Question

有人可以启动一个快速的扑动项目，并用以下内容替换main.dart，看看我做错了什么？我试图在ListView中拖放工作。

我甚至不确定这是正确的做法，所以如果没有，请告诉我。

我现在得到的错误是：

抛出了另一个异常：＆＃39; package：flutter / src / rendering / box.dart＆＃39;：失败断言：第1446行pos 12：＆＃39; hasSize＆＃39;：不是真的。

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 Material(child:
       new ListTile(
          leading: new Icon(Icons.photo),
          title: new Text('Row 1'),
          trailing: new Icon(Icons.reorder),

    ));


    var tile2 = new Material(
        child:
          new ListTile(
            leading: new Icon(Icons.photo),
            title: new Text('Row 2'),
            trailing: new Icon(Icons.reorder),
    ));


    return new MaterialApp(
      title: title,
      home: new Scaffold(
        appBar: new AppBar(
          title: new Text(title),
        ),
        body:
        new GestureDetector(
          onVerticalDragStart: startDrag,
          onVerticalDragEnd: endDrag,
          child: new ListView(
            shrinkWrap: true,
            children: [
                  new Flex (

                    children: <Widget>[
                      new Flexible(
                        child: new Draggable(child: tile1, feedback: 
tile1),
                      ),
                      new Flexible(
                        child: new Draggable(child: tile2, feedback: 
tile2),
                      ),
                    ],
                    direction: Axis.vertical,
                    mainAxisAlignment: MainAxisAlignment.start,
                    mainAxisSize: MainAxisSize.min,
                  ),
            ],
          ),
        ),
      ),
    );
  }

  void startDrag(DragStartDetails event) {}

  void endDrag(DragEndDetails event) {}
}

由于

Answer 1

在@Darky解决问题hasSize问题的过程中有一点帮助，这里是完成的可排序ListView示例：

https://github.com/marchampson/FluterSortableListView

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Flutter拖放ListView hasSize不是真的

1 个答案: