一个 RenderFlex 在底部溢出了 729 个像素。在 SingleChildScrollView

Posted 2023-02-23

【中文标题】一个 RenderFlex 在底部溢出了 729 个像素。在 SingleChildScrollView

【英文标题】：A RenderFlex overflowed by 729 pixels on the bottom. in SingleChildScrollView

【发布时间】：2020-02-18 02:12:58

【问题描述】：

一个 RenderFlex 在底部溢出了 676 像素。在 SingleChildScrollView 中

小部件仪表板（上下文） 返回动画定位（ 持续时间：持续时间， 顶部：0， 底部：0， 左：是折叠？ 0 : 0.6 * 屏幕宽度， 对：isCollapsed 吗？ 0 : -0.2 * 屏幕宽度， 孩子：ScaleTransition（ 规模：_scaleAnimation， 孩子：材料（ 动画持续时间：持续时间， 边界半径：边界半径.all（ 半径.圆形（40）， ), 海拔：8， 颜色：背景颜色， 孩子：列（ crossAxisAlignment：CrossAxisAlignment.start， 孩子们： [ 容器（ 填充：const EdgeInsets.only（左：16，右：16，上：48）， 孩子：行（ mainAxisAlignment: MainAxisAlignment.spaceBetween, mainAxisSize: MainAxisSize.max, 孩子们：[ 墨水井( 孩子：图标（ 图标.菜单， 颜色：颜色.白色 ), 点按：（） 设置状态（（） 如果（已折叠） _controller.forward(); 别的 _controller.reverse();

                        isCollapsed = !isCollapsed;
                      );
                    ,
                  ),
                  Text(
                    " Técnico",
                    style: TextStyle(
                      fontSize: 24,
                      color: Colors.white,
                    ),
                  ),
                  Icon(
                    Icons.settings,
                    color: Colors.white,
                  ),
                ]),
          ),
          Container(
              child: SingleChildScrollView(
                scrollDirection: Axis.vertical,
                physics: ClampingScrollPhysics(),
                child: Column(
                  children: <Widget>[
                  SizedBox(
                    height: 5,
                  ),
                  SizedBox(
                    height:20 ,
                  ),
                  Text("Chamados",
                  style: TextStyle(
                    color: Colors.white,
                    fontSize: 20,
                  ) ,
                  ),
                  SizedBox(
                    height:5 ,
                  ),
                  ListView.separated(
                      shrinkWrap: true,
                      itemBuilder: (context,index)
                    return ListTile(
                      title: Text("Falta de Sinal"),
                      subtitle: Text("João"),
                      trailing: Text("20mb"),
                    );
                  , separatorBuilder: (context,index)
                    return Divider(
                      height: 16,
                    );
                  , itemCount: 16),
                ],
                ),
              ),
          ),
      ],
      ),
    ),
  ),
);

【问题讨论】：

这能回答你的问题吗？ Center widget vertically inside a SingleChildScrollView

【参考方案1】：

如果您在列或行内使用SingleChildScrollView，则使用Expanded Widget 包装。

e.g. Column(
     childreen[
        Expanded(
            child : SingleChildScrollView(
                 // your code ...
          ),                  
       ]),

或者您可以为容器提供高度。

  e.g. -> Container(
              height : 300.0,
              child : SingleChildScrollView(
                // your code ...              
                 ),
              ),

编码愉快... :)

【参考方案2】：

用Container包裹ListView.separated并添加约束，设置maxHeight有效，如下图

代码sn-p

Container(
              constraints: BoxConstraints(
                maxHeight: 300.0,
              ),
              child: ListView.separated(
                  shrinkWrap: true,
                  itemBuilder: (context, index) 
                    return ListTile(
                      title: Text("Falta de Sinal"),
                      subtitle: Text("João"),
                      trailing: Text("20mb"),
                    );
                  ,
                  separatorBuilder: (context, index) 
                    return Divider(
                      height: 16,
                    );
                  ,
                  itemCount: 16),
            ),

完整的测试代码

    import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget 
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) 
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  


class MyHomePage extends StatefulWidget 
  MyHomePage(Key key, this.title) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();


class _MyHomePageState extends State<MyHomePage> 
  int _counter = 0;

  void _incrementCounter() 
    setState(() 
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    );
  

  @override
  Widget build(BuildContext context) 
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            dashboard(context),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  

  Widget dashboard(context) 
    return Container(
      child: SingleChildScrollView(
        scrollDirection: Axis.vertical,
        physics: ClampingScrollPhysics(),
        child: Column(
          children: <Widget>[
            SizedBox(
              height: 5,
            ),
            SizedBox(
              height: 20,
            ),
            Text(
              "Chamados",
              style: TextStyle(
                color: Colors.black,
                fontSize: 20,
              ),
            ),
            SizedBox(
              height: 5,
            ),
            Container(
              constraints: BoxConstraints(
                maxHeight: 300.0,
              ),
              child: ListView.separated(
                  shrinkWrap: true,
                  itemBuilder: (context, index) 
                    return ListTile(
                      title: Text("Falta de Sinal"),
                      subtitle: Text("João"),
                      trailing: Text("20mb"),
                    );
                  ,
                  separatorBuilder: (context, index) 
                    return Divider(
                      height: 16,
                    );
                  ,
                  itemCount: 16),
            ),
          ],
        ),
      ),
    );
  

【讨论】：

这取决于您的布局。您可以使用 MediaQuery.of(context).size.height / 3 来获取相对高度，参考此medium.com/flutter-community/…

【参考方案3】：

添加高度是一个不错的选择，但你应该使用 Expanded inside 列

【参考方案4】：

我正在回答它，因为没有人提到我们为什么会得到这个，

所以，这通常是因为内容对于 RenderFlex 来说太大了。 通过应用 flex 因子（例如，使用 Expanded 小部件或 Flexibel，它也是 Expanded 小部件的一种）来强制 Widget 的子级 RenderFlex 适应可用空间，而不是调整到它们的自然大小。 你甚至可以访问这个以获得更清晰的信息 Flutter (Dart): Exceptions caused by rendering / A RenderFlex overflowed。还有这个https://docs.flutter.dev/testing/common-errors，希望对你有帮助。

【参考方案5】：

在您的专栏中使用 mainAxisSize，将防止该问题 柱子（ mainAxisSize: MainAxisSize.min, 孩子们： [ ) ], ),

【参考方案6】：

Column( mainAxisSize: MainAxisSize.min, children: <Widget>[ Text( filename, style: TextStyle( color: dsecondaryColor, fontWeight: FontWeight.bold), ) ], ),

【讨论】：

欢迎来到 Stack Overflow。请阅读How to Answer。