examples/flutter_gallery/lib/gallery/options.dart - mirrors/flutter - Git at Google

 // Copyright 2018 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:flutter/material.dart';

 import 'about.dart';
 import 'scales.dart';
 import 'themes.dart';

 class GalleryOptions {
   GalleryOptions({
     this.theme,
     this.textScaleFactor,
     this.textDirection: TextDirection.ltr,
     this.timeDilation: 1.0,
     this.platform,
     this.showOffscreenLayersCheckerboard: false,
     this.showRasterCacheImagesCheckerboard: false,
     this.showPerformanceOverlay: false,
   });

   final GalleryTheme theme;
   final GalleryTextScaleValue textScaleFactor;
   final TextDirection textDirection;
   final double timeDilation;
   final TargetPlatform platform;
   final bool showPerformanceOverlay;
   final bool showRasterCacheImagesCheckerboard;
   final bool showOffscreenLayersCheckerboard;

   GalleryOptions copyWith({
     GalleryTheme theme,
     GalleryTextScaleValue textScaleFactor,
     TextDirection textDirection,
     double timeDilation,
     TargetPlatform platform,
     bool showPerformanceOverlay,
     bool showRasterCacheImagesCheckerboard,
     bool showOffscreenLayersCheckerboard,
   }) {
     return new GalleryOptions(
       theme: theme ?? this.theme,
       textScaleFactor: textScaleFactor ?? this.textScaleFactor,
       textDirection: textDirection ?? this.textDirection,
       timeDilation: timeDilation ?? this.timeDilation,
       platform: platform ?? this.platform,
       showPerformanceOverlay: showPerformanceOverlay ?? this.showPerformanceOverlay,
       showOffscreenLayersCheckerboard: showOffscreenLayersCheckerboard ?? this.showOffscreenLayersCheckerboard,
       showRasterCacheImagesCheckerboard: showRasterCacheImagesCheckerboard ?? this.showRasterCacheImagesCheckerboard,
     );
   }

   @override
   bool operator ==(dynamic other) {
     if (runtimeType != other.runtimeType)
       return false;
     final GalleryOptions typedOther = other;
     return theme == typedOther.theme
         && textScaleFactor == typedOther.textScaleFactor
         && textDirection == typedOther.textDirection
         && platform == typedOther.platform
         && showPerformanceOverlay == typedOther.showPerformanceOverlay
         && showRasterCacheImagesCheckerboard == typedOther.showRasterCacheImagesCheckerboard
         && showOffscreenLayersCheckerboard == typedOther.showRasterCacheImagesCheckerboard;
   }

   @override
   int get hashCode => hashValues(
     theme,
     textScaleFactor,
     textDirection,
     timeDilation,
     platform,
     showPerformanceOverlay,
     showRasterCacheImagesCheckerboard,
     showOffscreenLayersCheckerboard,
   );

   @override
   String toString() {
     return '$runtimeType($theme)';
   }
 }

 const double _kItemHeight = 48.0;
 const EdgeInsetsDirectional _kItemPadding = const EdgeInsetsDirectional.only(start: 56.0);

 class _OptionsItem extends StatelessWidget {
   const _OptionsItem({ Key key, this.child }) : super(key: key);

   final Widget child;

   @override
   Widget build(BuildContext context) {
     final double textScaleFactor = MediaQuery.textScaleFactorOf(context);

     return new MergeSemantics(
       child: new Container(
         constraints: new BoxConstraints(minHeight: _kItemHeight * textScaleFactor),
         padding: _kItemPadding,
         alignment: AlignmentDirectional.centerStart,
         child: new DefaultTextStyle(
           style: DefaultTextStyle.of(context).style,
           maxLines: 2,
           overflow: TextOverflow.fade,
           child: new IconTheme(
             data: Theme.of(context).primaryIconTheme,
             child: child,
           ),
         ),
       ),
     );
   }
 }

 class _BooleanItem extends StatelessWidget {
   const _BooleanItem(this.title, this.value, this.onChanged);

   final String title;
   final bool value;
   final ValueChanged<bool> onChanged;

   @override
   Widget build(BuildContext context) {
     final bool isDark = Theme.of(context).brightness == Brightness.dark;
     return new _OptionsItem(
       child: new Row(
         children: <Widget>[
           new Expanded(child: new Text(title)),
           new Switch(
             value: value,
             onChanged: onChanged,
             activeColor: const Color(0xFF39CEFD),
             activeTrackColor: isDark ? Colors.white30 : Colors.black26,
           ),
         ],
       ),
     );
   }
 }

 class _ActionItem extends StatelessWidget {
   const _ActionItem(this.text, this.onTap);

   final String text;
   final VoidCallback onTap;

   @override
   Widget build(BuildContext context) {
     return new _OptionsItem(
       child: new _FlatButton(
         onPressed: onTap,
         child: new Text(text),
       ),
     );
   }
 }

 class _FlatButton extends StatelessWidget {
   const _FlatButton({ Key key, this.onPressed, this.child }) : super(key: key);

   final VoidCallback onPressed;
   final Widget child;

   @override
   Widget build(BuildContext context) {
     return new FlatButton(
       padding: EdgeInsets.zero,
       onPressed: onPressed,
       child: new DefaultTextStyle(
         style: Theme.of(context).primaryTextTheme.subhead,
         child: child,
       ),
     );
   }
 }

 class _Heading extends StatelessWidget {
   const _Heading(this.text);

   final String text;

   @override
   Widget build(BuildContext context) {
     final ThemeData theme = Theme.of(context);
     return new _OptionsItem(
       child: new DefaultTextStyle(
         style: theme.textTheme.body1.copyWith(
           fontFamily: 'GoogleSans',
           color: theme.accentColor,
         ),
         child: new Semantics(
           child: new Text(text),
           header: true,
         ),
       ),
     );
   }
 }

 class _ThemeItem extends StatelessWidget {
   const _ThemeItem(this.options, this.onOptionsChanged);

   final GalleryOptions options;
   final ValueChanged<GalleryOptions> onOptionsChanged;

   @override
   Widget build(BuildContext context) {
     return new _BooleanItem(
       'Dark Theme',
       options.theme == kDarkGalleryTheme,
       (bool value) {
         onOptionsChanged(
           options.copyWith(
             theme: value ? kDarkGalleryTheme : kLightGalleryTheme,
           ),
         );
       },
     );
   }
 }

 class _TextScaleFactorItem extends StatelessWidget {
   const _TextScaleFactorItem(this.options, this.onOptionsChanged);

   final GalleryOptions options;
   final ValueChanged<GalleryOptions> onOptionsChanged;

   @override
   Widget build(BuildContext context) {
     return new _OptionsItem(
       child: new Row(
         children: <Widget>[
           new Expanded(
             child: new Column(
               crossAxisAlignment: CrossAxisAlignment.start,
               children: <Widget>[
                 const Text('Text size'),
                 new Text(
                   '${options.textScaleFactor.label}',
                   style: Theme.of(context).primaryTextTheme.body1,
                 ),
               ],
             ),
           ),
           new PopupMenuButton<GalleryTextScaleValue>(
             padding: const EdgeInsetsDirectional.only(end: 16.0),
             icon: const Icon(Icons.arrow_drop_down),
             itemBuilder: (BuildContext context) {
               return kAllGalleryTextScaleValues.map((GalleryTextScaleValue scaleValue) {
                 return new PopupMenuItem<GalleryTextScaleValue>(
                   value: scaleValue,
                   child: new Text(scaleValue.label),
                 );
               }).toList();
             },
             onSelected: (GalleryTextScaleValue scaleValue) {
               onOptionsChanged(
                 options.copyWith(textScaleFactor: scaleValue),
               );
             },
           ),
         ],
       ),
     );
   }
 }

 class _TextDirectionItem extends StatelessWidget {
   const _TextDirectionItem(this.options, this.onOptionsChanged);

   final GalleryOptions options;
   final ValueChanged<GalleryOptions> onOptionsChanged;

   @override
   Widget build(BuildContext context) {
     return new _BooleanItem(
       'Force RTL',
       options.textDirection == TextDirection.rtl,
       (bool value) {
         onOptionsChanged(
           options.copyWith(
             textDirection: value ? TextDirection.rtl : TextDirection.ltr,
           ),
         );
       },
     );
   }
 }

 class _TimeDilationItem extends StatelessWidget {
   const _TimeDilationItem(this.options, this.onOptionsChanged);

   final GalleryOptions options;
   final ValueChanged<GalleryOptions> onOptionsChanged;

   @override
   Widget build(BuildContext context) {
     return new _BooleanItem(
       'Slow motion',
       options.timeDilation != 1.0,
       (bool value) {
         onOptionsChanged(
           options.copyWith(
             timeDilation: value ? 20.0 : 1.0,
           ),
         );
       },
     );
   }
 }

 class _PlatformItem extends StatelessWidget {
   const _PlatformItem(this.options, this.onOptionsChanged);

   final GalleryOptions options;
   final ValueChanged<GalleryOptions> onOptionsChanged;

   String _platformLabel(TargetPlatform platform) {
     switch(platform) {
       case TargetPlatform.android:
         return 'Mountain View';
       case TargetPlatform.fuchsia:
         return 'Fuchsia';
       case TargetPlatform.iOS:
         return 'Cupertino';
     }
     assert(false);
     return null;
   }

   @override
   Widget build(BuildContext context) {
     return new _OptionsItem(
       child: new Row(
         children: <Widget>[
           new Expanded(
             child: new Column(
               crossAxisAlignment: CrossAxisAlignment.start,
               children: <Widget>[
                 const Text('Platform mechanics'),
                  new Text(
                    '${_platformLabel(options.platform)}',
                    style: Theme.of(context).primaryTextTheme.body1,
                  ),
               ],
             ),
           ),
           new PopupMenuButton<TargetPlatform>(
             padding: const EdgeInsetsDirectional.only(end: 16.0),
             icon: const Icon(Icons.arrow_drop_down),
             itemBuilder: (BuildContext context) {
               return TargetPlatform.values.map((TargetPlatform platform) {
                 return new PopupMenuItem<TargetPlatform>(
                   value: platform,
                   child: new Text(_platformLabel(platform)),
                 );
               }).toList();
             },
             onSelected: (TargetPlatform platform) {
               onOptionsChanged(
                 options.copyWith(platform: platform),
               );
             },
           ),
         ],
       ),
     );
   }
 }

 class GalleryOptionsPage extends StatelessWidget {
   const GalleryOptionsPage({
     Key key,
     this.options,
     this.onOptionsChanged,
     this.onSendFeedback,
   }) : super(key: key);

   final GalleryOptions options;
   final ValueChanged<GalleryOptions> onOptionsChanged;
   final VoidCallback onSendFeedback;

   List<Widget> _enabledDiagnosticItems() {
     // Boolean showFoo options with a value of null: don't display
     // the showFoo option at all.
     if (null == options.showOffscreenLayersCheckerboard
              ?? options.showRasterCacheImagesCheckerboard
              ?? options.showPerformanceOverlay)
       return const <Widget>[];

     final List<Widget> items = <Widget>[
       const Divider(),
       const _Heading('Diagnostics'),
     ];

     if (options.showOffscreenLayersCheckerboard != null) {
       items.add(
         new _BooleanItem(
           'Highlight offscreen layers',
           options.showOffscreenLayersCheckerboard,
           (bool value) {
             onOptionsChanged(options.copyWith(showOffscreenLayersCheckerboard: value));
           }
         ),
       );
     }
     if (options.showRasterCacheImagesCheckerboard != null) {
       items.add(
         new _BooleanItem(
           'Highlight raster cache images',
           options.showRasterCacheImagesCheckerboard,
           (bool value) {
             onOptionsChanged(options.copyWith(showRasterCacheImagesCheckerboard: value));
           },
         ),
       );
     }
     if (options.showPerformanceOverlay != null) {
       items.add(
         new _BooleanItem(
           'Show performance overlay',
           options.showPerformanceOverlay,
           (bool value) {
             onOptionsChanged(options.copyWith(showPerformanceOverlay: value));
           },
         ),
       );
     }

     return items;
   }

   @override
   Widget build(BuildContext context) {
     final ThemeData theme = Theme.of(context);

     return new DefaultTextStyle(
       style: theme.primaryTextTheme.subhead,
       child: new ListView(
         padding: const EdgeInsets.only(bottom: 124.0),
         children: <Widget>[
           const _Heading('Display'),
           new _ThemeItem(options, onOptionsChanged),
           new _TextScaleFactorItem(options, onOptionsChanged),
           new _TextDirectionItem(options, onOptionsChanged),
           new _TimeDilationItem(options, onOptionsChanged),
           const Divider(),
           const _Heading('Platform mechanics'),
           new _PlatformItem(options, onOptionsChanged),
         ]..addAll(
           _enabledDiagnosticItems(),
         )..addAll(
           <Widget>[
             const Divider(),
             const _Heading('Flutter gallery'),
             new _ActionItem('About Flutter Gallery', () {
               showGalleryAboutDialog(context);
             }),
             new _ActionItem('Send feedback', onSendFeedback),
           ],
         ),
       ),
     );
   }
 }
	// Copyright 2018 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:flutter/material.dart';

	import 'about.dart';
	import 'scales.dart';
	import 'themes.dart';

	class GalleryOptions {
	GalleryOptions({
	this.theme,
	this.textScaleFactor,
	this.textDirection: TextDirection.ltr,
	this.timeDilation: 1.0,
	this.platform,
	this.showOffscreenLayersCheckerboard: false,
	this.showRasterCacheImagesCheckerboard: false,
	this.showPerformanceOverlay: false,
	});

	final GalleryTheme theme;
	final GalleryTextScaleValue textScaleFactor;
	final TextDirection textDirection;
	final double timeDilation;
	final TargetPlatform platform;
	final bool showPerformanceOverlay;
	final bool showRasterCacheImagesCheckerboard;
	final bool showOffscreenLayersCheckerboard;

	GalleryOptions copyWith({
	GalleryTheme theme,
	GalleryTextScaleValue textScaleFactor,
	TextDirection textDirection,
	double timeDilation,
	TargetPlatform platform,
	bool showPerformanceOverlay,
	bool showRasterCacheImagesCheckerboard,
	bool showOffscreenLayersCheckerboard,
	}) {
	return new GalleryOptions(
	theme: theme ?? this.theme,
	textScaleFactor: textScaleFactor ?? this.textScaleFactor,
	textDirection: textDirection ?? this.textDirection,
	timeDilation: timeDilation ?? this.timeDilation,
	platform: platform ?? this.platform,
	showPerformanceOverlay: showPerformanceOverlay ?? this.showPerformanceOverlay,
	showOffscreenLayersCheckerboard: showOffscreenLayersCheckerboard ?? this.showOffscreenLayersCheckerboard,
	showRasterCacheImagesCheckerboard: showRasterCacheImagesCheckerboard ?? this.showRasterCacheImagesCheckerboard,
	);
	}

	@override
	bool operator ==(dynamic other) {
	if (runtimeType != other.runtimeType)
	return false;
	final GalleryOptions typedOther = other;
	return theme == typedOther.theme
	&& textScaleFactor == typedOther.textScaleFactor
	&& textDirection == typedOther.textDirection
	&& platform == typedOther.platform
	&& showPerformanceOverlay == typedOther.showPerformanceOverlay
	&& showRasterCacheImagesCheckerboard == typedOther.showRasterCacheImagesCheckerboard
	&& showOffscreenLayersCheckerboard == typedOther.showRasterCacheImagesCheckerboard;
	}

	@override
	int get hashCode => hashValues(
	theme,
	textScaleFactor,
	textDirection,
	timeDilation,
	platform,
	showPerformanceOverlay,
	showRasterCacheImagesCheckerboard,
	showOffscreenLayersCheckerboard,
	);

	@override
	String toString() {
	return '$runtimeType($theme)';
	}
	}

	const double _kItemHeight = 48.0;
	const EdgeInsetsDirectional _kItemPadding = const EdgeInsetsDirectional.only(start: 56.0);

	class _OptionsItem extends StatelessWidget {
	const _OptionsItem({ Key key, this.child }) : super(key: key);

	final Widget child;

	@override
	Widget build(BuildContext context) {
	final double textScaleFactor = MediaQuery.textScaleFactorOf(context);

	return new MergeSemantics(
	child: new Container(
	constraints: new BoxConstraints(minHeight: _kItemHeight * textScaleFactor),
	padding: _kItemPadding,
	alignment: AlignmentDirectional.centerStart,
	child: new DefaultTextStyle(
	style: DefaultTextStyle.of(context).style,
	maxLines: 2,
	overflow: TextOverflow.fade,
	child: new IconTheme(
	data: Theme.of(context).primaryIconTheme,
	child: child,
	),
	),
	),
	);
	}
	}

	class _BooleanItem extends StatelessWidget {
	const _BooleanItem(this.title, this.value, this.onChanged);

	final String title;
	final bool value;
	final ValueChanged<bool> onChanged;

	@override
	Widget build(BuildContext context) {
	final bool isDark = Theme.of(context).brightness == Brightness.dark;
	return new _OptionsItem(
	child: new Row(
	children: <Widget>[
	new Expanded(child: new Text(title)),
	new Switch(
	value: value,
	onChanged: onChanged,
	activeColor: const Color(0xFF39CEFD),
	activeTrackColor: isDark ? Colors.white30 : Colors.black26,
	),
	],
	),
	);
	}
	}

	class _ActionItem extends StatelessWidget {
	const _ActionItem(this.text, this.onTap);

	final String text;
	final VoidCallback onTap;

	@override
	Widget build(BuildContext context) {
	return new _OptionsItem(
	child: new _FlatButton(
	onPressed: onTap,
	child: new Text(text),
	),
	);
	}
	}

	class _FlatButton extends StatelessWidget {
	const _FlatButton({ Key key, this.onPressed, this.child }) : super(key: key);

	final VoidCallback onPressed;
	final Widget child;

	@override
	Widget build(BuildContext context) {
	return new FlatButton(
	padding: EdgeInsets.zero,
	onPressed: onPressed,
	child: new DefaultTextStyle(
	style: Theme.of(context).primaryTextTheme.subhead,
	child: child,
	),
	);
	}
	}

	class _Heading extends StatelessWidget {
	const _Heading(this.text);

	final String text;

	@override
	Widget build(BuildContext context) {
	final ThemeData theme = Theme.of(context);
	return new _OptionsItem(
	child: new DefaultTextStyle(
	style: theme.textTheme.body1.copyWith(
	fontFamily: 'GoogleSans',
	color: theme.accentColor,
	),
	child: new Semantics(
	child: new Text(text),
	header: true,
	),
	),
	);
	}
	}

	class _ThemeItem extends StatelessWidget {
	const _ThemeItem(this.options, this.onOptionsChanged);

	final GalleryOptions options;
	final ValueChanged<GalleryOptions> onOptionsChanged;

	@override
	Widget build(BuildContext context) {
	return new _BooleanItem(
	'Dark Theme',
	options.theme == kDarkGalleryTheme,
	(bool value) {
	onOptionsChanged(
	options.copyWith(
	theme: value ? kDarkGalleryTheme : kLightGalleryTheme,
	),
	);
	},
	);
	}
	}

	class _TextScaleFactorItem extends StatelessWidget {
	const _TextScaleFactorItem(this.options, this.onOptionsChanged);

	final GalleryOptions options;
	final ValueChanged<GalleryOptions> onOptionsChanged;

	@override
	Widget build(BuildContext context) {
	return new _OptionsItem(
	child: new Row(
	children: <Widget>[
	new Expanded(
	child: new Column(
	crossAxisAlignment: CrossAxisAlignment.start,
	children: <Widget>[
	const Text('Text size'),
	new Text(
	'${options.textScaleFactor.label}',
	style: Theme.of(context).primaryTextTheme.body1,
	),
	],
	),
	),
	new PopupMenuButton<GalleryTextScaleValue>(
	padding: const EdgeInsetsDirectional.only(end: 16.0),
	icon: const Icon(Icons.arrow_drop_down),
	itemBuilder: (BuildContext context) {
	return kAllGalleryTextScaleValues.map((GalleryTextScaleValue scaleValue) {
	return new PopupMenuItem<GalleryTextScaleValue>(
	value: scaleValue,
	child: new Text(scaleValue.label),
	);
	}).toList();
	},
	onSelected: (GalleryTextScaleValue scaleValue) {
	onOptionsChanged(
	options.copyWith(textScaleFactor: scaleValue),
	);
	},
	),
	],
	),
	);
	}
	}

	class _TextDirectionItem extends StatelessWidget {
	const _TextDirectionItem(this.options, this.onOptionsChanged);

	final GalleryOptions options;
	final ValueChanged<GalleryOptions> onOptionsChanged;

	@override
	Widget build(BuildContext context) {
	return new _BooleanItem(
	'Force RTL',
	options.textDirection == TextDirection.rtl,
	(bool value) {
	onOptionsChanged(
	options.copyWith(
	textDirection: value ? TextDirection.rtl : TextDirection.ltr,
	),
	);
	},
	);
	}
	}

	class _TimeDilationItem extends StatelessWidget {
	const _TimeDilationItem(this.options, this.onOptionsChanged);

	final GalleryOptions options;
	final ValueChanged<GalleryOptions> onOptionsChanged;

	@override
	Widget build(BuildContext context) {
	return new _BooleanItem(
	'Slow motion',
	options.timeDilation != 1.0,
	(bool value) {
	onOptionsChanged(
	options.copyWith(
	timeDilation: value ? 20.0 : 1.0,
	),
	);
	},
	);
	}
	}

	class _PlatformItem extends StatelessWidget {
	const _PlatformItem(this.options, this.onOptionsChanged);

	final GalleryOptions options;
	final ValueChanged<GalleryOptions> onOptionsChanged;

	String _platformLabel(TargetPlatform platform) {
	switch(platform) {
	case TargetPlatform.android:
	return 'Mountain View';
	case TargetPlatform.fuchsia:
	return 'Fuchsia';
	case TargetPlatform.iOS:
	return 'Cupertino';
	}
	assert(false);
	return null;
	}

	@override
	Widget build(BuildContext context) {
	return new _OptionsItem(
	child: new Row(
	children: <Widget>[
	new Expanded(
	child: new Column(
	crossAxisAlignment: CrossAxisAlignment.start,
	children: <Widget>[
	const Text('Platform mechanics'),
	new Text(
	'${_platformLabel(options.platform)}',
	style: Theme.of(context).primaryTextTheme.body1,
	),
	],
	),
	),
	new PopupMenuButton<TargetPlatform>(
	padding: const EdgeInsetsDirectional.only(end: 16.0),
	icon: const Icon(Icons.arrow_drop_down),
	itemBuilder: (BuildContext context) {
	return TargetPlatform.values.map((TargetPlatform platform) {
	return new PopupMenuItem<TargetPlatform>(
	value: platform,
	child: new Text(_platformLabel(platform)),
	);
	}).toList();
	},
	onSelected: (TargetPlatform platform) {
	onOptionsChanged(
	options.copyWith(platform: platform),
	);
	},
	),
	],
	),
	);
	}
	}

	class GalleryOptionsPage extends StatelessWidget {
	const GalleryOptionsPage({
	Key key,
	this.options,
	this.onOptionsChanged,
	this.onSendFeedback,
	}) : super(key: key);

	final GalleryOptions options;
	final ValueChanged<GalleryOptions> onOptionsChanged;
	final VoidCallback onSendFeedback;

	List<Widget> _enabledDiagnosticItems() {
	// Boolean showFoo options with a value of null: don't display
	// the showFoo option at all.
	if (null == options.showOffscreenLayersCheckerboard
	?? options.showRasterCacheImagesCheckerboard
	?? options.showPerformanceOverlay)
	return const <Widget>[];

	final List<Widget> items = <Widget>[
	const Divider(),
	const _Heading('Diagnostics'),
	];

	if (options.showOffscreenLayersCheckerboard != null) {
	items.add(
	new _BooleanItem(
	'Highlight offscreen layers',
	options.showOffscreenLayersCheckerboard,
	(bool value) {
	onOptionsChanged(options.copyWith(showOffscreenLayersCheckerboard: value));
	}
	),
	);
	}
	if (options.showRasterCacheImagesCheckerboard != null) {
	items.add(
	new _BooleanItem(
	'Highlight raster cache images',
	options.showRasterCacheImagesCheckerboard,
	(bool value) {
	onOptionsChanged(options.copyWith(showRasterCacheImagesCheckerboard: value));
	},
	),
	);
	}
	if (options.showPerformanceOverlay != null) {
	items.add(
	new _BooleanItem(
	'Show performance overlay',
	options.showPerformanceOverlay,
	(bool value) {
	onOptionsChanged(options.copyWith(showPerformanceOverlay: value));
	},
	),
	);
	}

	return items;
	}

	@override
	Widget build(BuildContext context) {
	final ThemeData theme = Theme.of(context);

	return new DefaultTextStyle(
	style: theme.primaryTextTheme.subhead,
	child: new ListView(
	padding: const EdgeInsets.only(bottom: 124.0),
	children: <Widget>[
	const _Heading('Display'),
	new _ThemeItem(options, onOptionsChanged),
	new _TextScaleFactorItem(options, onOptionsChanged),
	new _TextDirectionItem(options, onOptionsChanged),
	new _TimeDilationItem(options, onOptionsChanged),
	const Divider(),
	const _Heading('Platform mechanics'),
	new _PlatformItem(options, onOptionsChanged),
	]..addAll(
	_enabledDiagnosticItems(),
	)..addAll(
	<Widget>[
	const Divider(),
	const _Heading('Flutter gallery'),
	new _ActionItem('About Flutter Gallery', () {
	showGalleryAboutDialog(context);
	}),
	new _ActionItem('Send feedback', onSendFeedback),
	],
	),
	),
	);
	}
	}