我正在尝试向我的应用程序添加一个 DropdownButton，但它没有被渲染，出现“底部被无限像素溢出”消息，我尝试将它放在 SizeBox、Paddign、ConstrainedBox、Row 中，但没有任何效果，请参阅代码:
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text(
'Configurações',
style: TextStyle(color: Colors.white),
),
actions: <Widget>[new IconButton(icon: new Icon(Icons.check), onPressed: _salvar)],
),
body: new Container(
color: Colors.orange[50],
padding: EdgeInsets.all(16.0),
child: new Form(
child: new Column(
children: <Widget>[
new TextFormField(
decoration: new InputDecoration(labelText: 'Código da empresa'),
//border: OutlineInputBorder()
autofocus: true,
controller: _edCodigoEmpresa,
keyboardType: TextInputType.numberWithOptions(),
),
new TextFormField(
decoration: new InputDecoration(labelText: 'Código do funcionário'),
controller: _edCodigoFuncionario,
keyboardType: TextInputType.numberWithOptions(),
),
new DropdownButton(
value: _baseSelecionada,
items: _basesCliente,
onChanged: _baseChange,
)
],
),
),
),
);
}
}
但是当你运行应用程序时，会出现以下错误信息:
I/flutter (16684): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (16684): The following assertion was thrown during performLayout():
I/flutter (16684): RenderIndexedStack object was given an infinite size during layout.
I/flutter (16684): This probably means that it is a render object that tries to be as big as possible, but it was put
I/flutter (16684): inside another render object that allows its children to pick their own size.
I/flutter (16684): The nearest ancestor providing an unbounded width constraint is:
I/flutter (16684): RenderFlex#b60e0 relayoutBoundary=up9 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (16684): creator: Row ← Padding ← Container ← DefaultTextStyle ← Stack ← Listener ← _GestureSemantics ←
I/flutter (16684): RawGestureDetector ← GestureDetector ← Semantics ← DropdownButton<String> ← Column ← ⋯
I/flutter (16684): parentData: offset=Offset(0.0, 0.0) (can use size)
I/flutter (16684): constraints: BoxConstraints(0.0<=w<=328.0, 0.0<=h<=Infinity)
I/flutter (16684): size: Size(328.0, Infinity)
I/flutter (16684): direction: horizontal
I/flutter (16684): mainAxisAlignment: spaceBetween
I/flutter (16684): mainAxisSize: min
I/flutter (16684): crossAxisAlignment: center
I/flutter (16684): textDirection: ltr
I/flutter (16684): verticalDirection: down
I/flutter (16684): The nearest ancestor providing an unbounded height constraint is:
I/flutter (16684): RenderFlex#783bc relayoutBoundary=up3 NEEDS-LAYOUT NEEDS-PAINT OVERFLOWING
I/flutter (16684): creator: Column ← _FormScope ← WillPopScope ← Form ← Padding ← DecoratedBox ← Container ←
I/flutter (16684): MediaQuery ← LayoutId-[<_ScaffoldSlot.body>] ← CustomMultiChildLayout ← AnimatedBuilder ←
I/flutter (16684): DefaultTextStyle ← ⋯
I/flutter (16684): parentData: offset=Offset(16.0, 16.0) (can use size)
I/flutter (16684): constraints: BoxConstraints(0.0<=w<=328.0, 0.0<=h<=528.0)
I/flutter (16684): size: Size(328.0, 528.0)
I/flutter (16684): direction: vertical
I/flutter (16684): mainAxisAlignment: start
I/flutter (16684): mainAxisSize: max
I/flutter (16684): crossAxisAlignment: center
I/flutter (16684): verticalDirection: down
I/flutter (16684): The constraints that applied to the RenderIndexedStack were:
I/flutter (16684): BoxConstraints(unconstrained)
I/flutter (16684): The exact size it was given was:
I/flutter (16684): Size(Infinity, Infinity)
I/flutter (16684): See https://flutter.io/layout/ for more information.
I/flutter (16684):
I/flutter (16684): When the exception was thrown, this was the stack:
I/flutter (16684): #0 RenderBox.debugAssertDoesMeetConstraints.<anonymous closure> (package:flutter/src/rendering/box.dart:1749:9)
I/flutter (16684): #1 RenderBox.debugAssertDoesMeetConstraints (package:flutter/src/rendering/box.dart:1823:6)
I/flutter (16684): #2 RenderBox.size=.<anonymous closure> (package:flutter/src/rendering/box.dart:1543:17)
I/flutter (16684): #3 RenderBox.size= (package:flutter/src/rendering/box.dart:1543:65)
I/flutter (16684): #4 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:480:7)
I/flutter (16684): #5 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #6 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (16684): #7 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #8 RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:199:11)
I/flutter (16684): #9 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #10 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)
I/flutter (16684): #11 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #12 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #13 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #14 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #15 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #16 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #17 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #18 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (16684): #19 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #20 RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:199:11)
I/flutter (16684): #21 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #22 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #23 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #24 MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:141:11)
I/flutter (16684): #25 _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:339:7)
I/flutter (16684): #26 MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:211:7)
I/flutter (16684): #27 RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:355:14)
I/flutter (16684): #28 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #29 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #30 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #31 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #32 _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1188:11)
I/flutter (16684): #33 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #34 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #35 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #36 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #37 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #38 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #39 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #40 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #41 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #42 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #43 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #44 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #45 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #46 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #47 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #48 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #49 RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:2880:13)
I/flutter (16684): #50 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #51 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)
I/flutter (16684): #52 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #53 __RenderTheatre&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #54 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #55 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #56 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #57 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #58 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #59 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #60 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #61 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #62 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #63 RenderView.performLayout (package:flutter/src/rendering/view.dart:147:13)
I/flutter (16684): #64 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1507:7)
I/flutter (16684): #65 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:766:18)
I/flutter (16684): #66 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:281:19)
I/flutter (16684): #67 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:674:13)
I/flutter (16684): #68 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)
I/flutter (16684): #69 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter (16684): #70 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter (16684): #71 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter (16684): #73 _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (16684): #74 _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (16684): #75 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (16684): (elided one frame from package dart:async)
I/flutter (16684):
I/flutter (16684): The following RenderObject was being processed when the exception was fired:
I/flutter (16684): RenderIndexedStack#b8a3e relayoutBoundary=up10 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (16684): creator: IndexedStack ← Row ← Padding ← Container ← DefaultTextStyle ← Stack ← Listener ←
I/flutter (16684): _GestureSemantics ← RawGestureDetector ← GestureDetector ← Semantics ← DropdownButton<String> ← ⋯
I/flutter (16684): parentData: offset=Offset(0.0, 0.0); flex=null; fit=null (can use size)
I/flutter (16684): constraints: BoxConstraints(unconstrained)
I/flutter (16684): size: Size(Infinity, Infinity)
I/flutter (16684): alignment: AlignmentDirectional.centerStart
I/flutter (16684): textDirection: ltr
I/flutter (16684): fit: loose
I/flutter (16684): overflow: clip
I/flutter (16684): index: null
I/flutter (16684): This RenderObject has no descendants.
I/flutter (16684): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (16684): Another exception was thrown: RenderFlex object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderPadding object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderStack object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderPointerListener object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderSemanticsGestureHandler object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderSemanticsAnnotations object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
I/flutter (16684): Another exception was thrown: A RenderFlex overflowed by Infinity pixels on the bottom.
谁能帮帮我？
最佳答案
我使用了一个 ConstrainedBox 来设置一个 maxHeight，但它仍然向右无限溢出。我必须设置 isExpanded: true 然后将 ConstrainedBox 包装在 Row -> Expanded 内。
Column(
children: <Widget>[
Row(
children: <Widget>[
Expanded(
child: ConstrainedBox(
constraints: const BoxConstraints(maxHeight: 48.0),
child: DropdownButton<String>(
isExpanded: true, ...
)
)
)
]
)
]
)
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