Calling layout on TextPainter for conditional layouts can be slow #132421
Description
Details
To recreate:
Run TextPainter.layout multiple times, and it gets progressively worse; My main program runs layout a lot to conditionally paint text on a page, and it slowly crawls to a stop. I've provided sample code, and other requested information.
(My hypothesis is that it's compounding the calls to layout and calling every other CKParagragh that exists, but not sure)
- I ran it on both flutter stable branch and flutter master, both producing the same issue
flutter run --profile --trace-skiaproduced no output- flutter analyze produces no issues
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
useMaterial3: true,
),
home: const MyHomePage(title: 'Painting demo'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int difference = 0;
StringBuffer buffer = StringBuffer("Hello world");
TextStyle style = const TextStyle(fontSize: 20, color: Colors.black);
TextPainter painter = TextPainter(textDirection: TextDirection.ltr);
void paintMultiple() {
final startTime = DateTime.now();
difference = 0;
for (int i = 0; i < 200; i++) {
buffer.write("Hello world");
painter.text = TextSpan(text: buffer.toString(), style: style);
painter.layout();
}
final endTime = DateTime.now();
setState(() {
difference = endTime.difference(startTime).inMilliseconds;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title:
Text(widget.title, style: const TextStyle(color: Colors.white)),
backgroundColor: Colors.purple,
),
body: Center(
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: [
if (difference > 0) Text("Time to paint: $difference milliseconds"),
if (difference == 0) const Text("Time to paint: not painted"),
const SizedBox(height: 20),
OutlinedButton(
onPressed: () => paintMultiple(),
child: const Text("Paint multiple times"),
)
],
)));
}
}
MacOS - Apple M1 Max - 32 GB Ram - Ventura version 13.5 (22G74)
Chrome - Version 115.0.5790.170 (Official Build) (arm64)
IMG_2193.mov
[redacted]@[redacted] painter_sample % flutter doctor -v
[✓] Flutter (Channel master, 3.14.0-3.0.pre.45, on macOS 13.5 22G74 darwin-arm64, locale en-US)
• Flutter version 3.14.0-3.0.pre.45 on channel master at /Users/[redacted]/LocalFrameworks/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 36c40e4972 (50 minutes ago), 2023-08-11 18:48:13 -0400
• Engine revision 5669544866
• Dart version 3.2.0 (build 3.2.0-62.0.dev)
• DevTools version 2.26.1
[✓] Android toolchain - develop for Android devices (Android SDK version 32.0.0)
• Android SDK at /Users/[redacted]/Library/Android/sdk
• Platform android-33, build-tools 32.0.0
• Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b829.9-10027231)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 14.3.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 14E300c
• CocoaPods version 1.12.1
[✓] Chrome - develop for the web
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
[✓] Android Studio (version 2022.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b829.9-10027231)
[✓] VS Code (version 1.81.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.70.0
[✓] Connected device (2 available)
• macOS (desktop) • macos • darwin-arm64 • macOS 13.5 22G74 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 115.0.5790.170
[✓] Network resources
• All expected network resources are available.
• No issues found!