从代码调试 Flutter 应用
本指南介绍了可以在代码中启用的哪些调试功能。有关调试和性能分析工具的完整列表，请查看调试页面。
向你的应用添加日志记录
#您有两个应用程序日志记录选项。
使用
print()语句打印到stdout和stderr。导入
dart:io并调用stderr和stdout上的方法。例如dartstderr.writeln('print me');
如果一次输出过多内容，Android 可能会丢弃一些日志行。为避免这种情况，请使用 Flutter 的 foundation 库中的debugPrint()。此 print 包装器会限制输出，以避免 Android 内核丢弃输出。
您还可以使用 dart:developer 的log() 函数记录应用。这使您可以在日志输出中包含更细粒度的信息和更多信息。
示例 1
#dart
import 'dart:developer' as developer;
void main() {
developer.log('log me', name: 'my.app.category');
developer.log('log me 1', name: 'my.other.category');
developer.log('log me 2', name: 'my.other.category');
}您还可以将应用数据传递给日志调用。此处的约定是在 log() 调用上使用 error: 命名参数，对要发送的对象进行 JSON 编码，并将编码后的字符串传递给 error 参数。
示例 2
#dart
import 'dart:convert';
import 'dart:developer' as developer;
void main() {
var myCustomObject = MyCustomObject();
developer.log(
'log me',
name: 'my.app.category',
error: jsonEncode(myCustomObject),
);
}DevTool 的日志查看器将 JSON 编码的 error 参数解释为数据对象。DevTool 在该日志条目的详细信息视图中进行呈现。
设置断点
#您可以在 DevTools 的调试器或 IDE 的内置调试器中设置断点。
要设置编程断点
将
dart:developer包导入到相关文件中。使用
debugger()语句插入编程断点。此语句采用可选的when参数。此布尔参数在给定条件解析为 true 时设置断点。示例 3对此进行了说明。
示例 3
#dart
import 'dart:developer';
void someFunction(double offset) {
debugger(when: offset > 30);
// ...
}使用标志调试应用层
#Flutter 框架的每一层都提供了一个函数，可以使用 debugPrint 属性将其当前状态或事件转储到控制台。
打印 Widget 树
#要转储 Widgets 库的状态，请调用debugDumpApp() 函数。
- 打开您的源文件。
- 导入
package:flutter/rendering.dart。 - 从
runApp()函数内部调用debugDumpApp()函数。您的应用需要处于调试模式。当应用正在构建时，您不能在build()方法中调用此函数。 - 如果尚未启动应用，请使用 IDE 进行调试。
- 如果已启动应用，请保存源文件。热重载会重新渲染您的应用。
示例 4：调用 debugDumpApp()
#dart
import 'package:flutter/material.dart';
void main() {
runApp(
const MaterialApp(
home: AppHome(),
),
);
}
class AppHome extends StatelessWidget {
const AppHome({super.key});
@override
Widget build(BuildContext context) {
return Material(
child: Center(
child: TextButton(
onPressed: () {
debugDumpApp();
},
child: const Text('Dump Widget Tree'),
),
),
);
}
}此函数从 widget 树的根开始递归调用 toStringDeep() 方法。它返回一个“扁平化”的树。
示例 4生成以下 widget 树。它包括
通过其各种构建函数投影的所有 widget。
许多未出现在应用源代码中的 widget。框架的 widget 的构建函数在构建过程中插入它们。
例如，以下树显示了
_InkFeatures。该类实现了Materialwidget 的一部分。它在示例 4中的代码中任何地方都没有出现。
展开以查看示例 4 的 widget 树
flutter: WidgetsFlutterBinding - DEBUG MODE
flutter: [root](renderObject: RenderView#06beb)
flutter: └View-[GlobalObjectKey FlutterView#7971c]
flutter: └_ViewScope
flutter: └_MediaQueryFromView(state: _MediaQueryFromViewState#d790c)
flutter: └MediaQuery(MediaQueryData(size: Size(800.0, 600.0), devicePixelRatio: 1.0, textScaleFactor: 1.0, platformBrightness: Brightness.dark, padding: EdgeInsets.zero, viewPadding: EdgeInsets.zero, viewInsets: EdgeInsets.zero, systemGestureInsets: EdgeInsets.zero, alwaysUse24HourFormat: false, accessibleNavigation: false, highContrast: false, disableAnimations: false, invertColors: false, boldText: false, navigationMode: traditional, gestureSettings: DeviceGestureSettings(touchSlop: null), displayFeatures: []))
flutter: └MaterialApp(state: _MaterialAppState#27fa9)
flutter: └ScrollConfiguration(behavior: MaterialScrollBehavior)
flutter: └HeroControllerScope
flutter: └Focus(state: _FocusState#d7f97)
flutter: └_FocusInheritedScope
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#a6464)
flutter: └WidgetsApp-[GlobalObjectKey _MaterialAppState#27fa9](state: _WidgetsAppState#b5b17)
flutter: └RootRestorationScope(state: _RootRestorationScopeState#6b028)
flutter: └UnmanagedRestorationScope
flutter: └RestorationScope(dependencies: [UnmanagedRestorationScope], state: _RestorationScopeState#d1369)
flutter: └UnmanagedRestorationScope
flutter: └SharedAppData(state: _SharedAppDataState#95e82)
flutter: └_SharedAppModel
flutter: └Shortcuts(shortcuts: <Default WidgetsApp Shortcuts>, state: _ShortcutsState#272dc)
flutter: └Focus(debugLabel: "Shortcuts", dependencies: [_FocusInheritedScope], state: _FocusState#a3300)
flutter: └_FocusInheritedScope
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#db110)
flutter: └DefaultTextEditingShortcuts
flutter: └Shortcuts(shortcuts: <Default Text Editing Shortcuts>, state: _ShortcutsState#1d796)
flutter: └Focus(debugLabel: "Shortcuts", dependencies: [_FocusInheritedScope], state: _FocusState#0081b)
flutter: └_FocusInheritedScope
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#0d70e)
flutter: └Shortcuts(shortcuts: <Web Disabling Text Editing Shortcuts>, state: _ShortcutsState#56bac)
flutter: └Focus(debugLabel: "Shortcuts", dependencies: [_FocusInheritedScope], state: _FocusState#3152e)
flutter: └_FocusInheritedScope
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#b7eaf)
flutter: └Actions(dispatcher: null, actions: {DoNothingIntent: DoNothingAction#0fda1, DoNothingAndStopPropagationIntent: DoNothingAction#17f30, RequestFocusIntent: RequestFocusAction#10bd0, NextFocusIntent: NextFocusAction#60317, PreviousFocusIntent: PreviousFocusAction#2a933, DirectionalFocusIntent: DirectionalFocusAction#a6922, ScrollIntent: _OverridableContextAction<ScrollIntent>#964fe(defaultAction: ScrollAction#ffb50), PrioritizedIntents: PrioritizedAction#be0e2, VoidCallbackIntent: VoidCallbackAction#805fa}, state: _ActionsState#bbd25)
flutter: └_ActionsScope
flutter: └FocusTraversalGroup(policy: ReadingOrderTraversalPolicy#f1e76, state: _FocusTraversalGroupState#0c200)
flutter: └Focus(debugLabel: "FocusTraversalGroup", focusNode: _FocusTraversalGroupNode#ffcad(FocusTraversalGroup [IN FOCUS PATH]), dependencies: [_FocusInheritedScope], state: _FocusState#c7dc2)
flutter: └_FocusInheritedScope
flutter: └TapRegionSurface(renderObject: RenderTapRegionSurface#17aba)
flutter: └ShortcutRegistrar(state: _ShortcutRegistrarState#44954)
flutter: └_ShortcutRegistrarScope
flutter: └Shortcuts(manager: ShortcutManager#eb38c(shortcuts: {}), shortcuts: {}, state: _ShortcutsState#f85ac)
flutter: └Focus(debugLabel: "Shortcuts", dependencies: [_FocusInheritedScope], state: _FocusState#8c1a7)
flutter: └_FocusInheritedScope
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#1fc98)
flutter: └Localizations(locale: en_US, delegates: [DefaultMaterialLocalizations.delegate(en_US), DefaultCupertinoLocalizations.delegate(en_US), DefaultWidgetsLocalizations.delegate(en_US)], state: _LocalizationsState#ae3a0)
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, textDirection: ltr, renderObject: RenderSemanticsAnnotations#8776e)
flutter: └_LocalizationsScope-[GlobalKey#61ca6]
flutter: └Directionality(textDirection: ltr)
flutter: └Title(color: Color(0xff2196f3))
flutter: └CheckedModeBanner("DEBUG")
flutter: └Banner("DEBUG", textDirection: ltr, location: topEnd, Color(0xa0b71c1c), text inherit: true, text color: Color(0xffffffff), text size: 10.2, text weight: 900, text height: 1.0x, dependencies: [Directionality])
flutter: └CustomPaint(renderObject: RenderCustomPaint#c014d)
flutter: └DefaultTextStyle(debugLabel: fallback style; consider putting your text in a Material, inherit: true, color: Color(0xd0ff0000), family: monospace, size: 48.0, weight: 900, decoration: double Color(0xffffff00) TextDecoration.underline, softWrap: wrapping at box width, overflow: clip)
flutter: └Builder(dependencies: [MediaQuery])
flutter: └ScaffoldMessenger(dependencies: [MediaQuery], state: ScaffoldMessengerState#5b36e)
flutter: └_ScaffoldMessengerScope
flutter: └DefaultSelectionStyle
flutter: └AnimatedTheme(duration: 200ms, state: _AnimatedThemeState#cd149(ticker inactive, ThemeDataTween(ThemeData#ef3b2 → ThemeData#ef3b2)))
flutter: └Theme(ThemeData#ef3b2, dependencies: [DefaultSelectionStyle])
flutter: └_InheritedTheme
flutter: └CupertinoTheme(brightness: light, primaryColor: MaterialColor(primary value: Color(0xff2196f3)), primaryContrastingColor: Color(0xffffffff), scaffoldBackgroundColor: Color(0xfffafafa), actionTextStyle: TextStyle(inherit: false, color: MaterialColor(primary value: Color(0xff2196f3)), family: .SF Pro Text, size: 17.0, letterSpacing: -0.4, decoration: TextDecoration.none), navActionTextStyle: TextStyle(inherit: false, color: MaterialColor(primary value: Color(0xff2196f3)), family: .SF Pro Text, size: 17.0, letterSpacing: -0.4, decoration: TextDecoration.none))
flutter: └_InheritedCupertinoTheme
flutter: └IconTheme(color: MaterialColor(primary value: Color(0xff2196f3)))
flutter: └IconTheme(color: Color(0xdd000000))
flutter: └DefaultSelectionStyle
flutter: └FocusScope(debugLabel: "Navigator Scope", AUTOFOCUS, dependencies: [_FocusInheritedScope], state: _FocusScopeState#acbd8)
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#ab3f0)
flutter: └_FocusInheritedScope
flutter: └Navigator-[GlobalObjectKey<NavigatorState> _WidgetsAppState#b5b17](dependencies: [HeroControllerScope, UnmanagedRestorationScope], state: NavigatorState#1395a(tickers: tracking 1 ticker))
flutter: └HeroControllerScope
flutter: └Listener(listeners: [down, up, cancel], behavior: deferToChild, renderObject: RenderPointerListener#34172)
flutter: └AbsorbPointer(absorbing: false, renderObject: RenderAbsorbPointer#f8711)
flutter: └FocusTraversalGroup(policy: ReadingOrderTraversalPolicy#f1e76, state: _FocusTraversalGroupState#8d61a)
flutter: └Focus(debugLabel: "FocusTraversalGroup", focusNode: _FocusTraversalGroupNode#dd2b1(FocusTraversalGroup [IN FOCUS PATH]), dependencies: [_FocusInheritedScope], state: _FocusState#0bb03)
flutter: └_FocusInheritedScope
flutter: └Focus(debugLabel: "Navigator", AUTOFOCUS, focusNode: FocusNode#a3309(Navigator [IN FOCUS PATH]), dependencies: [_FocusInheritedScope], state: _FocusState#d3d07)
flutter: └_FocusInheritedScope
flutter: └UnmanagedRestorationScope
flutter: └Overlay-[LabeledGlobalKey<OverlayState>#5485a](state: OverlayState#5bd52(entries: [OverlayEntry#fc947(opaque: true; maintainState: false), OverlayEntry#05a32(opaque: false; maintainState: true)]))
flutter: └_Theater(skipCount: 0, dependencies: [Directionality], renderObject: _RenderTheater#e86c3)
flutter: ├_OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#1b37e](state: _OverlayEntryWidgetState#06ab0)
flutter: │└TickerMode(state: _TickerModeState#0b4ac(requested mode: enabled))
flutter: │ └_EffectiveTickerMode(effective mode: enabled)
flutter: │ └_RenderTheaterMarker
flutter: │ └IgnorePointer(ignoring: false, renderObject: RenderIgnorePointer#34c66)
flutter: │ └ModalBarrier
flutter: │ └BlockSemantics(blocking: true, renderObject: RenderBlockSemantics#97799)
flutter: │ └ExcludeSemantics(excluding: true, renderObject: RenderExcludeSemantics#8c4ce)
flutter: │ └_ModalBarrierGestureDetector
flutter: │ └RawGestureDetector(state: RawGestureDetectorState#556f6(gestures: [any tap], behavior: opaque))
flutter: │ └_GestureSemantics(renderObject: RenderSemanticsGestureHandler#616f1)
flutter: │ └Listener(listeners: [down, panZoomStart], behavior: opaque, renderObject: RenderPointerListener#c2b89)
flutter: │ └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#c3b31)
flutter: │ └MouseRegion(listeners: <none>, cursor: SystemMouseCursor(basic), renderObject: RenderMouseRegion#53cdb)
flutter: │ └ConstrainedBox(BoxConstraints(biggest), renderObject: RenderConstrainedBox#faa51)
flutter: └_OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#bc0aa](state: _OverlayEntryWidgetState#cbf35)
flutter: └TickerMode(state: _TickerModeState#23e73(requested mode: enabled))
flutter: └_EffectiveTickerMode(effective mode: enabled)
flutter: └_RenderTheaterMarker
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, sortKey: OrdinalSortKey#135f4(order: 0.0), renderObject: RenderSemanticsAnnotations#5565e)
flutter: └_ModalScope<dynamic>-[LabeledGlobalKey<_ModalScopeState<dynamic>>#4fe82](state: _ModalScopeState<dynamic>#4da7d)
flutter: └AnimatedBuilder(listenable: ValueNotifier<String?>#d87c6(null), state: _AnimatedState#dde81)
flutter: └RestorationScope(dependencies: [UnmanagedRestorationScope], state: _RestorationScopeState#78c51)
flutter: └UnmanagedRestorationScope
flutter: └_ModalScopeStatus(active)
flutter: └Offstage(offstage: false, renderObject: RenderOffstage#5e498)
flutter: └PageStorage
flutter: └Builder
flutter: └Actions(dispatcher: null, actions: {DismissIntent: _DismissModalAction#6279e}, state: _ActionsState#48019)
flutter: └_ActionsScope
flutter: └PrimaryScrollController(ScrollController#6a546(no clients))
flutter: └FocusScope(debugLabel: "_ModalScopeState<dynamic> Focus Scope", focusNode: FocusScopeNode#0e2af(_ModalScopeState<dynamic> Focus Scope [PRIMARY FOCUS]), dependencies: [_FocusInheritedScope], state: _FocusScopeState#0bac4)
flutter: └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#44b4e)
flutter: └_FocusInheritedScope
flutter: └RepaintBoundary(renderObject: RenderRepaintBoundary#38f41)
flutter: └AnimatedBuilder(listenable: Listenable.merge([AnimationController#9d623(⏭ 1.000; paused; for MaterialPageRoute<dynamic>(/))➩ProxyAnimation, kAlwaysDismissedAnimation➩ProxyAnimation➩ProxyAnimation]), dependencies: [_InheritedTheme, _LocalizationsScope-[GlobalKey#61ca6]], state: _AnimatedState#47725)
flutter: └CupertinoPageTransition(dependencies: [Directionality])
flutter: └SlideTransition(listenable: kAlwaysDismissedAnimation➩ProxyAnimation➩ProxyAnimation➩Cubic(0.35, 0.91, 0.33, 0.97)ₒₙ/Cubic(0.67, 0.03, 0.65, 0.09)➩Tween<Offset>(Offset(0.0, 0.0) → Offset(-0.3, 0.0))➩Offset(0.0, 0.0), state: _AnimatedState#b6162)
flutter: └FractionalTranslation(renderObject: RenderFractionalTranslation#fb461)
flutter: └SlideTransition(listenable: AnimationController#9d623(⏭ 1.000; paused; for MaterialPageRoute<dynamic>(/))➩ProxyAnimation➩ThreePointCubic ₒₙ/FlippedCurve(ThreePointCubic )➩Tween<Offset>(Offset(1.0, 0.0) → Offset(0.0, 0.0))➩Offset(0.0, 0.0), state: _AnimatedState#834bf)
flutter: └FractionalTranslation(renderObject: RenderFractionalTranslation#73ea4)
flutter: └DecoratedBoxTransition(listenable: AnimationController#9d623(⏭ 1.000; paused; for MaterialPageRoute<dynamic>(/))➩ProxyAnimation➩Cubic(0.35, 0.91, 0.33, 0.97)➩DecorationTween(_CupertinoEdgeShadowDecoration(colors: null) → _CupertinoEdgeShadowDecoration(colors: [Color(0x04000000), Color(0x00000000)]))➩_CupertinoEdgeShadowDecoration(colors: [Color(0x04000000), Color(0x00000000)]), state: _AnimatedState#a7fca)
flutter: └DecoratedBox(bg: _CupertinoEdgeShadowDecoration(colors: [Color(0x04000000), Color(0x00000000)]), dependencies: [Directionality, MediaQuery, _LocalizationsScope-[GlobalKey#61ca6]], renderObject: RenderDecoratedBox#9965c)
flutter: └_CupertinoBackGestureDetector<dynamic>(dependencies: [Directionality, MediaQuery], state: _CupertinoBackGestureDetectorState<dynamic>#ab8cd)
flutter: └Stack(alignment: AlignmentDirectional.topStart, fit: passthrough, dependencies: [Directionality], renderObject: RenderStack#b2b7c)
flutter: ├AnimatedBuilder(listenable: ValueNotifier<bool>#1a88e(false), state: _AnimatedState#6e33c)
flutter: │└IgnorePointer(ignoring: false, renderObject: RenderIgnorePointer#2b763)
flutter: │ └RepaintBoundary-[GlobalKey#628f4](renderObject: RenderRepaintBoundary#5a53b)
flutter: │ └Builder
flutter: │ └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#f8795)
flutter: │ └AppHome
flutter: │ └Material(type: canvas, dependencies: [_InheritedTheme, _LocalizationsScope-[GlobalKey#61ca6]], state: _MaterialState#7d183)
flutter: │ └AnimatedPhysicalModel(duration: 200ms, shape: rectangle, borderRadius: BorderRadius.zero, elevation: 0.0, color: Color(0xfffafafa), animateColor: false, shadowColor: Color(0xff000000), animateShadowColor: true, state: _AnimatedPhysicalModelState#d479e(ticker inactive))
flutter: │ └PhysicalModel(shape: rectangle, borderRadius: BorderRadius.zero, elevation: 0.0, color: Color(0xfffafafa), shadowColor: Color(0xff000000), renderObject: RenderPhysicalModel#c60b5)
flutter: │ └NotificationListener<LayoutChangedNotification>
flutter: │ └_InkFeatures-[GlobalKey#e9da0 ink renderer](renderObject: _RenderInkFeatures#d8e6d)
flutter: │ └AnimatedDefaultTextStyle(duration: 200ms, debugLabel: (englishLike bodyMedium 2014).merge(blackRedwoodCity bodyMedium), inherit: false, color: Color(0xdd000000), family: .AppleSystemUIFont, size: 14.0, weight: 400, baseline: alphabetic, decoration: TextDecoration.none, softWrap: wrapping at box width, overflow: clip, state: _AnimatedDefaultTextStyleState#12f43(ticker inactive))
flutter: │ └DefaultTextStyle(debugLabel: (englishLike bodyMedium 2014).merge(blackRedwoodCity bodyMedium), inherit: false, color: Color(0xdd000000), family: .AppleSystemUIFont, size: 14.0, weight: 400, baseline: alphabetic, decoration: TextDecoration.none, softWrap: wrapping at box width, overflow: clip)
flutter: │ └Center(alignment: Alignment.center, dependencies: [Directionality], renderObject: RenderPositionedBox#b088f)
flutter: │ └TextButton(dirty, dependencies: [MediaQuery, _InheritedTheme, _LocalizationsScope-[GlobalKey#61ca6]], state: _ButtonStyleState#687c9)
flutter: │ └Semantics(container: true, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#ca411 relayoutBoundary=up1)
flutter: │ └_InputPadding(renderObject: _RenderInputPadding#60ede relayoutBoundary=up2)
flutter: │ └ConstrainedBox(BoxConstraints(56.0<=w<=Infinity, 28.0<=h<=Infinity), renderObject: RenderConstrainedBox#34800 relayoutBoundary=up3)
flutter: │ └Material(type: button, color: Color(0x00000000), shadowColor: Color(0xff000000), textStyle.debugLabel: ((englishLike labelLarge 2014).merge(blackRedwoodCity labelLarge)).copyWith, textStyle.inherit: false, textStyle.color: MaterialColor(primary value: Color(0xff2196f3)), textStyle.family: .AppleSystemUIFont, textStyle.size: 14.0, textStyle.weight: 500, textStyle.baseline: alphabetic, textStyle.decoration: TextDecoration.none, shape: RoundedRectangleBorder(BorderSide(width: 0.0, style: none), BorderRadius.circular(4.0)), dependencies: [_InheritedTheme, _LocalizationsScope-[GlobalKey#61ca6]], state: _MaterialState#50a4d(tickers: tracking 5 tickers))
flutter: │ └_MaterialInterior(duration: 200ms, shape: RoundedRectangleBorder(BorderSide(width: 0.0, style: none), BorderRadius.circular(4.0)), elevation: 0.0, color: Color(0x00000000), shadowColor: Color(0xff000000), dependencies: [Directionality, _InheritedTheme, _LocalizationsScope-[GlobalKey#61ca6]], state: _MaterialInteriorState#d296d(ticker inactive))
flutter: │ └PhysicalShape(clipper: ShapeBorderClipper, elevation: 0.0, color: Color(0x00000000), shadowColor: Color(0xff000000), renderObject: RenderPhysicalShape#43df6 relayoutBoundary=up4)
flutter: │ └_ShapeBorderPaint(dependencies: [Directionality])
flutter: │ └CustomPaint(renderObject: RenderCustomPaint#c1a3c relayoutBoundary=up5)
flutter: │ └NotificationListener<LayoutChangedNotification>
flutter: │ └_InkFeatures-[GlobalKey#625bc ink renderer](renderObject: _RenderInkFeatures#54439 relayoutBoundary=up6)
flutter: │ └AnimatedDefaultTextStyle(duration: 200ms, debugLabel: ((englishLike labelLarge 2014).merge(blackRedwoodCity labelLarge)).copyWith, inherit: false, color: MaterialColor(primary value: Color(0xff2196f3)), family: .AppleSystemUIFont, size: 14.0, weight: 500, baseline: alphabetic, decoration: TextDecoration.none, softWrap: wrapping at box width, overflow: clip, state: _AnimatedDefaultTextStyleState#2f29d(ticker inactive))
flutter: │ └DefaultTextStyle(debugLabel: ((englishLike labelLarge 2014).merge(blackRedwoodCity labelLarge)).copyWith, inherit: false, color: MaterialColor(primary value: Color(0xff2196f3)), family: .AppleSystemUIFont, size: 14.0, weight: 500, baseline: alphabetic, decoration: TextDecoration.none, softWrap: wrapping at box width, overflow: clip)
flutter: │ └InkWell
flutter: │ └_InkResponseStateWidget(gestures: [tap], mouseCursor: ButtonStyleButton_MouseCursor, clipped to BoxShape.rectangle, dirty, dependencies: [Directionality, MediaQuery, _InheritedTheme, _LocalizationsScope-[GlobalKey#61ca6]], state: _InkResponseState#0b11d)
flutter: │ └_ParentInkResponseProvider
flutter: │ └Actions(dispatcher: null, actions: {ActivateIntent: CallbackAction<ActivateIntent>#018db, ButtonActivateIntent: CallbackAction<ButtonActivateIntent>#ef87a}, state: _ActionsState#a5eab)
flutter: │ └_ActionsScope
flutter: │ └Focus(dependencies: [_FocusInheritedScope], state: _FocusState#5a9de)
flutter: │ └_FocusInheritedScope
flutter: │ └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#8ac3e relayoutBoundary=up7)
flutter: │ └MouseRegion(listeners: [enter, exit], cursor: SystemMouseCursor(click), renderObject: RenderMouseRegion#13d4e relayoutBoundary=up8)
flutter: │ └Builder(dependencies: [DefaultSelectionStyle])
flutter: │ └DefaultSelectionStyle
flutter: │ └Semantics(container: false, properties: SemanticsProperties, tooltip: null, renderObject: RenderSemanticsAnnotations#d99cc relayoutBoundary=up9)
flutter: │ └GestureDetector(startBehavior: start, dependencies: [MediaQuery])
flutter: │ └RawGestureDetector(state: RawGestureDetectorState#b8d93(gestures: [tap], excludeFromSemantics: true, behavior: opaque))
flutter: │ └Listener(listeners: [down, panZoomStart], behavior: opaque, renderObject: RenderPointerListener#a4c3b relayoutBoundary=up10)
flutter: │ └Builder(dependencies: [IconTheme])
flutter: │ └IconTheme(color: MaterialColor(primary value: Color(0xff2196f3)))
flutter: │ └Padding(padding: EdgeInsets(8.0, 0.0, 8.0, 0.0), dependencies: [Directionality], renderObject: RenderPadding#18a87 relayoutBoundary=up11)
flutter: │ └Align(alignment: Alignment.center, widthFactor: 1.0, heightFactor: 1.0, dependencies: [Directionality], renderObject: RenderPositionedBox#fb8a8 relayoutBoundary=up12)
flutter: │ └Text("Dump Widget Tree", dependencies: [DefaultSelectionStyle, DefaultTextStyle, MediaQuery])
flutter: │ └RichText(softWrap: wrapping at box width, maxLines: unlimited, text: "Dump Widget Tree", dependencies: [Directionality, _LocalizationsScope-[GlobalKey#61ca6]], renderObject: RenderParagraph#d15aa relayoutBoundary=up13)
flutter: └PositionedDirectional(dependencies: [Directionality])
flutter: └Positioned(left: 0.0, top: 0.0, bottom: 0.0, width: 20.0)
flutter: └Listener(listeners: [down], behavior: translucent, renderObject: RenderPointerListener#d884c)
flutter:
flutter:当按钮从按下变为释放时，这会调用 debugDumpApp() 函数。它也与TextButton 对象调用setState() 并因此将其标记为脏有关。这解释了为什么 Flutter 将特定对象标记为“脏”。查看 widget 树时，查找类似于以下内容的行
└TextButton(dirty, dependencies: [MediaQuery, _InheritedTheme, _LocalizationsScope-[GlobalKey#5880d]], state: _ButtonStyleState#ab76e)如果您编写自己的 widget，请覆盖debugFillProperties() 方法以添加信息。将DiagnosticsProperty 对象添加到方法的参数中，然后调用超类方法。toString 方法使用此函数填充 widget 的描述。
打印渲染树
#调试布局问题时，Widgets 层的树可能缺乏细节。下一级调试可能需要渲染树。要转储渲染树
- 打开您的源文件。
- 调用
debugDumpRenderTree()函数。除了在布局或绘制阶段之外，您可以在任何时候调用此函数。考虑从帧回调或事件处理程序中调用它。 - 如果尚未启动应用，请使用 IDE 进行调试。
- 如果已启动应用，请保存源文件。热重载会重新渲染您的应用。
示例 5：调用 debugDumpRenderTree()
#dart
import 'package:flutter/material.dart';
void main() {
runApp(
const MaterialApp(
home: AppHome(),
),
);
}
class AppHome extends StatelessWidget {
const AppHome({super.key});
@override
Widget build(BuildContext context) {
return Material(
child: Center(
child: TextButton(
onPressed: () {
debugDumpRenderTree();
},
child: const Text('Dump Render Tree'),
),
),
);
}
}调试布局问题时，请查看 size 和 constraints 字段。约束向下流动到树中，大小向上流动。
展开以查看示例 5 的渲染树
flutter: RenderView#02c80
flutter: │ debug mode enabled - macos
flutter: │ view size: Size(800.0, 600.0) (in physical pixels)
flutter: │ device pixel ratio: 1.0 (physical pixels per logical pixel)
flutter: │ configuration: Size(800.0, 600.0) at 1.0x (in logical pixels)
flutter: │
flutter: └─child: RenderSemanticsAnnotations#fe6b5
flutter: │ needs compositing
flutter: │ creator: Semantics ← _FocusInheritedScope ← Focus ←
flutter: │ HeroControllerScope ← ScrollConfiguration ← MaterialApp ←
flutter: │ MediaQuery ← _MediaQueryFromView ← _ViewScope ←
flutter: │ View-[GlobalObjectKey FlutterView#6cffa] ← [root]
flutter: │ parentData: <none>
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderSemanticsAnnotations#6edef
flutter: │ needs compositing
flutter: │ creator: Semantics ← _FocusInheritedScope ← Focus ← Shortcuts ←
flutter: │ _SharedAppModel ← SharedAppData ← UnmanagedRestorationScope ←
flutter: │ RestorationScope ← UnmanagedRestorationScope ←
flutter: │ RootRestorationScope ← WidgetsApp-[GlobalObjectKey
flutter: │ _MaterialAppState#5c303] ← Semantics ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderSemanticsAnnotations#e8ce8
flutter: │ needs compositing
flutter: │ creator: Semantics ← _FocusInheritedScope ← Focus ← Shortcuts ←
flutter: │ DefaultTextEditingShortcuts ← Semantics ← _FocusInheritedScope
flutter: │ ← Focus ← Shortcuts ← _SharedAppModel ← SharedAppData ←
flutter: │ UnmanagedRestorationScope ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderSemanticsAnnotations#fc545
flutter: │ needs compositing
flutter: │ creator: Semantics ← _FocusInheritedScope ← Focus ← Shortcuts ←
flutter: │ Semantics ← _FocusInheritedScope ← Focus ← Shortcuts ←
flutter: │ DefaultTextEditingShortcuts ← Semantics ← _FocusInheritedScope
flutter: │ ← Focus ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderTapRegionSurface#ff857
flutter: │ needs compositing
flutter: │ creator: TapRegionSurface ← _FocusInheritedScope ← Focus ←
flutter: │ FocusTraversalGroup ← _ActionsScope ← Actions ← Semantics ←
flutter: │ _FocusInheritedScope ← Focus ← Shortcuts ← Semantics ←
flutter: │ _FocusInheritedScope ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │ behavior: deferToChild
flutter: │
flutter: └─child: RenderSemanticsAnnotations#fe316
flutter: │ needs compositing
flutter: │ creator: Semantics ← _FocusInheritedScope ← Focus ← Shortcuts ←
flutter: │ _ShortcutRegistrarScope ← ShortcutRegistrar ← TapRegionSurface
flutter: │ ← _FocusInheritedScope ← Focus ← FocusTraversalGroup ←
flutter: │ _ActionsScope ← Actions ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderSemanticsAnnotations#fa55c
flutter: │ needs compositing
flutter: │ creator: Semantics ← Localizations ← Semantics ←
flutter: │ _FocusInheritedScope ← Focus ← Shortcuts ←
flutter: │ _ShortcutRegistrarScope ← ShortcutRegistrar ← TapRegionSurface
flutter: │ ← _FocusInheritedScope ← Focus ← FocusTraversalGroup ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderCustomPaint#4b256
flutter: │ needs compositing
flutter: │ creator: CustomPaint ← Banner ← CheckedModeBanner ← Title ←
flutter: │ Directionality ← _LocalizationsScope-[GlobalKey#4a3aa] ←
flutter: │ Semantics ← Localizations ← Semantics ← _FocusInheritedScope ←
flutter: │ Focus ← Shortcuts ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │ painter: null
flutter: │ foregroundPainter: BannerPainter#1bfd7(Instance of
flutter: │ '_SystemFontsNotifier')
flutter: │
flutter: └─child: RenderSemanticsAnnotations#f470f
flutter: │ needs compositing
flutter: │ creator: Semantics ← FocusScope ← DefaultSelectionStyle ←
flutter: │ IconTheme ← IconTheme ← _InheritedCupertinoTheme ←
flutter: │ CupertinoTheme ← _InheritedTheme ← Theme ← AnimatedTheme ←
flutter: │ DefaultSelectionStyle ← _ScaffoldMessengerScope ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │
flutter: └─child: RenderPointerListener#f59c8
flutter: │ needs compositing
flutter: │ creator: Listener ← HeroControllerScope ←
flutter: │ Navigator-[GlobalObjectKey<NavigatorState>
flutter: │ _WidgetsAppState#0d73a] ← _FocusInheritedScope ← Semantics ←
flutter: │ FocusScope ← DefaultSelectionStyle ← IconTheme ← IconTheme ←
flutter: │ _InheritedCupertinoTheme ← CupertinoTheme ← _InheritedTheme ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │ behavior: deferToChild
flutter: │ listeners: down, up, cancel
flutter: │
flutter: └─child: RenderAbsorbPointer#c91bd
flutter: │ needs compositing
flutter: │ creator: AbsorbPointer ← Listener ← HeroControllerScope ←
flutter: │ Navigator-[GlobalObjectKey<NavigatorState>
flutter: │ _WidgetsAppState#0d73a] ← _FocusInheritedScope ← Semantics ←
flutter: │ FocusScope ← DefaultSelectionStyle ← IconTheme ← IconTheme ←
flutter: │ _InheritedCupertinoTheme ← CupertinoTheme ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │ absorbing: false
flutter: │ ignoringSemantics: null
flutter: │
flutter: └─child: _RenderTheater#07897
flutter: │ needs compositing
flutter: │ creator: _Theater ←
flutter: │ Overlay-[LabeledGlobalKey<OverlayState>#49a93] ←
flutter: │ UnmanagedRestorationScope ← _FocusInheritedScope ← Focus ←
flutter: │ _FocusInheritedScope ← Focus ← FocusTraversalGroup ←
flutter: │ AbsorbPointer ← Listener ← HeroControllerScope ←
flutter: │ Navigator-[GlobalObjectKey<NavigatorState>
flutter: │ _WidgetsAppState#0d73a] ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │ skipCount: 0
flutter: │ textDirection: ltr
flutter: │
flutter: ├─onstage 1: RenderIgnorePointer#3b659
flutter: │ │ creator: IgnorePointer ← _RenderTheaterMarker ←
flutter: │ │ _EffectiveTickerMode ← TickerMode ←
flutter: │ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#a47f4]
flutter: │ │ ← _Theater ← Overlay-[LabeledGlobalKey<OverlayState>#49a93] ←
flutter: │ │ UnmanagedRestorationScope ← _FocusInheritedScope ← Focus ←
flutter: │ │ _FocusInheritedScope ← Focus ← ⋯
flutter: │ │ parentData: not positioned; offset=Offset(0.0, 0.0) (can use
flutter: │ │ size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │ ignoring: false
flutter: │ │ ignoringSemantics: null
flutter: │ │
flutter: │ └─child: RenderBlockSemantics#7586c
flutter: │ │ creator: BlockSemantics ← ModalBarrier ← IgnorePointer ←
flutter: │ │ _RenderTheaterMarker ← _EffectiveTickerMode ← TickerMode ←
flutter: │ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#a47f4]
flutter: │ │ ← _Theater ← Overlay-[LabeledGlobalKey<OverlayState>#49a93] ←
flutter: │ │ UnmanagedRestorationScope ← _FocusInheritedScope ← Focus ← ⋯
flutter: │ │ parentData: <none> (can use size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ blocks semantics of earlier render objects below the common
flutter: │ │ boundary
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │ blocking: true
flutter: │ │
flutter: │ └─child: RenderExcludeSemantics#c1d3f
flutter: │ │ creator: ExcludeSemantics ← BlockSemantics ← ModalBarrier ←
flutter: │ │ IgnorePointer ← _RenderTheaterMarker ← _EffectiveTickerMode ←
flutter: │ │ TickerMode ←
flutter: │ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#a47f4]
flutter: │ │ ← _Theater ← Overlay-[LabeledGlobalKey<OverlayState>#49a93] ←
flutter: │ │ UnmanagedRestorationScope ← _FocusInheritedScope ← ⋯
flutter: │ │ parentData: <none> (can use size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │ excluding: true
flutter: │ │
flutter: │ └─child: RenderSemanticsGestureHandler#70b16
flutter: │ │ creator: _GestureSemantics ← RawGestureDetector ←
flutter: │ │ _ModalBarrierGestureDetector ← ExcludeSemantics ←
flutter: │ │ BlockSemantics ← ModalBarrier ← IgnorePointer ←
flutter: │ │ _RenderTheaterMarker ← _EffectiveTickerMode ← TickerMode ←
flutter: │ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#a47f4]
flutter: │ │ ← _Theater ← ⋯
flutter: │ │ parentData: <none> (can use size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │ behavior: opaque
flutter: │ │ gestures: <none>
flutter: │ │
flutter: │ └─child: RenderPointerListener#1f34a
flutter: │ │ creator: Listener ← _GestureSemantics ← RawGestureDetector ←
flutter: │ │ _ModalBarrierGestureDetector ← ExcludeSemantics ←
flutter: │ │ BlockSemantics ← ModalBarrier ← IgnorePointer ←
flutter: │ │ _RenderTheaterMarker ← _EffectiveTickerMode ← TickerMode ←
flutter: │ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#a47f4]
flutter: │ │ ← ⋯
flutter: │ │ parentData: <none> (can use size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │ behavior: opaque
flutter: │ │ listeners: down, panZoomStart
flutter: │ │
flutter: │ └─child: RenderSemanticsAnnotations#73467
flutter: │ │ creator: Semantics ← Listener ← _GestureSemantics ←
flutter: │ │ RawGestureDetector ← _ModalBarrierGestureDetector ←
flutter: │ │ ExcludeSemantics ← BlockSemantics ← ModalBarrier ←
flutter: │ │ IgnorePointer ← _RenderTheaterMarker ← _EffectiveTickerMode ←
flutter: │ │ TickerMode ← ⋯
flutter: │ │ parentData: <none> (can use size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │
flutter: │ └─child: RenderMouseRegion#560dc
flutter: │ │ creator: MouseRegion ← Semantics ← Listener ← _GestureSemantics ←
flutter: │ │ RawGestureDetector ← _ModalBarrierGestureDetector ←
flutter: │ │ ExcludeSemantics ← BlockSemantics ← ModalBarrier ←
flutter: │ │ IgnorePointer ← _RenderTheaterMarker ← _EffectiveTickerMode ← ⋯
flutter: │ │ parentData: <none> (can use size)
flutter: │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ │ size: Size(800.0, 600.0)
flutter: │ │ behavior: opaque
flutter: │ │ listeners: <none>
flutter: │ │ cursor: SystemMouseCursor(basic)
flutter: │ │
flutter: │ └─child: RenderConstrainedBox#01e8c
flutter: │ creator: ConstrainedBox ← MouseRegion ← Semantics ← Listener ←
flutter: │ _GestureSemantics ← RawGestureDetector ←
flutter: │ _ModalBarrierGestureDetector ← ExcludeSemantics ←
flutter: │ BlockSemantics ← ModalBarrier ← IgnorePointer ←
flutter: │ _RenderTheaterMarker ← ⋯
flutter: │ parentData: <none> (can use size)
flutter: │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: │ size: Size(800.0, 600.0)
flutter: │ additionalConstraints: BoxConstraints(biggest)
flutter: │
flutter: ├─onstage 2: RenderSemanticsAnnotations#8187b
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: Semantics ← _RenderTheaterMarker ← _EffectiveTickerMode
flutter: ╎ │ ← TickerMode ←
flutter: ╎ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#8cd54]
flutter: ╎ │ ← _Theater ← Overlay-[LabeledGlobalKey<OverlayState>#49a93] ←
flutter: ╎ │ UnmanagedRestorationScope ← _FocusInheritedScope ← Focus ←
flutter: ╎ │ _FocusInheritedScope ← Focus ← ⋯
flutter: ╎ │ parentData: not positioned; offset=Offset(0.0, 0.0) (can use
flutter: ╎ │ size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │
flutter: ╎ └─child: RenderOffstage#f211d
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: Offstage ← _ModalScopeStatus ← UnmanagedRestorationScope
flutter: ╎ │ ← RestorationScope ← AnimatedBuilder ←
flutter: ╎ │ _ModalScope<dynamic>-[LabeledGlobalKey<_ModalScopeState<dynamic>>#db401]
flutter: ╎ │ ← Semantics ← _RenderTheaterMarker ← _EffectiveTickerMode ←
flutter: ╎ │ TickerMode ←
flutter: ╎ │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#8cd54]
flutter: ╎ │ ← _Theater ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │ offstage: false
flutter: ╎ │
flutter: ╎ └─child: RenderSemanticsAnnotations#9436c
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: Semantics ← FocusScope ← PrimaryScrollController ←
flutter: ╎ │ _ActionsScope ← Actions ← Builder ← PageStorage ← Offstage ←
flutter: ╎ │ _ModalScopeStatus ← UnmanagedRestorationScope ←
flutter: ╎ │ RestorationScope ← AnimatedBuilder ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │
flutter: ╎ └─child: RenderRepaintBoundary#f8f28
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: RepaintBoundary ← _FocusInheritedScope ← Semantics ←
flutter: ╎ │ FocusScope ← PrimaryScrollController ← _ActionsScope ← Actions
flutter: ╎ │ ← Builder ← PageStorage ← Offstage ← _ModalScopeStatus ←
flutter: ╎ │ UnmanagedRestorationScope ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ layer: OffsetLayer#e73b7
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │ metrics: 66.7% useful (1 bad vs 2 good)
flutter: ╎ │ diagnosis: insufficient data to draw conclusion (less than five
flutter: ╎ │ repaints)
flutter: ╎ │
flutter: ╎ └─child: RenderFractionalTranslation#c3a54
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: FractionalTranslation ← SlideTransition ←
flutter: ╎ │ CupertinoPageTransition ← AnimatedBuilder ← RepaintBoundary ←
flutter: ╎ │ _FocusInheritedScope ← Semantics ← FocusScope ←
flutter: ╎ │ PrimaryScrollController ← _ActionsScope ← Actions ← Builder ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │ translation: Offset(0.0, 0.0)
flutter: ╎ │ transformHitTests: false
flutter: ╎ │
flutter: ╎ └─child: RenderFractionalTranslation#7fcf2
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: FractionalTranslation ← SlideTransition ←
flutter: ╎ │ FractionalTranslation ← SlideTransition ←
flutter: ╎ │ CupertinoPageTransition ← AnimatedBuilder ← RepaintBoundary ←
flutter: ╎ │ _FocusInheritedScope ← Semantics ← FocusScope ←
flutter: ╎ │ PrimaryScrollController ← _ActionsScope ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │ translation: Offset(0.0, 0.0)
flutter: ╎ │ transformHitTests: true
flutter: ╎ │
flutter: ╎ └─child: RenderDecoratedBox#713ec
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: DecoratedBox ← DecoratedBoxTransition ←
flutter: ╎ │ FractionalTranslation ← SlideTransition ← FractionalTranslation
flutter: ╎ │ ← SlideTransition ← CupertinoPageTransition ← AnimatedBuilder ←
flutter: ╎ │ RepaintBoundary ← _FocusInheritedScope ← Semantics ← FocusScope
flutter: ╎ │ ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │ ├─decoration: _CupertinoEdgeShadowDecoration
flutter: ╎ │ colors: Color(0x04000000), Color(0x00000000)
flutter: ╎ │
flutter: ╎ │ configuration: ImageConfiguration(bundle:
flutter: ╎ │ PlatformAssetBundle#164ca(), devicePixelRatio: 1.0, locale:
flutter: ╎ │ en_US, textDirection: TextDirection.ltr, platform: macOS)
flutter: ╎ │
flutter: ╎ └─child: RenderStack#83b13
flutter: ╎ │ needs compositing
flutter: ╎ │ creator: Stack ← _CupertinoBackGestureDetector<dynamic> ←
flutter: ╎ │ DecoratedBox ← DecoratedBoxTransition ← FractionalTranslation ←
flutter: ╎ │ SlideTransition ← FractionalTranslation ← SlideTransition ←
flutter: ╎ │ CupertinoPageTransition ← AnimatedBuilder ← RepaintBoundary ←
flutter: ╎ │ _FocusInheritedScope ← ⋯
flutter: ╎ │ parentData: <none> (can use size)
flutter: ╎ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ size: Size(800.0, 600.0)
flutter: ╎ │ alignment: AlignmentDirectional.topStart
flutter: ╎ │ textDirection: ltr
flutter: ╎ │ fit: passthrough
flutter: ╎ │
flutter: ╎ ├─child 1: RenderIgnorePointer#ad50f
flutter: ╎ │ │ needs compositing
flutter: ╎ │ │ creator: IgnorePointer ← AnimatedBuilder ← Stack ←
flutter: ╎ │ │ _CupertinoBackGestureDetector<dynamic> ← DecoratedBox ←
flutter: ╎ │ │ DecoratedBoxTransition ← FractionalTranslation ←
flutter: ╎ │ │ SlideTransition ← FractionalTranslation ← SlideTransition ←
flutter: ╎ │ │ CupertinoPageTransition ← AnimatedBuilder ← ⋯
flutter: ╎ │ │ parentData: not positioned; offset=Offset(0.0, 0.0) (can use
flutter: ╎ │ │ size)
flutter: ╎ │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ │ size: Size(800.0, 600.0)
flutter: ╎ │ │ ignoring: false
flutter: ╎ │ │ ignoringSemantics: null
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderRepaintBoundary#29754
flutter: ╎ │ │ needs compositing
flutter: ╎ │ │ creator: RepaintBoundary-[GlobalKey#75409] ← IgnorePointer ←
flutter: ╎ │ │ AnimatedBuilder ← Stack ←
flutter: ╎ │ │ _CupertinoBackGestureDetector<dynamic> ← DecoratedBox ←
flutter: ╎ │ │ DecoratedBoxTransition ← FractionalTranslation ←
flutter: ╎ │ │ SlideTransition ← FractionalTranslation ← SlideTransition ←
flutter: ╎ │ │ CupertinoPageTransition ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ │ layer: OffsetLayer#fa835
flutter: ╎ │ │ size: Size(800.0, 600.0)
flutter: ╎ │ │ metrics: 90.9% useful (1 bad vs 10 good)
flutter: ╎ │ │ diagnosis: this is an outstandingly useful repaint boundary and
flutter: ╎ │ │ should definitely be kept
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderSemanticsAnnotations#95566
flutter: ╎ │ │ creator: Semantics ← Builder ← RepaintBoundary-[GlobalKey#75409]
flutter: ╎ │ │ ← IgnorePointer ← AnimatedBuilder ← Stack ←
flutter: ╎ │ │ _CupertinoBackGestureDetector<dynamic> ← DecoratedBox ←
flutter: ╎ │ │ DecoratedBoxTransition ← FractionalTranslation ←
flutter: ╎ │ │ SlideTransition ← FractionalTranslation ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ │ size: Size(800.0, 600.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderPhysicalModel#bc9d7
flutter: ╎ │ │ creator: PhysicalModel ← AnimatedPhysicalModel ← Material ←
flutter: ╎ │ │ AppHome ← Semantics ← Builder ←
flutter: ╎ │ │ RepaintBoundary-[GlobalKey#75409] ← IgnorePointer ←
flutter: ╎ │ │ AnimatedBuilder ← Stack ←
flutter: ╎ │ │ _CupertinoBackGestureDetector<dynamic> ← DecoratedBox ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ │ size: Size(800.0, 600.0)
flutter: ╎ │ │ elevation: 0.0
flutter: ╎ │ │ color: Color(0xfffafafa)
flutter: ╎ │ │ shadowColor: Color(0xfffafafa)
flutter: ╎ │ │ shape: BoxShape.rectangle
flutter: ╎ │ │ borderRadius: BorderRadius.zero
flutter: ╎ │ │
flutter: ╎ │ └─child: _RenderInkFeatures#ac819
flutter: ╎ │ │ creator: _InkFeatures-[GlobalKey#d721e ink renderer] ←
flutter: ╎ │ │ NotificationListener<LayoutChangedNotification> ← PhysicalModel
flutter: ╎ │ │ ← AnimatedPhysicalModel ← Material ← AppHome ← Semantics ←
flutter: ╎ │ │ Builder ← RepaintBoundary-[GlobalKey#75409] ← IgnorePointer ←
flutter: ╎ │ │ AnimatedBuilder ← Stack ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ │ size: Size(800.0, 600.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderPositionedBox#dc1df
flutter: ╎ │ │ creator: Center ← DefaultTextStyle ← AnimatedDefaultTextStyle ←
flutter: ╎ │ │ _InkFeatures-[GlobalKey#d721e ink renderer] ←
flutter: ╎ │ │ NotificationListener<LayoutChangedNotification> ← PhysicalModel
flutter: ╎ │ │ ← AnimatedPhysicalModel ← Material ← AppHome ← Semantics ←
flutter: ╎ │ │ Builder ← RepaintBoundary-[GlobalKey#75409] ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(w=800.0, h=600.0)
flutter: ╎ │ │ size: Size(800.0, 600.0)
flutter: ╎ │ │ alignment: Alignment.center
flutter: ╎ │ │ textDirection: ltr
flutter: ╎ │ │ widthFactor: expand
flutter: ╎ │ │ heightFactor: expand
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderSemanticsAnnotations#a0a4b relayoutBoundary=up1
flutter: ╎ │ │ creator: Semantics ← TextButton ← Center ← DefaultTextStyle ←
flutter: ╎ │ │ AnimatedDefaultTextStyle ← _InkFeatures-[GlobalKey#d721e ink
flutter: ╎ │ │ renderer] ← NotificationListener<LayoutChangedNotification> ←
flutter: ╎ │ │ PhysicalModel ← AnimatedPhysicalModel ← Material ← AppHome ←
flutter: ╎ │ │ Semantics ← ⋯
flutter: ╎ │ │ parentData: offset=Offset(329.0, 286.0) (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)
flutter: ╎ │ │ semantic boundary
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: _RenderInputPadding#4672f relayoutBoundary=up2
flutter: ╎ │ │ creator: _InputPadding ← Semantics ← TextButton ← Center ←
flutter: ╎ │ │ DefaultTextStyle ← AnimatedDefaultTextStyle ←
flutter: ╎ │ │ _InkFeatures-[GlobalKey#d721e ink renderer] ←
flutter: ╎ │ │ NotificationListener<LayoutChangedNotification> ← PhysicalModel
flutter: ╎ │ │ ← AnimatedPhysicalModel ← Material ← AppHome ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderConstrainedBox#425d6 relayoutBoundary=up3
flutter: ╎ │ │ creator: ConstrainedBox ← _InputPadding ← Semantics ← TextButton
flutter: ╎ │ │ ← Center ← DefaultTextStyle ← AnimatedDefaultTextStyle ←
flutter: ╎ │ │ _InkFeatures-[GlobalKey#d721e ink renderer] ←
flutter: ╎ │ │ NotificationListener<LayoutChangedNotification> ← PhysicalModel
flutter: ╎ │ │ ← AnimatedPhysicalModel ← Material ← ⋯
flutter: ╎ │ │ parentData: offset=Offset(0.0, 0.0) (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │ additionalConstraints: BoxConstraints(56.0<=w<=Infinity,
flutter: ╎ │ │ 28.0<=h<=Infinity)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderPhysicalShape#8e171 relayoutBoundary=up4
flutter: ╎ │ │ creator: PhysicalShape ← _MaterialInterior ← Material ←
flutter: ╎ │ │ ConstrainedBox ← _InputPadding ← Semantics ← TextButton ←
flutter: ╎ │ │ Center ← DefaultTextStyle ← AnimatedDefaultTextStyle ←
flutter: ╎ │ │ _InkFeatures-[GlobalKey#d721e ink renderer] ←
flutter: ╎ │ │ NotificationListener<LayoutChangedNotification> ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │ elevation: 0.0
flutter: ╎ │ │ color: Color(0x00000000)
flutter: ╎ │ │ shadowColor: Color(0x00000000)
flutter: ╎ │ │ clipper: ShapeBorderClipper
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderCustomPaint#eea46 relayoutBoundary=up5
flutter: ╎ │ │ creator: CustomPaint ← _ShapeBorderPaint ← PhysicalShape ←
flutter: ╎ │ │ _MaterialInterior ← Material ← ConstrainedBox ← _InputPadding ←
flutter: ╎ │ │ Semantics ← TextButton ← Center ← DefaultTextStyle ←
flutter: ╎ │ │ AnimatedDefaultTextStyle ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │ painter: null
flutter: ╎ │ │ foregroundPainter: _ShapeBorderPainter#ac724()
flutter: ╎ │ │
flutter: ╎ │ └─child: _RenderInkFeatures#b19a7 relayoutBoundary=up6
flutter: ╎ │ │ creator: _InkFeatures-[GlobalKey#87971 ink renderer] ←
flutter: ╎ │ │ NotificationListener<LayoutChangedNotification> ← CustomPaint ←
flutter: ╎ │ │ _ShapeBorderPaint ← PhysicalShape ← _MaterialInterior ←
flutter: ╎ │ │ Material ← ConstrainedBox ← _InputPadding ← Semantics ←
flutter: ╎ │ │ TextButton ← Center ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderSemanticsAnnotations#4d1b3 relayoutBoundary=up7
flutter: ╎ │ │ creator: Semantics ← _FocusInheritedScope ← Focus ← _ActionsScope
flutter: ╎ │ │ ← Actions ← _ParentInkResponseProvider ←
flutter: ╎ │ │ _InkResponseStateWidget ← InkWell ← DefaultTextStyle ←
flutter: ╎ │ │ AnimatedDefaultTextStyle ← _InkFeatures-[GlobalKey#87971 ink
flutter: ╎ │ │ renderer] ← NotificationListener<LayoutChangedNotification> ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderMouseRegion#e5b3f relayoutBoundary=up8
flutter: ╎ │ │ creator: MouseRegion ← Semantics ← _FocusInheritedScope ← Focus ←
flutter: ╎ │ │ _ActionsScope ← Actions ← _ParentInkResponseProvider ←
flutter: ╎ │ │ _InkResponseStateWidget ← InkWell ← DefaultTextStyle ←
flutter: ╎ │ │ AnimatedDefaultTextStyle ← _InkFeatures-[GlobalKey#87971 ink
flutter: ╎ │ │ renderer] ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │ behavior: opaque
flutter: ╎ │ │ listeners: enter, exit
flutter: ╎ │ │ cursor: SystemMouseCursor(click)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderSemanticsAnnotations#deb9b relayoutBoundary=up9
flutter: ╎ │ │ creator: Semantics ← DefaultSelectionStyle ← Builder ←
flutter: ╎ │ │ MouseRegion ← Semantics ← _FocusInheritedScope ← Focus ←
flutter: ╎ │ │ _ActionsScope ← Actions ← _ParentInkResponseProvider ←
flutter: ╎ │ │ _InkResponseStateWidget ← InkWell ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderPointerListener#2017a relayoutBoundary=up10
flutter: ╎ │ │ creator: Listener ← RawGestureDetector ← GestureDetector ←
flutter: ╎ │ │ Semantics ← DefaultSelectionStyle ← Builder ← MouseRegion ←
flutter: ╎ │ │ Semantics ← _FocusInheritedScope ← Focus ← _ActionsScope ←
flutter: ╎ │ │ Actions ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │ behavior: opaque
flutter: ╎ │ │ listeners: down, panZoomStart
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderPadding#8455f relayoutBoundary=up11
flutter: ╎ │ │ creator: Padding ← IconTheme ← Builder ← Listener ←
flutter: ╎ │ │ RawGestureDetector ← GestureDetector ← Semantics ←
flutter: ╎ │ │ DefaultSelectionStyle ← Builder ← MouseRegion ← Semantics ←
flutter: ╎ │ │ _FocusInheritedScope ← ⋯
flutter: ╎ │ │ parentData: <none> (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(142.0, 28.0)
flutter: ╎ │ │ padding: EdgeInsets(8.0, 0.0, 8.0, 0.0)
flutter: ╎ │ │ textDirection: ltr
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderPositionedBox#80b8d relayoutBoundary=up12
flutter: ╎ │ │ creator: Align ← Padding ← IconTheme ← Builder ← Listener ←
flutter: ╎ │ │ RawGestureDetector ← GestureDetector ← Semantics ←
flutter: ╎ │ │ DefaultSelectionStyle ← Builder ← MouseRegion ← Semantics ← ⋯
flutter: ╎ │ │ parentData: offset=Offset(8.0, 0.0) (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(40.0<=w<=784.0, 28.0<=h<=600.0)
flutter: ╎ │ │ size: Size(126.0, 28.0)
flutter: ╎ │ │ alignment: Alignment.center
flutter: ╎ │ │ textDirection: ltr
flutter: ╎ │ │ widthFactor: 1.0
flutter: ╎ │ │ heightFactor: 1.0
flutter: ╎ │ │
flutter: ╎ │ └─child: RenderParagraph#59bc2 relayoutBoundary=up13
flutter: ╎ │ │ creator: RichText ← Text ← Align ← Padding ← IconTheme ← Builder
flutter: ╎ │ │ ← Listener ← RawGestureDetector ← GestureDetector ← Semantics ←
flutter: ╎ │ │ DefaultSelectionStyle ← Builder ← ⋯
flutter: ╎ │ │ parentData: offset=Offset(0.0, 6.0) (can use size)
flutter: ╎ │ │ constraints: BoxConstraints(0.0<=w<=784.0, 0.0<=h<=600.0)
flutter: ╎ │ │ size: Size(126.0, 16.0)
flutter: ╎ │ │ textAlign: start
flutter: ╎ │ │ textDirection: ltr
flutter: ╎ │ │ softWrap: wrapping at box width
flutter: ╎ │ │ overflow: clip
flutter: ╎ │ │ locale: en_US
flutter: ╎ │ │ maxLines: unlimited
flutter: ╎ │ ╘═╦══ text ═══
flutter: ╎ │ ║ TextSpan:
flutter: ╎ │ ║ debugLabel: ((englishLike labelLarge 2014).merge(blackRedwoodCity
flutter: ╎ │ ║ labelLarge)).copyWith
flutter: ╎ │ ║ inherit: false
flutter: ╎ │ ║ color: MaterialColor(primary value: Color(0xff2196f3))
flutter: ╎ │ ║ family: .AppleSystemUIFont
flutter: ╎ │ ║ size: 14.0
flutter: ╎ │ ║ weight: 500
flutter: ╎ │ ║ baseline: alphabetic
flutter: ╎ │ ║ decoration: TextDecoration.none
flutter: ╎ │ ║ "Dump Render Tree"
flutter: ╎ │ ╚═══════════
flutter: ╎ └─child 2: RenderPointerListener#db4b5
flutter: ╎ creator: Listener ← Positioned ← PositionedDirectional ← Stack ←
flutter: ╎ _CupertinoBackGestureDetector<dynamic> ← DecoratedBox ←
flutter: ╎ DecoratedBoxTransition ← FractionalTranslation ←
flutter: ╎ SlideTransition ← FractionalTranslation ← SlideTransition ←
flutter: ╎ CupertinoPageTransition ← ⋯
flutter: ╎ parentData: top=0.0; bottom=0.0; left=0.0; width=20.0;
flutter: ╎ offset=Offset(0.0, 0.0) (can use size)
flutter: ╎ constraints: BoxConstraints(w=20.0, h=600.0)
flutter: ╎ size: Size(20.0, 600.0)
flutter: ╎ behavior: translucent
flutter: ╎ listeners: down
flutter: ╎
flutter: └╌no offstage children
flutter:在示例 5的渲染树中
RenderView（或窗口大小）将所有渲染对象（直至且包括RenderPositionedBox#dc1df渲染对象）限制为屏幕大小。此示例将大小设置为Size(800.0, 600.0)每个渲染对象的
constraints属性限制每个子项的大小。此属性采用BoxConstraints渲染对象作为值。从RenderSemanticsAnnotations#fe6b5开始，约束等于BoxConstraints(w=800.0, h=600.0)。Centerwidget 在RenderSemanticsAnnotations#8187b子树下创建了RenderPositionedBox#dc1df渲染对象。此渲染对象下的每个子项都有
BoxConstraints，并且具有最小值和最大值。例如，RenderSemanticsAnnotations#a0a4b使用BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)。RenderPhysicalShape#8e171渲染对象的所有子项都使用BoxConstraints(BoxConstraints(56.0<=w<=800.0, 28.0<=h<=600.0))。子项
RenderPadding#8455f设置padding值为EdgeInsets(8.0, 0.0, 8.0, 0.0)。这将左侧和右侧填充设置为 8，适用于此渲染对象的所有后续子项。它们现在具有新的约束：BoxConstraints(40.0<=w<=784.0, 28.0<=h<=600.0)。
此对象（creator 字段告诉我们它可能是TextButton 的定义的一部分）在其内容上设置了 88 像素的最小宽度和 36.0 的特定高度。这是 TextButton 类实现关于按钮尺寸的 Material Design 指南。
RenderPositionedBox#80b8d 渲染对象再次放松了约束，以将文本居中于按钮内。RenderParagraph#59bc2 渲染对象根据其内容选择其大小。如果向上跟踪树中的大小，您会看到文本的大小如何影响构成按钮的所有框的宽度。所有父项都采用其子项的尺寸来调整自身的大小。
另一种注意到这一点的方法是查看每个框描述中的 relayoutBoundary 属性。这告诉您有多少祖先依赖于此元素的大小。
例如，最里面的 RenderPositionedBox 行具有 relayoutBoundary=up13。这意味着当 Flutter 将 RenderConstrainedBox 标记为脏时，它也会将框的 13 个祖先标记为脏，因为新尺寸可能会影响这些祖先。
如果您编写自己的渲染对象，要向转储添加信息，请覆盖debugFillProperties()。将DiagnosticsProperty 对象添加到方法的参数中，然后调用超类方法。
打印层树
#要调试合成问题，请使用debugDumpLayerTree()。
示例 6：调用 debugDumpLayerTree()
#dart
import 'package:flutter/material.dart';
void main() {
runApp(
const MaterialApp(
home: AppHome(),
),
);
}
class AppHome extends StatelessWidget {
const AppHome({super.key});
@override
Widget build(BuildContext context) {
return Material(
child: Center(
child: TextButton(
onPressed: () {
debugDumpLayerTree();
},
child: const Text('Dump Layer Tree'),
),
),
);
}
}展开以查看示例 6 的图层树输出
flutter: TransformLayer#214da
flutter: │ owner: RenderView#ebaaf
flutter: │ creator: [root]
flutter: │ engine layer: TransformEngineLayer#535de
flutter: │ handles: 1
flutter: │ offset: Offset(0.0, 0.0)
flutter: │ transform:
flutter: │ [0] 1.0,0.0,0.0,0.0
flutter: │ [1] 0.0,1.0,0.0,0.0
flutter: │ [2] 0.0,0.0,1.0,0.0
flutter: │ [3] 0.0,0.0,0.0,1.0
flutter: │
flutter: ├─child 1: OffsetLayer#0f766
flutter: │ │ creator: RepaintBoundary ← _FocusInheritedScope ← Semantics ←
flutter: │ │ FocusScope ← PrimaryScrollController ← _ActionsScope ← Actions
flutter: │ │ ← Builder ← PageStorage ← Offstage ← _ModalScopeStatus ←
flutter: │ │ UnmanagedRestorationScope ← ⋯
flutter: │ │ engine layer: OffsetEngineLayer#1768d
flutter: │ │ handles: 2
flutter: │ │ offset: Offset(0.0, 0.0)
flutter: │ │
flutter: │ ├─child 1: PictureLayer#dd023
flutter: │ │ handles: 1
flutter: │ │ paint bounds: Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: │ │ picture: _NativePicture#36f94
flutter: │ │ raster cache hints: isComplex = false, willChange = false
flutter: │ │
flutter: │ └─child 2: OffsetLayer#4cfc8
flutter: │ │ creator: RepaintBoundary-[GlobalKey#bd5d9] ← IgnorePointer ←
flutter: │ │ AnimatedBuilder ← Stack ←
flutter: │ │ _CupertinoBackGestureDetector<dynamic> ← DecoratedBox ←
flutter: │ │ DecoratedBoxTransition ← FractionalTranslation ←
flutter: │ │ SlideTransition ← FractionalTranslation ← SlideTransition ←
flutter: │ │ CupertinoPageTransition ← ⋯
flutter: │ │ engine layer: OffsetEngineLayer#a1676
flutter: │ │ handles: 2
flutter: │ │ offset: Offset(0.0, 0.0)
flutter: │ │
flutter: │ └─child 1: PictureLayer#aee55
flutter: │ handles: 1
flutter: │ paint bounds: Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: │ picture: _NativePicture#e732d
flutter: │ raster cache hints: isComplex = false, willChange = false
flutter: │
flutter: └─child 2: PictureLayer#b16e5
flutter: handles: 1
flutter: paint bounds: Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: picture: _NativePicture#eef0a
flutter: raster cache hints: isComplex = false, willChange = false
flutter:RepaintBoundary widget 创建
如示例 5的结果所示，在渲染树中创建
RenderRepaintBoundaryRenderObject。╎ └─child: RenderRepaintBoundary#f8f28 ╎ │ needs compositing ╎ │ creator: RepaintBoundary ← _FocusInheritedScope ← Semantics ← ╎ │ FocusScope ← PrimaryScrollController ← _ActionsScope ← Actions ╎ │ ← Builder ← PageStorage ← Offstage ← _ModalScopeStatus ← ╎ │ UnmanagedRestorationScope ← ⋯ ╎ │ parentData: <none> (can use size) ╎ │ constraints: BoxConstraints(w=800.0, h=600.0) ╎ │ layer: OffsetLayer#e73b7 ╎ │ size: Size(800.0, 600.0) ╎ │ metrics: 66.7% useful (1 bad vs 2 good) ╎ │ diagnosis: insufficient data to draw conclusion (less than five ╎ │ repaints)如示例 6的结果所示，在图层树中创建新图层。
├─child 1: OffsetLayer#0f766 │ │ creator: RepaintBoundary ← _FocusInheritedScope ← Semantics ← │ │ FocusScope ← PrimaryScrollController ← _ActionsScope ← Actions │ │ ← Builder ← PageStorage ← Offstage ← _ModalScopeStatus ← │ │ UnmanagedRestorationScope ← ⋯ │ │ engine layer: OffsetEngineLayer#1768d │ │ handles: 2 │ │ offset: Offset(0.0, 0.0)
这减少了需要重新绘制的内容。
打印焦点树
#要调试焦点或快捷方式问题，请使用debugDumpFocusTree() 函数转储焦点树。
debugDumpFocusTree() 方法返回应用的焦点树。
焦点树以以下方式标记节点
- 聚焦的节点标记为
PRIMARY FOCUS。 - 焦点节点的祖先标记为
IN FOCUS PATH。
如果您的应用使用Focus widget，请使用debugLabel 属性来简化在树中查找其焦点节点的操作。
您还可以使用debugFocusChanges 布尔属性在焦点更改时启用广泛的日志记录。
示例 7：调用 debugDumpFocusTree()
#dart
import 'package:flutter/material.dart';
void main() {
runApp(
const MaterialApp(
home: AppHome(),
),
);
}
class AppHome extends StatelessWidget {
const AppHome({super.key});
@override
Widget build(BuildContext context) {
return Material(
child: Center(
child: TextButton(
onPressed: () {
debugDumpFocusTree();
},
child: const Text('Dump Focus Tree'),
),
),
);
}
}展开以查看示例 7 的焦点树
flutter: FocusManager#9d096
flutter: │ primaryFocus: FocusScopeNode#926dc(_ModalScopeState<dynamic>
flutter: │ Focus Scope [PRIMARY FOCUS])
flutter: │ primaryFocusCreator: FocusScope ← PrimaryScrollController ←
flutter: │ _ActionsScope ← Actions ← Builder ← PageStorage ← Offstage ←
flutter: │ _ModalScopeStatus ← UnmanagedRestorationScope ←
flutter: │ RestorationScope ← AnimatedBuilder ←
flutter: │ _ModalScope<dynamic>-[LabeledGlobalKey<_ModalScopeState<dynamic>>#bd53e]
flutter: │ ← Semantics ← _RenderTheaterMarker ← _EffectiveTickerMode ←
flutter: │ TickerMode ←
flutter: │ _OverlayEntryWidget-[LabeledGlobalKey<_OverlayEntryWidgetState>#89dd7]
flutter: │ ← _Theater ← Overlay-[LabeledGlobalKey<OverlayState>#52f82] ←
flutter: │ UnmanagedRestorationScope ← ⋯
flutter: │
flutter: └─rootScope: FocusScopeNode#f4205(Root Focus Scope [IN FOCUS PATH])
flutter: │ IN FOCUS PATH
flutter: │ focusedChildren: FocusScopeNode#a0d10(Navigator Scope [IN FOCUS
flutter: │ PATH])
flutter: │
flutter: └─Child 1: FocusNode#088ec([IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusNode#85f70(Shortcuts [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusNode#f0c18(Shortcuts [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusNode#0749f(Shortcuts [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: _FocusTraversalGroupNode#28990(FocusTraversalGroup [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusNode#5b515(Shortcuts [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusScopeNode#a0d10(Navigator Scope [IN FOCUS PATH])
flutter: │ context: FocusScope
flutter: │ IN FOCUS PATH
flutter: │ focusedChildren: FocusScopeNode#926dc(_ModalScopeState<dynamic>
flutter: │ Focus Scope [PRIMARY FOCUS])
flutter: │
flutter: └─Child 1: _FocusTraversalGroupNode#72c8a(FocusTraversalGroup [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ NOT FOCUSABLE
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusNode#eb709(Navigator [IN FOCUS PATH])
flutter: │ context: Focus
flutter: │ IN FOCUS PATH
flutter: │
flutter: └─Child 1: FocusScopeNode#926dc(_ModalScopeState<dynamic> Focus Scope [PRIMARY FOCUS])
flutter: │ context: FocusScope
flutter: │ PRIMARY FOCUS
flutter: │
flutter: └─Child 1: FocusNode#a6b74
flutter: context: Focus
flutter:打印语义树
#debugDumpSemanticsTree() 函数打印应用的语义树。
语义树呈现给系统辅助功能 API。要获取语义树的转储
- 使用系统辅助功能工具或
SemanticsDebugger启用辅助功能 - 使用
debugDumpSemanticsTree()函数。
示例 8：调用 debugDumpSemanticsTree()
#dart
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(
const MaterialApp(
home: AppHome(),
),
);
}
class AppHome extends StatelessWidget {
const AppHome({super.key});
@override
Widget build(BuildContext context) {
return Material(
child: Center(
child: Semantics(
button: true,
enabled: true,
label: 'Clickable text here!',
child: GestureDetector(
onTap: () {
debugDumpSemanticsTree();
if (kDebugMode) {
print('Clicked!');
}
},
child: const Text('Click Me!', style: TextStyle(fontSize: 56))),
),
),
);
}
}展开以查看示例 8 的语义树
flutter: SemanticsNode#0
flutter: │ Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: │
flutter: └─SemanticsNode#1
flutter: │ Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: │ textDirection: ltr
flutter: │
flutter: └─SemanticsNode#2
flutter: │ Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: │ sortKey: OrdinalSortKey#824a2(order: 0.0)
flutter: │
flutter: └─SemanticsNode#3
flutter: │ Rect.fromLTRB(0.0, 0.0, 800.0, 600.0)
flutter: │ flags: scopesRoute
flutter: │
flutter: └─SemanticsNode#4
flutter: Rect.fromLTRB(278.0, 267.0, 522.0, 333.0)
flutter: actions: tap
flutter: flags: isButton, hasEnabledState, isEnabled
flutter: label:
flutter: "Clickable text here!
flutter: Click Me!"
flutter: textDirection: ltr
flutter:
flutter: Clicked!打印事件计时
#如果您想了解事件相对于帧的开始和结束发生的位置，可以设置打印来记录这些事件。要将帧的开始和结束打印到控制台，请切换debugPrintBeginFrameBanner和debugPrintEndFrameBanner。
示例 1 的打印帧横幅日志
I/flutter : ▄▄▄▄▄▄▄▄ Frame 12 30s 437.086ms ▄▄▄▄▄▄▄▄
I/flutter : Debug print: Am I performing this work more than once per frame?
I/flutter : Debug print: Am I performing this work more than once per frame?
I/flutter : ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀要打印导致当前帧被调度的调用栈，请使用debugPrintScheduleFrameStacks标志。
调试布局问题
#要使用 GUI 调试布局问题，请将debugPaintSizeEnabled设置为true。此标志可以在rendering库中找到。您可以随时启用它，并在true时影响所有绘制。考虑将其添加到void main()入口点的顶部。
示例 9
#请参阅以下代码中的示例
dart
// Add import to the Flutter rendering library.
import 'package:flutter/rendering.dart';
void main() {
debugPaintSizeEnabled = true;
runApp(const MyApp());
}启用后，Flutter 会对您的应用显示以下更改
- 以亮青色边框显示所有框。
- 将所有填充显示为一个带有淡蓝色填充和蓝色边框的框，围绕子部件。
- 使用黄色箭头显示所有对齐定位。
- 当间距没有子项时，以灰色显示所有间距。
debugPaintBaselinesEnabled标志执行类似的操作，但针对具有基线的对象。该应用以亮绿色显示字母字符的基线，以橙色显示表意字符的基线。字母字符“位于”字母基线上，但该基线“穿过”CJK 字符的底部。Flutter 将表意基线定位在文本行的最底部。
debugPaintPointersEnabled标志开启一种特殊模式，该模式会以青色突出显示您点击的任何对象。这可以帮助您确定对象是否未能进行点击测试。如果对象超出其父级边界，则可能发生这种情况，因此首先不会将其考虑用于点击测试。
如果您尝试调试合成器图层，请考虑使用以下标志。
使用
debugPaintLayerBordersEnabled标志查找每个图层的边界。此标志会导致以橙色描绘每个图层的边界。使用
debugRepaintRainbowEnabled标志显示重绘的图层。每当图层重绘时，它都会覆盖一组旋转的颜色。
Flutter 框架中以debug...开头的任何函数或方法仅在调试模式下有效。
调试动画问题
#将timeDilation变量（来自scheduler库）设置为大于 1.0 的数字，例如 50.0。最好只在应用启动时设置一次。如果您动态更改它，尤其是在动画运行时降低它，框架可能会观察到时间倒流，这可能会导致断言并通常干扰您的操作。
调试性能问题
#Flutter 提供了各种顶级属性和函数，可帮助您在开发周期的各个阶段调试您的应用。要使用这些功能，请在调试模式下编译您的应用。
以下列表重点介绍了一些来自渲染库的标志和一个函数，用于调试性能问题。
debugDumpRenderTree()要将渲染树转储到控制台，请在非布局或重绘阶段调用此函数。
要设置这些标志，请执行以下操作
- 编辑框架代码
- 导入模块，在您的
main()函数中设置值，然后热重启。
debugPaintLayerBordersEnabled- 要显示每个图层的边界，请将此属性设置为
true。设置后，每个图层都会在其边界周围绘制一个框。 debugRepaintRainbowEnabled- 要显示每个部件周围的彩色边框，请将此属性设置为
true。当应用用户在应用中滚动时，这些边框会改变颜色。要设置此标志，请在您的应用中添加debugRepaintRainbowEnabled = true;作为顶级属性。如果在设置此标志后任何静态部件旋转穿过颜色，请考虑向这些区域添加重绘边界。 debugPrintMarkNeedsLayoutStacks- 要确定您的应用是否创建了超出预期的布局，请将此属性设置为
true。此布局问题可能发生在时间线上、概要分析中或布局方法内的print语句中。设置后，框架会将堆栈跟踪输出到控制台，以解释您的应用为何标记每个渲染对象以进行布局。 debugPrintMarkNeedsPaintStacks- 要确定您的应用是否绘制了超出预期的布局，请将此属性设置为
true。
您也可以按需生成堆栈跟踪。要打印您自己的堆栈跟踪，请将debugPrintStack()函数添加到您的应用中。
跟踪 Dart 代码性能
#要执行自定义性能跟踪并测量任意 Dart 代码段的挂钟时间或 CPU 时间（如 Android 使用systrace所做的那样），请使用dart:developer Timeline实用程序。
打开您的源代码。
将要测量的代码包装在
Timeline方法中。dartimport 'dart:developer'; void main() { Timeline.startSync('interesting function'); // iWonderHowLongThisTakes(); Timeline.finishSync(); }连接到您的应用后，打开 DevTools 的时间线事件选项卡。
在“性能设置”中选择“Dart”录制选项。
执行要测量的函数。
要确保运行时性能特征与最终产品的特征非常接近，请在概要分析模式下运行您的应用。
添加性能覆盖层
#要在代码中启用PerformanceOverlay部件，请在MaterialApp、CupertinoApp或WidgetsApp构造函数上将showPerformanceOverlay属性设置为true
示例 10
#dart
import 'package:flutter/material.dart';
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
showPerformanceOverlay: true,
title: 'My Awesome App',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
),
home: const MyHomePage(title: 'My Awesome App'),
);
}
}（如果您未使用MaterialApp、CupertinoApp或WidgetsApp，则可以通过将您的应用包装在一个堆栈中并在堆栈上放置一个通过调用PerformanceOverlay.allEnabled()创建的部件来获得相同的效果。）
要了解如何解释覆盖图中的图表，请查看性能覆盖中的分析 Flutter 性能。
添加 Widget 对齐网格
#要在您的应用上添加覆盖到Material Design 基线网格以帮助验证对齐方式，请在MaterialApp构造函数中添加debugShowMaterialGrid参数。
要向非 Material 应用添加覆盖，请添加GridPaper部件。
除非另有说明，否则本网站上的文档反映了 Flutter 的最新稳定版本。页面上次更新于 2024-11-19。 查看源代码 或 报告问题.