packages/flutter/lib/src/material/toggleable.dart - mirrors/flutter - 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.

 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';

 import 'constants.dart';
 import 'material_state.dart';

 // Duration of the animation that moves the toggle from one state to another.
 const Duration _kToggleDuration = Duration(milliseconds: 200);

 // Duration of the fade animation for the reaction when focus and hover occur.
 const Duration _kReactionFadeDuration = Duration(milliseconds: 50);

 /// A mixin for [StatefulWidget]s that implement material-themed toggleable
 /// controls with toggle animations (e.g. [Switch]es, [Checkbox]es, and
 /// [Radio]s).
 ///
 /// The mixin implements the logic for toggling the control (e.g. when tapped)
 /// and provides a series of animation controllers to transition the control
 /// from one state to another. It does not have any opinion about the visual
 /// representation of the toggleable widget. The visuals are defined by a
 /// [CustomPainter] passed to the [buildToggleable]. [State] objects using this
 /// mixin should call that method from their [build] method.
 ///
 /// This mixin is used to implement the material components for [Switch],
 /// [Checkbox], and [Radio] controls.
 @optionalTypeArgs
 mixin ToggleableStateMixin<S extends StatefulWidget> on TickerProviderStateMixin<S> {
   /// Used by subclasses to manipulate the visual value of the control.
   ///
   /// Some controls respond to user input by updating their visual value. For
   /// example, the thumb of a switch moves from one position to another when
   /// dragged. These controls manipulate this animation controller to update
   /// their [position] and eventually trigger an [onChanged] callback when the
   /// animation reaches either 0.0 or 1.0.
   AnimationController get positionController => _positionController;
   late AnimationController _positionController;

   /// The visual value of the control.
   ///
   /// When the control is inactive, the [value] is false and this animation has
   /// the value 0.0. When the control is active, the value is either true or
   /// tristate is true and the value is null. When the control is active the
   /// animation has a value of 1.0. When the control is changing from inactive
   /// to active (or vice versa), [value] is the target value and this animation
   /// gradually updates from 0.0 to 1.0 (or vice versa).
   CurvedAnimation get position => _position;
   late CurvedAnimation _position;

   /// Used by subclasses to control the radial reaction animation.
   ///
   /// Some controls have a radial ink reaction to user input. This animation
   /// controller can be used to start or stop these ink reactions.
   ///
   /// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
   /// may be used.
   AnimationController get reactionController => _reactionController;
   late AnimationController _reactionController;

   /// The visual value of the radial reaction animation.
   ///
   /// Some controls have a radial ink reaction to user input. This animation
   /// controls the progress of these ink reactions.
   ///
   /// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
   /// may be used.
   Animation<double> get reaction => _reaction;
   late Animation<double> _reaction;

   /// Controls the radial reaction's opacity animation for hover changes.
   ///
   /// Some controls have a radial ink reaction to pointer hover. This animation
   /// controls these ink reaction fade-ins and
   /// fade-outs.
   ///
   /// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
   /// may be used.
   Animation<double> get reactionHoverFade => _reactionHoverFade;
   late Animation<double> _reactionHoverFade;
   late AnimationController _reactionHoverFadeController;

   /// Controls the radial reaction's opacity animation for focus changes.
   ///
   /// Some controls have a radial ink reaction to focus. This animation
   /// controls these ink reaction fade-ins and fade-outs.
   ///
   /// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
   /// may be used.
   Animation<double> get reactionFocusFade => _reactionFocusFade;
   late Animation<double> _reactionFocusFade;
   late AnimationController _reactionFocusFadeController;

   /// Whether [value] of this control can be changed by user interaction.
   ///
   /// The control is considered interactive if the [onChanged] callback is
   /// non-null. If the callback is null, then the control is disabled, and
   /// non-interactive. A disabled checkbox, for example, is displayed using a
   /// grey color and its value cannot be changed.
   bool get isInteractive => onChanged != null;

   late final Map<Type, Action<Intent>> _actionMap = <Type, Action<Intent>>{
     ActivateIntent: CallbackAction<ActivateIntent>(onInvoke: _handleTap),
   };

   /// Called when the control changes value.
   ///
   /// If the control is tapped, [onChanged] is called immediately with the new
   /// value.
   ///
   /// The control is considered interactive (see [isInteractive]) if this
   /// callback is non-null. If the callback is null, then the control is
   /// disabled, and non-interactive. A disabled checkbox, for example, is
   /// displayed using a grey color and its value cannot be changed.
   ValueChanged<bool?>? get onChanged;

   /// False if this control is "inactive" (not checked, off, or unselected).
   ///
   /// If value is true then the control "active" (checked, on, or selected). If
   /// tristate is true and value is null, then the control is considered to be
   /// in its third or "indeterminate" state.
   ///
   /// When the value changes, this object starts the [positionController] and
   /// [position] animations to animate the visual appearance of the control to
   /// the new value.
   bool? get value;

   /// If true, [value] can be true, false, or null, otherwise [value] must
   /// be true or false.
   ///
   /// When [tristate] is true and [value] is null, then the control is
   /// considered to be in its third or "indeterminate" state.
   bool get tristate;

   @override
   void initState() {
     super.initState();
     _positionController = AnimationController(
       duration: _kToggleDuration,
       value: value == false ? 0.0 : 1.0,
       vsync: this,
     );
     _position = CurvedAnimation(
       parent: _positionController,
       curve: Curves.easeIn,
       reverseCurve: Curves.easeOut,
     );
     _reactionController = AnimationController(
       duration: kRadialReactionDuration,
       vsync: this,
     );
     _reaction = CurvedAnimation(
       parent: _reactionController,
       curve: Curves.fastOutSlowIn,
     );
     _reactionHoverFadeController = AnimationController(
       duration: _kReactionFadeDuration,
       value: _hovering || _focused ? 1.0 : 0.0,
       vsync: this,
     );
     _reactionHoverFade = CurvedAnimation(
       parent: _reactionHoverFadeController,
       curve: Curves.fastOutSlowIn,
     );
     _reactionFocusFadeController = AnimationController(
       duration: _kReactionFadeDuration,
       value: _hovering || _focused ? 1.0 : 0.0,
       vsync: this,
     );
     _reactionFocusFade = CurvedAnimation(
       parent: _reactionFocusFadeController,
       curve: Curves.fastOutSlowIn,
     );
   }

   /// Runs the [position] animation to transition the Toggleable's appearance
   /// to match [value].
   ///
   /// This method must be called whenever [value] changes to ensure that the
   /// visual representation of the Toggleable matches the current [value].
   void animateToValue() {
     if (tristate) {
       if (value == null) {
         _positionController.value = 0.0;
       }
       if (value ?? true) {
         _positionController.forward();
       } else {
         _positionController.reverse();
       }
     } else {
       if (value ?? false) {
         _positionController.forward();
       } else {
         _positionController.reverse();
       }
     }
   }

   @override
   void dispose() {
     _positionController.dispose();
     _reactionController.dispose();
     _reactionHoverFadeController.dispose();
     _reactionFocusFadeController.dispose();
     super.dispose();
   }

   /// The most recent [Offset] at which a pointer touched the Toggleable.
   ///
   /// This is null if currently no pointer is touching the Toggleable or if
   /// [isInteractive] is false.
   Offset? get downPosition => _downPosition;
   Offset? _downPosition;

   void _handleTapDown(TapDownDetails details) {
     if (isInteractive) {
       setState(() {
         _downPosition = details.localPosition;
       });
       _reactionController.forward();
     }
   }

   void _handleTap([Intent? _]) {
     if (!isInteractive) {
       return;
     }
     switch (value) {
       case false:
         onChanged!(true);
         break;
       case true:
         onChanged!(tristate ? null : false);
         break;
       case null:
         onChanged!(false);
         break;
     }
     context.findRenderObject()!.sendSemanticsEvent(const TapSemanticEvent());
   }

   void _handleTapEnd([TapUpDetails? _]) {
     if (_downPosition != null) {
       setState(() { _downPosition = null; });
     }
     _reactionController.reverse();
   }

   bool _focused = false;
   void _handleFocusHighlightChanged(bool focused) {
     if (focused != _focused) {
       setState(() { _focused = focused; });
       if (focused) {
         _reactionFocusFadeController.forward();
       } else {
         _reactionFocusFadeController.reverse();
       }
     }
   }

   bool _hovering = false;
   void _handleHoverChanged(bool hovering) {
     if (hovering != _hovering) {
       setState(() { _hovering = hovering; });
       if (hovering) {
         _reactionHoverFadeController.forward();
       } else {
         _reactionHoverFadeController.reverse();
       }
     }
   }

   /// Describes the current [MaterialState] of the Toggleable.
   ///
   /// The returned set will include:
   ///
   ///  * [MaterialState.disabled], if [isInteractive] is false
   ///  * [MaterialState.hovered], if a pointer is hovering over the Toggleable
   ///  * [MaterialState.focused], if the Toggleable has input focus
   ///  * [MaterialState.selected], if [value] is true or null
   Set<MaterialState> get states => <MaterialState>{
     if (!isInteractive) MaterialState.disabled,
     if (_hovering) MaterialState.hovered,
     if (_focused) MaterialState.focused,
     if (value ?? true) MaterialState.selected,
   };

   /// Typically wraps a `painter` that draws the actual visuals of the
   /// Toggleable with logic to toggle it.
   ///
   /// Consider providing a subclass of [ToggleablePainter] as a `painter`, which
   /// implements logic to draw a radial ink reaction for this control. The
   /// painter is usually configured with the [reaction], [position],
   /// [reactionHoverFade], and [reactionFocusFade] animation provided by this
   /// mixin. It is expected to draw the visuals of the Toggleable based on the
   /// current value of these animations. The animations are triggered by
   /// this mixin to transition the Toggleable from one state to another.
   ///
   /// This method must be called from the [build] method of the [State] class
   /// that uses this mixin. The returned [Widget] must be returned from the
   /// build method - potentially after wrapping it in other widgets.
   Widget buildToggleable({
     FocusNode? focusNode,
     Function(bool)? onFocusChange,
     bool autofocus = false,
     required MaterialStateProperty<MouseCursor> mouseCursor,
     required Size size,
     required CustomPainter painter,
   }) {
     return FocusableActionDetector(
       actions: _actionMap,
       focusNode: focusNode,
       autofocus: autofocus,
       onFocusChange: onFocusChange,
       enabled: isInteractive,
       onShowFocusHighlight: _handleFocusHighlightChanged,
       onShowHoverHighlight: _handleHoverChanged,
       mouseCursor: mouseCursor.resolve(states),
       child: GestureDetector(
         excludeFromSemantics: !isInteractive,
         onTapDown: isInteractive ? _handleTapDown : null,
         onTap: isInteractive ? _handleTap : null,
         onTapUp: isInteractive ? _handleTapEnd : null,
         onTapCancel: isInteractive ? _handleTapEnd : null,
         child: Semantics(
           enabled: isInteractive,
           child: CustomPaint(
             size: size,
             painter: painter,
           ),
         ),
       ),
     );
   }
 }

 /// A base class for a [CustomPainter] that may be passed to
 /// [ToggleableStateMixin.buildToggleable] to draw the visual representation of
 /// a Toggleable.
 ///
 /// Subclasses must implement the [paint] method to draw the actual visuals of
 /// the Toggleable. In their [paint] method subclasses may call
 /// [paintRadialReaction] to draw a radial ink reaction for this control.
 abstract class ToggleablePainter extends ChangeNotifier implements CustomPainter {
   /// The visual value of the control.
   ///
   /// Usually set to [ToggleableStateMixin.position].
   Animation<double> get position => _position!;
   Animation<double>? _position;
   set position(Animation<double> value) {
     if (value == _position) {
       return;
     }
     _position?.removeListener(notifyListeners);
     value.addListener(notifyListeners);
     _position = value;
     notifyListeners();
   }

   /// The visual value of the radial reaction animation.
   ///
   /// Usually set to [ToggleableStateMixin.reaction].
   Animation<double> get reaction => _reaction!;
   Animation<double>? _reaction;
   set reaction(Animation<double> value) {
     if (value == _reaction) {
       return;
     }
     _reaction?.removeListener(notifyListeners);
     value.addListener(notifyListeners);
     _reaction = value;
     notifyListeners();
   }

   /// Controls the radial reaction's opacity animation for focus changes.
   ///
   /// Usually set to [ToggleableStateMixin.reactionFocusFade].
   Animation<double> get reactionFocusFade => _reactionFocusFade!;
   Animation<double>? _reactionFocusFade;
   set reactionFocusFade(Animation<double> value) {
     if (value == _reactionFocusFade) {
       return;
     }
     _reactionFocusFade?.removeListener(notifyListeners);
     value.addListener(notifyListeners);
     _reactionFocusFade = value;
     notifyListeners();
   }

   /// Controls the radial reaction's opacity animation for hover changes.
   ///
   /// Usually set to [ToggleableStateMixin.reactionHoverFade].
   Animation<double> get reactionHoverFade => _reactionHoverFade!;
   Animation<double>? _reactionHoverFade;
   set reactionHoverFade(Animation<double> value) {
     if (value == _reactionHoverFade) {
       return;
     }
     _reactionHoverFade?.removeListener(notifyListeners);
     value.addListener(notifyListeners);
     _reactionHoverFade = value;
     notifyListeners();
   }

   /// The color that should be used in the active state (i.e., when
   /// [ToggleableStateMixin.value] is true).
   ///
   /// For example, a checkbox should use this color when checked.
   Color get activeColor => _activeColor!;
   Color? _activeColor;
   set activeColor(Color value) {
     if (_activeColor == value) {
       return;
     }
     _activeColor = value;
     notifyListeners();
   }

   /// The color that should be used in the inactive state (i.e., when
   /// [ToggleableStateMixin.value] is false).
   ///
   /// For example, a checkbox should use this color when unchecked.
   Color get inactiveColor => _inactiveColor!;
   Color? _inactiveColor;
   set inactiveColor(Color value) {
     if (_inactiveColor == value) {
       return;
     }
     _inactiveColor = value;
     notifyListeners();
   }

   /// The color that should be used for the reaction when the toggleable is
   /// inactive.
   ///
   /// Used when the toggleable needs to change the reaction color/transparency
   /// that is displayed when the toggleable is inactive and tapped.
   Color get inactiveReactionColor => _inactiveReactionColor!;
   Color? _inactiveReactionColor;
   set inactiveReactionColor(Color value) {
     if (value == _inactiveReactionColor) {
       return;
     }
     _inactiveReactionColor = value;
     notifyListeners();
   }

   /// The color that should be used for the reaction when the toggleable is
   /// active.
   ///
   /// Used when the toggleable needs to change the reaction color/transparency
   /// that is displayed when the toggleable is active and tapped.
   Color get reactionColor => _reactionColor!;
   Color? _reactionColor;
   set reactionColor(Color value) {
     if (value == _reactionColor) {
       return;
     }
     _reactionColor = value;
     notifyListeners();
   }

   /// The color that should be used for the reaction when [isHovered] is true.
   ///
   /// Used when the toggleable needs to change the reaction color/transparency,
   /// when it is being hovered over.
   Color get hoverColor => _hoverColor!;
   Color? _hoverColor;
   set hoverColor(Color value) {
     if (value == _hoverColor) {
       return;
     }
     _hoverColor = value;
     notifyListeners();
   }

   /// The color that should be used for the reaction when [isFocused] is true.
   ///
   /// Used when the toggleable needs to change the reaction color/transparency,
   /// when it has focus.
   Color get focusColor => _focusColor!;
   Color? _focusColor;
   set focusColor(Color value) {
     if (value == _focusColor) {
       return;
     }
     _focusColor = value;
     notifyListeners();
   }

   /// The splash radius for the radial reaction.
   double get splashRadius => _splashRadius!;
   double? _splashRadius;
   set splashRadius(double value) {
     if (value == _splashRadius) {
       return;
     }
     _splashRadius = value;
     notifyListeners();
   }

   /// The [Offset] within the Toggleable at which a pointer touched the Toggleable.
   ///
   /// This is null if currently no pointer is touching the Toggleable.
   ///
   /// Usually set to [ToggleableStateMixin.downPosition].
   Offset? get downPosition => _downPosition;
   Offset? _downPosition;
   set downPosition(Offset? value) {
     if (value == _downPosition) {
       return;
     }
     _downPosition = value;
     notifyListeners();
   }

   /// True if this toggleable has the input focus.
   bool get isFocused => _isFocused!;
   bool? _isFocused;
   set isFocused(bool? value) {
     if (value == _isFocused) {
       return;
     }
     _isFocused = value;
     notifyListeners();
   }

   /// True if this toggleable is being hovered over by a pointer.
   bool get isHovered => _isHovered!;
   bool? _isHovered;
   set isHovered(bool? value) {
     if (value == _isHovered) {
       return;
     }
     _isHovered = value;
     notifyListeners();
   }

   /// Used by subclasses to paint the radial ink reaction for this control.
   ///
   /// The reaction is painted on the given canvas at the given offset. The
   /// origin is the center point of the reaction (usually distinct from the
   /// [downPosition] at which the user interacted with the control).
   void paintRadialReaction({
     required Canvas canvas,
     Offset offset = Offset.zero,
     required Offset origin,
   }) {
     if (!reaction.isDismissed || !reactionFocusFade.isDismissed || !reactionHoverFade.isDismissed) {
       final Paint reactionPaint = Paint()
         ..color = Color.lerp(
           Color.lerp(
             Color.lerp(inactiveReactionColor, reactionColor, position.value),
             hoverColor,
             reactionHoverFade.value,
           ),
           focusColor,
           reactionFocusFade.value,
         )!;
       final Animatable<double> radialReactionRadiusTween = Tween<double>(
         begin: 0.0,
         end: splashRadius,
       );
       final double reactionRadius = isFocused || isHovered
           ? splashRadius
           : radialReactionRadiusTween.evaluate(reaction);
       if (reactionRadius > 0.0) {
         canvas.drawCircle(origin + offset, reactionRadius, reactionPaint);
       }
     }
   }


   @override
   void dispose() {
     _position?.removeListener(notifyListeners);
     _reaction?.removeListener(notifyListeners);
     _reactionFocusFade?.removeListener(notifyListeners);
     _reactionHoverFade?.removeListener(notifyListeners);
     super.dispose();
   }

   @override
   bool shouldRepaint(covariant CustomPainter oldDelegate) => true;

   @override
   bool? hitTest(Offset position) => null;

   @override
   SemanticsBuilderCallback? get semanticsBuilder => null;

   @override
   bool shouldRebuildSemantics(covariant CustomPainter oldDelegate) => false;

   @override
   String toString() => describeIdentity(this);
 }
	// 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.

	import 'package:flutter/foundation.dart';
	import 'package:flutter/rendering.dart';
	import 'package:flutter/widgets.dart';

	import 'constants.dart';
	import 'material_state.dart';

	// Duration of the animation that moves the toggle from one state to another.
	const Duration _kToggleDuration = Duration(milliseconds: 200);

	// Duration of the fade animation for the reaction when focus and hover occur.
	const Duration _kReactionFadeDuration = Duration(milliseconds: 50);

	/// A mixin for [StatefulWidget]s that implement material-themed toggleable
	/// controls with toggle animations (e.g. [Switch]es, [Checkbox]es, and
	/// [Radio]s).
	///
	/// The mixin implements the logic for toggling the control (e.g. when tapped)
	/// and provides a series of animation controllers to transition the control
	/// from one state to another. It does not have any opinion about the visual
	/// representation of the toggleable widget. The visuals are defined by a
	/// [CustomPainter] passed to the [buildToggleable]. [State] objects using this
	/// mixin should call that method from their [build] method.
	///
	/// This mixin is used to implement the material components for [Switch],
	/// [Checkbox], and [Radio] controls.
	@optionalTypeArgs
	mixin ToggleableStateMixin<S extends StatefulWidget> on TickerProviderStateMixin<S> {
	/// Used by subclasses to manipulate the visual value of the control.
	///
	/// Some controls respond to user input by updating their visual value. For
	/// example, the thumb of a switch moves from one position to another when
	/// dragged. These controls manipulate this animation controller to update
	/// their [position] and eventually trigger an [onChanged] callback when the
	/// animation reaches either 0.0 or 1.0.
	AnimationController get positionController => _positionController;
	late AnimationController _positionController;

	/// The visual value of the control.
	///
	/// When the control is inactive, the [value] is false and this animation has
	/// the value 0.0. When the control is active, the value is either true or
	/// tristate is true and the value is null. When the control is active the
	/// animation has a value of 1.0. When the control is changing from inactive
	/// to active (or vice versa), [value] is the target value and this animation
	/// gradually updates from 0.0 to 1.0 (or vice versa).
	CurvedAnimation get position => _position;
	late CurvedAnimation _position;

	/// Used by subclasses to control the radial reaction animation.
	///
	/// Some controls have a radial ink reaction to user input. This animation
	/// controller can be used to start or stop these ink reactions.
	///
	/// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
	/// may be used.
	AnimationController get reactionController => _reactionController;
	late AnimationController _reactionController;

	/// The visual value of the radial reaction animation.
	///
	/// Some controls have a radial ink reaction to user input. This animation
	/// controls the progress of these ink reactions.
	///
	/// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
	/// may be used.
	Animation<double> get reaction => _reaction;
	late Animation<double> _reaction;

	/// Controls the radial reaction's opacity animation for hover changes.
	///
	/// Some controls have a radial ink reaction to pointer hover. This animation
	/// controls these ink reaction fade-ins and
	/// fade-outs.
	///
	/// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
	/// may be used.
	Animation<double> get reactionHoverFade => _reactionHoverFade;
	late Animation<double> _reactionHoverFade;
	late AnimationController _reactionHoverFadeController;

	/// Controls the radial reaction's opacity animation for focus changes.
	///
	/// Some controls have a radial ink reaction to focus. This animation
	/// controls these ink reaction fade-ins and fade-outs.
	///
	/// To paint the actual radial reaction, [ToggleablePainter.paintRadialReaction]
	/// may be used.
	Animation<double> get reactionFocusFade => _reactionFocusFade;
	late Animation<double> _reactionFocusFade;
	late AnimationController _reactionFocusFadeController;

	/// Whether [value] of this control can be changed by user interaction.
	///
	/// The control is considered interactive if the [onChanged] callback is
	/// non-null. If the callback is null, then the control is disabled, and
	/// non-interactive. A disabled checkbox, for example, is displayed using a
	/// grey color and its value cannot be changed.
	bool get isInteractive => onChanged != null;

	late final Map<Type, Action<Intent>> _actionMap = <Type, Action<Intent>>{
	ActivateIntent: CallbackAction<ActivateIntent>(onInvoke: _handleTap),
	};

	/// Called when the control changes value.
	///
	/// If the control is tapped, [onChanged] is called immediately with the new
	/// value.
	///
	/// The control is considered interactive (see [isInteractive]) if this
	/// callback is non-null. If the callback is null, then the control is
	/// disabled, and non-interactive. A disabled checkbox, for example, is
	/// displayed using a grey color and its value cannot be changed.
	ValueChanged<bool?>? get onChanged;

	/// False if this control is "inactive" (not checked, off, or unselected).
	///
	/// If value is true then the control "active" (checked, on, or selected). If
	/// tristate is true and value is null, then the control is considered to be
	/// in its third or "indeterminate" state.
	///
	/// When the value changes, this object starts the [positionController] and
	/// [position] animations to animate the visual appearance of the control to
	/// the new value.
	bool? get value;

	/// If true, [value] can be true, false, or null, otherwise [value] must
	/// be true or false.
	///
	/// When [tristate] is true and [value] is null, then the control is
	/// considered to be in its third or "indeterminate" state.
	bool get tristate;

	@override
	void initState() {
	super.initState();
	_positionController = AnimationController(
	duration: _kToggleDuration,
	value: value == false ? 0.0 : 1.0,
	vsync: this,
	);
	_position = CurvedAnimation(
	parent: _positionController,
	curve: Curves.easeIn,
	reverseCurve: Curves.easeOut,
	);
	_reactionController = AnimationController(
	duration: kRadialReactionDuration,
	vsync: this,
	);
	_reaction = CurvedAnimation(
	parent: _reactionController,
	curve: Curves.fastOutSlowIn,
	);
	_reactionHoverFadeController = AnimationController(
	duration: _kReactionFadeDuration,
	value: _hovering \|\| _focused ? 1.0 : 0.0,
	vsync: this,
	);
	_reactionHoverFade = CurvedAnimation(
	parent: _reactionHoverFadeController,
	curve: Curves.fastOutSlowIn,
	);
	_reactionFocusFadeController = AnimationController(
	duration: _kReactionFadeDuration,
	value: _hovering \|\| _focused ? 1.0 : 0.0,
	vsync: this,
	);
	_reactionFocusFade = CurvedAnimation(
	parent: _reactionFocusFadeController,
	curve: Curves.fastOutSlowIn,
	);
	}

	/// Runs the [position] animation to transition the Toggleable's appearance
	/// to match [value].
	///
	/// This method must be called whenever [value] changes to ensure that the
	/// visual representation of the Toggleable matches the current [value].
	void animateToValue() {
	if (tristate) {
	if (value == null) {
	_positionController.value = 0.0;
	}
	if (value ?? true) {
	_positionController.forward();
	} else {
	_positionController.reverse();
	}
	} else {
	if (value ?? false) {
	_positionController.forward();
	} else {
	_positionController.reverse();
	}
	}
	}

	@override
	void dispose() {
	_positionController.dispose();
	_reactionController.dispose();
	_reactionHoverFadeController.dispose();
	_reactionFocusFadeController.dispose();
	super.dispose();
	}

	/// The most recent [Offset] at which a pointer touched the Toggleable.
	///
	/// This is null if currently no pointer is touching the Toggleable or if
	/// [isInteractive] is false.
	Offset? get downPosition => _downPosition;
	Offset? _downPosition;

	void _handleTapDown(TapDownDetails details) {
	if (isInteractive) {
	setState(() {
	_downPosition = details.localPosition;
	});
	_reactionController.forward();
	}
	}

	void _handleTap([Intent? _]) {
	if (!isInteractive) {
	return;
	}
	switch (value) {
	case false:
	onChanged!(true);
	break;
	case true:
	onChanged!(tristate ? null : false);
	break;
	case null:
	onChanged!(false);
	break;
	}
	context.findRenderObject()!.sendSemanticsEvent(const TapSemanticEvent());
	}

	void _handleTapEnd([TapUpDetails? _]) {
	if (_downPosition != null) {
	setState(() { _downPosition = null; });
	}
	_reactionController.reverse();
	}

	bool _focused = false;
	void _handleFocusHighlightChanged(bool focused) {
	if (focused != _focused) {
	setState(() { _focused = focused; });
	if (focused) {
	_reactionFocusFadeController.forward();
	} else {
	_reactionFocusFadeController.reverse();
	}
	}
	}

	bool _hovering = false;
	void _handleHoverChanged(bool hovering) {
	if (hovering != _hovering) {
	setState(() { _hovering = hovering; });
	if (hovering) {
	_reactionHoverFadeController.forward();
	} else {
	_reactionHoverFadeController.reverse();
	}
	}
	}

	/// Describes the current [MaterialState] of the Toggleable.
	///
	/// The returned set will include:
	///
	/// * [MaterialState.disabled], if [isInteractive] is false
	/// * [MaterialState.hovered], if a pointer is hovering over the Toggleable
	/// * [MaterialState.focused], if the Toggleable has input focus
	/// * [MaterialState.selected], if [value] is true or null
	Set<MaterialState> get states => <MaterialState>{
	if (!isInteractive) MaterialState.disabled,
	if (_hovering) MaterialState.hovered,
	if (_focused) MaterialState.focused,
	if (value ?? true) MaterialState.selected,
	};

	/// Typically wraps a `painter` that draws the actual visuals of the
	/// Toggleable with logic to toggle it.
	///
	/// Consider providing a subclass of [ToggleablePainter] as a `painter`, which
	/// implements logic to draw a radial ink reaction for this control. The
	/// painter is usually configured with the [reaction], [position],
	/// [reactionHoverFade], and [reactionFocusFade] animation provided by this
	/// mixin. It is expected to draw the visuals of the Toggleable based on the
	/// current value of these animations. The animations are triggered by
	/// this mixin to transition the Toggleable from one state to another.
	///
	/// This method must be called from the [build] method of the [State] class
	/// that uses this mixin. The returned [Widget] must be returned from the
	/// build method - potentially after wrapping it in other widgets.
	Widget buildToggleable({
	FocusNode? focusNode,
	Function(bool)? onFocusChange,
	bool autofocus = false,
	required MaterialStateProperty<MouseCursor> mouseCursor,
	required Size size,
	required CustomPainter painter,
	}) {
	return FocusableActionDetector(
	actions: _actionMap,
	focusNode: focusNode,
	autofocus: autofocus,
	onFocusChange: onFocusChange,
	enabled: isInteractive,
	onShowFocusHighlight: _handleFocusHighlightChanged,
	onShowHoverHighlight: _handleHoverChanged,
	mouseCursor: mouseCursor.resolve(states),
	child: GestureDetector(
	excludeFromSemantics: !isInteractive,
	onTapDown: isInteractive ? _handleTapDown : null,
	onTap: isInteractive ? _handleTap : null,
	onTapUp: isInteractive ? _handleTapEnd : null,
	onTapCancel: isInteractive ? _handleTapEnd : null,
	child: Semantics(
	enabled: isInteractive,
	child: CustomPaint(
	size: size,
	painter: painter,
	),
	),
	),
	);
	}
	}

	/// A base class for a [CustomPainter] that may be passed to
	/// [ToggleableStateMixin.buildToggleable] to draw the visual representation of
	/// a Toggleable.
	///
	/// Subclasses must implement the [paint] method to draw the actual visuals of
	/// the Toggleable. In their [paint] method subclasses may call
	/// [paintRadialReaction] to draw a radial ink reaction for this control.
	abstract class ToggleablePainter extends ChangeNotifier implements CustomPainter {
	/// The visual value of the control.
	///
	/// Usually set to [ToggleableStateMixin.position].
	Animation<double> get position => _position!;
	Animation<double>? _position;
	set position(Animation<double> value) {
	if (value == _position) {
	return;
	}
	_position?.removeListener(notifyListeners);
	value.addListener(notifyListeners);
	_position = value;
	notifyListeners();
	}

	/// The visual value of the radial reaction animation.
	///
	/// Usually set to [ToggleableStateMixin.reaction].
	Animation<double> get reaction => _reaction!;
	Animation<double>? _reaction;
	set reaction(Animation<double> value) {
	if (value == _reaction) {
	return;
	}
	_reaction?.removeListener(notifyListeners);
	value.addListener(notifyListeners);
	_reaction = value;
	notifyListeners();
	}

	/// Controls the radial reaction's opacity animation for focus changes.
	///
	/// Usually set to [ToggleableStateMixin.reactionFocusFade].
	Animation<double> get reactionFocusFade => _reactionFocusFade!;
	Animation<double>? _reactionFocusFade;
	set reactionFocusFade(Animation<double> value) {
	if (value == _reactionFocusFade) {
	return;
	}
	_reactionFocusFade?.removeListener(notifyListeners);
	value.addListener(notifyListeners);
	_reactionFocusFade = value;
	notifyListeners();
	}

	/// Controls the radial reaction's opacity animation for hover changes.
	///
	/// Usually set to [ToggleableStateMixin.reactionHoverFade].
	Animation<double> get reactionHoverFade => _reactionHoverFade!;
	Animation<double>? _reactionHoverFade;
	set reactionHoverFade(Animation<double> value) {
	if (value == _reactionHoverFade) {
	return;
	}
	_reactionHoverFade?.removeListener(notifyListeners);
	value.addListener(notifyListeners);
	_reactionHoverFade = value;
	notifyListeners();
	}

	/// The color that should be used in the active state (i.e., when
	/// [ToggleableStateMixin.value] is true).
	///
	/// For example, a checkbox should use this color when checked.
	Color get activeColor => _activeColor!;
	Color? _activeColor;
	set activeColor(Color value) {
	if (_activeColor == value) {
	return;
	}
	_activeColor = value;
	notifyListeners();
	}

	/// The color that should be used in the inactive state (i.e., when
	/// [ToggleableStateMixin.value] is false).
	///
	/// For example, a checkbox should use this color when unchecked.
	Color get inactiveColor => _inactiveColor!;
	Color? _inactiveColor;
	set inactiveColor(Color value) {
	if (_inactiveColor == value) {
	return;
	}
	_inactiveColor = value;
	notifyListeners();
	}

	/// The color that should be used for the reaction when the toggleable is
	/// inactive.
	///
	/// Used when the toggleable needs to change the reaction color/transparency
	/// that is displayed when the toggleable is inactive and tapped.
	Color get inactiveReactionColor => _inactiveReactionColor!;
	Color? _inactiveReactionColor;
	set inactiveReactionColor(Color value) {
	if (value == _inactiveReactionColor) {
	return;
	}
	_inactiveReactionColor = value;
	notifyListeners();
	}

	/// The color that should be used for the reaction when the toggleable is
	/// active.
	///
	/// Used when the toggleable needs to change the reaction color/transparency
	/// that is displayed when the toggleable is active and tapped.
	Color get reactionColor => _reactionColor!;
	Color? _reactionColor;
	set reactionColor(Color value) {
	if (value == _reactionColor) {
	return;
	}
	_reactionColor = value;
	notifyListeners();
	}

	/// The color that should be used for the reaction when [isHovered] is true.
	///
	/// Used when the toggleable needs to change the reaction color/transparency,
	/// when it is being hovered over.
	Color get hoverColor => _hoverColor!;
	Color? _hoverColor;
	set hoverColor(Color value) {
	if (value == _hoverColor) {
	return;
	}
	_hoverColor = value;
	notifyListeners();
	}

	/// The color that should be used for the reaction when [isFocused] is true.
	///
	/// Used when the toggleable needs to change the reaction color/transparency,
	/// when it has focus.
	Color get focusColor => _focusColor!;
	Color? _focusColor;
	set focusColor(Color value) {
	if (value == _focusColor) {
	return;
	}
	_focusColor = value;
	notifyListeners();
	}

	/// The splash radius for the radial reaction.
	double get splashRadius => _splashRadius!;
	double? _splashRadius;
	set splashRadius(double value) {
	if (value == _splashRadius) {
	return;
	}
	_splashRadius = value;
	notifyListeners();
	}

	/// The [Offset] within the Toggleable at which a pointer touched the Toggleable.
	///
	/// This is null if currently no pointer is touching the Toggleable.
	///
	/// Usually set to [ToggleableStateMixin.downPosition].
	Offset? get downPosition => _downPosition;
	Offset? _downPosition;
	set downPosition(Offset? value) {
	if (value == _downPosition) {
	return;
	}
	_downPosition = value;
	notifyListeners();
	}

	/// True if this toggleable has the input focus.
	bool get isFocused => _isFocused!;
	bool? _isFocused;
	set isFocused(bool? value) {
	if (value == _isFocused) {
	return;
	}
	_isFocused = value;
	notifyListeners();
	}

	/// True if this toggleable is being hovered over by a pointer.
	bool get isHovered => _isHovered!;
	bool? _isHovered;
	set isHovered(bool? value) {
	if (value == _isHovered) {
	return;
	}
	_isHovered = value;
	notifyListeners();
	}

	/// Used by subclasses to paint the radial ink reaction for this control.
	///
	/// The reaction is painted on the given canvas at the given offset. The
	/// origin is the center point of the reaction (usually distinct from the
	/// [downPosition] at which the user interacted with the control).
	void paintRadialReaction({
	required Canvas canvas,
	Offset offset = Offset.zero,
	required Offset origin,
	}) {
	if (!reaction.isDismissed \|\| !reactionFocusFade.isDismissed \|\| !reactionHoverFade.isDismissed) {
	final Paint reactionPaint = Paint()
	..color = Color.lerp(
	Color.lerp(
	Color.lerp(inactiveReactionColor, reactionColor, position.value),
	hoverColor,
	reactionHoverFade.value,
	),
	focusColor,
	reactionFocusFade.value,
	)!;
	final Animatable<double> radialReactionRadiusTween = Tween<double>(
	begin: 0.0,
	end: splashRadius,
	);
	final double reactionRadius = isFocused \|\| isHovered
	? splashRadius
	: radialReactionRadiusTween.evaluate(reaction);
	if (reactionRadius > 0.0) {
	canvas.drawCircle(origin + offset, reactionRadius, reactionPaint);
	}
	}
	}


	@override
	void dispose() {
	_position?.removeListener(notifyListeners);
	_reaction?.removeListener(notifyListeners);
	_reactionFocusFade?.removeListener(notifyListeners);
	_reactionHoverFade?.removeListener(notifyListeners);
	super.dispose();
	}

	@override
	bool shouldRepaint(covariant CustomPainter oldDelegate) => true;

	@override
	bool? hitTest(Offset position) => null;

	@override
	SemanticsBuilderCallback? get semanticsBuilder => null;

	@override
	bool shouldRebuildSemantics(covariant CustomPainter oldDelegate) => false;

	@override
	String toString() => describeIdentity(this);
	}