Flutter：在动画、定位容器中获取 ListView 作为堆栈的一部分
Flutter: getting ListView in animated, positioned container being part of a stack
也许你们中的某个人已经遇到过这些问题。我花了很多时间试图将 ListView（我也尝试过 ExpansionPanelList）放入一个容器中，该容器从右边缘平移到现有小部件上的屏幕（帮助菜单）中。我已经创建了一个 mock-up，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，错误信息对我没有太大帮助。
一旦我添加了 AnimatedPositioned，就会抛出这些异常。主要信息似乎是 constraints.hasBoundedWidth' 的问题：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重复多次，可能每个动画步骤重复一次。然后消息以下面的消息结束，其中引用容器是 AnimatedPositiones > IgnorePointer > Container
════════ 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 看起来像这样，它显示 headers 个不同的标签，每个标签都可以展开以显示详细信息。
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()
),
]
);
}
),
],
),
)),
)
AnimatedPositioned 是
的一个小部件
return Container(
height: MediaQuery.of(context).size.height,
child: Stack(
fit: StackFit.expand,
children: <Widget>[
您是否知道如何继续进行此操作或异常消息是否为您提供了任何提示？
让 ListView 与 Row 一起工作的唯一方法是设置预定义的宽度。您的 ListView 试图无限扩展，因此您应该通过设置预定义的宽度来限制它。
这是一个例子：
Row(
children:[
SizedBox(
width:200,
child:ListView()
),
]),
也许你们中的某个人已经遇到过这些问题。我花了很多时间试图将 ListView（我也尝试过 ExpansionPanelList）放入一个容器中，该容器从右边缘平移到现有小部件上的屏幕（帮助菜单）中。我已经创建了一个 mock-up，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，错误信息对我没有太大帮助。
一旦我添加了 AnimatedPositioned，就会抛出这些异常。主要信息似乎是 constraints.hasBoundedWidth' 的问题：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重复多次，可能每个动画步骤重复一次。然后消息以下面的消息结束，其中引用容器是 AnimatedPositiones > IgnorePointer > Container
════════ 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 看起来像这样，它显示 headers 个不同的标签，每个标签都可以展开以显示详细信息。
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()
),
]
);
}
),
],
),
)),
)
AnimatedPositioned 是
的一个小部件 return Container(
height: MediaQuery.of(context).size.height,
child: Stack(
fit: StackFit.expand,
children: <Widget>[
您是否知道如何继续进行此操作或异常消息是否为您提供了任何提示？
让 ListView 与 Row 一起工作的唯一方法是设置预定义的宽度。您的 ListView 试图无限扩展，因此您应该通过设置预定义的宽度来限制它。
这是一个例子：
Row(
children:[
SizedBox(
width:200,
child:ListView()
),
]),