Flutter Web: Cannot scroll with mouse down (drag) (Flutter 2.5+)

Issue

[Update]

I can confirm this issue happened in flutter above 2.5. Using 2.2.3 is fine. The question becomes why this feature been removed in 2.5 ? And how to enable it in flutter 2.5?

[Origin Question]

I’m using SingleChildScrollView on flutter web with desktop browser. Scrolling only works on mouse wheel but not on mouse click (drag). How can I map mouse click to touch and scroll like mobile?

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: SingleChildScrollView(
        child: Column(
          children: List<Widget>.generate(50, (i) => Text(i.toString())).toList(),
        ),
      ),
    );
  }
}

flutter doctor -v
[✓] Flutter (Channel master, 2.6.0-6.0.pre.6, on Ubuntu 20.04.3 LTS 5.11.0-34-generic, locale en_US.UTF-8)
    • Flutter version 2.6.0-6.0.pre.6 at /home/XXX
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 0c5431d99c (12 days ago), 2021-09-05 22:31:02 -0400
    • Engine revision b9c633900e
    • Dart version 2.15.0 (build 2.15.0-82.0.dev)

[✓] Chrome - develop for the web
    • Chrome at google-chrome

[✓] Connected device (2 available)
    • Linux (desktop) • linux  • linux-x64      • Ubuntu 20.04.3 LTS 5.11.0-34-generic
    • Chrome (web)    • chrome • web-javascript • Google Chrome 93.0.4577.82

Solution

Flutter change mouse scroll behavior after 2.5. See this for detail.

class MyCustomScrollBehavior extends MaterialScrollBehavior {
  // Override behavior methods and getters like dragDevices
  @override
  Set<PointerDeviceKind> get dragDevices => { 
    PointerDeviceKind.touch,
    PointerDeviceKind.mouse,
    // etc.
  };
}

// ScrollBehavior can be set for a specific widget.
final ScrollController controller = ScrollController();
ScrollConfiguration(
  behavior: MyCustomScrollBehavior(),
  child: ListView.builder(
    controller: controller,
    itemBuilder: (BuildContext context, int index) {
     return Text('Item $index');
    }
  ),
);

Answered By – Josh Chiu

Answer Checked By – Pedro (FlutterFixes Volunteer)