Update the documentation of Semantics' onLongPress

Steps to Reproduce

A working repro is located at https://github.com/kpsroka/flutter_accessibility_demo/tree/onLongPress-Bug (notice the tag)

The core part of the problem is the following:

Semantics(
  label: 'Counter button',
  hint: 'Press to increase',
  value: '$_counter',
  enabled: true,
  container: true,
  excludeSemantics: true,
  onTap: _incrementCounter,
  onLongPress: _decrementCounter,
  child: Text(
    '$_counter',
    style: Theme.of(context).textTheme.display1,
  )),

Launch on an iOS device with VoiceOver enabled, or on an Android device with TalkBack enabled.
Launch the project mentioned above.
Move focus to the counter number. Double-tap to trigger the "tap" handler, double-tap & hold to trigger the "long press" handler.

Observed:

onTap handler is being executed, while onLongPress handler isn't.

However, when you enable semantics debugger (uncomment this line), you'll be able to trigger the onLongPress handler.

Logs

flutter run --verbose without SemanticsDebugger

flutter run --verbose with SemanticsDebugger

Notice that I removed the debugPrint statements from the code before executing the above commands.

$ flutter doctor -v
[✓] Flutter (Channel beta, v1.6.3, on Mac OS X 10.14.5 18F132, locale en-PL)
    • Flutter version 1.6.3 at /Users/krzysztofsroka/Library/Flutter
    • Framework revision bc7bc94083 (5 weeks ago), 2019-05-23 10:29:07 -0700
    • Engine revision 8dc3a4cde2
    • Dart version 2.3.2 (build 2.3.2-dev.0.0 e3edfd36b2)

 
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at /Users/krzysztofsroka/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • ANDROID_HOME = /Users/krzysztofsroka/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)
    • All Android licenses accepted.

[✓] iOS toolchain - develop for iOS devices (Xcode 10.2.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 10.2.1, Build version 10E1001
    • ios-deploy 1.9.4
    • CocoaPods version 1.6.1

[!] Android Studio (version 3.2)
    • Android Studio at /Applications/Android Studio.app/Contents
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)

[✓] VS Code (version 1.35.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.1.0

[✓] Connected device (1 available)
    • CK test • 7fd603d4b73339426ca23d745840a51dfcfbaecc • ios • iOS 12.2

! Doctor found issues in 1 category.

Reproducible on the latest master 1.21.0-6.0.pre.191.

Minimal reproducible code sample

import 'package:flutter/material.dart';

void main() {
 runApp(MyApp());
}

class MyApp extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
   return MaterialApp(
     //This makes onLongPress work
     //showSemanticsDebugger: true,
     title: 'Flutter Demo',
     theme: ThemeData(
       primarySwatch: Colors.blue,
     ),
     home: MyHomePage(),
   );
 }
}

class MyHomePage extends StatefulWidget {
 @override
 _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
 int _counter = 0;

 void _incrementCounter() {
   setState(() {
     _counter++;
   });
 }

 void _decrementCounter() {
   setState(() {
     _counter--;
   });
 }

 @override
 Widget build(BuildContext context) {
   return Scaffold(
     appBar: AppBar(
       title: Text('Sample'),
     ),
     body: Center(
       child: Column(
         mainAxisAlignment: MainAxisAlignment.spaceEvenly,
         children: <Widget>[
           Text(
             'You have pushed the button this many times:',
           ),
           Semantics(
             label: 'Counter button',
             hint: 'Press to increase',
             value: '$_counter',
             onTap: _incrementCounter,
             onLongPress: _decrementCounter,
             child: ExcludeSemantics(
               child: Text(
                 '$_counter',
                 style: Theme.of(context).textTheme.display1,
               ),
             ),
           ),
         ],
       ),
     ),
   );
 }
}

flutter doctor -v

[✓] Flutter (Channel master, 1.21.0-6.0.pre.191, on Mac OS X 10.15.6 19G73, locale en-GB)
   • Flutter version 1.21.0-6.0.pre.191 at /Users/markus/development/flutter_master
   • Framework revision f3b7788f77 (5 hours ago), 2020-08-05 00:11:03 -0400
   • Engine revision e1828008b9
   • Dart version 2.10.0 (build 2.10.0-3.0.dev 987c9e347c)


[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.1)
   • Android SDK at /Users/markus/Library/Android/sdk
   • Platform android-30, build-tools 30.0.1
   • Java binary at: /Users/markus/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/193.6626763/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
   • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
   • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.6)
   • Xcode at /Applications/Xcode.app/Contents/Developer
   • Xcode 11.6, Build version 11E708
   • CocoaPods version 1.9.3

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

[✓] Android Studio (version 4.0)
   • Android Studio at /Users/markus/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/193.6626763/Android Studio.app/Contents
   • Flutter plugin version 48.0.2
   • Dart plugin version 193.7361
   • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

[✓] Connected device (5 available)
   • sdk gphone x86 arm (mobile) • emulator-5554                            • android-x86    • Android 11 (API 30) (emulator)
   • Nevercode’s iPhone (mobile) • b668e524315069f3db3661ac11ff1f66afafebdb • ios            • iOS 13.6
   • macOS (desktop)             • macos                                    • darwin-x64     • Mac OS X 10.15.6 19G73
   • Web Server (web)            • web-server                               • web-javascript • Flutter Tools
   • Chrome (web)                • chrome                                   • web-javascript • Google Chrome 84.0.4147.105

• No issues found!

Reproducible on the latest master 2.9.0-1.0.pre.452.

Semantics(
  onLongPress: () {
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('Semantics onLongPress called.')),
    );
  },
  onLongPressHint: 'call snackbar',
  child: const Text('Test semantics', style: TextStyle(fontSize: 50)),
)

`showSemanticsDebugger` false

Record_2022-01-22-16-19-05_addc32bca73e9f6027afbb.mp4

`showSemanticsDebugger` true

Record_2022-01-22-16-20-23_addc32bca73e9f6027afbb.mp4

flutter doctor -v

[✓] Flutter (Channel master, 2.9.0-1.0.pre.452, on Microsoft Windows [Version 10.0.22000.434], locale zh-CN)
    • Flutter version 2.9.0-1.0.pre.452 at X:\SDK\flutter-master
    • Upstream repository https://github.com/AlexV525/flutter
    • Framework revision da7d7777e2 (3 hours ago), 2022-01-22 00:20:19 -0500
    • Engine revision 5061c0fb74
    • Dart version 2.17.0 (build 2.17.0-44.0.dev)
    • DevTools version 2.9.2

@chunhtai

/cc @chunhtai

Workaround for TalkBack:

Widget _buildSemantics(BuildContext context) {
  void _onLongPress() {
    // Implement your own call.
    print('onLongPress');
  }

  return Semantics(
    onLongPress: _onLongPress,
    onLongPressHint: 'call something',
    child: GestureDetector(
      onLongPress: MediaQuery.of(context).accessibleNavigation
          ? _onLongPress
          : null,
      child: const Text('Test Semantics onLongPress'),
    ),
  );
}

voiceover sends the long press directly to the application instead of semantics action. you need to use gesture recognizer in this case.

closing this issue

@chunhtai

@chunhtai This also happened to Talkback, see screen records above. Now they behave the same. I don't think there is a platform regression, but the framework might do.

@chunhtai

@chunhtai The documentation for SemanticsProperties.onLongPress [permalink] says:

VoiceOver users on iOS and TalkBack users on Android can trigger this action by double-tapping the screen without lifting the finger after the second tap.

So I believe that this is intended to to work on both VoiceOver and TalkBack, and if it's not the intention, then it should not have such documentation.

@goderbauer

/cc @goderbauer who originally wrote the doc. [blame ref]

We can't control how the platform decide to interpret the accessibility long press, it looks like in some case they are sent through semantics action and sometimes it synthesizes a screen long press. We need to update the documentation.

Clarifies semantics long press and semantics on tap documentation (#1…

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.

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Update the documentation of Semantics' onLongPress #35112

Steps to Reproduce

Logs

`showSemanticsDebugger` false

`showSemanticsDebugger` true

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Update the documentation of Semantics' onLongPress #35112

Description

Steps to Reproduce

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Activity

markusaksli-nc commented on Aug 5, 2020

AlexV525 commented on Jan 22, 2022

showSemanticsDebugger false

showSemanticsDebugger true

AlexV525 commented on Jan 22, 2022

AlexV525 commented on Jan 22, 2022

chunhtai commented on Jan 24, 2022

chunhtai commented on Jan 24, 2022

AlexV525 commented on Jan 25, 2022

kpsroka commented on Jan 25, 2022

AlexV525 commented on Jan 25, 2022

chunhtai commented on Jan 25, 2022

github-actions commented on Jun 23, 2023

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Issue actions

`showSemanticsDebugger` false

`showSemanticsDebugger` true