Incorrect caret position with complex scripts #118403

tgucio · 2023-01-12T17:56:47Z

Steps to Reproduce

Execute flutter run on the code sample on a platform with HW keyboard
Traverse the text using arrow left/right keys

Expected results: Caret advances correctly

Actual results: Caret jumps back and forth

Code sample

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(primarySwatch: Colors.blue),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    const TextStyle style = TextStyle(fontSize: 16.0);
    return Scaffold(
      appBar: AppBar(title: Text(widget.title)),
      body: Center(
        child: Column(
          children: <Widget>[
            const SizedBox(height: 100.0),
            TextField(controller: TextEditingController(text: 'प्राप्त वर्णन प्रव्रुति')),
            const SizedBox(height: 100.0),
          ],
        ),
      ),
    );
  }
}

Logs

% flutter --version
Flutter 3.7.0-20.0.pre.6 • channel master • https://github.com/flutter/flutter.git
Framework • revision f8628b5cb1 (15 hours ago) • 2023-01-11 18:48:03 -0800
Engine • revision 4a8d6866a1
Tools • Dart 3.0.0 (build 3.0.0-112.0.dev) • DevTools 2.20.0

The text was updated successfully, but these errors were encountered:

huycozy · 2023-01-13T08:15:56Z

Hi @tgucio, thanks for filing the issue. I also can reproduce this on the latest stable and master channels.

On the Web, it seems better even though the cursor doesn't move one step when moving to the space character between words.

This issue makes me remember the old issue that I have reproduced before: #106472. These issues seem to be similar since the it looks better on Web and they are all about cursor traversal (but they are different languages)

flutter doctor -v (stable and master)

[✓] Flutter (Channel stable, 3.3.10, on macOS 13.0.1 22A400 darwin-x64, locale en-VN)
    • Flutter version 3.3.10 on channel stable at /Users/huynq/Documents/GitHub/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 135454af32 (13 hours ago), 2022-12-15 07:36:55 -0800
    • Engine revision 3316dd8728
    • Dart version 2.18.6
    • DevTools version 2.15.0

[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
    • Android SDK at /Users/huynq/Library/Android/sdk
    • Platform android-33, build-tools 31.0.0
    • ANDROID_HOME = /Users/huynq/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jre/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 14.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14B47b
    • CocoaPods version 1.11.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2021.3)
    • 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 11.0.13+0-b1751.21-8125866)

[✓] IntelliJ IDEA Community Edition (version 2022.1.1)
    • IntelliJ at /Users/huynq/Library/Application Support/JetBrains/Toolbox/apps/IDEA-C/ch-0/221.5591.52/IntelliJ IDEA CE.app
    • 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

[✓] VS Code (version 1.73.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.54.0

[✓] Connected device (3 available)
    • SM T225 (mobile) • R9JT3004VRJ • android-arm64  • Android 12 (API 31)
    • macOS (desktop)  • macos       • darwin-x64     • macOS 13.0.1 22A400 darwin-x64
    • Chrome (web)     • chrome      • web-javascript • Google Chrome 108.0.5359.124

[✓] HTTP Host Availability
    • All required HTTP hosts are available

• No issues found!

[!] Flutter (Channel master, 3.7.0-20.0.pre.26, on macOS 13.0.1 22A400 darwin-x64, locale en-VN)
    • Flutter version 3.7.0-20.0.pre.26 on channel master at /Users/huynq/Documents/GitHub/flutter_master
    ! Warning: `flutter` on your path resolves to /Users/huynq/Documents/GitHub/flutter/bin/flutter, which is not inside your current Flutter SDK checkout at /Users/huynq/Documents/GitHub/flutter_master. Consider adding /Users/huynq/Documents/GitHub/flutter_master/bin to the front of your path.
    ! Warning: `dart` on your path resolves to /Users/huynq/Documents/GitHub/flutter/bin/dart, which is not inside your current Flutter SDK checkout at /Users/huynq/Documents/GitHub/flutter_master. Consider adding /Users/huynq/Documents/GitHub/flutter_master/bin to the front of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision f7b444e117 (17 minutes ago), 2023-01-13 03:11:08 +0100
    • Engine revision 8aa26baa9d
    • Dart version 3.0.0 (build 3.0.0-119.0.dev)
    • DevTools version 2.20.0
    • If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks and upgrades.

[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
    • Android SDK at /Users/huynq/Library/Android/sdk
    • Platform android-33, build-tools 31.0.0
    • ANDROID_HOME = /Users/huynq/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jre/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 14.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14B47b
    • CocoaPods version 1.11.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2021.3)
    • 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 11.0.13+0-b1751.21-8125866)

[✓] IntelliJ IDEA Community Edition (version 2022.1.1)
    • IntelliJ at /Users/huynq/Library/Application Support/JetBrains/Toolbox/apps/IDEA-C/ch-0/221.5591.52/IntelliJ IDEA CE.app
    • 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

[✓] VS Code (version 1.74.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.56.0

[✓] Connected device (2 available)
    • macOS (desktop) • macos  • darwin-x64     • macOS 13.0.1 22A400 darwin-x64
    • Chrome (web)    • chrome • web-javascript • Google Chrome 108.0.5359.124

[✓] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.

tgucio · 2023-01-13T09:29:27Z

Thanks @huycozy. I think they're actually different issues. This one, I believe, has to do with incorrect calcs when text shaping is used (either standard rules for Indic scripts or GSUB, GPOS in fonts). #106472 has to do with incorrect word boundaries, seen with Han script which normally doesn't use text shaping.

gspencergoog · 2023-01-19T19:22:05Z

cc @jason-simmons @justinmc

justinmc · 2023-01-19T22:55:40Z

Is this a duplicate of #118566? That issue may have a fix in progress in Skia.

tgucio · 2023-01-19T23:44:12Z

@justinmc I don't think so: the Skia fix appears to be specific to RTL runs. Here it's LTR and my bet is that it has to do with what happens when the text shaper substitutes glyphs.

…rics Fixes flutter#50563. Fixes flutter#98516. Fixes flutter#118403. Fixes flutter#122477. It turns out that `Paragraph.getBoxesForRange` will not accept a negative index for the start of the range; if you pass one, it will return an empty list. We'd been doing that in `TextPainter._getRectFromUpstream`; this was causing flutter#50563, flutter#98516, and flutter#118403. (Arguably this makes them duplicates of each other, but they looked quite distinct until being debugged: they involve complex emoji, zalgo text, and Indic script respectively.) Fix that by clamping the start to zero, because what we really intended here in that case is the whole text up to the given end offset. Then it turns out that we were sometimes reaching this line with a negative end index too (when the selection is empty on reaching `RenderEditable._updateSelectionExtentsVisibility`.) That was giving an empty list of boxes, but if we clamp the start but not the end, we'd get back boxes for the whole text instead. Avoid that by short-circuiting that case at the top of the function, like we do when the offset is out of bounds in the other direction. Finally, when we get back more than one box from `getBoxesForRange`, we were looking at the wrong end of the list: if we're looking upstream, we want the end of the *last* preceding box, not the first one. Similarly when looking downstream we want the start of the first following box, not the last one. This was causing flutter#122477, which I discovered while studying this code to diagnose flutter#50563. Fix that too.

github-actions · 2023-04-11T04:00:55Z

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

huycozy added the in triage Presently being triaged by the triage team label Jan 13, 2023

gspencergoog added the P2 Important issues not at the top of the work list label Jan 19, 2023

gspencergoog mentioned this issue Jan 19, 2023

Incorrect horizontal caret movement with Unicode combining characters #98516

Closed

tgucio mentioned this issue Feb 28, 2023

Add new test font flutter/engine#39809

Merged

8 tasks

This was referenced Mar 12, 2023

Caret misplaced for emoji plus text #122477

Closed

Caret can fail to move on keyboard left/right arrow in Indic script #122478

Open

gnprice mentioned this issue Mar 12, 2023

Fix out-of-bounds and reversed TextBox queries in computing caret metrics #122480

Merged

8 tasks

justinmc assigned gnprice Mar 24, 2023

auto-submit bot closed this as completed in #122480 Mar 28, 2023

huycozy added the r: fixed Issue is closed as already fixed in a newer version label Mar 28, 2023

github-actions bot locked as resolved and limited conversation to collaborators Apr 11, 2023

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Incorrect caret position with complex scripts #118403

Incorrect caret position with complex scripts #118403

tgucio commented Jan 12, 2023 •

edited

huycozy commented Jan 13, 2023

tgucio commented Jan 13, 2023

gspencergoog commented Jan 19, 2023

justinmc commented Jan 19, 2023

tgucio commented Jan 19, 2023

github-actions bot commented Apr 11, 2023

Incorrect caret position with complex scripts #118403

Incorrect caret position with complex scripts #118403

Comments

tgucio commented Jan 12, 2023 • edited

Steps to Reproduce

huycozy commented Jan 13, 2023

tgucio commented Jan 13, 2023

gspencergoog commented Jan 19, 2023

justinmc commented Jan 19, 2023

tgucio commented Jan 19, 2023

github-actions bot commented Apr 11, 2023

tgucio commented Jan 12, 2023 •

edited