Flutter Demo

铅笔侠_小龙虾2026-02-05 20:38

文章目录

前言

学习flutter时，flutter 官网加载比较慢, 那干脆直接看源码中的示例, 示例中包含了很多常用的组件, 这里收集一下, 方便后续查看.

正则查找

安装好 flutter, 在 ~/flutter/packages/flutter/lib/src 目录下有 flutter 源码, 可以直接查看.

bash 复制代码 
/// ```dart\s*\n(?:/// .*\n)*?/// ```

index

bash 复制代码 
AlertDialog,
Align,
Alignment,
AlwaysScrollableScrollPhysics,
AnimatedCrossFade,
AnimatedGrid,
AnimatedList,
AppBar,
AssetImage,

BackdropFilter,
BackdropGroup,
Border,
BorderSide,
BottomAppBar,
BouncingScrollPhysics,
BoxConstraints,
BoxDecoration,
BoxShadow,
Builder,
ButtonBar,
ButtonStyle,
ByteData,

Card,
CarouselView,
Center,
Checkbox,
CheckboxListTile,
Chip,
CircleAvatar,
ClipOval,
ClipRect,
Color,
ColoredBox,
Column,
ConstrainedBox,
ConstraintsTransformBox,
Container,
ContinuousRectangleBorder,
CupertinoApp,
CupertinoButton,
CupertinoListTile,
CupertinoNavigationBar,
CupertinoPageScaffold,
CupertinoSwitch,
CupertinoTextFormFieldRow,
CupertinoThemeData,
CurveTween,
CurvedAnimation,
CustomPaint,
CustomScrollView,

DecoratedBox,
DecorationImage,
DefaultAssetBundle,
DefaultTextEditingShortcuts,
Dialog,
Directionality,
DragBoundary,
Duration,

ElevatedButton,
ErrorSummary,
ExactAssetImage,
Expanded,

FadeInImage,
FadeTransition,
File,
FileImage,
FittedBox,
FlagProperty,
FlexibleSpaceBar,
FloatingActionButton,
FlutterErrorDetails,
FlutterLogo,
Foo,
FooLibraryBinding,
FooPlatformView,
FractionalOffset,

GestureDetector,
GradientRotation,
GravitySimulation,

HtmlElementView,

Icon,
IconButton,
IconData,
Image,
ImageFiltered,
IndexedSemantics,
Ink,
InkWell,
InputDecoration,

LinearGradient,
LinearProgressIndicator,
ListBody,
ListTile,
ListView,
LookupBoundary,

Material,
MaterialApp,
MaterialBanner,
MaterialScrollBehavior,
MediaQuery,
MemoryImage,
MenuStyle,
MenuThemeData,
MergeSemantics,
MessageProperty,
MyApp,
MyAppHome,
MyPage,
MyWidget,

NetworkImage,
NextFocusIntent,

Object,
Offset,
Opacity,
OutlinedButton,
OverflowBar,

Padding,
PageView,
Paint,
PlatformViewLink,
PlatformViewSurface,
PopupMenuDivider,
Positioned,
PreviousFocusIntent,
ProgressIndicatorTheme,
ProgressIndicatorThemeData,

RadialGradient,
RawGestureDetector,
ReorderableDragStartListener,
ReorderableList,
RequestFocusIntent,
ResizeImage,
RichText,
RotatedBox,
RotationTransition,
Row,

SafeArea,
Scaffold,
SelectAllTextIntent,
SelectableRegion,
SelectableText,
SemanticsLabelBuilder,
ShaderMask,
ShapeDecoration,
Shortcuts,
SimpleDialog,
SimpleDialogOption,
SingleActivator,
SingleChildScrollView,
Size,
SizedBox,
Sky,
SliverAppBar,
SliverChildBuilderDelegate,
SliverChildListDelegate,
SliverFixedExtentList,
SliverGrid,
SliverGridDelegateWithFixedCrossAxisCount,
SliverGridDelegateWithMaxCrossAxisExtent,
SliverList,
SliverPadding,
SliverReorderableList,
SnackBar,
Spacer,
SpringDescription,
SpringSimulation,
Stack,
StatefulBuilder,
Step,
StepStyle,
StringProperty,
StrutStyle,
SubmenuButton,
SuggestionSpan,
SweepGradient,
SwitchListTile,

TabController,
TapAndPanGestureRecognizer,
TapGestureRecognizer,
TestAssetBundle,
TestWidget,
Text,
TextButton,
TextButtonThemeData,
TextField,
TextFormField,
TextRange,
TextSelectionTheme,
TextSelectionThemeData,
TextSpan,
TextStyle,
ThemeData,
TimeOfDay,
ToggleButtons,
Tooltip,
TooltipTheme,
TooltipThemeData,
Transform,

View,
WidgetSpan,
Wrap

lib/src/animation

lib/src/animation/animation_controller.dart

dart 复制代码 
Future<void> fadeOutAndUpdateState() async {
  try {
    await fadeAnimationController.forward().orCancel;
    await sizeAnimationController.forward().orCancel;
    setState(() {
      dismissed = true;
    });
  } on TickerCanceled {
    // the animation got canceled, probably because we were disposed
  }
}

lib/src/animation/animations.dart

dart 复制代码 
final Animation<double> animation = CurvedAnimation(
  parent: controller,
  curve: Curves.ease,
);
dart 复制代码 
final Animation<double> animation = CurvedAnimation(
  parent: controller,
  curve: Curves.easeIn,
  reverseCurve: Curves.easeOut,
);

lib/src/animation/tween_sequence.dart

dart 复制代码 
final Animation<double> animation = TweenSequence<double>(
  <TweenSequenceItem<double>>[
    TweenSequenceItem<double>(
      tween: Tween<double>(begin: 5.0, end: 10.0)
        .chain(CurveTween(curve: Curves.ease)),
      weight: 40.0,
    ),
    TweenSequenceItem<double>(
      tween: ConstantTween<double>(10.0),
      weight: 20.0,
    ),
    TweenSequenceItem<double>(
      tween: Tween<double>(begin: 10.0, end: 5.0)
        .chain(CurveTween(curve: Curves.ease)),
      weight: 40.0,
    ),
  ],
).animate(myAnimationController);

lib/src/animation/tween.dart

dart 复制代码 
_animation = _controller.drive(
  Tween<Offset>(
    begin: const Offset(100.0, 50.0),
    end: const Offset(200.0, 300.0),
  ),
);
dart 复制代码 
_animation = Tween<Offset>(
  begin: const Offset(100.0, 50.0),
  end: const Offset(200.0, 300.0),
).animate(_controller);
dart 复制代码 
final Animation<double> animation = _controller.drive(
  CurveTween(curve: Curves.ease),
);

lib/src/cupertino

lib/src/cupertino/app.dart

dart 复制代码 
const CupertinoApp(
  home: CupertinoPageScaffold(
    navigationBar: CupertinoNavigationBar(
      middle: Text('Home'),
    ),
    child: Center(child: Icon(CupertinoIcons.share)),
  ),
  debugShowCheckedModeBanner: false,
)
dart 复制代码 
CupertinoApp(
  routes: <String, WidgetBuilder>{
    '/': (BuildContext context) {
      return const CupertinoPageScaffold(
        navigationBar: CupertinoNavigationBar(
          middle: Text('Home Route'),
        ),
        child: Center(child: Icon(CupertinoIcons.share)),
      );
    },
    '/about': (BuildContext context) {
      return const CupertinoPageScaffold(
        navigationBar: CupertinoNavigationBar(
          middle: Text('About Route'),
        ),
        child: Center(child: Icon(CupertinoIcons.share)),
      );
    }
  },
)
dart 复制代码 
const CupertinoApp(
  theme: CupertinoThemeData(
    brightness: Brightness.dark,
    primaryColor: CupertinoColors.systemOrange,
  ),
  home: CupertinoPageScaffold(
    navigationBar: CupertinoNavigationBar(
      middle: Text('CupertinoApp Theme'),
    ),
    child: Center(child: Icon(CupertinoIcons.share)),
  ),
)

lib/src/cupertino/colors.dart

dart 复制代码 
CupertinoButton(
  // CupertinoDynamicColor works out of box in a CupertinoButton.
  color: const CupertinoDynamicColor.withBrightness(
    color: CupertinoColors.white,
    darkColor: CupertinoColors.black,
  ),
  onPressed: () { },
  child: child,
)
dart 复制代码 
Container(
  // Container is not a Cupertino widget, but CupertinoTheme.of implicitly
  // resolves colors used in the retrieved CupertinoThemeData.
  color: CupertinoTheme.of(context).primaryColor,
)
dart 复制代码 
CupertinoNavigationBar(
  // CupertinoNavigationBar does not know how to resolve colors used in
  // a Border class.
  border: Border(
    bottom: BorderSide(
      color: CupertinoDynamicColor.resolve(CupertinoColors.systemBlue, context),
    ),
  ),
)
dart 复制代码 
Container(
  // Container is not a Cupertino widget.
  color: CupertinoDynamicColor.resolve(CupertinoColors.systemBlue, context),
)

lib/src/cupertino/debug.dart

dart 复制代码 
assert(debugCheckHasCupertinoLocalizations(context));

lib/src/cupertino/icons.dart

dart 复制代码 
const Row(
  mainAxisAlignment: MainAxisAlignment.spaceAround,
  children: <Widget>[
    Icon(
      CupertinoIcons.heart_fill,
      color: Colors.pink,
      size: 24.0,
      semanticLabel: 'Text to announce in accessibility modes',
    ),
    Icon(
      CupertinoIcons.bell_fill,
      color: Colors.green,
      size: 30.0,
    ),
    Icon(
      CupertinoIcons.umbrella_fill,
      color: Colors.blue,
      size: 36.0,
    ),
  ],
)

lib/src/cupertino/switch.dart

dart 复制代码 
MergeSemantics(
  child: CupertinoListTile(
    title: const Text('Lights'),
    trailing: CupertinoSwitch(
      value: _lights,
      onChanged: (bool value) { setState(() { _lights = value; }); },
    ),
    onTap: () { setState(() { _lights = !_lights; }); },
  ),
)

lib/src/cupertino/text_form_field_row.dart

dart 复制代码 
CupertinoTextFormFieldRow(
  prefix: const Text('Username'),
  onSaved: (String? value) {
    // This optional block of code can be used to run
    // code when the user saves the form.
  },
  validator: (String? value) {
    return (value != null && value.contains('@')) ? 'Do not use the @ char.' : null;
  },
)

lib/src/foundation

lib/src/foundation/annotations.dart

dart 复制代码 
/// A copper coffee pot, as desired by Ben Turpin.
/// ...documentation...
@Category(<String>['Pots', 'Coffee'])
@Category(<String>['Copper', 'Cookware'])
@DocumentationIcon('https://example.com/images/coffee.png')
@Summary('A proper cup of coffee is made in a proper copper coffee pot.')
class CopperCoffeePot {
  // ...code...
}
dart 复制代码 
/// Utility class for beginning a dream-sharing sequence.
/// ...documentation...
@Category(<String>['Military Technology', 'Experimental'])
@DocumentationIcon('https://docs.example.org/icons/top.png')
class DreamSharing {
  // ...code...
}
dart 复制代码 
/// A famous cat.
///
/// Instances of this class can hunt small animals.
/// This cat has three legs.
@Category(<String>['Animals', 'Cats'])
@Category(<String>['Cute', 'Pets'])
@DocumentationIcon('https://www.examples.net/docs/images/icons/pillar.jpeg')
@Summary('A famous three-legged cat.')
class Pillar extends Cat {
  // ...code...
}

lib/src/foundation/assertions.dart

dart 复制代码 
void main() {
  try {
    // Try to do something!
  } catch (error) {
    // Catch & report error.
    FlutterError.reportError(FlutterErrorDetails(
      exception: error,
      library: 'Flutter test framework',
      context: ErrorSummary('while running async test code'),
    ));
  }
}

lib/src/foundation/binding.dart

dart 复制代码 
// continuing from previous example...
class FooLibraryBinding extends BindingBase with BarBinding, FooBinding {
  static FooBinding ensureInitialized() {
    if (FooBinding._instance == null) {
      FooLibraryBinding();
    }
    return FooBinding.instance;
  }
}

lib/src/foundation/constants.dart

dart 复制代码 
assert(() {
  // ...debug-only code here...
  return true;
}());

lib/src/foundation/diagnostics.dart

dart 复制代码 
MessageProperty table = MessageProperty('table size', '$columns\u00D7$rows');
MessageProperty usefulness = MessageProperty('usefulness ratio', 'no metrics collected yet (never painted)');
dart 复制代码 
StringProperty name = StringProperty('name', _name);
dart 复制代码 
FlagProperty(
  'visible',
  value: true,
  ifFalse: 'hidden',
)
dart 复制代码 
FlagProperty(
  'inherit',
  value: inherit,
  ifTrue: '<all styles inherited>',
  ifFalse: '<no style specified>',
)

lib/src/foundation/print.dart

dart 复制代码 
if (kDebugMode) {
  debugPrint('A useful message');
}

lib/src/foundation/stack_frame.dart

dart 复制代码 
final List<StackFrame> currentFrames = StackFrame.fromStackTrace(StackTrace.current);

lib/src/gestures

lib/src/gestures/events.dart

dart 复制代码 
assert(smallestButton(0x01) == 0x01);
assert(smallestButton(0x11) == 0x01);
assert(smallestButton(0x10) == 0x10);
assert(smallestButton(0) == 0);
dart 复制代码 
  assert(isSingleButton(0x1));
  assert(!isSingleButton(0x11));
  assert(!isSingleButton(0));

lib/src/gestures/gesture_details.dart

dart 复制代码 
void handlePositionedGestures(PositionedGestureDetails details) {
  // Handle the positional information of the gesture details.
}

lib/src/gestures/pointer_signal_resolver.dart

dart 复制代码 
void handleSignalEvent(PointerSignalEvent event) {
  GestureBinding.instance.pointerSignalResolver.register(event, (PointerSignalEvent event) {
    // handle the event...
  });
}

lib/src/gestures/tap_and_drag.dart

dart 复制代码 
RawGestureDetector(
  gestures: <Type, GestureRecognizerFactory>{
    TapAndPanGestureRecognizer: GestureRecognizerFactoryWithHandlers<TapAndPanGestureRecognizer>(
      () => TapAndPanGestureRecognizer(),
      (TapAndPanGestureRecognizer instance) {
        instance
          ..onTapDown = (TapDragDownDetails details) { setState(() { _last = 'down_a'; }); }
          ..onDragStart = (TapDragStartDetails details) { setState(() { _last = 'drag_start_a'; }); }
          ..onDragUpdate = (TapDragUpdateDetails details) { setState(() { _last = 'drag_update_a'; }); }
          ..onDragEnd = (TapDragEndDetails details) { setState(() { _last = 'drag_end_a'; }); }
          ..onTapUp = (TapDragUpDetails details) { setState(() { _last = 'up_a'; }); }
          ..onCancel = () { setState(() { _last = 'cancel_a'; }); };
      },
    ),
  },
  child: Container(
    width: 300.0,
    height: 300.0,
    color: Colors.yellow,
    alignment: Alignment.center,
    child: RawGestureDetector(
      gestures: <Type, GestureRecognizerFactory>{
        TapAndPanGestureRecognizer: GestureRecognizerFactoryWithHandlers<TapAndPanGestureRecognizer>(
          () => TapAndPanGestureRecognizer(),
          (TapAndPanGestureRecognizer instance) {
            instance
              ..onTapDown = (TapDragDownDetails details) { setState(() { _last = 'down_b'; }); }
              ..onDragStart = (TapDragStartDetails details) { setState(() { _last = 'drag_start_b'; }); }
              ..onDragUpdate = (TapDragUpdateDetails details) { setState(() { _last = 'drag_update_b'; }); }
              ..onDragEnd = (TapDragEndDetails details) { setState(() { _last = 'drag_end_b'; }); }
              ..onTapUp = (TapDragUpDetails details) { setState(() { _last = 'up_b'; }); }
              ..onCancel = () { setState(() { _last = 'cancel_b'; }); };
          },
        ),
      },
      child: Container(
        width: 150.0,
        height: 150.0,
        color: Colors.blue,
        child: Text(_last),
      ),
    ),
  ),
)

lib/src/material

lib/src/material/app_bar.dart

dart 复制代码 
SliverAppBar(
  expandedHeight: 150.0,
  flexibleSpace: const FlexibleSpaceBar(
    title: Text('Available seats'),
  ),
  actions: <Widget>[
    IconButton(
      icon: const Icon(Icons.add_circle),
      tooltip: 'Add new entry',
      onPressed: () { /* ... */ },
    ),
  ]
)

lib/src/material/app.dart

dart 复制代码 
MaterialApp(
  home: Scaffold(
    appBar: AppBar(
      title: const Text('Home'),
    ),
  ),
  debugShowCheckedModeBanner: false,
)
dart 复制代码 
MaterialApp(
  routes: <String, WidgetBuilder>{
    '/': (BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: const Text('Home Route'),
        ),
      );
    },
    '/about': (BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: const Text('About Route'),
        ),
      );
     }
   },
)
dart 复制代码 
MaterialApp(
  theme: ThemeData(
    brightness: Brightness.dark,
    primaryColor: Colors.blueGrey
  ),
  home: Scaffold(
    appBar: AppBar(
      title: const Text('MaterialApp Theme'),
    ),
  ),
)
dart 复制代码 
const MaterialApp(
  title: 'Material App',
  home: Scaffold(
    body: Center(
      child: Text('Hello World'),
    ),
  ),
)

lib/src/material/banner.dart

dart 复制代码 
ScaffoldMessenger.of(context).showMaterialBanner(
  const MaterialBanner(
    content: Text('Message...'),
    actions: <Widget>[
      // ...
    ],
  )
).closed.then((MaterialBannerClosedReason reason) {
   // ...
});

lib/src/material/bottom_app_bar.dart

dart 复制代码 
Scaffold(
  bottomNavigationBar: BottomAppBar(
    color: Colors.white,
    child: bottomAppBarContents,
  ),
  floatingActionButton: const FloatingActionButton(onPressed: null),
)

lib/src/material/button_bar.dart

dart 复制代码 
// Before
ButtonBar(
  alignment: MainAxisAlignment.spaceEvenly,
  children: <Widget>[
    TextButton( child: const Text('Button 1'), onPressed: () {}),
    TextButton( child: const Text('Button 2'), onPressed: () {}),
    TextButton( child: const Text('Button 3'), onPressed: () {}),
  ],
);
dart 复制代码 
// After
OverflowBar(
  alignment: MainAxisAlignment.spaceEvenly,
  children: <Widget>[
    TextButton( child: const Text('Button 1'), onPressed: () {}),
    TextButton( child: const Text('Button 2'), onPressed: () {}),
    TextButton( child: const Text('Button 3'), onPressed: () {}),
  ],
);

lib/src/material/button_style.dart

dart 复制代码 
ElevatedButton(
  style: ButtonStyle(
    backgroundColor: WidgetStateProperty.resolveWith<Color?>(
      (Set<WidgetState> states) {
        if (states.contains(WidgetState.pressed)) {
          return Theme.of(context).colorScheme.primary.withOpacity(0.5);
        }
        return null; // Use the component's default.
      },
    ),
  ),
  child: const Text('Fly me to the moon'),
  onPressed: () {
    // ...
  },
),
dart 复制代码 
ElevatedButton(
  style: const ButtonStyle(
    backgroundColor: WidgetStatePropertyAll<Color>(Colors.green),
  ),
  child: const Text('Let me play among the stars'),
  onPressed: () {
    // ...
  },
),
dart 复制代码 
TextButton(
  style: TextButton.styleFrom(foregroundColor: Colors.green),
  child: const Text('Let me see what spring is like'),
  onPressed: () {
    // ...
  },
),
dart 复制代码 
MaterialApp(
  theme: ThemeData(
    textButtonTheme: TextButtonThemeData(
      style: TextButton.styleFrom(foregroundColor: Colors.green),
    ),
  ),
  home: const MyAppHome(),
),

lib/src/material/carousel.dart

dart 复制代码 
Scaffold(
  body: CarouselView(
    scrollDirection: Axis.vertical,
    itemExtent: double.infinity,
    children: List<Widget>.generate(10, (int index) {
      return Center(child: Text('Item $index'));
    }),
  ),
),
dart 复制代码 
Scaffold(
  body: CarouselView.weighted(
    scrollDirection: Axis.vertical,
    flexWeights: const <int>[1], // Or any positive integers as long as the length of the array is 1.
    children: List<Widget>.generate(10, (int index) {
      return Center(child: Text('Item $index'));
    }),
  ),
),

lib/src/material/checkbox_list_tile.dart

dart 复制代码 
ColoredBox(
  color: Colors.green,
  child: Material(
    child: CheckboxListTile(
      tileColor: Colors.red,
      title: const Text('CheckboxListTile with red background'),
      value: true,
      onChanged:(bool? value) { },
    ),
  ),
)

lib/src/material/chip.dart

dart 复制代码 
Chip(
  avatar: CircleAvatar(
    backgroundColor: Colors.grey.shade800,
    child: const Text('AB'),
  ),
  label: const Text('Aaron Burr'),
)

lib/src/material/circle_avatar.dart

dart 复制代码 
CircleAvatar(
  backgroundImage: NetworkImage(userAvatarUrl),
)
dart 复制代码 
CircleAvatar(
  backgroundColor: Colors.brown.shade800,
  child: const Text('AH'),
)

lib/src/material/colors.dart

dart 复制代码 
ThemeData(
  primarySwatch: Colors.amber,
)
dart 复制代码 
ThemeData(
 colorScheme: ColorScheme.fromSwatch(primarySwatch: Colors.amber),
)
dart 复制代码 
Color selection = Colors.green[400]!; // Selects a mid-range green.
dart 复制代码 
Container(
  color: Colors.blue, // same as Colors.blue[500] or Colors.blue.shade500
)

lib/src/material/debug.dart

dart 复制代码 
assert(debugCheckHasMaterial(context));
dart 复制代码 
assert(debugCheckHasMaterialLocalizations(context));
dart 复制代码 
assert(debugCheckHasScaffold(context));
dart 复制代码 
assert(debugCheckHasScaffoldMessenger(context));

lib/src/material/dialog.dart

dart 复制代码 
const Dialog(constraints: BoxConstraints(maxWidth: 560, minHeight: 280));
dart 复制代码 
Future<void> _showMyDialog() async {
  return showDialog<void>(
    context: context,
    barrierDismissible: false, // user must tap button!
    builder: (BuildContext context) {
      return AlertDialog(
        title: const Text('AlertDialog Title'),
        content: const SingleChildScrollView(
          child: ListBody(
            children: <Widget>[
              Text('This is a demo alert dialog.'),
              Text('Would you like to approve of this message?'),
            ],
          ),
        ),
        actions: <Widget>[
          TextButton(
            child: const Text('Approve'),
            onPressed: () {
              Navigator.of(context).pop();
            },
          ),
        ],
      );
    },
  );
}
dart 复制代码 
SimpleDialogOption(
  onPressed: () { Navigator.pop(context, Department.treasury); },
  child: const Text('Treasury department'),
)
dart 复制代码 
Future<void> _askedToLead() async {
  switch (await showDialog<Department>(
    context: context,
    builder: (BuildContext context) {
      return SimpleDialog(
        title: const Text('Select assignment'),
        children: <Widget>[
          SimpleDialogOption(
            onPressed: () { Navigator.pop(context, Department.treasury); },
            child: const Text('Treasury department'),
          ),
          SimpleDialogOption(
            onPressed: () { Navigator.pop(context, Department.state); },
            child: const Text('State department'),
          ),
        ],
      );
    }
  )) {
    case Department.treasury:
      // Let's go.
      // ...
    break;
    case Department.state:
      // ...
    break;
    case null:
      // dialog dismissed
    break;
  }
}

lib/src/material/drawer.dart

dart 复制代码 
ListTile(
  leading: const Icon(Icons.change_history),
  title: const Text('Change history'),
  onTap: () {
    // change app state...
    Navigator.pop(context); // close the drawer
  },
);

lib/src/material/icon_button.dart

dart 复制代码 
IconButton(
  iconSize: 72,
  icon: const Icon(Icons.favorite),
  onPressed: () {
    // ...
  },
),
dart 复制代码 
IconButton(
  icon: const Icon(Icons.favorite, size: 72),
  onPressed: () {
    // ...
  },
),

lib/src/material/icons.dart

dart 复制代码 
const Row(
  mainAxisAlignment: MainAxisAlignment.spaceAround,
  children: <Widget>[
    Icon(
      Icons.favorite,
      color: Colors.pink,
      size: 24.0,
      semanticLabel: 'Text to announce in accessibility modes',
    ),
    Icon(
      Icons.audiotrack,
      color: Colors.green,
      size: 30.0,
    ),
    Icon(
      Icons.beach_access,
      color: Colors.blue,
      size: 36.0,
    ),
  ],
)

lib/src/material/ink_decoration.dart

dart 复制代码 
Material(
  color: Colors.teal[900],
  child: Center(
    child: Ink(
      color: Colors.yellow,
      width: 200.0,
      height: 100.0,
      child: InkWell(
        onTap: () { /* ... */ },
        child: const Center(
          child: Text('YELLOW'),
        )
      ),
    ),
  ),
)
dart 复制代码 
Material(
  color: Colors.grey[800],
  child: Center(
    child: Ink.image(
      image: const AssetImage('cat.jpeg'),
      fit: BoxFit.cover,
      width: 300.0,
      height: 200.0,
      child: InkWell(
        onTap: () { /* ... */ },
        child: const Align(
          alignment: Alignment.topLeft,
          child: Padding(
            padding: EdgeInsets.all(10.0),
            child: Text(
              'KITTEN',
              style: TextStyle(
                fontWeight: FontWeight.w900,
                color: Colors.white,
              ),
            ),
          ),
        )
      ),
    ),
  ),
)

lib/src/material/ink_sparkle.dart

dart 复制代码 
ElevatedButton(
  style: ElevatedButton.styleFrom(splashFactory: InkSparkle.splashFactory),
  child: const Text('Sparkle!'),
  onPressed: () { },
)

lib/src/material/ink_well.dart

dart 复制代码 
assert(debugCheckHasMaterial(context));
dart 复制代码 
assert(debugCheckHasMaterial(context));

lib/src/material/list_tile.dart

dart 复制代码 
const ColoredBox(
  color: Colors.green,
  child: Material(
    child: ListTile(
      title: Text('ListTile with red background'),
      tileColor: Colors.red,
    ),
  ),
)
dart 复制代码 
const Row(
  children: <Widget>[
    Expanded(
      child: ListTile(
        leading: FlutterLogo(),
        title: Text('These ListTiles are expanded '),
      ),
    ),
    Expanded(
      child: ListTile(
        trailing: FlutterLogo(),
        title: Text('to fill the available space.'),
      ),
    ),
  ],
)
dart 复制代码 
ListTile(
  leading: const Icon(Icons.flight_land),
  title: const Text("Trix's airplane"),
  subtitle: _act != 2 ? const Text('The airplane is only in Act II.') : null,
  enabled: _act == 2,
  onTap: () { /* react to the tile being tapped */ }
)
dart 复制代码 
ListTile(
  leading: GestureDetector(
    behavior: HitTestBehavior.translucent,
    onTap: () {},
    child: Container(
      width: 48,
      height: 48,
      padding: const EdgeInsets.symmetric(vertical: 4.0),
      alignment: Alignment.center,
      child: const CircleAvatar(),
    ),
  ),
  title: const Text('title'),
  dense: false,
)

lib/src/material/menu_style.dart

dart 复制代码 
SubmenuButton(
  menuStyle: MenuStyle(
    backgroundColor: WidgetStateProperty.resolveWith<Color?>(
      (Set<WidgetState> states) {
        if (states.contains(WidgetState.focused)) {
          return Theme.of(context).colorScheme.primary.withOpacity(0.5);
        }
        return null; // Use the component's default.
      },
    ),
  ),
  menuChildren: const <Widget>[ /* ... */ ],
  child: const Text('Fly me to the moon'),
),
dart 复制代码 
const SubmenuButton(
  menuStyle: MenuStyle(
    backgroundColor: WidgetStatePropertyAll<Color>(Colors.green),
  ),
  menuChildren: <Widget>[ /* ... */ ],
  child: Text('Let me play among the stars'),
),
dart 复制代码 
MaterialApp(
  theme: ThemeData(
    menuTheme: const MenuThemeData(
      style: MenuStyle(backgroundColor: WidgetStatePropertyAll<Color>(Colors.red)),
    ),
  ),
  home: const MyAppHome(),
),

lib/src/material/no_splash.dart

dart 复制代码 
ElevatedButton(
  style: ElevatedButton.styleFrom(
    splashFactory: NoSplash.splashFactory,
  ),
  onPressed: () { },
  child: const Text('No Splash'),
)

lib/src/material/popup_menu.dart

dart 复制代码 
const PopupMenuItem<Menu>(
  value: Menu.itemOne,
  child: Text('Item 1'),
)
dart 复制代码 
PopupMenuButton<Commands>(
  onSelected: (Commands result) {
    switch (result) {
      case Commands.heroAndScholar:
        setState(() { _heroAndScholar = !_heroAndScholar; });
      case Commands.hurricaneCame:
        // ...handle hurricane option
        break;
      // ...other items handled here
    }
  },
  itemBuilder: (BuildContext context) => <PopupMenuEntry<Commands>>[
    CheckedPopupMenuItem<Commands>(
      checked: _heroAndScholar,
      value: Commands.heroAndScholar,
      child: const Text('Hero and scholar'),
    ),
    const PopupMenuDivider(),
    const PopupMenuItem<Commands>(
      value: Commands.hurricaneCame,
      child: ListTile(leading: Icon(null), title: Text('Bring hurricane')),
    ),
    // ...other items listed here
  ],
)

lib/src/material/progress_indicator_theme.dart

dart 复制代码 
const ProgressIndicatorTheme(
  data: ProgressIndicatorThemeData(
    color: Colors.red,
  ),
  child: LinearProgressIndicator()
)

lib/src/material/radio_list_tile.dart

dart 复制代码 
const ColoredBox(
  color: Colors.green,
  child: Material(
    child: RadioListTile<Meridiem>(
      tileColor: Colors.red,
      title: Text('AM'),
      value: Meridiem.am,
    ),
  ),
)

lib/src/material/refresh_indicator.dart

dart 复制代码 
ListView(
  physics: const AlwaysScrollableScrollPhysics(),
  // ...
)

lib/src/material/scaffold.dart

dart 复制代码 
TabController(vsync: tickerProvider, length: tabCount)..addListener(() {
  if (!tabController.indexIsChanging) {
    setState(() {
      // Rebuild the enclosing scaffold with a new AppBar title
      appBarTitle = 'Tab ${tabController.index}';
    });
  }
})

lib/src/material/selectable_text.dart

dart 复制代码 
const SelectableText(
  'Hello! How are you?',
  textAlign: TextAlign.center,
  style: TextStyle(fontWeight: FontWeight.bold),
)
dart 复制代码 
const SelectableText.rich(
  TextSpan(
    text: 'Hello', // default text style
    children: <TextSpan>[
      TextSpan(text: ' beautiful ', style: TextStyle(fontStyle: FontStyle.italic)),
      TextSpan(text: 'world', style: TextStyle(fontWeight: FontWeight.bold)),
    ],
  ),
)

lib/src/material/shadows.dart

dart 复制代码 
kElevationToShadow[12]!.map((BoxShadow shadow) => shadow.copyWith(blurStyle: BlurStyle.outer)).toList(),

lib/src/material/snack_bar.dart

dart 复制代码 
ScaffoldMessenger.of(context).showSnackBar(
  const SnackBar(
    content: Text('He likes me. I think he likes me.'),
  )
).closed.then((SnackBarClosedReason reason) {
   // ...
});

lib/src/material/stepper.dart

dart 复制代码 
Step(
  title: const Text('Step 1'),
  content: const Text('Content for Step 1'),
  stepStyle: StepStyle(
    color: Colors.blue,
    errorColor: Colors.red,
    border: Border.all(color: Colors.grey),
    boxShadow: const BoxShadow(blurRadius: 3.0, color: Colors.black26),
    gradient: const LinearGradient(colors: <Color>[Colors.red, Colors.blue]),
    indexStyle: const TextStyle(color: Colors.white),
  ),
)

lib/src/material/switch_list_tile.dart

dart 复制代码 
ColoredBox(
  color: Colors.green,
  child: Material(
    child: SwitchListTile(
      tileColor: Colors.red,
      title: const Text('SwitchListTile with red background'),
      value: true,
      onChanged:(bool? value) { },
    ),
  ),
)

lib/src/material/text_form_field.dart

dart 复制代码 
TextFormField(
  decoration: const InputDecoration(
    icon: Icon(Icons.person),
    hintText: 'What do people call you?',
    labelText: 'Name *',
  ),
  onSaved: (String? value) {
    // This optional block of code can be used to run
    // code when the user saves the form.
  },
  validator: (String? value) {
    return (value != null && value.contains('@')) ? 'Do not use the @ char.' : null;
  },
)

lib/src/material/text_selection_theme.dart

dart 复制代码 
const TextSelectionTheme(
  data: TextSelectionThemeData(
    cursorColor: Colors.blue,
    selectionHandleColor: Colors.lightBlue,
  ),
  child: TextField(),
)

lib/src/material/time_picker.dart

dart 复制代码 
Future<TimeOfDay?> selectedTime = showTimePicker(
  initialTime: TimeOfDay.now(),
  context: context,
);
dart 复制代码 
Future<TimeOfDay?> selectedTimeRTL = showTimePicker(
  context: context,
  initialTime: TimeOfDay.now(),
  builder: (BuildContext context, Widget? child) {
    return Directionality(
      textDirection: TextDirection.rtl,
      child: child!,
    );
  },
);
dart 复制代码 
Future<TimeOfDay?> selectedTime24Hour = showTimePicker(
  context: context,
  initialTime: const TimeOfDay(hour: 10, minute: 47),
  builder: (BuildContext context, Widget? child) {
    return MediaQuery(
      data: MediaQuery.of(context).copyWith(alwaysUse24HourFormat: true),
      child: child!,
    );
  },
);

lib/src/material/time.dart

dart 复制代码 
TimeOfDay now = TimeOfDay.now();
const TimeOfDay releaseTime = TimeOfDay(hour: 15, minute: 0); // 3:00pm
TimeOfDay roomBooked = TimeOfDay.fromDateTime(DateTime.parse('2018-10-20 16:30:04Z')); // 4:30pm

lib/src/material/toggle_buttons.dart

dart 复制代码 
ToggleButtons(
  isSelected: isSelected,
  onPressed: (int index) {
    setState(() {
      isSelected[index] = !isSelected[index];
    });
  },
  children: const <Widget>[
    Icon(Icons.ac_unit),
    Icon(Icons.call),
    Icon(Icons.cake),
  ],
),
dart 复制代码 
ToggleButtons(
  isSelected: isSelected,
  onPressed: (int index) {
    setState(() {
      for (int buttonIndex = 0; buttonIndex < isSelected.length; buttonIndex++) {
        if (buttonIndex == index) {
          isSelected[buttonIndex] = true;
        } else {
          isSelected[buttonIndex] = false;
        }
      }
    });
  },
  children: const <Widget>[
    Icon(Icons.ac_unit),
    Icon(Icons.call),
    Icon(Icons.cake),
  ],
),
dart 复制代码 
ToggleButtons(
  isSelected: isSelected,
  onPressed: (int index) {
    setState(() {
      for (int buttonIndex = 0; buttonIndex < isSelected.length; buttonIndex++) {
        if (buttonIndex == index) {
          isSelected[buttonIndex] = !isSelected[buttonIndex];
        } else {
          isSelected[buttonIndex] = false;
        }
      }
    });
  },
  children: const <Widget>[
    Icon(Icons.ac_unit),
    Icon(Icons.call),
    Icon(Icons.cake),
  ],
),
dart 复制代码 
ToggleButtons(
  isSelected: isSelected,
  onPressed: (int index) {
    int count = 0;
    for (final bool value in isSelected) {
      if (value) {
        count += 1;
      }
    }
    if (isSelected[index] && count < 2) {
      return;
    }
    setState(() {
      isSelected[index] = !isSelected[index];
    });
  },
  children: const <Widget>[
    Icon(Icons.ac_unit),
    Icon(Icons.call),
    Icon(Icons.cake),
  ],
),

lib/src/material/tooltip_theme.dart

dart 复制代码 
TooltipTheme(
  data: TooltipThemeData(
    decoration: BoxDecoration(
      color: Colors.blue.withOpacity(0.9),
      borderRadius: BorderRadius.zero,
    ),
  ),
  child: Tooltip(
    message: 'Example tooltip',
    child: IconButton(
      iconSize: 36.0,
      icon: const Icon(Icons.touch_app),
      onPressed: () {},
    ),
  ),
)

lib/src/material/typography.dart

dart 复制代码 
typography: Typography.material2018(platform: platform)

lib/src/painting

lib/src/painting/borders.dart

dart 复制代码 
Container(
  padding: const EdgeInsets.all(8.0),
  decoration: BoxDecoration(
    border: Border(
      top: BorderSide(width: 16.0, color: Colors.lightBlue.shade50),
      bottom: BorderSide(width: 16.0, color: Colors.lightBlue.shade900),
    ),
  ),
  child: const Text('Flutter in the sky', textAlign: TextAlign.center),
)

lib/src/painting/box_border.dart

dart 复制代码 
Border.all(width: 2.0, color: const Color(0xFFFFFFFF))
dart 复制代码 
Border(bottom: BorderSide(color: Theme.of(context).dividerColor))
dart 复制代码 
Container(
  decoration: const BoxDecoration(
    border: Border(
      top: BorderSide(color: Color(0xFFFFFFFF)),
      left: BorderSide(color: Color(0xFFFFFFFF)),
      right: BorderSide(),
      bottom: BorderSide(),
    ),
  ),
  child: Container(
    padding: const EdgeInsets.symmetric(horizontal: 20.0, vertical: 2.0),
    decoration: const BoxDecoration(
      border: Border(
        top: BorderSide(color: Color(0xFFDFDFDF)),
        left: BorderSide(color: Color(0xFFDFDFDF)),
        right: BorderSide(color: Color(0xFF7F7F7F)),
        bottom: BorderSide(color: Color(0xFF7F7F7F)),
      ),
      color: Color(0xFFBFBFBF),
    ),
    child: const Text(
      'OK',
      textAlign: TextAlign.center,
      style: TextStyle(color: Color(0xFF000000))
    ),
  ),
)

lib/src/painting/box_decoration.dart

dart 复制代码 
Container(
  decoration: BoxDecoration(
    color: const Color(0xff7c94b6),
    image: const DecorationImage(
      image: NetworkImage('https://flutter.github.io/assets-for-api-docs/assets/widgets/owl-2.jpg'),
      fit: BoxFit.cover,
    ),
    border: Border.all(
      width: 8,
    ),
    borderRadius: BorderRadius.circular(12),
  ),
)

lib/src/painting/box_fit.dart

dart 复制代码 
void paintImage(ui.Image image, Rect outputRect, Canvas canvas, Paint paint, BoxFit fit) {
  final Size imageSize = Size(image.width.toDouble(), image.height.toDouble());
  final FittedSizes sizes = applyBoxFit(fit, imageSize, outputRect.size);
  final Rect inputSubrect = Alignment.center.inscribe(sizes.source, Offset.zero & imageSize);
  final Rect outputSubrect = Alignment.center.inscribe(sizes.destination, outputRect);
  canvas.drawImageRect(image, inputSubrect, outputSubrect, paint);
}

lib/src/painting/continuous_rectangle_border.dart

dart 复制代码 
Widget build(BuildContext context) {
  return Material(
    shape: ContinuousRectangleBorder(
      borderRadius: BorderRadius.circular(28.0),
    ),
  );
}

lib/src/painting/edge_insets.dart

dart 复制代码 
const EdgeInsets.all(8.0)
dart 复制代码 
const EdgeInsets.symmetric(vertical: 8.0)
dart 复制代码 
const EdgeInsets.only(left: 40.0)

lib/src/painting/gradient.dart

dart 复制代码 
const SweepGradient gradient = SweepGradient(
  colors: <Color>[Color(0xFFFFFFFF), Color(0xFF009900)],
  transform: GradientRotation(math.pi/4),
);
dart 复制代码 
void paintSky(Canvas canvas, Rect rect) {
  const RadialGradient gradient = RadialGradient(
    center: Alignment(0.7, -0.6), // near the top right
    radius: 0.2,
    colors: <Color>[
      Color(0xFFFFFF00), // yellow sun
      Color(0xFF0099FF), // blue sky
    ],
    stops: <double>[0.4, 1.0],
  );
  // rect is the area we are painting over
  final Paint paint = Paint()
    ..shader = gradient.createShader(rect);
  canvas.drawRect(rect, paint);
}
dart 复制代码 
Container(
  decoration: const BoxDecoration(
    gradient: SweepGradient(
      center: FractionalOffset.center,
      colors: <Color>[
        Color(0xFF4285F4), // blue
        Color(0xFF34A853), // green
        Color(0xFFFBBC05), // yellow
        Color(0xFFEA4335), // red
        Color(0xFF4285F4), // blue again to seamlessly transition to the start
      ],
      stops: <double>[0.0, 0.25, 0.5, 0.75, 1.0],
    ),
  )
)
dart 复制代码 
Container(
  decoration: const BoxDecoration(
    gradient: SweepGradient(
      center: FractionalOffset.center,
      colors: <Color>[
        Color(0xFF4285F4), // blue
        Color(0xFF34A853), // green
        Color(0xFFFBBC05), // yellow
        Color(0xFFEA4335), // red
        Color(0xFF4285F4), // blue again to seamlessly transition to the start
      ],
      stops: <double>[0.0, 0.25, 0.5, 0.75, 1.0],
      transform: GradientRotation(math.pi/4),
    ),
  ),
)

lib/src/painting/image_provider.dart

dart 复制代码 
   Image(
     image: ResizeImage(
       FileImage(File('path/to/image')),
       width: MediaQuery.widthOf(context) ~/ 2, // Half of the screen's width.
     ),
   );
dart 复制代码 
const ExactAssetImage('icons/heart.png', scale: 1.5)
dart 复制代码 
const ExactAssetImage('icons/heart.png', scale: 1.5, package: 'my_icons')

lib/src/painting/image_resolution.dart

dart 复制代码 
const AssetImage('icons/heart.png')
dart 复制代码 
const AssetImage('icons/heart.png', package: 'my_icons')

lib/src/painting/inline_span.dart

dart 复制代码 
Text.rich(
  TextSpan(
    text: 'My name is ',
    style: const TextStyle(color: Colors.black),
    children: <InlineSpan>[
      WidgetSpan(
        alignment: PlaceholderAlignment.baseline,
        baseline: TextBaseline.alphabetic,
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 100),
          child: const TextField(),
        )
      ),
      const TextSpan(
        text: '.',
      ),
    ],
  ),
)

lib/src/painting/shape_decoration.dart

dart 复制代码 
Container(
  decoration: ShapeDecoration(
    color: Colors.white,
    shape: Border.all(
      color: Colors.red,
      width: 8.0,
    ) + Border.all(
      color: Colors.green,
      width: 8.0,
    ) + Border.all(
      color: Colors.blue,
      width: 8.0,
    ),
  ),
  child: const Text('RGB', textAlign: TextAlign.center),
)

lib/src/painting/strut_style.dart

dart 复制代码 
const Text(
  'Hello, world!\nSecond line!',
  style: TextStyle(
    fontSize: 10,
    fontFamily: 'Raleway',
  ),
  strutStyle: StrutStyle(
    fontFamily: 'Roboto',
    fontSize: 30,
    height: 1.5,
  ),
)
dart 复制代码 
const Text.rich(
  TextSpan(
    text: 'First line!\n',
    style: TextStyle(
      fontSize: 14,
      fontFamily: 'Roboto'
    ),
    children: <TextSpan>[
      TextSpan(
        text: 'Second line!\n',
        style: TextStyle(
          fontSize: 16,
          fontFamily: 'Roboto',
        ),
      ),
      TextSpan(
        text: 'Third line!\n',
        style: TextStyle(
          fontSize: 14,
          fontFamily: 'Roboto',
        ),
      ),
    ],
  ),
  strutStyle: StrutStyle(
    fontFamily: 'Roboto',
    height: 1.5,
  ),
)
dart 复制代码 
const Text.rich(
  TextSpan(
    text: '---------         ---------\n',
    style: TextStyle(
      fontSize: 14,
      fontFamily: 'Roboto',
    ),
    children: <TextSpan>[
      TextSpan(
        text: '^^^M^^^\n',
        style: TextStyle(
          fontSize: 30,
          fontFamily: 'Roboto',
        ),
      ),
      TextSpan(
        text: 'M------M\n',
        style: TextStyle(
          fontSize: 30,
          fontFamily: 'Roboto',
        ),
      ),
    ],
  ),
  strutStyle: StrutStyle(
    fontFamily: 'Roboto',
    fontSize: 14,
    height: 1,
    forceStrutHeight: true,
  ),
)
dart 复制代码 
const Text.rich(
  TextSpan(
    text: '       he candle flickered\n',
    style: TextStyle(
      fontSize: 14,
      fontFamily: 'Serif'
    ),
    children: <TextSpan>[
      TextSpan(
        text: 'T',
        style: TextStyle(
          fontSize: 37,
          fontFamily: 'Serif'
        ),
      ),
      TextSpan(
        text: 'in the moonlight as\n',
        style: TextStyle(
          fontSize: 14,
          fontFamily: 'Serif'
        ),
      ),
      TextSpan(
        text: 'Dash the bird fluttered\n',
        style: TextStyle(
          fontSize: 14,
          fontFamily: 'Serif'
        ),
      ),
      TextSpan(
        text: 'off into the distance.',
        style: TextStyle(
          fontSize: 14,
          fontFamily: 'Serif'
        ),
      ),
    ],
  ),
  strutStyle: StrutStyle(
    fontFamily: 'Serif',
    fontSize: 14,
    forceStrutHeight: true,
  ),
)

lib/src/painting/text_span.dart

dart 复制代码 
const TextSpan(
  text: 'Hello world!',
  style: TextStyle(color: Colors.black),
)

lib/src/painting/text_style.dart

dart 复制代码 
const Text(
  'No, we need bold strokes. We need this plan.',
  style: TextStyle(fontWeight: FontWeight.bold),
)
dart 复制代码 
const Text(
  "Welcome to the present, we're running a real nation.",
  style: TextStyle(fontStyle: FontStyle.italic),
)
dart 复制代码 
RichText(
  text: TextSpan(
    style: DefaultTextStyle.of(context).style,
    children: <TextSpan>[
      TextSpan(
        text: "You don't have the votes.\n",
        style: TextStyle(color: Colors.black.withOpacity(0.6)),
      ),
      TextSpan(
        text: "You don't have the votes!\n",
        style: TextStyle(color: Colors.black.withOpacity(0.8)),
      ),
      TextSpan(
        text: "You're gonna need congressional approval and you don't have the votes!\n",
        style: TextStyle(color: Colors.black.withOpacity(1.0)),
      ),
    ],
  ),
)
dart 复制代码 
Text(
  "These are wise words, enterprising men quote 'em.",
  style: DefaultTextStyle.of(context).style.apply(fontSizeFactor: 2.0),
)
dart 复制代码 
const Text(
  'Ladies and gentlemen, you coulda been anywhere in the world tonight, but you're here with us in New York City.',
  style: TextStyle(height: 5, fontSize: 10),
)
dart 复制代码 
RichText(
  text: const TextSpan(
    text: "Don't tax the South ",
    children: <TextSpan>[
      TextSpan(
        text: 'cuz',
        style: TextStyle(
          color: Colors.black,
          decoration: TextDecoration.underline,
          decorationColor: Colors.red,
          decorationStyle: TextDecorationStyle.wavy,
        ),
      ),
      TextSpan(
        text: ' we got it made in the shade',
      ),
    ],
  ),
)
dart 复制代码 
Stack(
  children: <Widget>[
    // Stroked text as border.
    Text(
      'Greetings, planet!',
      style: TextStyle(
        fontSize: 40,
        foreground: Paint()
          ..style = PaintingStyle.stroke
          ..strokeWidth = 6
          ..color = Colors.blue[700]!,
      ),
    ),
    // Solid text as fill.
    Text(
      'Greetings, planet!',
      style: TextStyle(
        fontSize: 40,
        color: Colors.grey[300],
      ),
    ),
  ],
)
dart 复制代码 
Text(
  'Greetings, planet!',
  style: TextStyle(
    fontSize: 40,
    foreground: Paint()
      ..shader = ui.Gradient.linear(
        const Offset(0, 20),
        const Offset(150, 20),
        <Color>[
          Colors.red,
          Colors.yellow,
        ],
      )
  ),
)
dart 复制代码 
const TextStyle(fontFamily: 'Raleway')
dart 复制代码 
const TextStyle(fontFamily: 'Raleway', package: 'my_package')
dart 复制代码 
const TextStyle(fontFamily: 'Raleway')
dart 复制代码 
const TextStyle(
  fontFamily: 'Raleway',
  fontFamilyFallback: <String>[
    'Noto Sans CJK SC',
    'Noto Color Emoji',
  ],
)

lib/src/physics

lib/src/physics/gravity_simulation.dart

dart 复制代码 
void _startFall() {
  _controller.animateWith(GravitySimulation(
    10.0, // acceleration, pixels per second per second
    0.0, // starting position, pixels
    300.0, // ending position, pixels
    0.0, // starting velocity, pixels per second
  ));
}

lib/src/physics/spring_simulation.dart

dart 复制代码 
void _startSpringMotion() {
  _controller.animateWith(SpringSimulation(
    const SpringDescription(
      mass: 1.0,
      stiffness: 300.0,
      damping: 15.0,
    ),
    0.0, // starting position
    1.0, // ending position
    0.0, // starting velocity
  ));
}

lib/src/rendering/box.dart

dart 复制代码 
AxisDirection get axis => _axis;
AxisDirection _axis = AxisDirection.down; // or initialized in constructor
set axis(AxisDirection value) {
  if (value == _axis) {
    return;
  }
  _axis = value;
  markNeedsLayout();
}
dart 复制代码 
class RenderFoo extends RenderBox
  with RenderObjectWithChildMixin<RenderBar> {
  // ...
}
dart 复制代码 
class FooParentData extends ContainerBoxParentData<RenderBox> {
  // (any fields you might need for these children)
}
dart 复制代码 
// continuing from previous example...
class RenderFoo extends RenderBox with
  ContainerRenderObjectMixin<RenderBox, FooParentData>,
  RenderBoxContainerDefaultsMixin<RenderBox, FooParentData> {
  // ...
}
dart 复制代码 
// continuing from previous example...
RenderBox? child = firstChild;
while (child != null) {
  final FooParentData childParentData = child.parentData! as FooParentData;
  // ...operate on child and childParentData...
  assert(child.parentData == childParentData);
  child = childParentData.nextSibling;
}

lib/src/semantics

lib/src/semantics/semantics.dart

dart 复制代码 
SemanticsLabelBuilder builder = SemanticsLabelBuilder()
  ..addPart('Hello')
  ..addPart('world');
String label = builder.build(); // "Hello world"
dart 复制代码 
SemanticsLabelBuilder builder = SemanticsLabelBuilder(textDirection: TextDirection.ltr)
  ..addPart('Welcome', textDirection: TextDirection.ltr)
  ..addPart('مرحبا', textDirection: TextDirection.rtl); // Arabic
String label = builder.build(); // "Welcome \u202Bمرحبا\u202C" (with Unicode embedding)

lib/src/services

lib/src/services/hardware_keyboard.dart

dart 复制代码 
void handleMessage(FocusNode node, KeyMessage message) {
  final List<KeyEventResult> results = <KeyEventResult>[];
  if (node.onKeyEvent != null) {
    for (final KeyEvent event in message.events) {
      results.add(node.onKeyEvent!(node, event));
    }
  }
  if (node.onKey != null && message.rawEvent != null) {
    results.add(node.onKey!(node, message.rawEvent!));
  }
  final KeyEventResult result = combineKeyEventResults(results);
  // Progress based on `result`...
}

lib/src/services/spell_check.dart

dart 复制代码 
SuggestionSpan suggestionSpan =
  const SuggestionSpan(
    TextRange(start: 7, end: 12),
    <String>['word', 'world', 'old'],
);

lib/src/services/text_formatter.dart

dart 复制代码 
// _pattern is a RegExp or other Pattern object
TextInputFormatter.withFunction(
  (TextEditingValue oldValue, TextEditingValue newValue) {
    return _pattern.hasMatch(newValue.text) ? newValue : oldValue;
  },
),

lib/src/widgets

lib/src/widgets/animated_cross_fade.dart

dart 复制代码 
Widget defaultLayoutBuilder(Widget topChild, Key topChildKey, Widget bottomChild, Key bottomChildKey) {
  return Stack(
    children: <Widget>[
      Positioned(
        key: bottomChildKey,
        left: 0.0,
        top: 0.0,
        right: 0.0,
        child: bottomChild,
      ),
      Positioned(
        key: topChildKey,
        child: topChild,
      )
    ],
  );
}
dart 复制代码 
AnimatedCrossFade(
  duration: const Duration(seconds: 3),
  firstChild: const FlutterLogo(style: FlutterLogoStyle.horizontal, size: 100.0),
  secondChild: const FlutterLogo(style: FlutterLogoStyle.stacked, size: 100.0),
  crossFadeState: _first ? CrossFadeState.showFirst : CrossFadeState.showSecond,
)

lib/src/widgets/animated_scroll_view.dart

dart 复制代码 
Widget myWidget(BuildContext context) {
  return MediaQuery.removePadding(
    context: context,
    removeTop: true,
    removeBottom: true,
    child: AnimatedList(
      initialItemCount: 50,
      itemBuilder: (BuildContext context, int index, Animation<double> animation) {
        return Card(
          color: Colors.amber,
          child: Center(child: Text('$index')),
        );
      }
    ),
  );
}
dart 复制代码 
Widget myWidget(BuildContext context) {
  return MediaQuery.removePadding(
    context: context,
    removeTop: true,
    removeBottom: true,
    child: AnimatedGrid(
      gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 3,
      ),
      initialItemCount: 50,
      itemBuilder: (BuildContext context, int index, Animation<double> animation) {
        return Card(
          color: Colors.amber,
          child: Center(child: Text('$index')),
        );
      }
    ),
  );
}

lib/src/widgets/autocomplete.dart

dart 复制代码 
int highlightedIndex = AutocompleteHighlightedOption.of(context);

lib/src/widgets/basic.dart

dart 复制代码 
Directionality(
  textDirection: TextDirection.rtl,
  child: Container(
    margin: const EdgeInsetsDirectional.only(start: 8),
    color: Colors.blue,
  ),
)
dart 复制代码 
Opacity(
  opacity: _visible ? 1.0 : 0.0,
  child: const Text("Now you see me, now you don't!"),
)
dart 复制代码 
Image.network(
  'https://raw.githubusercontent.com/flutter/assets-for-api-docs/main/packages/diagrams/assets/blend_mode_destination.jpeg',
  color: const Color.fromRGBO(255, 255, 255, 0.5),
  colorBlendMode: BlendMode.modulate
)
dart 复制代码 
ShaderMask(
  shaderCallback: (Rect bounds) {
    return RadialGradient(
      center: Alignment.topLeft,
      radius: 1.0,
      colors: <Color>[Colors.yellow, Colors.deepOrange.shade900],
      tileMode: TileMode.mirror,
    ).createShader(bounds);
  },
  child: const Text(
    "I'm burning the memories",
    style: TextStyle(color: Colors.white),
  ),
)
dart 复制代码 
 Widget build(BuildContext context) {
   return BackdropGroup(
     child: ListView.builder(
       itemCount: 60,
       itemBuilder: (BuildContext context, int index) {
         return ClipRect(
           child: BackdropFilter.grouped(
             filter: ui.ImageFilter.blur(
               sigmaX: 40,
               sigmaY: 40,
             ),
             child: Container(
               color: Colors.black.withOpacity(0.2),
               height: 200,
               child: const Text('Blur item'),
             ),
           ),
         );
      }
    ),
  );
}
dart 复制代码 
Stack(
  fit: StackFit.expand,
  children: <Widget>[
    Text('0' * 10000),
    Center(
      child: ClipRect(  // <-- clips to the 200x200 [Container] below
        child: BackdropFilter(
          filter: ui.ImageFilter.blur(
            sigmaX: 5.0,
            sigmaY: 5.0,
          ),
          child: Container(
            alignment: Alignment.center,
            width: 200.0,
            height: 200.0,
            child: const Text('Hello World'),
          ),
        ),
      ),
    ),
  ],
)
dart 复制代码 
 Widget buildBackdrop() {
   return Stack(
     children: <Widget>[
       Positioned.fill(child: Image.asset('image.png')),
       Positioned.fill(
         child: BackdropFilter(
           filter: ui.ImageFilter.blur(sigmaX: 6, sigmaY: 6),
         ),
       ),
     ],
   );
 }
dart 复制代码 
 Widget buildFilter() {
   return ImageFiltered(
     imageFilter: ui.ImageFilter.blur(sigmaX: 6, sigmaY: 6),
     child: Image.asset('image.png'),
   );
 }
dart 复制代码 
CustomPaint(
  painter: Sky(),
  child: const Center(
    child: Text(
      'Once upon a time...',
      style: TextStyle(
        fontSize: 40.0,
        fontWeight: FontWeight.w900,
        color: Color(0xFFFFFFFF),
      ),
    ),
  ),
)
dart 复制代码 
ClipRect(
  child: Align(
    alignment: Alignment.topCenter,
    heightFactor: 0.5,
    child: Image.network(userAvatarUrl),
  ),
)
dart 复制代码 
ClipOval(
  child: Image.asset('images/cat.png'),
)
dart 复制代码 
ColoredBox(
  color: Colors.black,
  child: Transform(
    alignment: Alignment.topRight,
    transform: Matrix4.skewY(0.3)..rotateZ(-math.pi / 12.0),
    child: Container(
      padding: const EdgeInsets.all(8.0),
      color: const Color(0xFFE8581C),
      child: const Text('Apartment for rent!'),
    ),
  ),
)
dart 复制代码 
const RotatedBox(
  quarterTurns: 3,
  child: Text('Hello World!'),
)
dart 复制代码 
const Card(
  child: Padding(
    padding: EdgeInsets.all(16.0),
    child: Text('Hello World!'),
  ),
)
dart 复制代码 
Center(
  child: Container(
    height: 120.0,
    width: 120.0,
    color: Colors.blue[50],
    child: const Align(
      alignment: Alignment.topRight,
      child: FlutterLogo(
        size: 60,
      ),
    ),
  ),
)
dart 复制代码 
Center(
  child: Container(
    height: 120.0,
    width: 120.0,
    color: Colors.blue[50],
    child: const Align(
      alignment: Alignment(0.2, 0.6),
      child: FlutterLogo(
        size: 60,
      ),
    ),
  ),
)
dart 复制代码 
Center(
  child: Container(
    height: 120.0,
    width: 120.0,
    color: Colors.blue[50],
    child: const Align(
      alignment: FractionalOffset(0.2, 0.6),
      child: FlutterLogo(
        size: 60,
      ),
    ),
  ),
)
dart 复制代码 
const SizedBox(
  width: 200.0,
  height: 300.0,
  child: Card(child: Text('Hello World!')),
)
dart 复制代码 
ConstrainedBox(
  constraints: const BoxConstraints.expand(),
  child: const Card(child: Text('Hello World!')),
)
dart 复制代码 
Container(
  constraints: const BoxConstraints(minHeight: 40, maxHeight: 100),
  alignment: Alignment.center,
  child: const ConstraintsTransformBox(
    constraintsTransform: ConstraintsTransformBox.maxHeightUnconstrained,
    child: Card(child: Text('Hello World!')),
  )
)
dart 复制代码 
Stack(
  children: <Widget>[
    Container(
      width: 100,
      height: 100,
      color: Colors.red,
    ),
    Container(
      width: 90,
      height: 90,
      color: Colors.green,
    ),
    Container(
      width: 80,
      height: 80,
      color: Colors.blue,
    ),
  ],
)
dart 复制代码 
SizedBox(
  width: 250,
  height: 250,
  child: Stack(
    children: <Widget>[
      Container(
        width: 250,
        height: 250,
        color: Colors.white,
      ),
      Container(
        padding: const EdgeInsets.all(5.0),
        alignment: Alignment.bottomCenter,
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topCenter,
            end: Alignment.bottomCenter,
            colors: <Color>[
              Colors.black.withAlpha(0),
              Colors.black12,
              Colors.black45
            ],
          ),
        ),
        child: const Text(
          'Foreground Text',
          style: TextStyle(color: Colors.white, fontSize: 20.0),
        ),
      ),
    ],
  ),
)
dart 复制代码 
const Row(
  children: <Widget>[
    Expanded(
      child: Text('Deliver features faster', textAlign: TextAlign.center),
    ),
    Expanded(
      child: Text('Craft beautiful UIs', textAlign: TextAlign.center),
    ),
    Expanded(
      child: FittedBox(
        child: FlutterLogo(),
      ),
    ),
  ],
)
dart 复制代码 
const Row(
  children: <Widget>[
    FlutterLogo(),
    Text("Flutter's hot reload helps you quickly and easily experiment, build UIs, add features, and fix bug faster. Experience sub-second reload times, without losing state, on emulators, simulators, and hardware for iOS and Android."),
    Icon(Icons.sentiment_very_satisfied),
  ],
)
dart 复制代码 
const Row(
  children: <Widget>[
    FlutterLogo(),
    Expanded(
      child: Text("Flutter's hot reload helps you quickly and easily experiment, build UIs, add features, and fix bug faster. Experience sub-second reload times, without losing state, on emulators, simulators, and hardware for iOS and Android."),
    ),
    Icon(Icons.sentiment_very_satisfied),
  ],
)
dart 复制代码 
const Row(
  textDirection: TextDirection.rtl,
  children: <Widget>[
    FlutterLogo(),
    Expanded(
      child: Text("Flutter's hot reload helps you quickly and easily experiment, build UIs, add features, and fix bug faster. Experience sub-second reload times, without losing state, on emulators, simulators, and hardware for iOS and Android."),
    ),
    Icon(Icons.sentiment_very_satisfied),
  ],
)
dart 复制代码 
const Column(
  children: <Widget>[
    Text('Deliver features faster'),
    Text('Craft beautiful UIs'),
    Expanded(
      child: FittedBox(
        child: FlutterLogo(),
      ),
    ),
  ],
)
dart 复制代码 
Column(
  crossAxisAlignment: CrossAxisAlignment.start,
  mainAxisSize: MainAxisSize.min,
  children: <Widget>[
    const Text('We move under cover and we move as one'),
    const Text('Through the night, we have one shot to live another day'),
    const Text('We cannot let a stray gunshot give us away'),
    const Text('We will fight up close, seize the moment and stay in it'),
    const Text("It's either that or meet the business end of a bayonet"),
    const Text("The code word is 'Rochambeau,' dig me?"),
    Text('Rochambeau!', style: DefaultTextStyle.of(context).style.apply(fontSizeFactor: 2.0)),
  ],
)
dart 复制代码 
Wrap(
  spacing: 8.0, // gap between adjacent chips
  runSpacing: 4.0, // gap between lines
  children: <Widget>[
    Chip(
      avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: const Text('AH')),
      label: const Text('Hamilton'),
    ),
    Chip(
      avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: const Text('ML')),
      label: const Text('Lafayette'),
    ),
    Chip(
      avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: const Text('HM')),
      label: const Text('Mulligan'),
    ),
    Chip(
      avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: const Text('JL')),
      label: const Text('Laurens'),
    ),
  ],
)
dart 复制代码 
RichText(
  text: TextSpan(
    text: 'Hello ',
    style: DefaultTextStyle.of(context).style,
    children: const <TextSpan>[
      TextSpan(text: 'bold', style: TextStyle(fontWeight: FontWeight.bold)),
      TextSpan(text: ' world!'),
    ],
  ),
)
dart 复制代码 
RichText(
  text: const TextSpan(text: 'Hello'),
  selectionRegistrar: SelectionContainer.maybeOf(context),
  selectionColor: const Color(0xAF6694e8),
)
dart 复制代码 
class TestAssetBundle extends CachingAssetBundle {
  @override
  Future<ByteData> load(String key) async {
    if (key == 'resources/test') {
      return ByteData.sublistView(utf8.encode('Hello World!'));
    }
    return ByteData(0);
  }
}
dart 复制代码 
// continuing from previous example...
await tester.pumpWidget(
  MaterialApp(
    home: DefaultAssetBundle(
      bundle: TestAssetBundle(),
      child: const TestWidget(),
    ),
  ),
);
dart 复制代码 
MergeSemantics(
  child: Row(
    children: <Widget>[
      Checkbox(
        value: true,
        onChanged: (bool? value) {},
      ),
      const Text('Settings'),
    ],
  ),
)
dart 复制代码 
ListView(
  addSemanticIndexes: false,
  semanticChildCount: 2,
  children: const <Widget>[
    IndexedSemantics(index: 0, child: Text('First')),
    Spacer(),
    IndexedSemantics(index: 1, child: Text('Second')),
    Spacer(),
  ],
)
dart 复制代码 
class Foo extends StatelessWidget {
  const Foo({super.key});
  @override
  Widget build(BuildContext context) => const Text('foo');
}
dart 复制代码 
// continuing from previous example...
const Center(child: Foo())
dart 复制代码 
Center(
  child: Builder(
    builder: (BuildContext context) => const Text('foo'),
  ),
)
dart 复制代码 
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: TextButton(
        onPressed: () {
          // Fails because Scaffold.of() doesn't find anything
          // above this widget's context.
          print(Scaffold.of(context).hasAppBar);
        },
        child: const Text('hasAppBar'),
      )
    ),
  );
}
dart 复制代码 
Widget build(BuildContext context) {
  return Scaffold(
    body: Builder(
      builder: (BuildContext context) {
        return Center(
          child: TextButton(
            onPressed: () {
              print(Scaffold.of(context).hasAppBar);
            },
            child: const Text('hasAppBar'),
          ),
        );
      },
    ),
  );
}
dart 复制代码 
await showDialog<void>(
  context: context,
  builder: (BuildContext context) {
    int? selectedRadio = 0;
    return AlertDialog(
      content: StatefulBuilder(
        builder: (BuildContext context, StateSetter setState) {
          return Column(
            mainAxisSize: MainAxisSize.min,
            children: List<Widget>.generate(4, (int index) {
              return Radio<int>(
                value: index,
                groupValue: selectedRadio,
                onChanged: (int? value) {
                  setState(() => selectedRadio = value);
                },
              );
            }),
          );
        },
      ),
    );
  },
);

lib/src/widgets/binding.dart

dart 复制代码 
runWidget(
  View(
    view: myFlutterView,
    child: const MyApp(),
  ),
);

lib/src/widgets/container.dart

dart 复制代码 
const DecoratedBox(
  decoration: BoxDecoration(
    gradient: RadialGradient(
      center: Alignment(-0.5, -0.6),
      radius: 0.15,
      colors: <Color>[
        Color(0xFFEEEEEE),
        Color(0xFF111133),
      ],
      stops: <double>[0.9, 1.0],
    ),
  ),
)
dart 复制代码 
Center(
  child: Container(
    margin: const EdgeInsets.all(10.0),
    color: Colors.amber[600],
    width: 48.0,
    height: 48.0,
  ),
)
dart 复制代码 
Container(
  constraints: BoxConstraints.expand(
    height: Theme.of(context).textTheme.headlineMedium!.fontSize! * 1.1 + 200.0,
  ),
  padding: const EdgeInsets.all(8.0),
  color: Colors.blue[600],
  alignment: Alignment.center,
  transform: Matrix4.rotationZ(0.1),
  child: Text('Hello World',
    style: Theme.of(context)
        .textTheme
        .headlineMedium!
        .copyWith(color: Colors.white)),
)

lib/src/widgets/debug.dart

dart 复制代码 
assert(!debugItemsHaveDuplicateKeys(items));
dart 复制代码 
assert(debugCheckHasTable(context));
dart 复制代码 
assert(debugCheckHasMediaQuery(context));
dart 复制代码 
assert(debugCheckHasDirectionality(context));
dart 复制代码 
assert(debugCheckHasWidgetsLocalizations(context));
dart 复制代码 
assert(debugCheckHasOverlay(context));

lib/src/widgets/default_text_editing_shortcuts.dart

dart 复制代码 
@override
Widget build(BuildContext context) {
  // If using WidgetsApp or its descendants MaterialApp or CupertinoApp,
  // then DefaultTextEditingShortcuts is already being inserted into the
  // widget tree.
  return const DefaultTextEditingShortcuts(
    child: Center(
      child: Shortcuts(
        shortcuts: <ShortcutActivator, Intent>{
          SingleActivator(LogicalKeyboardKey.arrowDown, alt: true): NextFocusIntent(),
          SingleActivator(LogicalKeyboardKey.arrowUp, alt: true): PreviousFocusIntent(),
        },
        child: Column(
          children: <Widget>[
            TextField(
              decoration: InputDecoration(
                hintText: 'alt + down moves to the next field.',
              ),
            ),
            TextField(
              decoration: InputDecoration(
                hintText: 'And alt + up moves to the previous.',
              ),
            ),
          ],
        ),
      ),
    ),
  );
}

lib/src/widgets/editable_text.dart

dart 复制代码 
onChanged: (String newText) {
  if (newText.isNotEmpty) {
    SemanticsService.announce('\$$newText', Directionality.of(context));
  }
}

lib/src/widgets/fade_in_image.dart

dart 复制代码 
FadeInImage(
  // here `bytes` is a Uint8List containing the bytes for the in-memory image
  placeholder: MemoryImage(bytes),
  image: const NetworkImage('https://backend.example.com/image.png'),
)

lib/src/widgets/focus_traversal.dart

dart 复制代码 
Actions.invoke(context, RequestFocusIntent(focusNode));

lib/src/widgets/framework.dart

dart 复制代码 
class Bar {
  final Object? bar = kDebugMode ? Object() : null;
}
dart 复制代码 
class _MyKey extends GlobalObjectKey {
  const _MyKey(super.value);
}
dart 复制代码 
@override
Widget build(BuildContext context) {
  // here, Scaffold.of(context) returns null
  return Scaffold(
    appBar: AppBar(title: const Text('Demo')),
    body: Builder(
      builder: (BuildContext context) {
        return TextButton(
          child: const Text('BUTTON'),
          onPressed: () {
            Scaffold.of(context).showBottomSheet(
              (BuildContext context) {
                return Container(
                  alignment: Alignment.center,
                  height: 200,
                  color: Colors.amber,
                  child: Center(
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: <Widget>[
                        const Text('BottomSheet'),
                        ElevatedButton(
                          child: const Text('Close BottomSheet'),
                          onPressed: () {
                            Navigator.pop(context);
                          },
                        )
                      ],
                    ),
                  ),
                );
              },
            );
          },
        );
      },
    )
  );
}
dart 复制代码 
  @override
  Widget build(BuildContext context) {
    return OutlinedButton(
      onPressed: () async {
        await Future<void>.delayed(const Duration(seconds: 1));
        if (context.mounted) {
          Navigator.of(context).pop();
        }
      },
      child: const Text('Delayed pop'),
    );
  }

lib/src/widgets/gesture_detector.dart

dart 复制代码 
RawGestureDetector(
  gestures: <Type, GestureRecognizerFactory>{
    TapGestureRecognizer: GestureRecognizerFactoryWithHandlers<TapGestureRecognizer>(
      () => TapGestureRecognizer(),
      (TapGestureRecognizer instance) {
        instance
          ..onTapDown = (TapDownDetails details) { setState(() { _last = 'down'; }); }
          ..onTapUp = (TapUpDetails details) { setState(() { _last = 'up'; }); }
          ..onTap = () { setState(() { _last = 'tap'; }); }
          ..onTapCancel = () { setState(() { _last = 'cancel'; }); };
      },
    ),
  },
  child: Container(width: 300.0, height: 300.0, color: Colors.yellow, child: Text(_last)),
)

lib/src/widgets/icon_data.dart

dart 复制代码 
@staticIconProvider
abstract final class MyCustomIcons {
  static const String fontFamily = 'MyCustomIcons';
  static const IconData happyFace = IconData(1, fontFamily: fontFamily);
  static const IconData sadFace = IconData(2, fontFamily: fontFamily);
}

lib/src/widgets/icon.dart

dart 复制代码 
const Row(
  mainAxisAlignment: MainAxisAlignment.spaceAround,
  children: <Widget>[
    Icon(
      Icons.favorite,
      color: Colors.pink,
      size: 24.0,
      semanticLabel: 'Text to announce in accessibility modes',
    ),
    Icon(
      Icons.audiotrack,
      color: Colors.green,
      size: 30.0,
    ),
    Icon(
      Icons.beach_access,
      color: Colors.blue,
      size: 36.0,
    ),
  ],
)

lib/src/widgets/image.dart

dart 复制代码 
const Image(
  image: NetworkImage('https://flutter.github.io/assets-for-api-docs/assets/widgets/owl.jpg'),
)
dart 复制代码 
Image.network('https://flutter.github.io/assets-for-api-docs/assets/widgets/owl-2.jpg')

lib/src/widgets/localizations.dart

dart 复制代码 
// continuing from previous example...
MyLocalizations.of(context).title()

lib/src/widgets/lookup_boundary.dart

dart 复制代码 
MyWidget(
  child: LookupBoundary(
    child: Builder(
      builder: (BuildContext context) {
        MyWidget? widget = LookupBoundary.findAncestorWidgetOfExactType<MyWidget>(context);
        return Text('$widget'); // "null"
      },
    ),
  ),
)

lib/src/widgets/navigator.dart

dart 复制代码 
void main() {
  runApp(const MaterialApp(home: MyAppHome()));
}
dart 复制代码 
Navigator.push(context, MaterialPageRoute<void>(
  builder: (BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('My Page')),
      body: Center(
        child: TextButton(
          child: const Text('POP'),
          onPressed: () {
            Navigator.pop(context);
          },
        ),
      ),
    );
  },
));
dart 复制代码 
Navigator.pop(context);
dart 复制代码 
void main() {
  runApp(MaterialApp(
    home: const MyAppHome(), // becomes the route named '/'
    routes: <String, WidgetBuilder> {
      '/a': (BuildContext context) => const MyPage(title: Text('page A')),
      '/b': (BuildContext context) => const MyPage(title: Text('page B')),
      '/c': (BuildContext context) => const MyPage(title: Text('page C')),
    },
  ));
}
dart 复制代码 
Navigator.pushNamed(context, '/b');
dart 复制代码 
bool? value = await Navigator.push(context, MaterialPageRoute<bool>(
  builder: (BuildContext context) {
    return Center(
      child: GestureDetector(
        child: const Text('OK'),
        onTap: () { Navigator.pop(context, true); }
      ),
    );
  }
));
dart 复制代码 
Navigator.push(context, PageRouteBuilder<void>(
  opaque: false,
  pageBuilder: (BuildContext context, _, _) {
    return const Center(child: Text('My PageRoute'));
  },
  transitionsBuilder: (_, Animation<double> animation, _, Widget child) {
    return FadeTransition(
      opacity: animation,
      child: RotationTransition(
        turns: Tween<double>(begin: 0.5, end: 1.0).animate(animation),
        child: child,
      ),
    );
  }
));

lib/src/widgets/platform_menu_bar.dart

dart 复制代码 
List<PlatformMenuItem> menus = <PlatformMenuItem>[ /* Define menus... */ ];
WidgetsBinding.instance.platformMenuDelegate.setMenus(menus);

lib/src/widgets/platform_view.dart

dart 复制代码 
// In a `build` method...
HtmlElementView.fromTagName(
  tagName: 'div',
  onElementCreated: myOnElementCreated,
);
dart 复制代码 
// In a `build` method...
const HtmlElementView(
  viewType: 'my-view-type',
  onPlatformViewCreated: myOnPlatformViewCreated,
  creationParams: <String, Object?>{
    'key': 'someValue',
  },
);
dart 复制代码 
class FooPlatformView extends StatelessWidget {
  const FooPlatformView({super.key});
  @override
  Widget build(BuildContext context) {
    return PlatformViewLink(
      viewType: 'webview',
      onCreatePlatformView: createFooWebView,
      surfaceFactory: (BuildContext context, PlatformViewController controller) {
        return PlatformViewSurface(
          gestureRecognizers: gestureRecognizers,
          controller: controller,
          hitTestBehavior: PlatformViewHitTestBehavior.opaque,
        );
      },
   );
  }
}

lib/src/widgets/reorderable_list.dart

dart 复制代码 
DragBoundary(
 child: CustomScrollView(
   slivers: <Widget>[
     SliverReorderableList(
       itemBuilder: (BuildContext context, int index) {
         return ReorderableDragStartListener(
           key: ValueKey<int>(index),
           index: index,
           child: Text('$index'),
         );
       },
       dragBoundaryProvider: (BuildContext context) {
         return DragBoundary.forRectOf(context);
       },
       itemCount: 5,
       onReorder: (int fromIndex, int toIndex) {},
     ),
   ],
 )
)
dart 复制代码 
GlobalKey<ReorderableListState> listKey = GlobalKey<ReorderableListState>();
// ...
Widget build(BuildContext context) {
  return ReorderableList(
    key: listKey,
    itemBuilder: (BuildContext context, int index) => const SizedBox(height: 10.0),
    itemCount: 5,
    onReorder: (int oldIndex, int newIndex) {
       // ...
    },
  );
}
// ...
listKey.currentState!.cancelReorder();

lib/src/widgets/safe_area.dart

dart 复制代码 
SafeArea(
  child: Container(
    constraints: const BoxConstraints.expand(),
    alignment: Alignment.center,
    color: Colors.blue,
    child: const Text('Hello, World!'),
  ),
)

lib/src/widgets/scroll_controller.dart

dart 复制代码 
PageView(
  children: <Widget>[
    ListView(
      controller: _trackingScrollController,
      children: List<Widget>.generate(100, (int i) => Text('page 0 item $i')).toList(),
    ),
    ListView(
      controller: _trackingScrollController,
      children: List<Widget>.generate(200, (int i) => Text('page 1 item $i')).toList(),
    ),
    ListView(
     controller: _trackingScrollController,
     children: List<Widget>.generate(300, (int i) => Text('page 2 item $i')).toList(),
    ),
  ],
)

lib/src/widgets/scroll_delegate.dart

dart 复制代码 
CustomScrollView(
  semanticChildCount: 4,
  slivers: <Widget>[
    SliverGrid(
      gridDelegate: _gridDelegate,
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
           return const Text('...');
         },
         childCount: 2,
       ),
     ),
    SliverGrid(
      gridDelegate: _gridDelegate,
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
           return const Text('...');
         },
         childCount: 2,
         semanticIndexOffset: 2,
       ),
     ),
  ],
)
dart 复制代码 
CustomScrollView(
  semanticChildCount: 5,
  slivers: <Widget>[
    SliverGrid(
      gridDelegate: _gridDelegate,
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
           if (index.isEven) {
             return const Text('...');
           }
           return const Spacer();
         },
         semanticIndexCallback: (Widget widget, int localIndex) {
           if (localIndex.isEven) {
             return localIndex ~/ 2;
           }
           return null;
         },
         childCount: 10,
       ),
     ),
  ],
)

lib/src/widgets/scroll_notification_observer.dart

dart 复制代码 
ScrollNotificationObserver.of(context).addListener(_listener);
dart 复制代码 
ScrollNotificationObserver.of(context).removeListener(_listener);
dart 复制代码 
// (e.g. in a stateful widget)
void _listener(ScrollNotification notification) {
  // Do something, maybe setState()
}

lib/src/widgets/scroll_physics.dart

dart 复制代码 
const BouncingScrollPhysics(parent: AlwaysScrollableScrollPhysics())
dart 复制代码 
ScrollPhysics physics = const BouncingScrollPhysics();
// ...
final ScrollPhysics mergedPhysics = physics.applyTo(const AlwaysScrollableScrollPhysics());
dart 复制代码 
const BouncingScrollPhysics(parent: AlwaysScrollableScrollPhysics())

lib/src/widgets/scroll_view.dart

dart 复制代码 
CustomScrollView(
  slivers: <Widget>[
    const SliverAppBar(
      pinned: true,
      expandedHeight: 250.0,
      flexibleSpace: FlexibleSpaceBar(
        title: Text('Demo'),
      ),
    ),
    SliverGrid(
      gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
        maxCrossAxisExtent: 200.0,
        mainAxisSpacing: 10.0,
        crossAxisSpacing: 10.0,
        childAspectRatio: 4.0,
      ),
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
          return Container(
            alignment: Alignment.center,
            color: Colors.teal[100 * (index % 9)],
            child: Text('Grid Item $index'),
          );
        },
        childCount: 20,
      ),
    ),
    SliverFixedExtentList(
      itemExtent: 50.0,
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
          return Container(
            alignment: Alignment.center,
            color: Colors.lightBlue[100 * (index % 9)],
            child: Text('List Item $index'),
          );
        },
      ),
    ),
  ],
)
dart 复制代码 
ListView(
  padding: const EdgeInsets.all(8),
  children: <Widget>[
    Container(
      height: 50,
      color: Colors.amber[600],
      child: const Center(child: Text('Entry A')),
    ),
    Container(
      height: 50,
      color: Colors.amber[500],
      child: const Center(child: Text('Entry B')),
    ),
    Container(
      height: 50,
      color: Colors.amber[100],
      child: const Center(child: Text('Entry C')),
    ),
  ],
)
dart 复制代码 
ListView(
  padding: const EdgeInsets.all(20.0),
  children: const <Widget>[
    Text("I'm dedicating every day to you"),
    Text('Domestic life was never quite my style'),
    Text('When you smile, you knock me out, I fall apart'),
    Text('And I thought I was so smart'),
  ],
)
dart 复制代码 
CustomScrollView(
  slivers: <Widget>[
    SliverPadding(
      padding: const EdgeInsets.all(20.0),
      sliver: SliverList(
        delegate: SliverChildListDelegate(
          <Widget>[
            const Text("I'm dedicating every day to you"),
            const Text('Domestic life was never quite my style'),
            const Text('When you smile, you knock me out, I fall apart'),
            const Text('And I thought I was so smart'),
          ],
        ),
      ),
    ),
  ],
)
dart 复制代码 
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(title: const Text('Empty List Test')),
    body: itemCount > 0
      ? ListView.builder(
          itemCount: itemCount,
          itemBuilder: (BuildContext context, int index) {
            return ListTile(
              title: Text('Item ${index + 1}'),
            );
          },
        )
      : const Center(child: Text('No items')),
  );
}
dart 复制代码 
GridView.count(
  primary: false,
  padding: const EdgeInsets.all(20),
  crossAxisSpacing: 10,
  mainAxisSpacing: 10,
  crossAxisCount: 2,
  children: <Widget>[
    Container(
      padding: const EdgeInsets.all(8),
      color: Colors.teal[100],
      child: const Text("He'd have you all unravel at the"),
    ),
    Container(
      padding: const EdgeInsets.all(8),
      color: Colors.teal[200],
      child: const Text('Heed not the rabble'),
    ),
    Container(
      padding: const EdgeInsets.all(8),
      color: Colors.teal[300],
      child: const Text('Sound of screams but the'),
    ),
    Container(
      padding: const EdgeInsets.all(8),
      color: Colors.teal[400],
      child: const Text('Who scream'),
    ),
    Container(
      padding: const EdgeInsets.all(8),
      color: Colors.teal[500],
      child: const Text('Revolution is coming...'),
    ),
    Container(
      padding: const EdgeInsets.all(8),
      color: Colors.teal[600],
      child: const Text('Revolution, they...'),
    ),
  ],
)
dart 复制代码 
CustomScrollView(
  primary: false,
  slivers: <Widget>[
    SliverPadding(
      padding: const EdgeInsets.all(20),
      sliver: SliverGrid.count(
        crossAxisSpacing: 10,
        mainAxisSpacing: 10,
        crossAxisCount: 2,
        children: <Widget>[
          Container(
            padding: const EdgeInsets.all(8),
            color: Colors.green[100],
            child: const Text("He'd have you all unravel at the"),
          ),
          Container(
            padding: const EdgeInsets.all(8),
            color: Colors.green[200],
            child: const Text('Heed not the rabble'),
          ),
          Container(
            padding: const EdgeInsets.all(8),
            color: Colors.green[300],
            child: const Text('Sound of screams but the'),
          ),
          Container(
            padding: const EdgeInsets.all(8),
            color: Colors.green[400],
            child: const Text('Who scream'),
          ),
          Container(
            padding: const EdgeInsets.all(8),
            color: Colors.green[500],
            child: const Text('Revolution is coming...'),
          ),
          Container(
            padding: const EdgeInsets.all(8),
            color: Colors.green[600],
            child: const Text('Revolution, they...'),
          ),
        ],
      ),
    ),
  ],
)
dart 复制代码 
Widget myWidget(BuildContext context) {
  return MediaQuery.removePadding(
    context: context,
    removeTop: true,
    child: GridView.builder(
      gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 3,
      ),
      itemCount: 300,
      itemBuilder: (BuildContext context, int index) {
        return Card(
          color: Colors.amber,
          child: Center(child: Text('$index')),
        );
      }
    ),
  );
}

lib/src/widgets/scrollbar.dart

dart 复制代码 
MaterialApp(
  scrollBehavior: const MaterialScrollBehavior()
    .copyWith(scrollbars: false),
  home: Scaffold(
    appBar: AppBar(title: const Text('Home')),
  ),
)

lib/src/widgets/selectable_region.dart

dart 复制代码 
MaterialApp(
  home: SelectableRegion(
    selectionControls: materialTextSelectionControls,
    child: Scaffold(
      appBar: AppBar(title: const Text('Flutter Code Sample')),
      body: ListView(
        children: const <Widget>[
          Text('Item 0', style: TextStyle(fontSize: 50.0)),
          Text('Item 1', style: TextStyle(fontSize: 50.0)),
        ],
      ),
    ),
  ),
)
dart 复制代码 
Actions.invoke(key.currentContext!, const SelectAllTextIntent(SelectionChangedCause.keyboard));

lib/src/widgets/sliver.dart

dart 复制代码 
SliverFixedExtentList(
  itemExtent: 50.0,
  delegate: SliverChildBuilderDelegate(
    (BuildContext context, int index) {
      return Container(
        alignment: Alignment.center,
        color: Colors.lightBlue[100 * (index % 9)],
        child: Text('list item $index'),
      );
    },
  ),
)
dart 复制代码 
SliverGrid.builder(
  gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
    maxCrossAxisExtent: 200.0,
    mainAxisSpacing: 10.0,
    crossAxisSpacing: 10.0,
    childAspectRatio: 4.0,
  ),
  itemCount: 20,
  itemBuilder: (BuildContext context, int index) {
    return Container(
      alignment: Alignment.center,
      color: Colors.teal[100 * (index % 9)],
      child: Text('grid item $index'),
    );
  },
)

lib/src/widgets/snapshot_widget.dart

dart 复制代码 
void paint(PaintingContext context, Offset offset, Size size, ui.Image image, double pixelRatio) {
  const double radians = 0.5; // Could be driven by an animation.
  final Matrix4 transform = Matrix4.rotationZ(radians);
  context.canvas.transform(transform.storage);
  final Rect src = Rect.fromLTWH(0, 0, image.width.toDouble(), image.height.toDouble());
  final Rect dst = Rect.fromLTWH(offset.dx, offset.dy, size.width, size.height);
  final Paint paint = Paint()
    ..filterQuality = FilterQuality.medium;
  context.canvas.drawImageRect(image, src, dst, paint);
}

lib/src/widgets/spacer.dart

dart 复制代码 
const Row(
  children: <Widget>[
    Text('Begin'),
    Spacer(), // Defaults to a flex of one.
    Text('Middle'),
    // Gives twice the space between Middle and End than Begin and Middle.
    Spacer(flex: 2),
    Text('End'),
  ],
)

lib/src/widgets/text.dart

dart 复制代码 
Container(
  width: 100,
  decoration: BoxDecoration(border: Border.all()),
  child: const Text(
    'Hello, how are you?',
    overflow: TextOverflow.ellipsis,
  ),
)
dart 复制代码 
const Text(
  'Hello, how are you?',
  overflow: TextOverflow.fade,
  maxLines: 1,
)
dart 复制代码 
const Text(
  'Hello, how are you?',
  overflow: TextOverflow.fade,
  softWrap: false,
)
dart 复制代码 
const Text.rich(
  TextSpan(
    text: 'Hello', // default text style
    children: <TextSpan>[
      TextSpan(text: ' beautiful ', style: TextStyle(fontStyle: FontStyle.italic)),
      TextSpan(text: 'world', style: TextStyle(fontWeight: FontWeight.bold)),
    ],
  ),
)

lib/src/widgets/widget_inspector.dart

dart 复制代码 
extension PaddingModifier on Widget {
  @widgetFactory
  Widget padding(EdgeInsetsGeometry padding) {
    return Padding(padding: padding, child: this);
  }
}
dart 复制代码 
// continuing from previous example...
const Text('Hello World!')
    .padding(const EdgeInsets.all(8));

lib/src/widgets/widget_span.dart

dart 复制代码 
const Text.rich(
  TextSpan(
    children: <InlineSpan>[
      TextSpan(text: 'Flutter is'),
      WidgetSpan(
        child: SizedBox(
          width: 120,
          height: 50,
          child: Card(
            child: Center(
              child: Text('Hello World!')
            )
          ),
        )
      ),
      TextSpan(text: 'the best!'),
    ],
  )
)
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