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iOS mid-fling scroll simulation inaccurate #13171

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iOS mid-fling scroll simulation inaccurate#13171
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P2Important issues not at the top of the work lista: fidelityMatching the OEM platforms bettercustomer: crowdAffects or could affect many people, though not necessarily a specific customer.f: scrollingViewports, list views, slivers, etc.found in release: 3.6Found to occur in 3.6has reproducible stepsThe issue has been confirmed reproducible and is ready to work onp: cupertino_uicupertino_ui package in flutter/packagespackageflutter/packages repository. See also p: labels.platform-iosiOS applications specificallyteam-iosOwned by iOS platform teamtriaged-iosTriaged by iOS platform team

Description

@xster
xster
opened on Nov 23, 2017

The scroll motions during the ~50ms in the middle of a fast fling motion on iOS is not accurate.

In the middle of the fling itself (and generally), the scrollable's position offset follows the finger exactly whereas on iOS, when the finger moves too fast, the scrollable has an inertia and follows the finger with a spring motion the entire time instead of just at the end when it goes ballistic.

https://streamable.com/ki7an

Activity

  1. xster
    added
    p: cupertino_uicupertino_ui package in flutter/packages
    platform-iosiOS applications specifically
    on Nov 23, 2017
  2. xster
    added this to the milestone on Dec 1, 2017
  3. zoechi
    added
    frameworkflutter/packages/flutter repository. See also f: labels.
    on Jul 22, 2018
  4. jslavitz
    self-assigned this
    on Nov 29, 2018
  5. jslavitz
    removed their assignment
    on Feb 11, 2019
  6. HansMuller
    added
    a: fidelityMatching the OEM platforms better
    on May 14, 2019
  7. TahaTesser
    added
    customer: crowdAffects or could affect many people, though not necessarily a specific customer.
    on Mar 26, 2020
  8. kf6gpe
    added
    P2Important issues not at the top of the work list
    on May 29, 2020
  9. Hixie
    removed this from the milestone on Aug 17, 2020

  10. markusaksli-nc commented on Sep 7, 2020

    @markusaksli-nc
    markusaksli-nc
    on Sep 7, 2020
    Contributor

    Still seems reproducible on the latest master 1.22.0-10.0.pre.87.

    flutter doctor -v 
    [✓] Flutter (Channel master, 1.22.0-10.0.pre.87, on Mac OS X 10.15.6 19G2021, locale en-GB)
    • Flutter version 1.22.0-10.0.pre.87 at /Users/markus/development/flutter_master
    • Framework revision 4732a214a7 (2 days ago), 2020-09-04 21:05:02 -0400
    • Engine revision ac8b9c4c52
    • Dart version 2.10.0 (build 2.10.0-86.0.dev)

 
[✓] 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 48.1.2
    • Dart plugin version 193.7361
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

[✓] Connected device (5 available)
    • Nevercode’s iPhone (mobile)         • b668e524315069f3db3661ac11ff1f66afafebdb • ios            • iOS 13.6
    • iPhone SE (2nd generation) (mobile) • E88D23AA-71AC-49A6-A418-058CDE0D2FC4     • ios            • com.apple.CoreSimulator.SimRuntime.iOS-13-6 (simulator)
    • macOS (desktop)                     • macos                                    • darwin-x64     • Mac OS X 10.15.6 19G2021
    • Web Server (web)                    • web-server                               • web-javascript • Flutter Tools
    • Chrome (web)                        • chrome                                   • web-javascript • Google Chrome 85.0.4183.83

• No issues found!
    Minimal reproducible code sample 
    import 'dart:math';

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  final random = new Random();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Sample',
      home: Scaffold(
        appBar: AppBar(
          title: Text('Sample'),
        ),
        body: ListView.builder(itemCount: 100,
          itemBuilder: (context, i) {
            return Container(
              height: 50,
              color: Color((random.nextDouble() * 0xFFFFFF).toInt())
                  .withOpacity(1.0),
            );
          },
        ),
      ),
    );
  }
}
  11. markusaksli-nc
    added
    found in release: 1.22Found to occur in 1.22
    has reproducible stepsThe issue has been confirmed reproducible and is ready to work on
    on Sep 7, 2020

  12. huycozy commented on Nov 23, 2022

    @huycozy
    huycozy
    on Nov 23, 2022
    Member

    Adding a demo video of the sample code running on the latest Flutter master channel for further insights from the team. Looks like it has been improved but still not quite the same with iOS native app.

    PXL_20221123_120732028.mp4
    flutter doctor -v (stable and master) 
    [✓] Flutter (Channel stable, 3.3.8, on macOS 13.0 22A380 darwin-x64, locale en-VN)
    • Flutter version 3.3.8 on channel stable at /Users/huynq/Documents/GitHub/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 52b3dc25f6 (23 hours ago), 2022-11-09 12:09:26 +0800
    • Engine revision 857bd6b74c
    • Dart version 2.18.4
    • 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 14.0.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14A400
    • 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 2022.2.2)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 70.0.5
    • Dart plugin version 222.4167.21

[✓] 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 1.73.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.52.0

[✓] Connected device (3 available)
    • iPhone 14 Pro Max (mobile) • 332079AF-E895-4685-910E-7B1E18B0C6B8 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-16-0 (simulator)
    • macOS (desktop)            • macos                                • darwin-x64     • macOS 13.0 22A380 darwin-x64
    • Chrome (web)               • chrome                               • web-javascript • Google Chrome 107.0.5304.110

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

• No issues found!

    [!] Flutter (Channel master, 3.6.0-7.0.pre.33, on macOS 13.0 22A380 darwin-x64, locale en-VN)
    • Flutter version 3.6.0-7.0.pre.33 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 b7023e843a (2 hours ago), 2022-11-22 20:47:07 -0500
    • Engine revision f75287af0b
    • Dart version 2.19.0 (build 2.19.0-416.0.dev)
    • DevTools version 2.19.0
    • 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 14.0.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14A400
    • 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 2022.2.2)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 70.0.5
    • Dart plugin version 222.4167.21

[✓] 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 3.52.0

[✓] Connected device (4 available)
    • SM T225 (mobile)           • R9JT3004VRJ                          • android-arm64  • Android 12 (API 31)
    • iPhone 14 Pro Max (mobile) • 332079AF-E895-4685-910E-7B1E18B0C6B8 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-16-0 (simulator)
    • macOS (desktop)            • macos                                • darwin-x64     • macOS 13.0 22A380 darwin-x64
    • Chrome (web)               • chrome                               • web-javascript • Google Chrome 107.0.5304.110

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

! Doctor found issues in 1 category.
  13. huycozy
    added
    found in release: 3.6Found to occur in 3.6
    f: scrollingViewports, list views, slivers, etc.
    and removed
    found in release: 1.22Found to occur in 1.22
    on Nov 23, 2022
  14. flutter-triage-bot
    added
    multiteam-retriage-candidate
    team-iosOwned by iOS platform team
    triaged-iosTriaged by iOS platform team
    on Jul 8, 2023
  15. Hixie
    removed
    multiteam-retriage-candidate
    on Mar 6, 2024
  16. Piinks
    added this to Cupertino Refreshon Jul 25, 2024
  17. Piinks
    moved this to Todo in Cupertino Refreshon Jul 25, 2024
  18. Piinks
    self-assigned this
    on May 5, 2025
  19. Piinks
    removed their assignment
    on Jul 16, 2025
  20. Piinks
    added
    packageflutter/packages repository. See also p: labels.
    and removed
    frameworkflutter/packages/flutter repository. See also f: labels.
    on Aug 18, 2026
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    P2Important issues not at the top of the work lista: fidelityMatching the OEM platforms bettercustomer: crowdAffects or could affect many people, though not necessarily a specific customer.f: scrollingViewports, list views, slivers, etc.found in release: 3.6Found to occur in 3.6has reproducible stepsThe issue has been confirmed reproducible and is ready to work onp: cupertino_uicupertino_ui package in flutter/packagespackageflutter/packages repository. See also p: labels.platform-iosiOS applications specificallyteam-iosOwned by iOS platform teamtriaged-iosTriaged by iOS platform team

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