The following assertion was thrown building Text(“Deliver features faster”,textAlign: center):
No Directionality widget found.
我认为问题可能在TextDirection类属性中,但我一直无法找到它.
这是我的代码：
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
void main(){
runApp( new MyHome());
}
class MyHome extends StatelessWidget{
@override
Widget build(BuildContext context) {
// TODO: implement build
return new Material(
child: new Container(
color: Colors.red,margin: const EdgeInsets.all(5.0),child: new Row(
children: <Widget>[
new Expanded(
child: new Text('Deliver features faster',textAlign: TextAlign.center),),new Expanded(
child: new Text('Craft beautiful UIs',new Expanded(
child: new FittedBox(
fit: BoxFit.contain,// otherwise the logo will be tiny
child: const FlutterLogo(),],)
),);
}
}
以下是错误的完整堆栈跟踪：
The following assertion was thrown building Text("Deliver features faster",textAlign: center):
No Directionality widget found.
RichText widgets require a Directionality widget ancestor.
The specific widget that could not find a Directionality ancestor was:
RichText(textAlign: center,softWrap: wrapping at box width,maxLines: unlimited,text: "Deliver
features faster")
The ownership chain for the affected widget is:
RichText ← Text ← Expanded ← Row ← DecoratedBox ← Padding ← Container ← DefaultTextStyle ←
AnimatedDefaultTextStyle ← _InkFeatures-[GlobalKey#978b7 ink renderer] ← ?
Typically,the Directionality widget is introduced by the MaterialApp or WidgetsApp widget at the
top of your application widget tree. It determines the ambient reading direction and is used,for
example,to determine how to lay out text,how to interpret "start" and "end" values,and to resolve
EdgeInsetsDirectional,AlignmentDirectional,and other *Directional objects.
When the exception was thrown,this was the stack:
#0 debugCheckHasDirectionality.<anonymous closure> (package:flutter/src/widgets/debug.dart:223:7)
#1 debugCheckHasDirectionality (package:flutter/src/widgets/debug.dart:239:4)
#2 RichText.createRenderObject (package:flutter/src/widgets/basic.dart:4245:37)
#3 RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4259:28)
#4 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#5 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#6 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#7 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#8 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#9 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#10 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#11 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#12 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#13 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#14 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#15 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#16 ParentDataElement.mount (package:flutter/src/widgets/framework.dart:3938:16)
#17 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#18 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4738:32)
#19 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#20 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#21 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4633:14)
#22 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#23 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#24 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4633:14)
#25 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#26 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#27 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#28 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#29 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#30 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#31 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#32 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#33 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#34 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#35 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#36 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#37 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#38 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#39 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#40 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#41 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#42 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3752:22)
#43 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#44 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#45 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#46 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4633:14)
#47 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#48 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#49 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#50 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#51 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#52 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#53 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#54 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#55 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4633:14)
#56 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#57 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#58 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#59 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#60 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#61 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3752:22)
#62 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#63 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#64 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#65 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#66 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#67 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#68 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3752:22)
#69 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#70 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#71 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#72 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#73 Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#74 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#75 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#76 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#77 Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#78 RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:852:16)
#79 RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:823:5)
#80 RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure> (package:flutter/src/widgets/binding.dart:769:17)
#81 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2205:19)
#82 RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:768:13)
#83 BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&RendererBinding&WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:657:7)
#84 runApp (package:flutter/src/widgets/binding.dart:699:7)
#85 main (/data/user/0/com.yourcompany.flutterproject/cache/flutter_projectENWZDI/flutter_project/lib/main.dart:6:3)
#86 _startIsolate.<anonymous closure> (dart:isolate-patch/dart:isolate/isolate_patch.dart:279)
#87 _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:165)
════════════════════════════════════════════════════════════════════════════════════════════════════
Another exception was thrown: No Directionality widget found.
Another exception was thrown: Horizontal RenderFlex with multiple children has a null textDirection,so the layout order is undefined.
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1446 pos 12: 'hasSize': is not true.
uid=10079(com.yourcompany.flutterproject) Thread-5 identical 2 lines
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1446 pos 12: 'hasSize': is not true.
Another exception was thrown: 'package:flutter/src/rendering/proxy_box.dart': Failed assertion: line 1564 pos 12: 'hasSize': is not true.
