也许你们中的一个人已经遇到了这些问题。我花了很多小时试图将ListView(我还尝试了ExpansionPanelList(放入一个容器中，该容器从右边缘平移到屏幕(帮助菜单(上的现有小部件上。我已经创建了一个模型，从基本的ListView开始，然后再次逐个添加功能。但现在我被卡住了，错误信息对我没有多大帮助。
一旦添加了AnimatedPosited，就会抛出这些异常。主消息似乎是约束的问题。hasBoundedWidth"：不正确
════════ Exception caught by rendering library ═════════════════════════════════════════════════════
The following assertion was thrown during performLayout():
'package:flutter/src/rendering/viewport.dart': Failed assertion: line 1754 pos 16: 'constraints.hasBoundedWidth': is not true.
Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new?template=BUG.md
The relevant error-causing widget was:
ListView file:///Users/holger/IdeaProjects/math/lib/tmp.dart:496:40
When the exception was thrown, this was the stack:
#2 RenderShrinkWrappingViewport.performLayout (package:flutter/src/rendering/viewport.dart:1754:16)
#3 RenderObject.layout (package:flutter/src/rendering/object.dart:1775:7)
#4 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:13)
#5 RenderObject.layout (package:flutter/src/rendering/object.dart:1775:7)
#6 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:13)
...
The following RenderObject was being processed when the exception was fired: RenderShrinkWrappingViewport#a1875 relayoutBoundary=up7 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... needs compositing
... parentData: <none> (can use size)
... constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
... size: MISSING
... axisDirection: down
... crossAxisDirection: right
... offset: ScrollPositionWithSingleContext#20c01(offset: 0.0, range: null..null, viewport: null, ScrollableState, AlwaysScrollableScrollPhysics -> BouncingScrollPhysics, IdleScrollActivity#3e990, ScrollDirection.idle)
RenderObject: RenderShrinkWrappingViewport#a1875 relayoutBoundary=up7 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
needs compositing
parentData: <none> (can use size)
constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
size: MISSING
axisDirection: down
crossAxisDirection: right
offset: ScrollPositionWithSingleContext#20c01(offset: 0.0, range: null..null, viewport: null, ScrollableState, AlwaysScrollableScrollPhysics -> BouncingScrollPhysics, IdleScrollActivity#3e990, ScrollDirection.idle)
... child 0: RenderSliverPadding#078d5 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: layoutOffset=None
... constraints: MISSING
... geometry: null
... padding: EdgeInsets.zero
... textDirection: ltr
... child: RenderSliverList#fd0a6 NEEDS-LAYOUT NEEDS-PAINT
... parentData: paintOffset=Offset(0.0, 0.0)
... constraints: MISSING
... geometry: null
... no children current live
════════════════════════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by rendering library ═════════════════════════════════════════════════════
RenderBox was not laid out: RenderShrinkWrappingViewport#a1875 relayoutBoundary=up7 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1713 pos 12: 'hasSize'
The relevant error-causing widget was:
ListView file:///Users/holger/IdeaProjects/math/lib/tmp.dart:496:40
异常消息的下半部分会重复多次，可能每个动画步骤都会重复一次。然后消息以下面的消息结束，其中引用容器是AnimatedPositions>忽略指针>集装箱
════════ Exception caught by rendering library ═════════════════════════════════════════════════════
The following assertion was thrown during paint():
RenderBox was not laid out: RenderDecoratedBox#a83d8
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1713 pos 12: 'hasSize'
Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new?template=BUG.md
The relevant error-causing widget was:
Container file:///Users/holger/IdeaProjects/math/lib/tmp3.dart:474:32
When the exception was thrown, this was the stack:
#2 RenderBox.size (package:flutter/src/rendering/box.dart:1713:12)
#3 RenderDecoratedBox.paint (package:flutter/src/rendering/proxy_box.dart:2067:12)
#4 RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:2307:7)
#5 PaintingContext.paintChild (package:flutter/src/rendering/object.dart:191:13)
#6 RenderProxyBoxMixin.paint (package:flutter/src/rendering/proxy_box.dart:133:15)
...
The following RenderObject was being processed when the exception was fired: RenderDecoratedBox#a83d8
... needs compositing
... parentData: <none> (can use size)
... constraints: BoxConstraints(w=331.2, h=716.8)
... size: MISSING
... decoration: BoxDecoration
... color: Color(0xffffffff)
... configuration: ImageConfiguration(bundle: PlatformAssetBundle#b6597(), devicePixelRatio: 3.0, locale: en_US, textDirection: TextDirection.ltr, platform: iOS)
RenderObject: RenderDecoratedBox#a83d8
needs compositing
parentData: <none> (can use size)
constraints: BoxConstraints(w=331.2, h=716.8)
size: MISSING
decoration: BoxDecoration
color: Color(0xffffffff)
configuration: ImageConfiguration(bundle: PlatformAssetBundle#b6597(), devicePixelRatio: 3.0, locale: en_US, textDirection: TextDirection.ltr, platform: iOS)
... child: RenderFlex#28045 NEEDS-PAINT
... needs compositing
... parentData: <none> (can use size)
... constraints: BoxConstraints(w=331.2, h=716.8)
... size: MISSING
... direction: horizontal
... mainAxisAlignment: start
... mainAxisSize: max
... crossAxisAlignment: center
... textDirection: ltr
... verticalDirection: down
... textBaseline: alphabetic
... child 1: RenderPadding#b537d relayoutBoundary=up1 NEEDS-PAINT
... parentData: offset=Offset(0.0, 0.0); flex=null; fit=null (can use size)
... constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
... size: Size(59.0, 716.8)
... padding: EdgeInsets(3.0, 0.0, 0.0, 0.0)
... textDirection: ltr
... child: RenderFlex#4c2a2 relayoutBoundary=up2 NEEDS-PAINT
... parentData: offset=Offset(3.0, 0.0) (can use size)
... constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
... size: Size(56.0, 716.8)
... direction: vertical
... mainAxisAlignment: spaceEvenly
... mainAxisSize: max
... crossAxisAlignment: center
... verticalDirection: down
... child 1: RenderSemanticsGestureHandler#c07e2 relayoutBoundary=up3 NEEDS-PAINT
... parentData: offset=Offset(0.0, 330.4); flex=null; fit=null (can use size)
... constraints: BoxConstraints(unconstrained)
... size: Size(56.0, 56.0)
... gestures: tap
... child 2: _RenderScrollSemantics#80100 relayoutBoundary=up1 NEEDS-PAINT
... needs compositing
... parentData: offset=Offset(0.0, 0.0); flex=null; fit=null (can use size)
... constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
... semantic boundary
... size: MISSING
... child: RenderPointerListener#695c7 relayoutBoundary=up2 NEEDS-PAINT
... needs compositing
... parentData: <none> (can use size)
... constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
... size: MISSING
... behavior: deferToChild
... listeners: signal
... child: RenderSemanticsGestureHandler#db442 relayoutBoundary=up3 NEEDS-PAINT
... needs compositing
... parentData: <none> (can use size)
... constraints: BoxConstraints(0.0<=w<=Infinity, 0.0<=h<=716.8)
... size: MISSING
... gestures: <none>
════════════════════════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by rendering library ═════════════════════════════════════════════════════
RenderBox was not laid out: RenderDecoratedBox#a83d8
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1713 pos 12: 'hasSize'
The relevant error-causing widget was:
Container file:///Users/holger/IdeaProjects/math/lib/tmp3.dart:474:32
ListView看起来是这样的，它显示了不同标签的标题，每个标签都可以扩展以显示详细信息。
AnimatedPositioned(duration: Duration(milliseconds: 800),
left: _drawerLeft,
top:5,
child: IgnorePointer(ignoring: (_drawerLeft <= MediaQuery.of(context).size.width / 3 ? false:true),
child: Container(
height:0.8*1 * MediaQuery.of(context).size.height, width:0.8 * MediaQuery.of(context).size.width,
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
CupertinoButton(
child: Icon(fwdBtn),
onPressed: () {
setState(() {
_drawerLeft = 1 * MediaQuery.of(context).size.width;
controller.reverse();
});
},
),
ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemCount: usedTagData.length, itemBuilder: (BuildContext context, int index) {
return Column(
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Text(usedTagData[index].header, style: TextStyle(color: CupertinoColors.link)),
CupertinoButton(
child: Icon(dwnBtn),
onPressed: () {
setState(() {
usedTagData[index].isExpanded = !usedTagData[index].isExpanded;
});
},
),
],
),
(usedTagData[index].isExpanded ?
Text(usedTagData[index].content)
:
Container()
),
]
);
}
),
],
),
)),
)
动画定位是的一个小部件
return Container(
height: MediaQuery.of(context).size.height,
child: Stack(
fit: StackFit.expand,
children: <Widget>[
你知道如何处理这个问题吗？或者异常消息是否为你提供了任何提示？
让ListView与Row一起工作的唯一方法是设置预定义的宽度。ListView试图无限扩展，因此应该通过设置预定义的宽度来约束它。这里有一个例子：
Row(
children:[
SizedBox(
width:200,
child:ListView()
),
]),