flutter 使用SingleChildScrollView报错RenderBox was not laid out，为什么？

Question

在一个页面中通过Scaffold>SafeArea>SingleChildScrollView>column>(container,row)布局，希望内容能超出时进行滚动，但报错RenderBox was not laid out，网上百度了几个方法试了一下，没有效果，我应该怎么解决这个问题？谢谢--

[代码]

import 'package:bruno/bruno.dart';
import 'package:flutter/material.dart';
import 'package:flutter_demo/widget/m_button.dart';
import 'package:flutter_demo/widget/m_head.dart';

class HomePage extends StatefulWidget {
  
  const HomePage({Key? key, this.params}) : super(key: key);

  static const String title = "xxx";
  final dynamic params;

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: MHead(
        title: HomePage.title,
        actions: [
          UnconstrainedBox(
            child: MIconButton(icon: Icon(Icons.settings),text: "偏好设置",),
          )
          
        ],
      ),
      body:  SafeArea(
          child: SingleChildScrollView(
              child: _content(context),
          )
      ),
      // body: _content(context),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }


  Widget _content(BuildContext context){

    String htmlcontent = """
  如上图所示，当用户点击绿色光点位置之后，首先我们可以根据点击事件确认被点击是哪一个Element所渲染的RenderObject；
首先我们通过globalToLocal方法将手势回调的globalPosition转换为相对于Mural的localPosition；接下来遍历MuralRenderEditable的child，寻找包含localPosition的child；

作者：闲鱼技术
链接：https://juejin.cn/post/7106732801906606116
来源：稀土掘金
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。
""";

    return Column(
          // mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Image.network(
              'https://cube.elemecdn.com/6/94/4d3ea53c084bad6931a56d5158a48jpeg.jpeg'),
            
            Container(
              padding: EdgeInsets.all(10),
              margin: EdgeInsets.only(bottom: 10),
              decoration: BoxDecoration(
                color: Colors.white
              ),
              child: Column(
                children: [
                  Row(
                    children: [
                      Icon(Icons.man),
                      Text("李白xxxx", style: TextStyle(fontSize: 18),)
                    ],
                  ),
                  SizedBox(
                    height: 10,
                  ),
                  Row(
                    children: [
                      Padding(padding: EdgeInsets.only(right: 10),child: Text("xx"),), 
                      Padding(padding: EdgeInsets.only(right: 10),child: Text("xx"),), 
                      Padding(padding: EdgeInsets.only(right: 10),child: Text("xx"),), 
                    ],
                  ),
                  SizedBox(
                    height: 10,
                  ),
                  Row(
                    children: [
                      Padding(padding: EdgeInsets.only(right: 10),child: Text("xx"),), 
                      Padding(padding: EdgeInsets.only(right: 10),child: Text("xx"),), 
                      Padding(padding: EdgeInsets.only(right: 10),child: Text("xx"),), 
                    ],
                  ),
                ],
              ),
            ),

            Expanded(
              child: Container(
                decoration: BoxDecoration(color: Colors.white),
                padding: EdgeInsets.all(10),
                margin: EdgeInsets.only(bottom: 20),
                child: Container(
                  decoration: BoxDecoration(color: Colors.green),
                  padding: EdgeInsets.all(10),
                  child: RichText(text: TextSpan(
                    text: htmlcontent
                  )),
                ),
              )
            )

          ],
    );
  }
}

Answer 1

SingleChildScrollView 已经可以滚动了， 把 Expanded 拿掉就可以了。