Web - Fix selection jump on Chrome for Android (#41202)
## Description
This PR fixes cursor jump on Chrome for Android when the user taps in a multiline `TextField`.
Using the following code sample:
<details><summary>Code sample</summary>
```dart
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: 'Text Field Focus',
home: MyCustomForm(),
);
}
}
// Define a custom Form widget.
class MyCustomForm extends StatelessWidget {
const MyCustomForm({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Text Field Focus'),
),
backgroundColor: Colors.amber,
body: Padding(
padding: const EdgeInsets.all(16.0),
child: TextField(
decoration: const InputDecoration(
fillColor: Colors.white,
filled: true
),
autofocus: true,
maxLines: 3,
controller: TextEditingController(text: '1\n2\n3\n4\n'),
),
),// This trailing comma makes auto-formatting nicer for build methods.
);
}
}
```
</details>
On a mobile browser, once the page is loaded, tap after the number 3:
- Before this PR: the TextField content is automaticaly scrolled and the selection is set after number 1.
https://user-images.githubusercontent.com/840911/232051413-b913f890-6cb1-4c60-92d0-7a3bf74cc688.mov
## Implementation
A multiline `TextField` relies on an HTML `<textarea>` elements. When a tap occurs the selection should be updated from Flutter not by the HTML element itself.
This PR prevents mouse events on Chrome for Android. Those events conflicts with Flutter selection changes.
Previously, mouse events were only prevented on desktop but they are also emitted on mobile, see https://bugs.chromium.org/p/chromium/issues/detail?id=119216#c11.
## Related Issue
Related to https://github.com/flutter/flutter/issues/124483 (partial fix because the issue is also reproducible on iOS/Safari).
## Tests
Adds 1 test.
https://dart.googlesource.com/external/github.com/flutter/engine/+/c4a2712e8f4d41f4184b4253011c312f42edfca2
Monorepo is:
With depot_tools installed and on your path, create a directory for your monorepo checkout and run these commands to create a gclient solution in that directory:
mkdir monorepo cd monorepo gclient config --unmanaged https://dart.googlesource.com/monorepo gclient sync -D
This gives you a checkout in the monorepo directory that contains:
monorepo/ DEPS - the DEPS used for this gclient checkout commits.json - the pinned commits for Dart, flutter/engine, and flutter/flutter tools/ - scripts used to create monorepo DEPS engine/src/ - the flutter/buildroot repo flutter/ - the flutter/engine repo out/ - the build directory, where Flutter engine builds are created third_party/ - Flutter dependencies checked out by DEPS dart/ - the Dart SDK checkout. third_party - Dart dependencies, also used by Flutter flutter/ - the flutter/flutter repo
Flutter's instructions for building the engine are at Compiling the engine
They can be followed closely, with a few changes:
goma_ctl ensure_start is sufficient.Example build commands that work on linux:
MONOREPO_PATH=$PWD if [[ ! $PATH =~ (^|:)$MONOREPO_PATH/flutter/bin(:|$) ]]; then PATH=$MONOREPO_PATH/flutter/bin:$PATH fi export GOMA_DIR=$(dirname $(command -v gclient))/.cipd_bin goma_ctl ensure_start pushd engine/src flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk autoninja -C out/host_debug_unopt popd
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For example, to build and run the Flutter spinning square sample on the web platform,
MONOREPO_PATH=$PWD cd flutter/examples/layers flutter --local-engine=host_debug_unopt \ -d chrome run widgets/spinning_square.dart cd $MONOREPO_PATH
To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command
flutter create --platforms=windows,macos,linux
on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter
Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:
MONOREPO_PATH=$PWD cd flutter/packages/flutter flutter test --local-engine=host_debug_unopt cd $MONOREPO_PATH
Please file an issue or email the dart-engprod team with any problems with or questions about using monorepo.
We will update this documentation to address them.
flutter commands may download the engine and Dart SDK files for the configured channel, even though they will be using the local engine and its SDK.gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.