我正在尝试显示一个内部带有2 AlertDialog的RadioListTile小部件，但出现渲染异常。
这是AlertDialog的代码:
enum _Theme { light, dark }
class ChangeThemeDialog extends StatefulWidget {
@override
_ChangeThemeDialogState createState() => _ChangeThemeDialogState();
}
class _ChangeThemeDialogState extends State<ChangeThemeDialog> {
_Theme _theme = _Theme.light;
@override
Widget build(BuildContext context) {
return AlertDialog(
title: Text(AppLocalizations.of(context).changeThemeDialogTitle),
content: Text(AppLocalizations.of(context).changeThemeDialogContent),
actions: <Widget>[
RadioListTile<_Theme>(
title: const Text('Light'),
value: _Theme.light,
groupValue: _theme,
onChanged: (_Theme value) {
setState(() {
_theme = value;
});
},
),
RadioListTile<_Theme>(
title: const Text('Dark'),
value: _Theme.dark,
groupValue: _theme,
onChanged: (_Theme value) {
setState(() {
_theme = value;
});
},
),
],
);
}
}
这是引发的异常:
════════ Exception caught by rendering library ═════════════════════════════════
The following assertion was thrown during performLayout():
BoxConstraints forces an infinite width.
These invalid constraints were provided to RenderParagraph's layout() function by the following function, which probably computed the invalid constraints in question:
_RenderListTile._layoutBox (package:flutter/src/material/list_tile.dart:1318:9)
The offending constraints were: BoxConstraints(w=Infinity, 0.0<=h<=Infinity)
The relevant error-causing widget was
RadioListTile<_Theme>
lib\…\widgets\change_theme_dialog.dart:21
When the exception was thrown, this was the stack
#0 BoxConstraints.debugAssertIsValid.<anonymous closure>.throwError
package:flutter/…/rendering/box.dart:517
#1 BoxConstraints.debugAssertIsValid.<anonymous closure>
package:flutter/…/rendering/box.dart:559
#2 BoxConstraints.debugAssertIsValid
package:flutter/…/rendering/box.dart:565
#3 RenderObject.layout
package:flutter/…/rendering/object.dart:1670
#4 _RenderListTile._layoutBox
package:flutter/…/material/list_tile.dart:1318
...
The following RenderObject was being processed when the exception was fired: _RenderListTile#940e2 relayoutBoundary=up18 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
RenderObject: _RenderListTile#940e2 relayoutBoundary=up18 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
parentData: offset=Offset(0.0, 0.0) (can use size)
constraints: BoxConstraints(unconstrained)
size: MISSING
leading: RenderMouseRegion#0f7c8 relayoutBoundary=up19 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
parentData: offset=Offset(0.0, 0.0) (can use size)
constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=56.0)
size: Size(40.0, 40.0)
listeners: enter, exit
child: RenderSemanticsAnnotations#f6e87 relayoutBoundary=up20 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
parentData: <none> (can use size)
constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=56.0)
size: Size(40.0, 40.0)
child: _RenderRadio#76d2d relayoutBoundary=up21 NEEDS-PAINT
parentData: <none> (can use size)
constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=56.0)
size: Size(40.0, 40.0)
additionalConstraints: BoxConstraints(w=40.0, h=40.0)
value: checked
title: RenderParagraph#88552 NEEDS-LAYOUT NEEDS-PAINT
parentData: offset=Offset(0.0, 0.0)
constraints: MISSING
size: MISSING
textAlign: start
textDirection: ltr
softWrap: wrapping at box width
overflow: clip
locale: it_IT
maxLines: unlimited
text: TextSpan
debugLabel: ((englishLike subhead 2014).merge(((blackMountainView subtitle1).apply).merge(unknown))).copyWith
inherit: false
color: Color(0xdd000000)
family: Prompt
size: 16.0
weight: 400
letterSpacing: 0.1
baseline: alphabetic
decoration: TextDecoration.none
"Light"
════════ Exception caught by rendering library ═════════════════════════════════
RenderBox was not laid out: _RenderListTile#940e2 relayoutBoundary=up18 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1694 pos 12: 'hasSize'
The relevant error-causing widget was
RadioListTile<_Theme>
lib\…\widgets\change_theme_dialog.dart:21
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by rendering library ═════════════════════════════════
RenderBox was not laid out: RenderPadding#399f0 relayoutBoundary=up17 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1694 pos 12: 'hasSize'
The relevant error-causing widget was
RadioListTile<_Theme>
lib\…\widgets\change_theme_dialog.dart:21
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by rendering library ═════════════════════════════════
RenderBox was not laid out: RenderSemanticsAnnotations#b25db relayoutBoundary=up16 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1694 pos 12: 'hasSize'
The relevant error-causing widget was
RadioListTile<_Theme>
lib\…\widgets\change_theme_dialog.dart:21
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by rendering library ═════════════════════════════════
最佳答案
您可以在下面复制粘贴运行完整代码
您可以将RadioListTile与Container包装在一起并提供width程式码片段
Container(
width: 150,
child: RadioListTile<_Theme>(
工作演示
完整的代码
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
enum _Theme { light, dark }
class ChangeThemeDialog extends StatefulWidget {
@override
_ChangeThemeDialogState createState() => _ChangeThemeDialogState();
}
class _ChangeThemeDialogState extends State<ChangeThemeDialog> {
_Theme _theme = _Theme.light;
@override
Widget build(BuildContext context) {
return AlertDialog(
title: Text("title"),
content: Text("content"),
actions: <Widget>[
Container(
width: 150,
child: RadioListTile<_Theme>(
title: const Text('Light'),
value: _Theme.light,
groupValue: _theme,
onChanged: (_Theme value) {
setState(() {
_theme = value;
});
},
),
),
Container(
width: 150,
child: RadioListTile<_Theme>(
title: const Text('Dark'),
value: _Theme.dark,
groupValue: _theme,
onChanged: (_Theme value) {
setState(() {
_theme = value;
});
},
),
)
],
);
}
}
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: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
ChangeThemeDialog(),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
关于flutter - BoxConstraints强制在Flutter中在AlertDialog中使用RadioListTile时引发无限宽度异常，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/62178773/