation and reproduce the issue.
Note: The issue can also reproduced with other Transfom type such as X/Y position. It can be reproduced with packages such as marquee (position animation) or bounce (scale and rotation animation).
Expected results
Spacing between glyphs should be constant across the entire animation, like when using Skia.
Actual results
Glyphs are jittering throughout the animation, making the spacing between glyphs inconsistent when animated.
The video recordings were taken on a physical iPhone XR because the issue was very noticeable on it.
@jonahwilliams IMHO, this looks very similar to some other typography issues (#140475, #138386 or #127815), which were fixed by flutter/engine#53042 a few days ago. Although static text now looks great, unfortunately it did not fix this specific issue during animations. Maybe some kind of rounding error is remaining ?
@chinmaygarde This is the last issue preventing us from opting in to Impeller for our production apps — should it be part of Slimpeller's last blockers before opt-out is no longer supported ? (xref #144739, #144439)
Issues aside, Impeller is truly incredible and performance improvements are outstanding compared to the previous engine. It really does feel native, now. Thanks and congratulations to the Flutter teams for this amazing project!
Code sample
Code sample
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({super.key});
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
late final controller = AnimationController(vsync: this, duration: const Duration(seconds: 2));
TextStyle? get textStyle =>
Theme.of(context).textTheme.headlineLarge?.copyWith(fontSize: 50.0, fontWeight: FontWeight.bold);
bool isScaled = false;
@override
void dispose() {
controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) => MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(colorScheme: ColorScheme.fromSeed(seedColor: const Color(0xffffffff))),
home: Scaffold(
body: GestureDetector(
onTap: _onTap,
child: Center(
child: AnimatedBuilder(
animation: controller,
builder: (_, child) => Transform.scale(
scale: 0.7 + (CurvedAnimation(parent: controller, curve: Curves.easeInOutCubic).value * 0.3),
child: child,
),
child: Center(child: Text('Large headline', style: textStyle))),
),
),
),
);
void _onTap() => setState(() {
isScaled = !isScaled;
if (isScaled) {
controller.forward();
} else {
controller.reverse();
}
});
}Screenshots or Video
Screenshots / Video demonstration
IMPORTANT NOTE: Please watch the videos in fullscreen, as the small web viewport causes an overall aliasing effect which makes the difference almost un-noticeable. Ideally, you can open it in your native video player.
| Skia ✅ | Impeller ⛔ |
|---|---|
Skia.mov |
Impeller.mov |
Logs
Logs
Flutter Doctor output
Doctor output
[✓] Flutter (Channel master, 3.23.0-13.0.pre.87, on macOS 14.5 23F79 darwin-arm64, locale en)
• Flutter version 3.23.0-13.0.pre.87 on channel master at /Users/redacted/Documents/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision c246ecdf8e (8 hours ago), 2024-06-03 18:06:22 -0700
• Engine revision a6aa5d8266
• Dart version 3.5.0 (build 3.5.0-218.0.dev)
• DevTools version 2.36.0
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• Android SDK at /Users/redacted/Library/Android/sdk
• Platform android-34, build-tools 34.0.0
• ANDROID_HOME = /Users/redacted/Library/Android/sdk
• Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 17.0.10+0-17.0.10b1087.21-11572160)
• All Android licenses accepted.
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• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 15F31d
• CocoaPods version 1.15.2
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• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
[✓] Android Studio (version 2023.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
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🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 17.0.10+0-17.0.10b1087.21-11572160)
[✓] VS Code (version 1.89.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.90.0
[✓] Connected device (5 available)
• iPhone de Dev (mobile) • redacted • ios • iOS 17.4.1 21E236
• macOS (desktop) • macos • darwin-arm64 • macOS 14.5 23F79 darwin-arm64
• Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin • macOS 14.5 23F79 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 125.0.6422.141
[✓] Network resources
• All expected network resources are available.
• No issues found!Metadata
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