lib/ui/pointer.dart - mirrors/engine - Git at Google

 // Copyright 2013 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.

 part of dart.ui;

 /// How the pointer has changed since the last report.
 enum PointerChange {
   /// The input from the pointer is no longer directed towards this receiver.
   cancel,

   /// The device has started tracking the pointer.
   ///
   /// For example, the pointer might be hovering above the device, having not yet
   /// made contact with the surface of the device.
   add,

   /// The device is no longer tracking the pointer.
   ///
   /// For example, the pointer might have drifted out of the device's hover
   /// detection range or might have been disconnected from the system entirely.
   remove,

   /// The pointer has moved with respect to the device while not in contact with
   /// the device.
   hover,

   /// The pointer has made contact with the device.
   down,

   /// The pointer has moved with respect to the device while in contact with the
   /// device.
   move,

   /// The pointer has stopped making contact with the device.
   up,

   /// A pan/zoom has started on this pointer.
   ///
   /// This type of event will always have kind [PointerDeviceKind.trackpad].
   panZoomStart,

   /// The pan/zoom on this pointer has updated.
   ///
   /// This type of event will always have kind [PointerDeviceKind.trackpad].
   panZoomUpdate,

   /// The pan/zoom on this pointer has ended.
   ///
   /// This type of event will always have kind [PointerDeviceKind.trackpad].
   panZoomEnd,
 }

 /// The kind of pointer device.
 enum PointerDeviceKind {
   /// A touch-based pointer device.
   ///
   /// The most common case is a touch screen.
   ///
   /// When the user is operating with a trackpad on iOS, clicking will also
   /// dispatch events with kind [touch] if
   /// `UIApplicationSupportsIndirectInputEvents` is not present in `Info.plist`
   /// or returns NO.
   ///
   /// See also:
   ///
   ///  * [UIApplicationSupportsIndirectInputEvents](https://developer.apple.com/documentation/bundleresources/information_property_list/uiapplicationsupportsindirectinputevents?language=objc).
   touch,

   /// A mouse-based pointer device.
   ///
   /// The most common case is a mouse on the desktop or Web.
   ///
   /// When the user is operating with a trackpad on iOS, moving the pointing
   /// cursor will also dispatch events with kind [mouse], and clicking will
   /// dispatch events with kind [mouse] if
   /// `UIApplicationSupportsIndirectInputEvents` is not present in `Info.plist`
   /// or returns NO.
   ///
   /// See also:
   ///
   ///  * [UIApplicationSupportsIndirectInputEvents](https://developer.apple.com/documentation/bundleresources/information_property_list/uiapplicationsupportsindirectinputevents?language=objc).
   mouse,

   /// A pointer device with a stylus.
   stylus,

   /// A pointer device with a stylus that has been inverted.
   invertedStylus,

   /// Gestures from a trackpad.
   ///
   /// A trackpad here is defined as a touch-based pointer device with an
   /// indirect surface (the user operates the screen by touching something that
   /// is not the screen).
   ///
   /// When the user makes zoom, pan, scroll or rotate gestures with a physical
   /// trackpad, supporting platforms dispatch events with kind [trackpad].
   ///
   /// Events with kind [trackpad] can only have a [PointerChange] of `add`,
   /// `remove`, and pan-zoom related values.
   ///
   /// Some platforms don't support (or don't fully support) trackpad
   /// gestures, and might convert trackpad gestures into fake pointer events
   /// that simulate dragging. These events typically have kind [touch] or
   /// [mouse] instead of [trackpad]. This includes (but is not limited to) Web,
   /// and iOS when `UIApplicationSupportsIndirectInputEvents` isn't present in
   /// `Info.plist` or returns NO.
   ///
   /// Moving the pointing cursor or clicking with a trackpad typically triggers
   /// [touch] or [mouse] events, but never triggers [trackpad] events.
   ///
   /// See also:
   ///
   ///  * [UIApplicationSupportsIndirectInputEvents](https://developer.apple.com/documentation/bundleresources/information_property_list/uiapplicationsupportsindirectinputevents?language=objc).
   trackpad,

   /// An unknown pointer device.
   unknown
 }

 /// The kind of pointer signal event.
 enum PointerSignalKind {
   /// The event is not associated with a pointer signal.
   none,

   /// A pointer-generated scroll (e.g., mouse wheel or trackpad scroll).
   scroll,

   /// A pointer-generated scroll-inertia cancel.
   scrollInertiaCancel,

   /// A pointer-generated scale event (e.g. trackpad pinch).
   scale,

   /// An unknown pointer signal kind.
   unknown
 }

 /// Information about the state of a pointer.
 class PointerData {
   /// Creates an object that represents the state of a pointer.
   const PointerData({
     this.viewId = 0,
     this.embedderId = 0,
     this.timeStamp = Duration.zero,
     this.change = PointerChange.cancel,
     this.kind = PointerDeviceKind.touch,
     this.signalKind,
     this.device = 0,
     this.pointerIdentifier = 0,
     this.physicalX = 0.0,
     this.physicalY = 0.0,
     this.physicalDeltaX = 0.0,
     this.physicalDeltaY = 0.0,
     this.buttons = 0,
     this.obscured = false,
     this.synthesized = false,
     this.pressure = 0.0,
     this.pressureMin = 0.0,
     this.pressureMax = 0.0,
     this.distance = 0.0,
     this.distanceMax = 0.0,
     this.size = 0.0,
     this.radiusMajor = 0.0,
     this.radiusMinor = 0.0,
     this.radiusMin = 0.0,
     this.radiusMax = 0.0,
     this.orientation = 0.0,
     this.tilt = 0.0,
     this.platformData = 0,
     this.scrollDeltaX = 0.0,
     this.scrollDeltaY = 0.0,
     this.panX = 0.0,
     this.panY = 0.0,
     this.panDeltaX = 0.0,
     this.panDeltaY = 0.0,
     this.scale = 0.0,
     this.rotation = 0.0,
   });

   /// The ID of the [FlutterView] this [PointerEvent] originated from.
   final int viewId;

   /// Unique identifier that ties the [PointerEvent] to the embedder
   /// event that created it.
   /// it.
   ///
   /// No two pointer events can have the same [embedderId]. This is different
   /// from [pointerIdentifier] - used for hit-testing, whereas [embedderId] is
   /// used to identify the platform event.
   final int embedderId;

   /// Time of event dispatch, relative to an arbitrary timeline.
   final Duration timeStamp;

   /// How the pointer has changed since the last report.
   final PointerChange change;

   /// The kind of input device for which the event was generated.
   final PointerDeviceKind kind;

   /// The kind of signal for a pointer signal event.
   final PointerSignalKind? signalKind;

   /// Unique identifier for the pointing device, reused across interactions.
   final int device;

   /// Unique identifier for the pointer.
   ///
   /// This field changes for each new pointer down event. Framework uses this
   /// identifier to determine hit test result.
   final int pointerIdentifier;

   /// X coordinate of the position of the pointer, in physical pixels in the
   /// global coordinate space.
   final double physicalX;

   /// Y coordinate of the position of the pointer, in physical pixels in the
   /// global coordinate space.
   final double physicalY;

   /// The distance of pointer movement on X coordinate in physical pixels.
   final double physicalDeltaX;

   /// The distance of pointer movement on Y coordinate in physical pixels.
   final double physicalDeltaY;

   /// Bit field using the *Button constants (primaryMouseButton,
   /// secondaryStylusButton, etc). For example, if this has the value 6 and the
   /// [kind] is [PointerDeviceKind.invertedStylus], then this indicates an
   /// upside-down stylus with both its primary and secondary buttons pressed.
   final int buttons;

   /// Set if an application from a different security domain is in any way
   /// obscuring this application's window. (Aspirational; not currently
   /// implemented.)
   final bool obscured;

   /// Set if this pointer data was synthesized by pointer data packet converter.
   /// pointer data packet converter will synthesize additional pointer datas if
   /// the input sequence of pointer data is illegal.
   ///
   /// For example, a down pointer data will be synthesized if the converter receives
   /// a move pointer data while the pointer is not previously down.
   final bool synthesized;

   /// The pressure of the touch as a number ranging from 0.0, indicating a touch
   /// with no discernible pressure, to 1.0, indicating a touch with "normal"
   /// pressure, and possibly beyond, indicating a stronger touch. For devices
   /// that do not detect pressure (e.g. mice), returns 1.0.
   final double pressure;

   /// The minimum value that [pressure] can return for this pointer. For devices
   /// that do not detect pressure (e.g. mice), returns 1.0. This will always be
   /// a number less than or equal to 1.0.
   final double pressureMin;

   /// The maximum value that [pressure] can return for this pointer. For devices
   /// that do not detect pressure (e.g. mice), returns 1.0. This will always be
   /// a greater than or equal to 1.0.
   final double pressureMax;

   /// The distance of the detected object from the input surface (e.g. the
   /// distance of a stylus or finger from a touch screen), in arbitrary units on
   /// an arbitrary (not necessarily linear) scale. If the pointer is down, this
   /// is 0.0 by definition.
   final double distance;

   /// The maximum value that a distance can return for this pointer. If this
   /// input device cannot detect "hover touch" input events, then this will be
   /// 0.0.
   final double distanceMax;

   /// The area of the screen being pressed, scaled to a value between 0 and 1.
   /// The value of size can be used to determine fat touch events. This value
   /// is only set on Android, and is a device specific approximation within
   /// the range of detectable values. So, for example, the value of 0.1 could
   /// mean a touch with the tip of the finger, 0.2 a touch with full finger,
   /// and 0.3 the full palm.
   final double size;

   /// The radius of the contact ellipse along the major axis, in logical pixels.
   final double radiusMajor;

   /// The radius of the contact ellipse along the minor axis, in logical pixels.
   final double radiusMinor;

   /// The minimum value that could be reported for radiusMajor and radiusMinor
   /// for this pointer, in logical pixels.
   final double radiusMin;

   /// The minimum value that could be reported for radiusMajor and radiusMinor
   /// for this pointer, in logical pixels.
   final double radiusMax;

   /// For PointerDeviceKind.touch events:
   ///
   /// The angle of the contact ellipse, in radius in the range:
   ///
   ///    -pi/2 < orientation <= pi/2
   ///
   /// ...giving the angle of the major axis of the ellipse with the y-axis
   /// (negative angles indicating an orientation along the top-left /
   /// bottom-right diagonal, positive angles indicating an orientation along the
   /// top-right / bottom-left diagonal, and zero indicating an orientation
   /// parallel with the y-axis).
   ///
   /// For PointerDeviceKind.stylus and PointerDeviceKind.invertedStylus events:
   ///
   /// The angle of the stylus, in radians in the range:
   ///
   ///    -pi < orientation <= pi
   ///
   /// ...giving the angle of the axis of the stylus projected onto the input
   /// surface, relative to the positive y-axis of that surface (thus 0.0
   /// indicates the stylus, if projected onto that surface, would go from the
   /// contact point vertically up in the positive y-axis direction, pi would
   /// indicate that the stylus would go down in the negative y-axis direction;
   /// pi/4 would indicate that the stylus goes up and to the right, -pi/2 would
   /// indicate that the stylus goes to the left, etc).
   final double orientation;

   /// For PointerDeviceKind.stylus and PointerDeviceKind.invertedStylus events:
   ///
   /// The angle of the stylus, in radians in the range:
   ///
   ///    0 <= tilt <= pi/2
   ///
   /// ...giving the angle of the axis of the stylus, relative to the axis
   /// perpendicular to the input surface (thus 0.0 indicates the stylus is
   /// orthogonal to the plane of the input surface, while pi/2 indicates that
   /// the stylus is flat on that surface).
   final double tilt;

   /// Opaque platform-specific data associated with the event.
   final int platformData;

   /// For events with signalKind of PointerSignalKind.scroll:
   ///
   /// The amount to scroll in the x direction, in physical pixels.
   final double scrollDeltaX;

   /// For events with signalKind of PointerSignalKind.scroll:
   ///
   /// The amount to scroll in the y direction, in physical pixels.
   final double scrollDeltaY;

   /// For events with change of PointerChange.panZoomUpdate:
   ///
   /// The current panning magnitude of the pan/zoom in the x direction, in
   /// physical pixels.
   final double panX;

   /// For events with change of PointerChange.panZoomUpdate:
   ///
   /// The current panning magnitude of the pan/zoom in the y direction, in
   /// physical pixels.
   final double panY;

   /// For events with change of PointerChange.panZoomUpdate:
   ///
   /// The difference in panning of the pan/zoom in the x direction since the
   /// latest panZoomUpdate event, in physical pixels.
   final double panDeltaX;

   /// For events with change of PointerChange.panZoomUpdate:
   ///
   /// The difference in panning of the pan/zoom in the y direction since the
   /// last panZoomUpdate event, in physical pixels.
   final double panDeltaY;

   /// For events with change of PointerChange.panZoomUpdate:
   ///
   /// The current scale of the pan/zoom (unitless), with 1.0 as the initial scale.
   final double scale;

   /// For events with change of PointerChange.panZoomUpdate:
   ///
   /// The current angle of the pan/zoom in radians, with 0.0 as the initial angle.
   final double rotation;

   @override
   String toString() => 'PointerData(x: $physicalX, y: $physicalY)';

   /// Returns a complete textual description of the information in this object.
   String toStringFull() {
     return '$runtimeType('
              'embedderId: $embedderId, '
              'timeStamp: $timeStamp, '
              'change: $change, '
              'kind: $kind, '
              'signalKind: $signalKind, '
              'device: $device, '
              'pointerIdentifier: $pointerIdentifier, '
              'physicalX: $physicalX, '
              'physicalY: $physicalY, '
              'physicalDeltaX: $physicalDeltaX, '
              'physicalDeltaY: $physicalDeltaY, '
              'buttons: $buttons, '
              'synthesized: $synthesized, '
              'pressure: $pressure, '
              'pressureMin: $pressureMin, '
              'pressureMax: $pressureMax, '
              'distance: $distance, '
              'distanceMax: $distanceMax, '
              'size: $size, '
              'radiusMajor: $radiusMajor, '
              'radiusMinor: $radiusMinor, '
              'radiusMin: $radiusMin, '
              'radiusMax: $radiusMax, '
              'orientation: $orientation, '
              'tilt: $tilt, '
              'platformData: $platformData, '
              'scrollDeltaX: $scrollDeltaX, '
              'scrollDeltaY: $scrollDeltaY, '
              'panX: $panX, '
              'panY: $panY, '
              'panDeltaX: $panDeltaX, '
              'panDeltaY: $panDeltaY, '
              'scale: $scale, '
              'rotation: $rotation, '
              'viewId: $viewId'
            ')';
   }
 }

 /// A sequence of reports about the state of pointers.
 class PointerDataPacket {
   /// Creates a packet of pointer data reports.
   const PointerDataPacket({ this.data = const <PointerData>[] });

   /// Data about the individual pointers in this packet.
   ///
   /// This list might contain multiple pieces of data about the same pointer.
   final List<PointerData> data;
 }
	// Copyright 2013 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.

	part of dart.ui;

	/// How the pointer has changed since the last report.
	enum PointerChange {
	/// The input from the pointer is no longer directed towards this receiver.
	cancel,

	/// The device has started tracking the pointer.
	///
	/// For example, the pointer might be hovering above the device, having not yet
	/// made contact with the surface of the device.
	add,

	/// The device is no longer tracking the pointer.
	///
	/// For example, the pointer might have drifted out of the device's hover
	/// detection range or might have been disconnected from the system entirely.
	remove,

	/// The pointer has moved with respect to the device while not in contact with
	/// the device.
	hover,

	/// The pointer has made contact with the device.
	down,

	/// The pointer has moved with respect to the device while in contact with the
	/// device.
	move,

	/// The pointer has stopped making contact with the device.
	up,

	/// A pan/zoom has started on this pointer.
	///
	/// This type of event will always have kind [PointerDeviceKind.trackpad].
	panZoomStart,

	/// The pan/zoom on this pointer has updated.
	///
	/// This type of event will always have kind [PointerDeviceKind.trackpad].
	panZoomUpdate,

	/// The pan/zoom on this pointer has ended.
	///
	/// This type of event will always have kind [PointerDeviceKind.trackpad].
	panZoomEnd,
	}

	/// The kind of pointer device.
	enum PointerDeviceKind {
	/// A touch-based pointer device.
	///
	/// The most common case is a touch screen.
	///
	/// When the user is operating with a trackpad on iOS, clicking will also
	/// dispatch events with kind [touch] if
	/// `UIApplicationSupportsIndirectInputEvents` is not present in `Info.plist`
	/// or returns NO.
	///
	/// See also:
	///
	/// * [UIApplicationSupportsIndirectInputEvents](https://developer.apple.com/documentation/bundleresources/information_property_list/uiapplicationsupportsindirectinputevents?language=objc).
	touch,

	/// A mouse-based pointer device.
	///
	/// The most common case is a mouse on the desktop or Web.
	///
	/// When the user is operating with a trackpad on iOS, moving the pointing
	/// cursor will also dispatch events with kind [mouse], and clicking will
	/// dispatch events with kind [mouse] if
	/// `UIApplicationSupportsIndirectInputEvents` is not present in `Info.plist`
	/// or returns NO.
	///
	/// See also:
	///
	/// * [UIApplicationSupportsIndirectInputEvents](https://developer.apple.com/documentation/bundleresources/information_property_list/uiapplicationsupportsindirectinputevents?language=objc).
	mouse,

	/// A pointer device with a stylus.
	stylus,

	/// A pointer device with a stylus that has been inverted.
	invertedStylus,

	/// Gestures from a trackpad.
	///
	/// A trackpad here is defined as a touch-based pointer device with an
	/// indirect surface (the user operates the screen by touching something that
	/// is not the screen).
	///
	/// When the user makes zoom, pan, scroll or rotate gestures with a physical
	/// trackpad, supporting platforms dispatch events with kind [trackpad].
	///
	/// Events with kind [trackpad] can only have a [PointerChange] of `add`,
	/// `remove`, and pan-zoom related values.
	///
	/// Some platforms don't support (or don't fully support) trackpad
	/// gestures, and might convert trackpad gestures into fake pointer events
	/// that simulate dragging. These events typically have kind [touch] or
	/// [mouse] instead of [trackpad]. This includes (but is not limited to) Web,
	/// and iOS when `UIApplicationSupportsIndirectInputEvents` isn't present in
	/// `Info.plist` or returns NO.
	///
	/// Moving the pointing cursor or clicking with a trackpad typically triggers
	/// [touch] or [mouse] events, but never triggers [trackpad] events.
	///
	/// See also:
	///
	/// * [UIApplicationSupportsIndirectInputEvents](https://developer.apple.com/documentation/bundleresources/information_property_list/uiapplicationsupportsindirectinputevents?language=objc).
	trackpad,

	/// An unknown pointer device.
	unknown
	}

	/// The kind of pointer signal event.
	enum PointerSignalKind {
	/// The event is not associated with a pointer signal.
	none,

	/// A pointer-generated scroll (e.g., mouse wheel or trackpad scroll).
	scroll,

	/// A pointer-generated scroll-inertia cancel.
	scrollInertiaCancel,

	/// A pointer-generated scale event (e.g. trackpad pinch).
	scale,

	/// An unknown pointer signal kind.
	unknown
	}

	/// Information about the state of a pointer.
	class PointerData {
	/// Creates an object that represents the state of a pointer.
	const PointerData({
	this.viewId = 0,
	this.embedderId = 0,
	this.timeStamp = Duration.zero,
	this.change = PointerChange.cancel,
	this.kind = PointerDeviceKind.touch,
	this.signalKind,
	this.device = 0,
	this.pointerIdentifier = 0,
	this.physicalX = 0.0,
	this.physicalY = 0.0,
	this.physicalDeltaX = 0.0,
	this.physicalDeltaY = 0.0,
	this.buttons = 0,
	this.obscured = false,
	this.synthesized = false,
	this.pressure = 0.0,
	this.pressureMin = 0.0,
	this.pressureMax = 0.0,
	this.distance = 0.0,
	this.distanceMax = 0.0,
	this.size = 0.0,
	this.radiusMajor = 0.0,
	this.radiusMinor = 0.0,
	this.radiusMin = 0.0,
	this.radiusMax = 0.0,
	this.orientation = 0.0,
	this.tilt = 0.0,
	this.platformData = 0,
	this.scrollDeltaX = 0.0,
	this.scrollDeltaY = 0.0,
	this.panX = 0.0,
	this.panY = 0.0,
	this.panDeltaX = 0.0,
	this.panDeltaY = 0.0,
	this.scale = 0.0,
	this.rotation = 0.0,
	});

	/// The ID of the [FlutterView] this [PointerEvent] originated from.
	final int viewId;

	/// Unique identifier that ties the [PointerEvent] to the embedder
	/// event that created it.
	/// it.
	///
	/// No two pointer events can have the same [embedderId]. This is different
	/// from [pointerIdentifier] - used for hit-testing, whereas [embedderId] is
	/// used to identify the platform event.
	final int embedderId;

	/// Time of event dispatch, relative to an arbitrary timeline.
	final Duration timeStamp;

	/// How the pointer has changed since the last report.
	final PointerChange change;

	/// The kind of input device for which the event was generated.
	final PointerDeviceKind kind;

	/// The kind of signal for a pointer signal event.
	final PointerSignalKind? signalKind;

	/// Unique identifier for the pointing device, reused across interactions.
	final int device;

	/// Unique identifier for the pointer.
	///
	/// This field changes for each new pointer down event. Framework uses this
	/// identifier to determine hit test result.
	final int pointerIdentifier;

	/// X coordinate of the position of the pointer, in physical pixels in the
	/// global coordinate space.
	final double physicalX;

	/// Y coordinate of the position of the pointer, in physical pixels in the
	/// global coordinate space.
	final double physicalY;

	/// The distance of pointer movement on X coordinate in physical pixels.
	final double physicalDeltaX;

	/// The distance of pointer movement on Y coordinate in physical pixels.
	final double physicalDeltaY;

	/// Bit field using the *Button constants (primaryMouseButton,
	/// secondaryStylusButton, etc). For example, if this has the value 6 and the
	/// [kind] is [PointerDeviceKind.invertedStylus], then this indicates an
	/// upside-down stylus with both its primary and secondary buttons pressed.
	final int buttons;

	/// Set if an application from a different security domain is in any way
	/// obscuring this application's window. (Aspirational; not currently
	/// implemented.)
	final bool obscured;

	/// Set if this pointer data was synthesized by pointer data packet converter.
	/// pointer data packet converter will synthesize additional pointer datas if
	/// the input sequence of pointer data is illegal.
	///
	/// For example, a down pointer data will be synthesized if the converter receives
	/// a move pointer data while the pointer is not previously down.
	final bool synthesized;

	/// The pressure of the touch as a number ranging from 0.0, indicating a touch
	/// with no discernible pressure, to 1.0, indicating a touch with "normal"
	/// pressure, and possibly beyond, indicating a stronger touch. For devices
	/// that do not detect pressure (e.g. mice), returns 1.0.
	final double pressure;

	/// The minimum value that [pressure] can return for this pointer. For devices
	/// that do not detect pressure (e.g. mice), returns 1.0. This will always be
	/// a number less than or equal to 1.0.
	final double pressureMin;

	/// The maximum value that [pressure] can return for this pointer. For devices
	/// that do not detect pressure (e.g. mice), returns 1.0. This will always be
	/// a greater than or equal to 1.0.
	final double pressureMax;

	/// The distance of the detected object from the input surface (e.g. the
	/// distance of a stylus or finger from a touch screen), in arbitrary units on
	/// an arbitrary (not necessarily linear) scale. If the pointer is down, this
	/// is 0.0 by definition.
	final double distance;

	/// The maximum value that a distance can return for this pointer. If this
	/// input device cannot detect "hover touch" input events, then this will be
	/// 0.0.
	final double distanceMax;

	/// The area of the screen being pressed, scaled to a value between 0 and 1.
	/// The value of size can be used to determine fat touch events. This value
	/// is only set on Android, and is a device specific approximation within
	/// the range of detectable values. So, for example, the value of 0.1 could
	/// mean a touch with the tip of the finger, 0.2 a touch with full finger,
	/// and 0.3 the full palm.
	final double size;

	/// The radius of the contact ellipse along the major axis, in logical pixels.
	final double radiusMajor;

	/// The radius of the contact ellipse along the minor axis, in logical pixels.
	final double radiusMinor;

	/// The minimum value that could be reported for radiusMajor and radiusMinor
	/// for this pointer, in logical pixels.
	final double radiusMin;

	/// The minimum value that could be reported for radiusMajor and radiusMinor
	/// for this pointer, in logical pixels.
	final double radiusMax;

	/// For PointerDeviceKind.touch events:
	///
	/// The angle of the contact ellipse, in radius in the range:
	///
	/// -pi/2 < orientation <= pi/2
	///
	/// ...giving the angle of the major axis of the ellipse with the y-axis
	/// (negative angles indicating an orientation along the top-left /
	/// bottom-right diagonal, positive angles indicating an orientation along the
	/// top-right / bottom-left diagonal, and zero indicating an orientation
	/// parallel with the y-axis).
	///
	/// For PointerDeviceKind.stylus and PointerDeviceKind.invertedStylus events:
	///
	/// The angle of the stylus, in radians in the range:
	///
	/// -pi < orientation <= pi
	///
	/// ...giving the angle of the axis of the stylus projected onto the input
	/// surface, relative to the positive y-axis of that surface (thus 0.0
	/// indicates the stylus, if projected onto that surface, would go from the
	/// contact point vertically up in the positive y-axis direction, pi would
	/// indicate that the stylus would go down in the negative y-axis direction;
	/// pi/4 would indicate that the stylus goes up and to the right, -pi/2 would
	/// indicate that the stylus goes to the left, etc).
	final double orientation;

	/// For PointerDeviceKind.stylus and PointerDeviceKind.invertedStylus events:
	///
	/// The angle of the stylus, in radians in the range:
	///
	/// 0 <= tilt <= pi/2
	///
	/// ...giving the angle of the axis of the stylus, relative to the axis
	/// perpendicular to the input surface (thus 0.0 indicates the stylus is
	/// orthogonal to the plane of the input surface, while pi/2 indicates that
	/// the stylus is flat on that surface).
	final double tilt;

	/// Opaque platform-specific data associated with the event.
	final int platformData;

	/// For events with signalKind of PointerSignalKind.scroll:
	///
	/// The amount to scroll in the x direction, in physical pixels.
	final double scrollDeltaX;

	/// For events with signalKind of PointerSignalKind.scroll:
	///
	/// The amount to scroll in the y direction, in physical pixels.
	final double scrollDeltaY;

	/// For events with change of PointerChange.panZoomUpdate:
	///
	/// The current panning magnitude of the pan/zoom in the x direction, in
	/// physical pixels.
	final double panX;

	/// For events with change of PointerChange.panZoomUpdate:
	///
	/// The current panning magnitude of the pan/zoom in the y direction, in
	/// physical pixels.
	final double panY;

	/// For events with change of PointerChange.panZoomUpdate:
	///
	/// The difference in panning of the pan/zoom in the x direction since the
	/// latest panZoomUpdate event, in physical pixels.
	final double panDeltaX;

	/// For events with change of PointerChange.panZoomUpdate:
	///
	/// The difference in panning of the pan/zoom in the y direction since the
	/// last panZoomUpdate event, in physical pixels.
	final double panDeltaY;

	/// For events with change of PointerChange.panZoomUpdate:
	///
	/// The current scale of the pan/zoom (unitless), with 1.0 as the initial scale.
	final double scale;

	/// For events with change of PointerChange.panZoomUpdate:
	///
	/// The current angle of the pan/zoom in radians, with 0.0 as the initial angle.
	final double rotation;

	@override
	String toString() => 'PointerData(x: $physicalX, y: $physicalY)';

	/// Returns a complete textual description of the information in this object.
	String toStringFull() {
	return '$runtimeType('
	'embedderId: $embedderId, '
	'timeStamp: $timeStamp, '
	'change: $change, '
	'kind: $kind, '
	'signalKind: $signalKind, '
	'device: $device, '
	'pointerIdentifier: $pointerIdentifier, '
	'physicalX: $physicalX, '
	'physicalY: $physicalY, '
	'physicalDeltaX: $physicalDeltaX, '
	'physicalDeltaY: $physicalDeltaY, '
	'buttons: $buttons, '
	'synthesized: $synthesized, '
	'pressure: $pressure, '
	'pressureMin: $pressureMin, '
	'pressureMax: $pressureMax, '
	'distance: $distance, '
	'distanceMax: $distanceMax, '
	'size: $size, '
	'radiusMajor: $radiusMajor, '
	'radiusMinor: $radiusMinor, '
	'radiusMin: $radiusMin, '
	'radiusMax: $radiusMax, '
	'orientation: $orientation, '
	'tilt: $tilt, '
	'platformData: $platformData, '
	'scrollDeltaX: $scrollDeltaX, '
	'scrollDeltaY: $scrollDeltaY, '
	'panX: $panX, '
	'panY: $panY, '
	'panDeltaX: $panDeltaX, '
	'panDeltaY: $panDeltaY, '
	'scale: $scale, '
	'rotation: $rotation, '
	'viewId: $viewId'
	')';
	}
	}

	/// A sequence of reports about the state of pointers.
	class PointerDataPacket {
	/// Creates a packet of pointer data reports.
	const PointerDataPacket({ this.data = const <PointerData>[] });

	/// Data about the individual pointers in this packet.
	///
	/// This list might contain multiple pieces of data about the same pointer.
	final List<PointerData> data;
	}