ink_well.dart

// 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 'dart:collection';

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

import 'debug.dart';
import 'feedback.dart';
import 'ink_highlight.dart';
import 'material.dart';
import 'theme.dart';

/// An ink feature that displays a [color] "splash" in response to a user
/// gesture that can be confirmed or canceled.
///
/// Subclasses call [confirm] when an input gesture is recognized. For
/// example a press event might trigger an ink feature that's confirmed
/// when the corresponding up event is seen.
///
/// Subclasses call [cancel] when an input gesture is aborted before it
/// is recognized. For example a press event might trigger an ink feature
/// that's canceled when the pointer is dragged out of the reference
/// box.
///
/// The [InkWell] and [InkResponse] widgets generate instances of this
/// class.
abstract class InteractiveInkFeature extends InkFeature {
  /// Creates an InteractiveInkFeature.
  ///
  /// The [controller] and [referenceBox] arguments must not be null.
  InteractiveInkFeature({
    @required MaterialInkController controller,
    @required RenderBox referenceBox,
    Color color,
    VoidCallback onRemoved,
  }) : assert(controller != null),
       assert(referenceBox != null),
       _color = color,
       super(controller: controller, referenceBox: referenceBox, onRemoved: onRemoved);

  /// Called when the user input that triggered this feature's appearance was confirmed.
  ///
  /// Typically causes the ink to propagate faster across the material. By default this
  /// method does nothing.
  void confirm() { }

  /// Called when the user input that triggered this feature's appearance was canceled.
  ///
  /// Typically causes the ink to gradually disappear. By default this method does
  /// nothing.
  void cancel() { }

  /// The ink's color.
  Color get color => _color;
  Color _color;
  set color(Color value) {
    if (value == _color)
      return;
    _color = value;
    controller.markNeedsPaint();
  }
}

/// An encapsulation of an [InteractiveInkFeature] constructor used by
/// [InkWell], [InkResponse], and [ThemeData].
///
/// Interactive ink feature implementations should provide a static const
/// `splashFactory` value that's an instance of this class. The `splashFactory`
/// can be used to configure an [InkWell], [InkResponse] or [ThemeData].
///
/// See also:
///
///  * [InkSplash.splashFactory]
///  * [InkRipple.splashFactory]
abstract class InteractiveInkFeatureFactory {
  /// Subclasses should provide a const constructor.
  const InteractiveInkFeatureFactory();

  /// The factory method.
  ///
  /// Subclasses should override this method to return a new instance of an
  /// [InteractiveInkFeature].
  InteractiveInkFeature create({
    @required MaterialInkController controller,
    @required RenderBox referenceBox,
    @required Offset position,
    @required Color color,
    @required TextDirection textDirection,
    bool containedInkWell = false,
    RectCallback rectCallback,
    BorderRadius borderRadius,
    ShapeBorder customBorder,
    double radius,
    VoidCallback onRemoved,
  });
}

/// An area of a [Material] that responds to touch. Has a configurable shape and
/// can be configured to clip splashes that extend outside its bounds or not.
///
/// For a variant of this widget that is specialized for rectangular areas that
/// always clip splashes, see [InkWell].
///
/// An [InkResponse] widget does two things when responding to a tap:
///
///  * It starts to animate a _highlight_. The shape of the highlight is
///    determined by [highlightShape]. If it is a [BoxShape.circle], the
///    default, then the highlight is a circle of fixed size centered in the
///    [InkResponse]. If it is [BoxShape.rectangle], then the highlight is a box
///    the size of the [InkResponse] itself, unless [getRectCallback] is
///    provided, in which case that callback defines the rectangle. The color of
///    the highlight is set by [highlightColor].
///
///  * Simultaneously, it starts to animate a _splash_. This is a growing circle
///    initially centered on the tap location. If this is a [containedInkWell],
///    the splash grows to the [radius] while remaining centered at the tap
///    location. Otherwise, the splash migrates to the center of the box as it
///    grows.
///
/// The following two diagrams show how [InkResponse] looks when tapped if the
/// [highlightShape] is [BoxShape.circle] (the default) and [containedInkWell]
/// is false (also the default).
///
/// The first diagram shows how it looks if the [InkResponse] is relatively
/// large:
///
/// ![The highlight is a disc centered in the box, smaller than the child widget.](https://flutter.github.io/assets-for-api-docs/assets/material/ink_response_large.png)
///
/// The second diagram shows how it looks if the [InkResponse] is small:
///
/// ![The highlight is a disc overflowing the box, centered on the child.](https://flutter.github.io/assets-for-api-docs/assets/material/ink_response_small.png)
///
/// The main thing to notice from these diagrams is that the splashes happily
/// exceed the bounds of the widget (because [containedInkWell] is false).
///
/// The following diagram shows the effect when the [InkResponse] has a
/// [highlightShape] of [BoxShape.rectangle] with [containedInkWell] set to
/// true. These are the values used by [InkWell].
///
/// ![The highlight is a rectangle the size of the box.](https://flutter.github.io/assets-for-api-docs/assets/material/ink_well.png)
///
/// The [InkResponse] widget must have a [Material] widget as an ancestor. The
/// [Material] widget is where the ink reactions are actually painted. This
/// matches the material design premise wherein the [Material] is what is
/// actually reacting to touches by spreading ink.
///
/// If a Widget uses this class directly, it should include the following line
/// at the top of its build function to call [debugCheckHasMaterial]:
///
/// ```dart
/// assert(debugCheckHasMaterial(context));
/// ```
///
/// ## Troubleshooting
///
/// ### The ink splashes aren't visible!
///
/// If there is an opaque graphic, e.g. painted using a [Container], [Image], or
/// [DecoratedBox], between the [Material] widget and the [InkResponse] widget,
/// then the splash won't be visible because it will be under the opaque graphic.
/// This is because ink splashes draw on the underlying [Material] itself, as
/// if the ink was spreading inside the material.
///
/// The [Ink] widget can be used as a replacement for [Image], [Container], or
/// [DecoratedBox] to ensure that the image or decoration also paints in the
/// [Material] itself, below the ink.
///
/// If this is not possible for some reason, e.g. because you are using an
/// opaque [CustomPaint] widget, alternatively consider using a second
/// [Material] above the opaque widget but below the [InkResponse] (as an
/// ancestor to the ink response). The [MaterialType.transparency] material
/// kind can be used for this purpose.
///
/// See also:
///
///  * [GestureDetector], for listening for gestures without ink splashes.
///  * [RaisedButton] and [FlatButton], two kinds of buttons in material design.
///  * [IconButton], which combines [InkResponse] with an [Icon].
class InkResponse extends StatefulWidget {
  /// Creates an area of a [Material] that responds to touch.
  ///
  /// Must have an ancestor [Material] widget in which to cause ink reactions.
  ///
  /// The [containedInkWell], [highlightShape], [enableFeedback], and
  /// [excludeFromSemantics] arguments must not be null.
  const InkResponse({
    Key key,
    this.child,
    this.onTap,
    this.onTapDown,
    this.onTapCancel,
    this.onDoubleTap,
    this.onLongPress,
    this.onHighlightChanged,
    this.onHover,
    this.containedInkWell = false,
    this.highlightShape = BoxShape.circle,
    this.radius,
    this.borderRadius,
    this.customBorder,
    this.focusColor,
    this.hoverColor,
    this.highlightColor,
    this.splashColor,
    this.splashFactory,
    this.enableFeedback = true,
    this.excludeFromSemantics = false,
    this.focusNode,
    this.canRequestFocus = true,
    this.onFocusChange,
    this.autofocus = false,
  }) : assert(containedInkWell != null),
       assert(highlightShape != null),
       assert(enableFeedback != null),
       assert(excludeFromSemantics != null),
       assert(autofocus != null),
       assert(canRequestFocus != null),
       super(key: key);

  /// The widget below this widget in the tree.
  ///
  /// {@macro flutter.widgets.child}
  final Widget child;

  /// Called when the user taps this part of the material.
  final GestureTapCallback onTap;

  /// Called when the user taps down this part of the material.
  final GestureTapDownCallback onTapDown;

  /// Called when the user cancels a tap that was started on this part of the
  /// material.
  final GestureTapCallback onTapCancel;

  /// Called when the user double taps this part of the material.
  final GestureTapCallback onDoubleTap;

  /// Called when the user long-presses on this part of the material.
  final GestureLongPressCallback onLongPress;

  /// Called when this part of the material either becomes highlighted or stops
  /// being highlighted.
  ///
  /// The value passed to the callback is true if this part of the material has
  /// become highlighted and false if this part of the material has stopped
  /// being highlighted.
  ///
  /// If all of [onTap], [onDoubleTap], and [onLongPress] become null while a
  /// gesture is ongoing, then [onTapCancel] will be fired and
  /// [onHighlightChanged] will be fired with the value false _during the
  /// build_. This means, for instance, that in that scenario [State.setState]
  /// cannot be called.
  final ValueChanged<bool> onHighlightChanged;

  /// Called when a pointer enters or exits the ink response area.
  ///
  /// The value passed to the callback is true if a pointer has entered this
  /// part of the material and false if a pointer has exited this part of the
  /// material.
  final ValueChanged<bool> onHover;

  /// Whether this ink response should be clipped its bounds.
  ///
  /// This flag also controls whether the splash migrates to the center of the
  /// [InkResponse] or not. If [containedInkWell] is true, the splash remains
  /// centered around the tap location. If it is false, the splash migrates to
  /// the center of the [InkResponse] as it grows.
  ///
  /// See also:
  ///
  ///  * [highlightShape], the shape of the focus, hover, and pressed
  ///    highlights.
  ///  * [borderRadius], which controls the corners when the box is a rectangle.
  ///  * [getRectCallback], which controls the size and position of the box when
  ///    it is a rectangle.
  final bool containedInkWell;

  /// The shape (e.g., circle, rectangle) to use for the highlight drawn around
  /// this part of the material when pressed, hovered over, or focused.
  ///
  /// The same shape is used for the pressed highlight (see [highlightColor]),
  /// the focus highlight (see [focusColor]), and the hover highlight (see
  /// [hoverColor]).
  ///
  /// If the shape is [BoxShape.circle], then the highlight is centered on the
  /// [InkResponse]. If the shape is [BoxShape.rectangle], then the highlight
  /// fills the [InkResponse], or the rectangle provided by [getRectCallback] if
  /// the callback is specified.
  ///
  /// See also:
  ///
  ///  * [containedInkWell], which controls clipping behavior.
  ///  * [borderRadius], which controls the corners when the box is a rectangle.
  ///  * [highlightColor], the color of the highlight.
  ///  * [getRectCallback], which controls the size and position of the box when
  ///    it is a rectangle.
  final BoxShape highlightShape;

  /// The radius of the ink splash.
  ///
  /// Splashes grow up to this size. By default, this size is determined from
  /// the size of the rectangle provided by [getRectCallback], or the size of
  /// the [InkResponse] itself.
  ///
  /// See also:
  ///
  ///  * [splashColor], the color of the splash.
  ///  * [splashFactory], which defines the appearance of the splash.
  final double radius;

  /// The clipping radius of the containing rect. This is effective only if
  /// [customBorder] is null.
  ///
  /// If this is null, it is interpreted as [BorderRadius.zero].
  final BorderRadius borderRadius;

  /// The custom clip border which overrides [borderRadius].
  final ShapeBorder customBorder;

  /// The color of the ink response when the parent widget is focused. If this
  /// property is null then the focus color of the theme,
  /// [ThemeData.focusColor], will be used.
  ///
  /// See also:
  ///
  ///  * [highlightShape], the shape of the focus, hover, and pressed
  ///    highlights.
  ///  * [hoverColor], the color of the hover highlight.
  ///  * [splashColor], the color of the splash.
  ///  * [splashFactory], which defines the appearance of the splash.
  final Color focusColor;

  /// The color of the ink response when a pointer is hovering over it. If this
  /// property is null then the hover color of the theme,
  /// [ThemeData.hoverColor], will be used.
  ///
  /// See also:
  ///
  ///  * [highlightShape], the shape of the focus, hover, and pressed
  ///    highlights.
  ///  * [highlightColor], the color of the pressed highlight.
  ///  * [focusColor], the color of the focus highlight.
  ///  * [splashColor], the color of the splash.
  ///  * [splashFactory], which defines the appearance of the splash.
  final Color hoverColor;

  /// The highlight color of the ink response when pressed. If this property is
  /// null then the highlight color of the theme, [ThemeData.highlightColor],
  /// will be used.
  ///
  /// See also:
  ///
  ///  * [hoverColor], the color of the hover highlight.
  ///  * [focusColor], the color of the focus highlight.
  ///  * [highlightShape], the shape of the focus, hover, and pressed
  ///    highlights.
  ///  * [splashColor], the color of the splash.
  ///  * [splashFactory], which defines the appearance of the splash.
  final Color highlightColor;

  /// The splash color of the ink response. If this property is null then the
  /// splash color of the theme, [ThemeData.splashColor], will be used.
  ///
  /// See also:
  ///
  ///  * [splashFactory], which defines the appearance of the splash.
  ///  * [radius], the (maximum) size of the ink splash.
  ///  * [highlightColor], the color of the highlight.
  final Color splashColor;

  /// Defines the appearance of the splash.
  ///
  /// Defaults to the value of the theme's splash factory: [ThemeData.splashFactory].
  ///
  /// See also:
  ///
  ///  * [radius], the (maximum) size of the ink splash.
  ///  * [splashColor], the color of the splash.
  ///  * [highlightColor], the color of the highlight.
  ///  * [InkSplash.splashFactory], which defines the default splash.
  ///  * [InkRipple.splashFactory], which defines a splash that spreads out
  ///    more aggressively than the default.
  final InteractiveInkFeatureFactory splashFactory;

  /// Whether detected gestures should provide acoustic and/or haptic feedback.
  ///
  /// For example, on Android a tap will produce a clicking sound and a
  /// long-press will produce a short vibration, when feedback is enabled.
  ///
  /// See also:
  ///
  ///  * [Feedback] for providing platform-specific feedback to certain actions.
  final bool enableFeedback;

  /// Whether to exclude the gestures introduced by this widget from the
  /// semantics tree.
  ///
  /// For example, a long-press gesture for showing a tooltip is usually
  /// excluded because the tooltip itself is included in the semantics
  /// tree directly and so having a gesture to show it would result in
  /// duplication of information.
  final bool excludeFromSemantics;

  /// Handler called when the focus changes.
  ///
  /// Called with true if this widget's node gains focus, and false if it loses
  /// focus.
  final ValueChanged<bool> onFocusChange;

  /// {@macro flutter.widgets.Focus.autofocus}
  final bool autofocus;

  /// {@macro flutter.widgets.Focus.focusNode}
  final FocusNode focusNode;

  /// {@template flutter.widgets.Focus.canRequestFocus}
  final bool canRequestFocus;

  /// The rectangle to use for the highlight effect and for clipping
  /// the splash effects if [containedInkWell] is true.
  ///
  /// This method is intended to be overridden by descendants that
  /// specialize [InkResponse] for unusual cases. For example,
  /// [TableRowInkWell] implements this method to return the rectangle
  /// corresponding to the row that the widget is in.
  ///
  /// The default behavior returns null, which is equivalent to
  /// returning the referenceBox argument's bounding box (though
  /// slightly more efficient).
  RectCallback getRectCallback(RenderBox referenceBox) => null;

  /// Asserts that the given context satisfies the prerequisites for
  /// this class.
  ///
  /// This method is intended to be overridden by descendants that
  /// specialize [InkResponse] for unusual cases. For example,
  /// [TableRowInkWell] implements this method to verify that the widget is
  /// in a table.
  @mustCallSuper
  bool debugCheckContext(BuildContext context) {
    assert(debugCheckHasMaterial(context));
    assert(debugCheckHasDirectionality(context));
    return true;
  }

  @override
  _InkResponseState<InkResponse> createState() => _InkResponseState<InkResponse>();

  @override
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
    final List<String> gestures = <String>[
      if (onTap != null) 'tap',
      if (onDoubleTap != null) 'double tap',
      if (onLongPress != null) 'long press',
      if (onTapDown != null) 'tap down',
      if (onTapCancel != null) 'tap cancel',
    ];
    properties.add(IterableProperty<String>('gestures', gestures, ifEmpty: '<none>'));
    properties.add(DiagnosticsProperty<bool>('containedInkWell', containedInkWell, level: DiagnosticLevel.fine));
    properties.add(DiagnosticsProperty<BoxShape>(
      'highlightShape',
      highlightShape,
      description: '${containedInkWell ? "clipped to " : ""}$highlightShape',
      showName: false,
    ));
  }
}

/// Used to index the allocated highlights for the different types of highlights
/// in [_InkResponseState].
enum _HighlightType {
  pressed,
  hover,
  focus,
}

class _InkResponseState<T extends InkResponse> extends State<T> with AutomaticKeepAliveClientMixin<T> {
  Set<InteractiveInkFeature> _splashes;
  InteractiveInkFeature _currentSplash;
  bool _hovering = false;
  final Map<_HighlightType, InkHighlight> _highlights = <_HighlightType, InkHighlight>{};
  Map<LocalKey, ActionFactory> _actionMap;

  bool get highlightsExist => _highlights.values.where((InkHighlight highlight) => highlight != null).isNotEmpty;

  void _handleAction(FocusNode node, Intent intent) {
    _startSplash(context: node.context);
    _handleTap(node.context);
  }

  Action _createAction() {
    return CallbackAction(
      ActivateAction.key,
      onInvoke:  _handleAction,
    );
  }

  @override
  void initState() {
    super.initState();
    _actionMap = <LocalKey, ActionFactory>{
      ActivateAction.key: _createAction,
    };
    FocusManager.instance.addHighlightModeListener(_handleFocusHighlightModeChange);
  }

  @override
  void didUpdateWidget(T oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (_isWidgetEnabled(widget) != _isWidgetEnabled(oldWidget)) {
      _handleHoverChange(_hovering);
      _updateFocusHighlights();
    }
  }

  @override
  void dispose() {
    FocusManager.instance.removeHighlightModeListener(_handleFocusHighlightModeChange);
    super.dispose();
  }

  @override
  bool get wantKeepAlive => highlightsExist || (_splashes != null && _splashes.isNotEmpty);

  Color getHighlightColorForType(_HighlightType type) {
    switch (type) {
      case _HighlightType.pressed:
        return widget.highlightColor ?? Theme.of(context).highlightColor;
      case _HighlightType.focus:
        return widget.focusColor ?? Theme.of(context).focusColor;
      case _HighlightType.hover:
        return widget.hoverColor ?? Theme.of(context).hoverColor;
    }
    assert(false, 'Unhandled $_HighlightType $type');
    return null;
  }

  Duration getFadeDurationForType(_HighlightType type) {
    switch (type) {
      case _HighlightType.pressed:
        return const Duration(milliseconds: 200);
      case _HighlightType.hover:
      case _HighlightType.focus:
        return const Duration(milliseconds: 50);
    }
    assert(false, 'Unhandled $_HighlightType $type');
    return null;
  }

  void updateHighlight(_HighlightType type, {@required bool value}) {
    final InkHighlight highlight = _highlights[type];
    void handleInkRemoval() {
      assert(_highlights[type] != null);
      _highlights[type] = null;
      updateKeepAlive();
    }

    if (value == (highlight != null && highlight.active))
      return;
    if (value) {
      if (highlight == null) {
        final RenderBox referenceBox = context.findRenderObject() as RenderBox;
        _highlights[type] = InkHighlight(
          controller: Material.of(context),
          referenceBox: referenceBox,
          color: getHighlightColorForType(type),
          shape: widget.highlightShape,
          borderRadius: widget.borderRadius,
          customBorder: widget.customBorder,
          rectCallback: widget.getRectCallback(referenceBox),
          onRemoved: handleInkRemoval,
          textDirection: Directionality.of(context),
          fadeDuration: getFadeDurationForType(type),
        );
        updateKeepAlive();
      } else {
        highlight.activate();
      }
    } else {
      highlight.deactivate();
    }
    assert(value == (_highlights[type] != null && _highlights[type].active));

    switch (type) {
      case _HighlightType.pressed:
        if (widget.onHighlightChanged != null)
          widget.onHighlightChanged(value);
        break;
      case _HighlightType.hover:
        if (widget.onHover != null)
          widget.onHover(value);
        break;
      case _HighlightType.focus:
        break;
    }
  }

  InteractiveInkFeature _createInkFeature(Offset globalPosition) {
    final MaterialInkController inkController = Material.of(context);
    final RenderBox referenceBox = context.findRenderObject() as RenderBox;
    final Offset position = referenceBox.globalToLocal(globalPosition);
    final Color color = widget.splashColor ?? Theme.of(context).splashColor;
    final RectCallback rectCallback = widget.containedInkWell ? widget.getRectCallback(referenceBox) : null;
    final BorderRadius borderRadius = widget.borderRadius;
    final ShapeBorder customBorder = widget.customBorder;

    InteractiveInkFeature splash;
    void onRemoved() {
      if (_splashes != null) {
        assert(_splashes.contains(splash));
        _splashes.remove(splash);
        if (_currentSplash == splash)
          _currentSplash = null;
        updateKeepAlive();
      } // else we're probably in deactivate()
    }

    splash = (widget.splashFactory ?? Theme.of(context).splashFactory).create(
      controller: inkController,
      referenceBox: referenceBox,
      position: position,
      color: color,
      containedInkWell: widget.containedInkWell,
      rectCallback: rectCallback,
      radius: widget.radius,
      borderRadius: borderRadius,
      customBorder: customBorder,
      onRemoved: onRemoved,
      textDirection: Directionality.of(context),
    );

    return splash;
  }

  void _handleFocusHighlightModeChange(FocusHighlightMode mode) {
    if (!mounted) {
      return;
    }
    setState(() {
      _updateFocusHighlights();
    });
  }

  void _updateFocusHighlights() {
    bool showFocus;
    switch (FocusManager.instance.highlightMode) {
      case FocusHighlightMode.touch:
        showFocus = false;
        break;
      case FocusHighlightMode.traditional:
        showFocus = enabled && _hasFocus;
        break;
    }
    updateHighlight(_HighlightType.focus, value: showFocus);
  }

  bool _hasFocus = false;
  void _handleFocusUpdate(bool hasFocus) {
    _hasFocus = hasFocus;
    _updateFocusHighlights();
    if (widget.onFocusChange != null) {
      widget.onFocusChange(hasFocus);
    }
  }

  void _handleTapDown(TapDownDetails details) {
    _startSplash(details: details);
    if (widget.onTapDown != null) {
      widget.onTapDown(details);
    }
  }

  void _startSplash({TapDownDetails details, BuildContext context}) {
    assert(details != null || context != null);

    Offset globalPosition;
    if (context != null) {
      final RenderBox referenceBox = context.findRenderObject() as RenderBox;
      assert(referenceBox.hasSize, 'InkResponse must be done with layout before starting a splash.');
      globalPosition = referenceBox.localToGlobal(referenceBox.paintBounds.center);
    } else {
      globalPosition = details.globalPosition;
    }
    final InteractiveInkFeature splash = _createInkFeature(globalPosition);
    _splashes ??= HashSet<InteractiveInkFeature>();
    _splashes.add(splash);
    _currentSplash = splash;
    updateKeepAlive();
    updateHighlight(_HighlightType.pressed, value: true);
  }

  void _handleTap(BuildContext context) {
    _currentSplash?.confirm();
    _currentSplash = null;
    updateHighlight(_HighlightType.pressed, value: false);
    if (widget.onTap != null) {
      if (widget.enableFeedback)
        Feedback.forTap(context);
      widget.onTap();
    }
  }

  void _handleTapCancel() {
    _currentSplash?.cancel();
    _currentSplash = null;
    if (widget.onTapCancel != null) {
      widget.onTapCancel();
    }
    updateHighlight(_HighlightType.pressed, value: false);
  }

  void _handleDoubleTap() {
    _currentSplash?.confirm();
    _currentSplash = null;
    if (widget.onDoubleTap != null)
      widget.onDoubleTap();
  }

  void _handleLongPress(BuildContext context) {
    _currentSplash?.confirm();
    _currentSplash = null;
    if (widget.onLongPress != null) {
      if (widget.enableFeedback)
        Feedback.forLongPress(context);
      widget.onLongPress();
    }
  }

  @override
  void deactivate() {
    if (_splashes != null) {
      final Set<InteractiveInkFeature> splashes = _splashes;
      _splashes = null;
      for (final InteractiveInkFeature splash in splashes)
        splash.dispose();
      _currentSplash = null;
    }
    assert(_currentSplash == null);
    for (final _HighlightType highlight in _highlights.keys) {
      _highlights[highlight]?.dispose();
      _highlights[highlight] = null;
    }
    super.deactivate();
  }

  bool _isWidgetEnabled(InkResponse widget) {
    return widget.onTap != null || widget.onDoubleTap != null || widget.onLongPress != null;
  }

  bool get enabled => _isWidgetEnabled(widget);

  void _handleMouseEnter(PointerEnterEvent event) => _handleHoverChange(true);
  void _handleMouseExit(PointerExitEvent event) => _handleHoverChange(false);
  void _handleHoverChange(bool hovering) {
    if (_hovering != hovering) {
      _hovering = hovering;
      updateHighlight(_HighlightType.hover, value: enabled && _hovering);
    }
  }

  @override
  Widget build(BuildContext context) {
    assert(widget.debugCheckContext(context));
    super.build(context); // See AutomaticKeepAliveClientMixin.
    for (final _HighlightType type in _highlights.keys) {
      _highlights[type]?.color = getHighlightColorForType(type);
    }
    _currentSplash?.color = widget.splashColor ?? Theme.of(context).splashColor;
    final bool canRequestFocus = enabled && widget.canRequestFocus;
    return Actions(
      actions: _actionMap,
      child: Focus(
        focusNode: widget.focusNode,
        canRequestFocus: canRequestFocus,
        onFocusChange: _handleFocusUpdate,
        autofocus: widget.autofocus,
        child: MouseRegion(
          onEnter: enabled ? _handleMouseEnter : null,
          onExit: enabled ? _handleMouseExit : null,
          child: GestureDetector(
            onTapDown: enabled ? _handleTapDown : null,
            onTap: enabled ? () => _handleTap(context) : null,
            onTapCancel: enabled ? _handleTapCancel : null,
            onDoubleTap: widget.onDoubleTap != null ? _handleDoubleTap : null,
            onLongPress: widget.onLongPress != null ? () => _handleLongPress(context) : null,
            behavior: HitTestBehavior.opaque,
            excludeFromSemantics: widget.excludeFromSemantics,
            child: widget.child,
          ),
        ),
      ),
    );
  }
}

/// A rectangular area of a [Material] that responds to touch.
///
/// For a variant of this widget that does not clip splashes, see [InkResponse].
///
/// The following diagram shows how an [InkWell] looks when tapped, when using
/// default values.
///
/// ![The highlight is a rectangle the size of the box.](https://flutter.github.io/assets-for-api-docs/assets/material/ink_well.png)
///
/// The [InkWell] widget must have a [Material] widget as an ancestor. The
/// [Material] widget is where the ink reactions are actually painted. This
/// matches the material design premise wherein the [Material] is what is
/// actually reacting to touches by spreading ink.
///
/// If a Widget uses this class directly, it should include the following line
/// at the top of its build function to call [debugCheckHasMaterial]:
///
/// ```dart
/// assert(debugCheckHasMaterial(context));
/// ```
///
/// ## Troubleshooting
///
/// ### The ink splashes aren't visible!
///
/// If there is an opaque graphic, e.g. painted using a [Container], [Image], or
/// [DecoratedBox], between the [Material] widget and the [InkWell] widget, then
/// the splash won't be visible because it will be under the opaque graphic.
/// This is because ink splashes draw on the underlying [Material] itself, as
/// if the ink was spreading inside the material.
///
/// The [Ink] widget can be used as a replacement for [Image], [Container], or
/// [DecoratedBox] to ensure that the image or decoration also paints in the
/// [Material] itself, below the ink.
///
/// If this is not possible for some reason, e.g. because you are using an
/// opaque [CustomPaint] widget, alternatively consider using a second
/// [Material] above the opaque widget but below the [InkWell] (as an
/// ancestor to the ink well). The [MaterialType.transparency] material
/// kind can be used for this purpose.
///
/// ### The ink splashes don't track the size of an animated container
/// If the size of an InkWell's [Material] ancestor changes while the InkWell's
/// splashes are expanding, you may notice that the splashes aren't clipped
/// correctly. This can't be avoided.
///
/// An example of this situation is as follows:
///
/// {@tool sample --template=stateful_widget_scaffold_center}
///
/// Tap the container to cause it to grow. Then, tap it again and hold before
/// the widget reaches its maximum size to observe the clipped ink splash.
///
/// ```dart
/// double sideLength = 50;
///
/// Widget build(BuildContext context) {
///   return AnimatedContainer(
///     height: sideLength,
///     width: sideLength,
///     duration: Duration(seconds: 2),
///     curve: Curves.easeIn,
///     child: Material(
///       color: Colors.yellow,
///       child: InkWell(
///         onTap: () {
///           setState(() {
///             sideLength == 50 ? sideLength = 100 : sideLength = 50;
///           });
///         },
///       ),
///     ),
///   );
/// }
/// ```
/// {@end-tool}
///
/// An InkWell's splashes will not properly update to conform to changes if the
/// size of its underlying [Material], where the splashes are rendered, changes
/// during animation. You should avoid using InkWells within [Material] widgets
/// that are changing size.
///
/// See also:
///
///  * [GestureDetector], for listening for gestures without ink splashes.
///  * [RaisedButton] and [FlatButton], two kinds of buttons in material design.
///  * [InkResponse], a variant of [InkWell] that doesn't force a rectangular
///    shape on the ink reaction.
class InkWell extends InkResponse {
  /// Creates an ink well.
  ///
  /// Must have an ancestor [Material] widget in which to cause ink reactions.
  ///
  /// The [enableFeedback] and [excludeFromSemantics] arguments must not be
  /// null.
  const InkWell({
    Key key,
    Widget child,
    GestureTapCallback onTap,
    GestureTapCallback onDoubleTap,
    GestureLongPressCallback onLongPress,
    GestureTapDownCallback onTapDown,
    GestureTapCancelCallback onTapCancel,
    ValueChanged<bool> onHighlightChanged,
    ValueChanged<bool> onHover,
    Color focusColor,
    Color hoverColor,
    Color highlightColor,
    Color splashColor,
    InteractiveInkFeatureFactory splashFactory,
    double radius,
    BorderRadius borderRadius,
    ShapeBorder customBorder,
    bool enableFeedback = true,
    bool excludeFromSemantics = false,
    FocusNode focusNode,
    bool canRequestFocus = true,
    ValueChanged<bool> onFocusChange,
    bool autofocus = false,
  }) : super(
    key: key,
    child: child,
    onTap: onTap,
    onDoubleTap: onDoubleTap,
    onLongPress: onLongPress,
    onTapDown: onTapDown,
    onTapCancel: onTapCancel,
    onHighlightChanged: onHighlightChanged,
    onHover: onHover,
    containedInkWell: true,
    highlightShape: BoxShape.rectangle,
    focusColor: focusColor,
    hoverColor: hoverColor,
    highlightColor: highlightColor,
    splashColor: splashColor,
    splashFactory: splashFactory,
    radius: radius,
    borderRadius: borderRadius,
    customBorder: customBorder,
    enableFeedback: enableFeedback ?? true,
    excludeFromSemantics: excludeFromSemantics ?? false,
    focusNode: focusNode,
    canRequestFocus: canRequestFocus ?? true,
    onFocusChange: onFocusChange,
    autofocus: autofocus ?? false,
  );
}