Flutter 如何在小部件层次结构中约束ListTile
如何使Flutter 如何在小部件层次结构中约束ListTile,flutter,flutter-layout,Flutter,Flutter Layout,如何使listile在此小部件层次结构中工作: SingleChildScrollView( 滚动方向:轴垂直, 子:列( 儿童:[ 划船( mainAxisSize:mainAxisSize.min, 儿童:[ 无线电( 价值:1, 组值:1, 一旦更改:(sel){}, ), 手势检测器( 孩子:排( 儿童:[ //Text('Title'),--这是可以的,但ListTile失败 列表砖( 标题:文本(“标题”), 字幕:文本(“字幕”), ), ], ), onTap:(){}, ),
listile
在此小部件层次结构中工作:
SingleChildScrollView(
滚动方向:轴垂直,
子:列(
儿童:[
划船(
mainAxisSize:mainAxisSize.min,
儿童:[
无线电(
价值:1,
组值:1,
一旦更改:(sel){},
),
手势检测器(
孩子:排(
儿童:[
//Text('Title'),--这是可以的,但ListTile失败
列表砖(
标题:文本(“标题”),
字幕:文本(“字幕”),
),
],
),
onTap:(){},
),
],
),
],
),
),
请理解,我并不是完全控制小部件层次结构——一个框架正在构建SingleChildScrollView
,Radio
,GestureDetector
,等等。我只是试图为一个选项提供一个子小部件。(我以简化的形式复制了层次结构以进行调试和实验。)
我得到一个例外:
flutter: ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
flutter: The following assertion was thrown during performLayout():
flutter: BoxConstraints forces an infinite width.
flutter: These invalid constraints were provided to RenderParagraph's layout() function by the following
flutter: function, which probably computed the invalid constraints in question:
flutter: _RenderListTile._layoutBox (package:flutter/src/material/list_tile.dart:1318:9)
flutter: The offending constraints were:
flutter: BoxConstraints(w=Infinity, 0.0<=h<=Infinity)
颤振:══╡ 呈现库捕获到异常╞═════════════════════════════════════════════════════════
颤振:在performLayout()期间抛出了以下断言:
颤振:BoxConstraints强制无限宽。
颤振:这些无效约束是由以下程序提供给RenderParagraph的layout()函数的
颤振:函数,它可能计算了所讨论的无效约束:
颤振:_renderList._layoutBox(包装:颤振/src/material/list_tile.dart:1318:9)
颤振:有问题的约束是:
颤振:BoxConstraints(w=无穷大,0.0您可以将列表磁贴
包装在容器
或约束框
中,并设置其最大宽度
:
ConstrainedBox(
constraints: BoxConstraints(
maxWidth: MediaQuery.of(context).size.width - 50,
),
child: ListTile(
title: Text('Title'),
subtitle: Text('Subtitle'),
trailing: Text('Trailing'),
),
),
您可以复制粘贴运行下面的完整代码
您可以使用IntrinsicWidth
wrapRow
和Expanded
wrapListTile
,并且可以有多个Expaned ListTile
GestureDetector(
child: IntrinsicWidth(
child: Row(
children: <Widget>[
//Text('Title'), -- This is OK, but ListTile fails
Expanded(
child: ListTile(
title: Text('Title'),
subtitle: Text('Subtitle'),
),
),
],
),
),
手势检测器(
子:内部宽度(
孩子:排(
儿童:[
//Text('Title'),--这是可以的,但ListTile失败
扩大(
孩子:ListTile(
标题:文本(“标题”),
字幕:文本(“字幕”),
),
),
],
),
),
工作演示
完整代码
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: SingleChildScrollView(
scrollDirection: Axis.vertical,
child: Column(
children: [
Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Radio(
value: 1,
groupValue: 1,
onChanged: (sel) {},
),
GestureDetector(
child: IntrinsicWidth(
child: Row(
children: <Widget>[
//Text('Title'), -- This is OK, but ListTile fails
Expanded(
child: ListTile(
isThreeLine: true,
title: Text('Title'),
subtitle: Text('this is long text this is long text this is long text \n'* 10),
),
),
],
),
),
onTap: () {},
),
],
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
导入“包装:颤振/材料.省道”;
void main(){
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
主样本:颜色。蓝色,
视觉密度:视觉密度。自适应平台密度,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
int _计数器=0;
void _incrementCounter(){
设置状态(){
_计数器++;
});
}
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(widget.title),
),
正文:SingleChildScrollView(
滚动方向:轴垂直,
子:列(
儿童:[
划船(
mainAxisSize:mainAxisSize.min,
儿童:[
无线电(
价值:1,
组值:1,
一旦更改:(sel){},
),
手势检测器(
子:内部宽度(
孩子:排(
儿童:[
//Text('Title'),--这是可以的,但ListTile失败
扩大(
孩子:ListTile(
伊斯特里琳:是的,
标题:文本(“标题”),
字幕:Text('这是长文本这是长文本这是长文本\n'*10),
),
),
],
),
),
onTap:(){},
),
],
),
],
),
),
浮动操作按钮:浮动操作按钮(
按下时:\ u递增计数器,
工具提示:“增量”,
子:图标(Icons.add),
),
);
}
}
完整代码2重新播放
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: SingleChildScrollView(
scrollDirection: Axis.vertical,
child: Column(
children: [
Row(
mainAxisSize: MainAxisSize.min,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Expanded(
flex: 1,
child: Radio(
value: 1,
groupValue: 1,
onChanged: (sel) {},
),
),
Expanded(
flex: 5,
child: GestureDetector(
child: LayoutBuilder(
builder:(context, constraints) {
print(constraints.maxWidth);
print(constraints.minWidth);
return ConstrainedBox(
constraints: BoxConstraints(
maxWidth: constraints.maxWidth),
child: ListTile(
//isThreeLine: true,
title: Text('Title'),
subtitle: Text(
'Textlargeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee',
overflow: TextOverflow.ellipsis,
maxLines: 2,
style: TextStyle(
fontSize: 13.0,
fontFamily: 'Roboto',
color: Color(0xFF212121),
fontWeight: FontWeight.bold,
),
),
),
);
}
),
onTap: () {},
),
),
],
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
import'包装:flift/cupertino.dart';
进口“包装:颤振/材料.省道”;
void main(){
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
主样本:颜色。蓝色,
视觉密度:视觉密度。自适应平台密度,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
F