packages/flutter/lib/src/widgets/banner.dart - mirrors/flutter.git - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 /// @docImport 'package:flutter/material.dart';
 ///
 /// @docImport 'app.dart';
 library;

 import 'dart:math' as math;

 import 'package:flutter/foundation.dart';

 import 'basic.dart';
 import 'debug.dart';
 import 'framework.dart';

 const double _kOffset = 40.0; // distance to bottom of banner, at a 45 degree angle inwards
 const double _kHeight = 12.0; // height of banner
 const double _kBottomOffset = _kOffset + math.sqrt1_2 * _kHeight;
 const Rect _kRect = Rect.fromLTWH(-_kOffset, _kOffset - _kHeight, _kOffset * 2.0, _kHeight);
 const BoxShadow _kShadow = BoxShadow(color: Color(0x7F000000), blurRadius: 6.0);

 const Color _kColor = Color(0xA0B71C1C);
 const TextStyle _kTextStyle = TextStyle(
   color: Color(0xFFFFFFFF),
   fontSize: _kHeight * 0.85,
   fontWeight: FontWeight.w900,
   height: 1.0,
 );

 const String _flutterWidgetsLibrary = 'package:flutter/widgets.dart';

 /// Where to show a [Banner].
 ///
 /// The start and end locations are relative to the ambient [Directionality]
 /// (which can be overridden by [Banner.layoutDirection]).
 enum BannerLocation {
   /// Show the banner in the top-right corner when the ambient [Directionality]
   /// (or [Banner.layoutDirection]) is [TextDirection.rtl] and in the top-left
   /// corner when the ambient [Directionality] is [TextDirection.ltr].
   topStart,

   /// Show the banner in the top-left corner when the ambient [Directionality]
   /// (or [Banner.layoutDirection]) is [TextDirection.rtl] and in the top-right
   /// corner when the ambient [Directionality] is [TextDirection.ltr].
   topEnd,

   /// Show the banner in the bottom-right corner when the ambient
   /// [Directionality] (or [Banner.layoutDirection]) is [TextDirection.rtl] and
   /// in the bottom-left corner when the ambient [Directionality] is
   /// [TextDirection.ltr].
   bottomStart,

   /// Show the banner in the bottom-left corner when the ambient
   /// [Directionality] (or [Banner.layoutDirection]) is [TextDirection.rtl] and
   /// in the bottom-right corner when the ambient [Directionality] is
   /// [TextDirection.ltr].
   bottomEnd,
 }

 /// Paints a [Banner].
 class BannerPainter extends CustomPainter {
   /// Creates a banner painter.
   BannerPainter({
     required this.message,
     required this.textDirection,
     required this.location,
     required this.layoutDirection,
     this.color = _kColor,
     this.textStyle = _kTextStyle,
     this.shadow = _kShadow,
   }) : super(repaint: PaintingBinding.instance.systemFonts) {
     // TODO(polina-c): stop duplicating code across disposables
     // https://github.com/flutter/flutter/issues/137435
     if (kFlutterMemoryAllocationsEnabled) {
       FlutterMemoryAllocations.instance.dispatchObjectCreated(
         library: _flutterWidgetsLibrary,
         className: '$BannerPainter',
         object: this,
       );
     }
   }

   /// The message to show in the banner.
   final String message;

   /// The directionality of the text.
   ///
   /// This value is used to disambiguate how to render bidirectional text. For
   /// example, if the message is an English phrase followed by a Hebrew phrase,
   /// in a [TextDirection.ltr] context the English phrase will be on the left
   /// and the Hebrew phrase to its right, while in a [TextDirection.rtl]
   /// context, the English phrase will be on the right and the Hebrew phrase on
   /// its left.
   ///
   /// See also:
   ///
   ///  * [layoutDirection], which controls the interpretation of values in
   ///    [location].
   final TextDirection textDirection;

   /// Where to show the banner (e.g., the upper right corner).
   final BannerLocation location;

   /// The directionality of the layout.
   ///
   /// This value is used to interpret the [location] of the banner.
   ///
   /// See also:
   ///
   ///  * [textDirection], which controls the reading direction of the [message].
   final TextDirection layoutDirection;

   /// The color to paint behind the [message].
   ///
   /// Defaults to a dark red.
   final Color color;

   /// The text style to use for the [message].
   ///
   /// Defaults to bold, white text.
   final TextStyle textStyle;

   /// The shadow properties for the banner.
   ///
   /// Use a [BoxShadow] object to define the shadow's color, blur radius,
   /// and spread radius. These properties can be used to create different
   /// shadow effects.
   final BoxShadow shadow;

   bool _prepared = false;
   TextPainter? _textPainter;
   late Paint _paintShadow;
   late Paint _paintBanner;

   /// Release resources held by this painter.
   ///
   /// After calling this method, this object is no longer usable.
   void dispose() {
     // TODO(polina-c): stop duplicating code across disposables
     // https://github.com/flutter/flutter/issues/137435
     if (kFlutterMemoryAllocationsEnabled) {
       FlutterMemoryAllocations.instance.dispatchObjectDisposed(object: this);
     }
     _textPainter?.dispose();
     _textPainter = null;
   }

   void _prepare() {
     _paintShadow = shadow.toPaint();
     _paintBanner = Paint()..color = color;
     _textPainter?.dispose();
     _textPainter = TextPainter(
       text: TextSpan(style: textStyle, text: message),
       textAlign: TextAlign.center,
       textDirection: textDirection,
     );
     _prepared = true;
   }

   @override
   void paint(Canvas canvas, Size size) {
     if (!_prepared) {
       _prepare();
     }
     canvas
       ..translate(_translationX(size.width), _translationY(size.height))
       ..rotate(_rotation)
       ..drawRect(_kRect, _paintShadow)
       ..drawRect(_kRect, _paintBanner);
     const double width = _kOffset * 2.0;
     _textPainter!.layout(minWidth: width, maxWidth: width);
     _textPainter!.paint(
       canvas,
       _kRect.topLeft + Offset(0.0, (_kRect.height - _textPainter!.height) / 2.0),
     );
   }

   @override
   bool shouldRepaint(BannerPainter oldDelegate) {
     return message != oldDelegate.message ||
         location != oldDelegate.location ||
         color != oldDelegate.color ||
         textStyle != oldDelegate.textStyle;
   }

   @override
   bool hitTest(Offset position) => false;

   double _translationX(double width) {
     return switch ((layoutDirection, location)) {
       (TextDirection.rtl, BannerLocation.topStart) => width,
       (TextDirection.ltr, BannerLocation.topStart) => 0.0,
       (TextDirection.rtl, BannerLocation.topEnd) => 0.0,
       (TextDirection.ltr, BannerLocation.topEnd) => width,
       (TextDirection.rtl, BannerLocation.bottomStart) => width - _kBottomOffset,
       (TextDirection.ltr, BannerLocation.bottomStart) => _kBottomOffset,
       (TextDirection.rtl, BannerLocation.bottomEnd) => _kBottomOffset,
       (TextDirection.ltr, BannerLocation.bottomEnd) => width - _kBottomOffset,
     };
   }

   double _translationY(double height) {
     return switch (location) {
       BannerLocation.bottomStart || BannerLocation.bottomEnd => height - _kBottomOffset,
       BannerLocation.topStart || BannerLocation.topEnd => 0.0,
     };
   }

   double get _rotation {
     return math.pi /
         4.0 *
         switch ((layoutDirection, location)) {
           (TextDirection.rtl, BannerLocation.topStart || BannerLocation.bottomEnd) => 1,
           (TextDirection.ltr, BannerLocation.topStart || BannerLocation.bottomEnd) => -1,
           (TextDirection.rtl, BannerLocation.bottomStart || BannerLocation.topEnd) => -1,
           (TextDirection.ltr, BannerLocation.bottomStart || BannerLocation.topEnd) => 1,
         };
   }
 }

 /// Displays a diagonal message above the corner of another widget.
 ///
 /// Useful for showing the execution mode of an app (e.g., that asserts are
 /// enabled.)
 ///
 /// See also:
 ///
 ///  * [CheckedModeBanner], which the [WidgetsApp] widget includes by default in
 ///    debug mode, to show a banner that says "DEBUG".
 class Banner extends StatefulWidget {
   /// Creates a banner.
   const Banner({
     super.key,
     this.child,
     required this.message,
     this.textDirection,
     required this.location,
     this.layoutDirection,
     this.color = _kColor,
     this.textStyle = _kTextStyle,
     this.shadow = _kShadow,
   });

   /// The widget to show behind the banner.
   ///
   /// {@macro flutter.widgets.ProxyWidget.child}
   final Widget? child;

   /// The message to show in the banner.
   final String message;

   /// The directionality of the text.
   ///
   /// This is used to disambiguate how to render bidirectional text. For
   /// example, if the message is an English phrase followed by a Hebrew phrase,
   /// in a [TextDirection.ltr] context the English phrase will be on the left
   /// and the Hebrew phrase to its right, while in a [TextDirection.rtl]
   /// context, the English phrase will be on the right and the Hebrew phrase on
   /// its left.
   ///
   /// Defaults to the ambient [Directionality], if any.
   ///
   /// See also:
   ///
   ///  * [layoutDirection], which controls the interpretation of the [location].
   final TextDirection? textDirection;

   /// Where to show the banner (e.g., the upper right corner).
   final BannerLocation location;

   /// The directionality of the layout.
   ///
   /// This is used to resolve the [location] values.
   ///
   /// Defaults to the ambient [Directionality], if any.
   ///
   /// See also:
   ///
   ///  * [textDirection], which controls the reading direction of the [message].
   final TextDirection? layoutDirection;

   /// The color of the banner.
   final Color color;

   /// The style of the text shown on the banner.
   final TextStyle textStyle;

   /// The shadow properties for the banner.
   ///
   /// Use a [BoxShadow] object to define the shadow's color, blur radius,
   /// and spread radius. These properties can be used to create different
   /// shadow effects.
   final BoxShadow shadow;

   @override
   State<Banner> createState() => _BannerState();
 }

 class _BannerState extends State<Banner> {
   BannerPainter? _painter;

   @override
   void dispose() {
     _painter?.dispose();
     super.dispose();
   }

   @override
   Widget build(BuildContext context) {
     assert(
       (widget.textDirection != null && widget.layoutDirection != null) ||
           debugCheckHasDirectionality(context),
     );

     _painter?.dispose();
     _painter = BannerPainter(
       message: widget.message,
       textDirection: widget.textDirection ?? Directionality.of(context),
       location: widget.location,
       layoutDirection: widget.layoutDirection ?? Directionality.of(context),
       color: widget.color,
       textStyle: widget.textStyle,
       shadow: widget.shadow,
     );

     return CustomPaint(foregroundPainter: _painter, child: widget.child);
   }

   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
     properties.add(StringProperty('message', widget.message, showName: false));
     properties.add(
       EnumProperty<TextDirection>('textDirection', widget.textDirection, defaultValue: null),
     );
     properties.add(EnumProperty<BannerLocation>('location', widget.location));
     properties.add(
       EnumProperty<TextDirection>('layoutDirection', widget.layoutDirection, defaultValue: null),
     );
     properties.add(ColorProperty('color', widget.color, showName: false));
     widget.textStyle.debugFillProperties(properties, prefix: 'text ');
   }
 }

 /// Displays a [Banner] saying "DEBUG" when running in debug mode.
 /// [MaterialApp] builds one of these by default.
 ///
 /// Does nothing in release mode.
 class CheckedModeBanner extends StatelessWidget {
   /// Creates a const debug mode banner.
   const CheckedModeBanner({super.key, required this.child});

   /// The widget to show behind the banner.
   ///
   /// {@macro flutter.widgets.ProxyWidget.child}
   final Widget child;

   @override
   Widget build(BuildContext context) {
     Widget result = child;
     assert(() {
       result = Banner(
         message: 'DEBUG',
         textDirection: TextDirection.ltr,
         location: BannerLocation.topEnd,
         child: result,
       );
       return true;
     }());
     return result;
   }

   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
     String message = 'disabled';
     assert(() {
       message = '"DEBUG"';
       return true;
     }());
     properties.add(DiagnosticsNode.message(message));
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	/// @docImport 'package:flutter/material.dart';
	///
	/// @docImport 'app.dart';
	library;

	import 'dart:math' as math;

	import 'package:flutter/foundation.dart';

	import 'basic.dart';
	import 'debug.dart';
	import 'framework.dart';

	const double _kOffset = 40.0; // distance to bottom of banner, at a 45 degree angle inwards
	const double _kHeight = 12.0; // height of banner
	const double _kBottomOffset = _kOffset + math.sqrt1_2 * _kHeight;
	const Rect _kRect = Rect.fromLTWH(-_kOffset, _kOffset - _kHeight, _kOffset * 2.0, _kHeight);
	const BoxShadow _kShadow = BoxShadow(color: Color(0x7F000000), blurRadius: 6.0);

	const Color _kColor = Color(0xA0B71C1C);
	const TextStyle _kTextStyle = TextStyle(
	color: Color(0xFFFFFFFF),
	fontSize: _kHeight * 0.85,
	fontWeight: FontWeight.w900,
	height: 1.0,
	);

	const String _flutterWidgetsLibrary = 'package:flutter/widgets.dart';

	/// Where to show a [Banner].
	///
	/// The start and end locations are relative to the ambient [Directionality]
	/// (which can be overridden by [Banner.layoutDirection]).
	enum BannerLocation {
	/// Show the banner in the top-right corner when the ambient [Directionality]
	/// (or [Banner.layoutDirection]) is [TextDirection.rtl] and in the top-left
	/// corner when the ambient [Directionality] is [TextDirection.ltr].
	topStart,

	/// Show the banner in the top-left corner when the ambient [Directionality]
	/// (or [Banner.layoutDirection]) is [TextDirection.rtl] and in the top-right
	/// corner when the ambient [Directionality] is [TextDirection.ltr].
	topEnd,

	/// Show the banner in the bottom-right corner when the ambient
	/// [Directionality] (or [Banner.layoutDirection]) is [TextDirection.rtl] and
	/// in the bottom-left corner when the ambient [Directionality] is
	/// [TextDirection.ltr].
	bottomStart,

	/// Show the banner in the bottom-left corner when the ambient
	/// [Directionality] (or [Banner.layoutDirection]) is [TextDirection.rtl] and
	/// in the bottom-right corner when the ambient [Directionality] is
	/// [TextDirection.ltr].
	bottomEnd,
	}

	/// Paints a [Banner].
	class BannerPainter extends CustomPainter {
	/// Creates a banner painter.
	BannerPainter({
	required this.message,
	required this.textDirection,
	required this.location,
	required this.layoutDirection,
	this.color = _kColor,
	this.textStyle = _kTextStyle,
	this.shadow = _kShadow,
	}) : super(repaint: PaintingBinding.instance.systemFonts) {
	// TODO(polina-c): stop duplicating code across disposables
	// https://github.com/flutter/flutter/issues/137435
	if (kFlutterMemoryAllocationsEnabled) {
	FlutterMemoryAllocations.instance.dispatchObjectCreated(
	library: _flutterWidgetsLibrary,
	className: '$BannerPainter',
	object: this,
	);
	}
	}

	/// The message to show in the banner.
	final String message;

	/// The directionality of the text.
	///
	/// This value is used to disambiguate how to render bidirectional text. For
	/// example, if the message is an English phrase followed by a Hebrew phrase,
	/// in a [TextDirection.ltr] context the English phrase will be on the left
	/// and the Hebrew phrase to its right, while in a [TextDirection.rtl]
	/// context, the English phrase will be on the right and the Hebrew phrase on
	/// its left.
	///
	/// See also:
	///
	/// * [layoutDirection], which controls the interpretation of values in
	/// [location].
	final TextDirection textDirection;

	/// Where to show the banner (e.g., the upper right corner).
	final BannerLocation location;

	/// The directionality of the layout.
	///
	/// This value is used to interpret the [location] of the banner.
	///
	/// See also:
	///
	/// * [textDirection], which controls the reading direction of the [message].
	final TextDirection layoutDirection;

	/// The color to paint behind the [message].
	///
	/// Defaults to a dark red.
	final Color color;

	/// The text style to use for the [message].
	///
	/// Defaults to bold, white text.
	final TextStyle textStyle;

	/// The shadow properties for the banner.
	///
	/// Use a [BoxShadow] object to define the shadow's color, blur radius,
	/// and spread radius. These properties can be used to create different
	/// shadow effects.
	final BoxShadow shadow;

	bool _prepared = false;
	TextPainter? _textPainter;
	late Paint _paintShadow;
	late Paint _paintBanner;

	/// Release resources held by this painter.
	///
	/// After calling this method, this object is no longer usable.
	void dispose() {
	// TODO(polina-c): stop duplicating code across disposables
	// https://github.com/flutter/flutter/issues/137435
	if (kFlutterMemoryAllocationsEnabled) {
	FlutterMemoryAllocations.instance.dispatchObjectDisposed(object: this);
	}
	_textPainter?.dispose();
	_textPainter = null;
	}

	void _prepare() {
	_paintShadow = shadow.toPaint();
	_paintBanner = Paint()..color = color;
	_textPainter?.dispose();
	_textPainter = TextPainter(
	text: TextSpan(style: textStyle, text: message),
	textAlign: TextAlign.center,
	textDirection: textDirection,
	);
	_prepared = true;
	}

	@override
	void paint(Canvas canvas, Size size) {
	if (!_prepared) {
	_prepare();
	}
	canvas
	..translate(_translationX(size.width), _translationY(size.height))
	..rotate(_rotation)
	..drawRect(_kRect, _paintShadow)
	..drawRect(_kRect, _paintBanner);
	const double width = _kOffset * 2.0;
	_textPainter!.layout(minWidth: width, maxWidth: width);
	_textPainter!.paint(
	canvas,
	_kRect.topLeft + Offset(0.0, (_kRect.height - _textPainter!.height) / 2.0),
	);
	}

	@override
	bool shouldRepaint(BannerPainter oldDelegate) {
	return message != oldDelegate.message \|\|
	location != oldDelegate.location \|\|
	color != oldDelegate.color \|\|
	textStyle != oldDelegate.textStyle;
	}

	@override
	bool hitTest(Offset position) => false;

	double _translationX(double width) {
	return switch ((layoutDirection, location)) {
	(TextDirection.rtl, BannerLocation.topStart) => width,
	(TextDirection.ltr, BannerLocation.topStart) => 0.0,
	(TextDirection.rtl, BannerLocation.topEnd) => 0.0,
	(TextDirection.ltr, BannerLocation.topEnd) => width,
	(TextDirection.rtl, BannerLocation.bottomStart) => width - _kBottomOffset,
	(TextDirection.ltr, BannerLocation.bottomStart) => _kBottomOffset,
	(TextDirection.rtl, BannerLocation.bottomEnd) => _kBottomOffset,
	(TextDirection.ltr, BannerLocation.bottomEnd) => width - _kBottomOffset,
	};
	}

	double _translationY(double height) {
	return switch (location) {
	BannerLocation.bottomStart \|\| BannerLocation.bottomEnd => height - _kBottomOffset,
	BannerLocation.topStart \|\| BannerLocation.topEnd => 0.0,
	};
	}

	double get _rotation {
	return math.pi /
	4.0 *
	switch ((layoutDirection, location)) {
	(TextDirection.rtl, BannerLocation.topStart \|\| BannerLocation.bottomEnd) => 1,
	(TextDirection.ltr, BannerLocation.topStart \|\| BannerLocation.bottomEnd) => -1,
	(TextDirection.rtl, BannerLocation.bottomStart \|\| BannerLocation.topEnd) => -1,
	(TextDirection.ltr, BannerLocation.bottomStart \|\| BannerLocation.topEnd) => 1,
	};
	}
	}

	/// Displays a diagonal message above the corner of another widget.
	///
	/// Useful for showing the execution mode of an app (e.g., that asserts are
	/// enabled.)
	///
	/// See also:
	///
	/// * [CheckedModeBanner], which the [WidgetsApp] widget includes by default in
	/// debug mode, to show a banner that says "DEBUG".
	class Banner extends StatefulWidget {
	/// Creates a banner.
	const Banner({
	super.key,
	this.child,
	required this.message,
	this.textDirection,
	required this.location,
	this.layoutDirection,
	this.color = _kColor,
	this.textStyle = _kTextStyle,
	this.shadow = _kShadow,
	});

	/// The widget to show behind the banner.
	///
	/// {@macro flutter.widgets.ProxyWidget.child}
	final Widget? child;

	/// The message to show in the banner.
	final String message;

	/// The directionality of the text.
	///
	/// This is used to disambiguate how to render bidirectional text. For
	/// example, if the message is an English phrase followed by a Hebrew phrase,
	/// in a [TextDirection.ltr] context the English phrase will be on the left
	/// and the Hebrew phrase to its right, while in a [TextDirection.rtl]
	/// context, the English phrase will be on the right and the Hebrew phrase on
	/// its left.
	///
	/// Defaults to the ambient [Directionality], if any.
	///
	/// See also:
	///
	/// * [layoutDirection], which controls the interpretation of the [location].
	final TextDirection? textDirection;

	/// Where to show the banner (e.g., the upper right corner).
	final BannerLocation location;

	/// The directionality of the layout.
	///
	/// This is used to resolve the [location] values.
	///
	/// Defaults to the ambient [Directionality], if any.
	///
	/// See also:
	///
	/// * [textDirection], which controls the reading direction of the [message].
	final TextDirection? layoutDirection;

	/// The color of the banner.
	final Color color;

	/// The style of the text shown on the banner.
	final TextStyle textStyle;

	/// The shadow properties for the banner.
	///
	/// Use a [BoxShadow] object to define the shadow's color, blur radius,
	/// and spread radius. These properties can be used to create different
	/// shadow effects.
	final BoxShadow shadow;

	@override
	State<Banner> createState() => _BannerState();
	}

	class _BannerState extends State<Banner> {
	BannerPainter? _painter;

	@override
	void dispose() {
	_painter?.dispose();
	super.dispose();
	}

	@override
	Widget build(BuildContext context) {
	assert(
	(widget.textDirection != null && widget.layoutDirection != null) \|\|
	debugCheckHasDirectionality(context),
	);

	_painter?.dispose();
	_painter = BannerPainter(
	message: widget.message,
	textDirection: widget.textDirection ?? Directionality.of(context),
	location: widget.location,
	layoutDirection: widget.layoutDirection ?? Directionality.of(context),
	color: widget.color,
	textStyle: widget.textStyle,
	shadow: widget.shadow,
	);

	return CustomPaint(foregroundPainter: _painter, child: widget.child);
	}

	@override
	void debugFillProperties(DiagnosticPropertiesBuilder properties) {
	super.debugFillProperties(properties);
	properties.add(StringProperty('message', widget.message, showName: false));
	properties.add(
	EnumProperty<TextDirection>('textDirection', widget.textDirection, defaultValue: null),
	);
	properties.add(EnumProperty<BannerLocation>('location', widget.location));
	properties.add(
	EnumProperty<TextDirection>('layoutDirection', widget.layoutDirection, defaultValue: null),
	);
	properties.add(ColorProperty('color', widget.color, showName: false));
	widget.textStyle.debugFillProperties(properties, prefix: 'text ');
	}
	}

	/// Displays a [Banner] saying "DEBUG" when running in debug mode.
	/// [MaterialApp] builds one of these by default.
	///
	/// Does nothing in release mode.
	class CheckedModeBanner extends StatelessWidget {
	/// Creates a const debug mode banner.
	const CheckedModeBanner({super.key, required this.child});

	/// The widget to show behind the banner.
	///
	/// {@macro flutter.widgets.ProxyWidget.child}
	final Widget child;

	@override
	Widget build(BuildContext context) {
	Widget result = child;
	assert(() {
	result = Banner(
	message: 'DEBUG',
	textDirection: TextDirection.ltr,
	location: BannerLocation.topEnd,
	child: result,
	);
	return true;
	}());
	return result;
	}

	@override
	void debugFillProperties(DiagnosticPropertiesBuilder properties) {
	super.debugFillProperties(properties);
	String message = 'disabled';
	assert(() {
	message = '"DEBUG"';
	return true;
	}());
	properties.add(DiagnosticsNode.message(message));
	}
	}