Flutter：如何在列表视图中通过拖放对项目进行排序？

Question

我有一个 flutter 应用程序，该应用程序在列表视图中有一个记录列表，我希望用户能够使用拖放方法重新排序。所以我想在列表视图中使用拖放功能对项目进行重新排序。我该怎么做？

我想做这样的事情

Answer 1

为此，您可以使用 ReorderableListView

reorderable List 是一个可拖动的列表，用户可以重新排列/修改对象。

ReorderableListview 包含诸如 childred、header、onReorder、scrollDirection...< /p>

children：我们会将列表项加载到此属性

  children: <Widget>[
    for (int index = 0; index < _items.length; index++)
      ListTile(
        key: Key('$index'),
        tileColor: _items[index].isOdd ? oddItemColor : evenItemColor,
        title: Text('Item ${_items[index]}'),
      ),
  ],

onReorder：这是我们将处理拖动列表项的属性

  onReorder: (int oldIndex, int newIndex) {
    setState(() {
      if (oldIndex < newIndex) {
        newIndex -= 1;
      }
      final int item = _items.removeAt(oldIndex);
      _items.insert(newIndex, item);
    });
  },

完整示例

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

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

/// This is the private State class that goes with MyStatefulWidget.
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++)
          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);
        });
      },
    );
  }
}