ReorderableListView throws when Slider in item list

Question

I've got a ReorderableListView where the ListTile contains a Slider() widget. If I don't touch any of the Slider() widgets, I can reorder the ListTiles with no issue. But, as soon as you click-on or interact with any of the Slider() widgets, then attempting to reorder the items throws() with this error in the debug console (many of them):

════════ Exception caught by scheduler library ═════════════════════════════════
Assertion failed:
../…/rendering/layer.dart:2498
leader._lastOffset != null
"LeaderLayer anchor must come before FollowerLayer in paint order, but the reverse was true."

On Flutter 2.8.1, Stable Channel.

Here is the code to duplicate. I used the example code from the ReorderableListView widget documentation, and the only things I changed was the Text() to a Slider() as well as autogenerate some values for the Slider(). Other than that it's the same example as the documentation. This works fine with a Text() widget, but the Slider() fails. Is there a way to use a Slider() inside a ReorderableListView()?:

import 'dart:math';
import 'package:flutter/material.dart';

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: const Scaffold(
        body: Center(
          child: ListViewTestWidget(),
        ),
      ),
    );
  }
}

class ListViewTestWidget extends StatefulWidget {
  const ListViewTestWidget({Key? key}) : super(key: key);

  @override
  _ListViewTestWidgetState createState() => _ListViewTestWidgetState();
}

class _ListViewTestWidgetState extends State<ListViewTestWidget> {
  final List<int> _items = List<int>.generate(50, (int index) => index);
  final List<double> _values =
      List<double>.generate(50, (int index) => Random().nextDouble() * 100);

  _changeValue(int index, double newValue) {
    if (newValue < 1 || newValue > 100) return;
    setState(() {
      _values[index] = newValue;
    });
  }

  @override
  Widget build(BuildContext context) {
    final ColorScheme colorScheme = Theme.of(context).colorScheme;
    final Color oddItemColor = colorScheme.primary.withOpacity(0.05);
    final Color evenItemColor = colorScheme.primary.withOpacity(0.15);

    return ReorderableListView(
      padding: const EdgeInsets.symmetric(horizontal: 40),
      children: <Widget>[
        for (int index = 0; index < _items.length; index += 1)
          ListTile(
            key: Key('$index'),
            tileColor: _items[index].isOdd ? oddItemColor : evenItemColor,
            title: Slider(
              min: 1,
              max: 100,
              value: _values[index],
              onChanged: (newValue) =>
                  setState(() => _changeValue(index, newValue)),
            ),
          ),
      ],
      onReorder: (int oldIndex, int newIndex) {
        setState(() {
          if (oldIndex < newIndex) {
            newIndex -= 1;
          }
          final int item = _items.removeAt(oldIndex);
          _items.insert(newIndex, item);
        });
      },
    );
  }
}

Answer 1

This is a known issue on the flutter framework itself. You can track the progress of this issue on GitHub: https://github.com/flutter/flutter/issues/97292

Meanwhile (before they fix it), you can perhaps try to use CupertinoSlider to replace the (Material) Slider . The issue does not occur on the Cupertino widget. And yes, they look a little different but the main functionalities are the same. Or you can write your own slider widget and customize it however you want.