颤振可拖动列表项 - 未找到材质小部件

Question

在没有任何用于拖放列表视图的说明书示例的情况下，我正在尝试创建自己的示例，但是当尝试拖动一行时，我收到错误：找不到材料小部件。我尝试将 ListTiles 包装在容器中，但似乎总是收到相同的错误。

import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final title = 'Basic List';
    var tile1 = new ListTile(
      leading: new Icon(Icons.photo),
      title: new Text('Row 1'),
    );
    var tile2 = new ListTile(
      leading: new Icon(Icons.photo),
      title: new Text('Row 2'),
    );
    var tile3 = new ListTile(
      leading: new Icon(Icons.photo),
      title: new Text('Row 3'),
    );
    return new MaterialApp(
      title: title,
      home: new Scaffold(
        appBar: new AppBar(
          title: new Text(title),
        ),
        body: new ListView(
            children: [
              new Draggable(child: tile1, feedback: tile1),
              new Draggable(child: tile2, feedback: tile2),
              new Draggable(child: tile3, feedback: tile3),
            ],
        ),
      ),
    );
  }
}

Answer 1

也许不是最好的解决方案，但它适合我

Draggable(
  axis: Axis.vertical,
  maxSimultaneousDrags: 1,
  child: tile,
  childWhenDragging: Opacity(
    opacity: 0.5,
    child: tile,
  ),
  feedback: Material(
    child: ConstrainedBox(
      constraints:
          BoxConstraints(maxWidth: MediaQuery.of(context).size.width),
      child: tile,
    ),
    elevation: 4.0,
  ),

我已经用屏幕尺寸的宽度包裹了ConstrainedBox瓷砖。