Make widget drag'n'drop able and allow to scroll view

Question

Assume you have a ListView with some Widgets to get scrolled up and down. Additionally, the Widget should be draggable

May I tell the Draggable, that a drag should start, if the user taps longer. And a scroll should happen, if the user taps shorter?

Code of the Draggable:

Draggable<EItem>(
                  data: widget.eItemStore.state,
                  dragAnchorStrategy: pointerDragAnchorStrategy,
                  feedback: feedbackWidget,
                  child: ConstrainedBox(
                    constraints: BoxConstraints( maxWidth: 350, minHeight: 30 ),
                      child: innerWidget(context, widget.eItemStore.state)),
                  onDragStarted: () {
                    // print('Drag started');
                  });

This problem appears solely on touch devices, since on a mouse pointer device, users may use the scroll wheel to scroll.

Answer 1

There is a widget especially to handle this case ReorderableListView. It will allow to reorder only on long press and allow scroll on shorter press

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const MyStatefulWidget(),
      ),
    );
  }
}

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

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  final List<int> _items = List<int>.generate(50, (int index) => index);

  @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: Text('Item ${_items[index]}'),
          ),
      ],
      onReorder: (int oldIndex, int newIndex) {
        setState(() {
          if (oldIndex < newIndex) {
            newIndex -= 1;
          }
          final int item = _items.removeAt(oldIndex);
          _items.insert(newIndex, item);
        });
      },
    );
  }
}