1 files changed, 767 insertions, 0 deletions
diff --git a/widget/InputData.h b/widget/InputData.h
new file mode 100644
index 0000000000..e70d152d8f
--- /dev/null
+++ b/widget/InputData.h
@@ -0,0 +1,767 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef InputData_h__
+#define InputData_h__
+
+#include "nsDebug.h"
+#include "nsPoint.h"
+#include "nsTArray.h"
+#include "Units.h"
+#include "mozilla/ScrollTypes.h"
+#include "mozilla/DefineEnum.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/WheelHandlingHelper.h"  // for WheelDeltaAdjustmentStrategy
+#include "mozilla/gfx/MatrixFwd.h"
+#include "mozilla/layers/APZPublicUtils.h"
+#include "mozilla/layers/KeyboardScrollAction.h"
+#include "mozilla/TextEvents.h"
+
+template <class E>
+struct already_AddRefed;
+class nsIWidget;
+
+namespace mozilla {
+
+namespace layers {
+class APZInputBridgeChild;
+class PAPZInputBridgeParent;
+}  // namespace layers
+
+namespace dom {
+class Touch;
+}  // namespace dom
+
+// clang-format off
+MOZ_DEFINE_ENUM(
+  InputType, (
+    MULTITOUCH_INPUT,
+    MOUSE_INPUT,
+    PANGESTURE_INPUT,
+    PINCHGESTURE_INPUT,
+    TAPGESTURE_INPUT,
+    SCROLLWHEEL_INPUT,
+    KEYBOARD_INPUT
+));
+// clang-format on
+
+class MultiTouchInput;
+class MouseInput;
+class PanGestureInput;
+class PinchGestureInput;
+class TapGestureInput;
+class ScrollWheelInput;
+class KeyboardInput;
+
+// This looks unnecessary now, but as we add more and more classes that derive
+// from InputType (eventually probably almost as many as *Events.h has), it
+// will be more and more clear what's going on with a macro that shortens the
+// definition of the RTTI functions.
+#define INPUTDATA_AS_CHILD_TYPE(type, enumID)                       \
+  const type& As##type() const {                                    \
+    MOZ_ASSERT(mInputType == enumID, "Invalid cast of InputData."); \
+    return (const type&)*this;                                      \
+  }                                                                 \
+  type& As##type() {                                                \
+    MOZ_ASSERT(mInputType == enumID, "Invalid cast of InputData."); \
+    return (type&)*this;                                            \
+  }
+
+/** Base input data class. Should never be instantiated. */
+class InputData {
+ public:
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  InputType mInputType;
+  // Time in milliseconds that this data is relevant to. This only really
+  // matters when this data is used as an event. We use uint32_t instead of
+  // TimeStamp because it is easier to convert from WidgetInputEvent. The time
+  // is platform-specific but it in the case of B2G and Fennec it is since
+  // startup.
+  uint32_t mTime;
+  // Set in parallel to mTime until we determine it is safe to drop
+  // platform-specific event times (see bug 77992).
+  TimeStamp mTimeStamp;
+  // The sequence number of the last potentially focus changing event handled
+  // by APZ. This is used to track when that event has been processed by
+  // content, and focus can be reconfirmed for async keyboard scrolling.
+  uint64_t mFocusSequenceNumber;
+
+  // The LayersId of the content process that the corresponding WidgetEvent
+  // should be dispatched to.
+  layers::LayersId mLayersId;
+
+  Modifiers modifiers;
+
+  INPUTDATA_AS_CHILD_TYPE(MultiTouchInput, MULTITOUCH_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(MouseInput, MOUSE_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(PanGestureInput, PANGESTURE_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(PinchGestureInput, PINCHGESTURE_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(TapGestureInput, TAPGESTURE_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(ScrollWheelInput, SCROLLWHEEL_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(KeyboardInput, KEYBOARD_INPUT)
+
+  virtual ~InputData();
+  explicit InputData(InputType aInputType);
+
+ protected:
+  InputData(InputType aInputType, uint32_t aTime, TimeStamp aTimeStamp,
+            Modifiers aModifiers);
+};
+
+/**
+ * Data container for a single touch input. Similar to dom::Touch, but used in
+ * off-main-thread situations. This is more for just storing touch data, whereas
+ * dom::Touch is more useful for dispatching through the DOM (which can only
+ * happen on the main thread). dom::Touch also bears the problem of storing
+ * pointers to nsIWidget instances which can only be used on the main thread,
+ * so if instead we used dom::Touch and ever set these pointers
+ * off-main-thread, Bad Things Can Happen(tm).
+ *
+ * Note that this doesn't inherit from InputData because this itself is not an
+ * event. It is only a container/struct that should have any number of instances
+ * within a MultiTouchInput.
+ *
+ * fixme/bug 775746: Make dom::Touch inherit from this class.
+ */
+class SingleTouchData {
+ public:
+  // Construct a SingleTouchData from a Screen point.
+  // mLocalScreenPoint remains (0,0) unless it's set later.
+  SingleTouchData(int32_t aIdentifier, ScreenIntPoint aScreenPoint,
+                  ScreenSize aRadius, float aRotationAngle, float aForce);
+
+  // Construct a SingleTouchData from a ParentLayer point.
+  // mScreenPoint remains (0,0) unless it's set later.
+  // Note: if APZ starts using the radius for anything, we should add a local
+  // version of that too, and have this constructor take it as a
+  // ParentLayerSize.
+  SingleTouchData(int32_t aIdentifier, ParentLayerPoint aLocalScreenPoint,
+                  ScreenSize aRadius, float aRotationAngle, float aForce);
+
+  SingleTouchData();
+
+  already_AddRefed<dom::Touch> ToNewDOMTouch() const;
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+
+  // Historical data of this touch, which  was coalesced into this event.
+  // Touch event coalescing can happen at the system level when the touch
+  // screen's sampling frequency is higher than the vsync rate, or when the
+  // UI thread is busy. When multiple "samples" of touch data are coalesced into
+  // one touch event, the touch event's regular position information is the
+  // information from the last sample. And the previous, "coalesced-away"
+  // samples are stored in mHistoricalData.
+
+  struct HistoricalTouchData {
+    // The timestamp at which the information in this "sample" was originally
+    // sampled.
+    TimeStamp mTimeStamp;
+
+    // The touch data of this historical sample.
+    ScreenIntPoint mScreenPoint;
+    ParentLayerPoint mLocalScreenPoint;
+    ScreenSize mRadius;
+    float mRotationAngle = 0.0f;
+    float mForce = 0.0f;
+  };
+  CopyableTArray<HistoricalTouchData> mHistoricalData;
+
+  // A unique number assigned to each SingleTouchData within a MultiTouchInput
+  // so that they can be easily distinguished when handling a touch
+  // start/move/end.
+  int32_t mIdentifier;
+
+  // Point on the screen that the touch hit, in device pixels. They are
+  // coordinates on the screen.
+  ScreenIntPoint mScreenPoint;
+
+  // |mScreenPoint| transformed to the local coordinates of the APZC targeted
+  // by the hit. This is set and used by APZ.
+  ParentLayerPoint mLocalScreenPoint;
+
+  // Radius that the touch covers, i.e. if you're using your thumb it will
+  // probably be larger than using your pinky, even with the same force.
+  // Radius can be different along x and y. For example, if you press down with
+  // your entire finger vertically, the y radius will be much larger than the x
+  // radius.
+  ScreenSize mRadius;
+
+  float mRotationAngle;
+
+  // How hard the screen is being pressed.
+  float mForce;
+};
+
+/**
+ * Similar to WidgetTouchEvent, but for use off-main-thread. Also only stores a
+ * screen touch point instead of the many different coordinate spaces
+ * WidgetTouchEvent stores its touch point in. This includes a way to initialize
+ * itself from a WidgetTouchEvent by copying all relevant data over. Note that
+ * this copying from WidgetTouchEvent functionality can only be used on the main
+ * thread.
+ *
+ * Stores an array of SingleTouchData.
+ */
+class MultiTouchInput : public InputData {
+ public:
+  // clang-format off
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    MultiTouchType, (
+      MULTITOUCH_START,
+      MULTITOUCH_MOVE,
+      MULTITOUCH_END,
+      MULTITOUCH_CANCEL
+  ));
+  // clang-format on
+
+  MultiTouchInput(MultiTouchType aType, uint32_t aTime, TimeStamp aTimeStamp,
+                  Modifiers aModifiers);
+  MultiTouchInput();
+  MultiTouchInput(MultiTouchInput&&) = default;
+  MultiTouchInput(const MultiTouchInput& aOther);
+  explicit MultiTouchInput(const WidgetTouchEvent& aTouchEvent);
+
+  MultiTouchInput& operator=(MultiTouchInput&&) = default;
+  MultiTouchInput& operator=(const MultiTouchInput&) = default;
+
+  void Translate(const ScreenPoint& aTranslation);
+
+  WidgetTouchEvent ToWidgetTouchEvent(nsIWidget* aWidget) const;
+
+  // Return the index into mTouches of the SingleTouchData with the given
+  // identifier, or -1 if there is no such SingleTouchData.
+  int32_t IndexOfTouch(int32_t aTouchIdentifier);
+
+  bool TransformToLocal(const ScreenToParentLayerMatrix4x4& aTransform);
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  MultiTouchType mType;
+  CopyableTArray<SingleTouchData> mTouches;
+  // The screen offset of the root widget. This can be changing along with
+  // the touch interaction, so we sstore it in the event.
+  ExternalPoint mScreenOffset;
+  bool mHandledByAPZ;
+};
+
+class MouseInput : public InputData {
+ protected:
+  friend mozilla::layers::APZInputBridgeChild;
+  friend mozilla::layers::PAPZInputBridgeParent;
+
+  MouseInput();
+
+ public:
+  // clang-format off
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    MouseType, (
+      MOUSE_NONE,
+      MOUSE_MOVE,
+      MOUSE_DOWN,
+      MOUSE_UP,
+      MOUSE_DRAG_START,
+      MOUSE_DRAG_END,
+      MOUSE_WIDGET_ENTER,
+      MOUSE_WIDGET_EXIT,
+      MOUSE_HITTEST
+  ));
+
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    ButtonType, (
+      PRIMARY_BUTTON,
+      MIDDLE_BUTTON,
+      SECONDARY_BUTTON,
+      NONE
+  ));
+  // clang-format on
+
+  MouseInput(MouseType aType, ButtonType aButtonType, uint16_t aInputSource,
+             int16_t aButtons, const ScreenPoint& aPoint, uint32_t aTime,
+             TimeStamp aTimeStamp, Modifiers aModifiers);
+  explicit MouseInput(const WidgetMouseEventBase& aMouseEvent);
+
+  bool IsLeftButton() const;
+
+  bool TransformToLocal(const ScreenToParentLayerMatrix4x4& aTransform);
+  WidgetMouseEvent ToWidgetEvent(nsIWidget* aWidget) const;
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  MouseType mType;
+  ButtonType mButtonType;
+  uint16_t mInputSource;
+  int16_t mButtons;
+  ScreenPoint mOrigin;
+  ParentLayerPoint mLocalOrigin;
+  bool mHandledByAPZ;
+};
+
+/**
+ * Encapsulation class for pan events, can be used off-main-thread.
+ * These events are currently only used for scrolling on desktop.
+ */
+class PanGestureInput : public InputData {
+ protected:
+  friend mozilla::layers::APZInputBridgeChild;
+  friend mozilla::layers::PAPZInputBridgeParent;
+
+  PanGestureInput();
+
+ public:
+  // clang-format off
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    PanGestureType, (
+      // MayStart: Dispatched before any actual panning has occurred but when a
+      // pan gesture is probably about to start, for example when the user
+      // starts touching the touchpad. Should interrupt any ongoing APZ
+      // animation and can be used to trigger scrollability indicators (e.g.
+      // flashing overlay scrollbars).
+      PANGESTURE_MAYSTART,
+
+      // Cancelled: Dispatched after MayStart when no pan gesture is going to
+      // happen after all, for example when the user lifts their fingers from a
+      // touchpad without having done any scrolling.
+      PANGESTURE_CANCELLED,
+
+      // Start: A pan gesture is starting.
+      // For devices that do not support the MayStart event type, this event can
+      // be used to interrupt ongoing APZ animations.
+      PANGESTURE_START,
+
+      // Pan: The actual pan motion by mPanDisplacement.
+      PANGESTURE_PAN,
+
+      // End: The pan gesture has ended, for example because the user has lifted
+      // their fingers from a touchpad after scrolling.
+      // Any potential momentum events fire after this event.
+      PANGESTURE_END,
+
+      // The following momentum event types are used in order to control the pan
+      // momentum animation. Using these instead of our own animation ensures
+      // that the animation curve is OS native and that the animation stops
+      // reliably if it is cancelled by the user.
+
+      // MomentumStart: Dispatched between the End event of the actual
+      // user-controlled pan, and the first MomentumPan event of the momentum
+      // animation.
+      PANGESTURE_MOMENTUMSTART,
+
+      // MomentumPan: The actual momentum motion by mPanDisplacement.
+      PANGESTURE_MOMENTUMPAN,
+
+      // MomentumEnd: The momentum animation has ended, for example because the
+      // momentum velocity has gone below the stopping threshold, or because the
+      // user has stopped the animation by putting their fingers on a touchpad.
+      PANGESTURE_MOMENTUMEND
+  ));
+
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    PanDeltaType, (
+      // There are three kinds of scroll delta modes in Gecko: "page", "line"
+      // and "pixel". Touchpad pan gestures only support "page" and "pixel".
+      //
+      // NOTE: PANDELTA_PAGE currently replicates Gtk behavior
+      // (see AsyncPanZoomController::OnPan).
+      PANDELTA_PAGE,
+      PANDELTA_PIXEL
+  ));
+  // clang-format on
+
+  PanGestureInput(PanGestureType aType, uint32_t aTime, TimeStamp aTimeStamp,
+                  const ScreenPoint& aPanStartPoint,
+                  const ScreenPoint& aPanDisplacement, Modifiers aModifiers);
+
+  bool IsMomentum() const;
+
+  WidgetWheelEvent ToWidgetEvent(nsIWidget* aWidget) const;
+
+  bool TransformToLocal(const ScreenToParentLayerMatrix4x4& aTransform);
+
+  ScreenPoint UserMultipliedPanDisplacement() const;
+  ParentLayerPoint UserMultipliedLocalPanDisplacement() const;
+
+  static gfx::IntPoint GetIntegerDeltaForEvent(bool aIsStart, float x, float y);
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  PanGestureType mType;
+  ScreenPoint mPanStartPoint;
+
+  // The delta. This can be non-zero on any type of event.
+  ScreenPoint mPanDisplacement;
+
+  // Versions of |mPanStartPoint| and |mPanDisplacement| in the local
+  // coordinates of the APZC receiving the pan. These are set and used by APZ.
+  ParentLayerPoint mLocalPanStartPoint;
+  ParentLayerPoint mLocalPanDisplacement;
+
+  // See lineOrPageDeltaX/Y on WidgetWheelEvent.
+  int32_t mLineOrPageDeltaX;
+  int32_t mLineOrPageDeltaY;
+
+  // User-set delta multipliers.
+  double mUserDeltaMultiplierX;
+  double mUserDeltaMultiplierY;
+
+  PanDeltaType mDeltaType = PANDELTA_PIXEL;
+
+  bool mHandledByAPZ : 1;
+
+  // true if this is a PANGESTURE_END event that will be followed by a
+  // PANGESTURE_MOMENTUMSTART event.
+  bool mFollowedByMomentum : 1;
+
+  // If this is true, and this event started a new input block that couldn't
+  // find a scrollable target which is scrollable in the horizontal component
+  // of the scroll start direction, then this input block needs to be put on
+  // hold until a content response has arrived, even if the block has a
+  // confirmed target.
+  // This is used by events that can result in a swipe instead of a scroll.
+  bool mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection : 1;
+
+  // This is used by APZ to communicate to the macOS widget code whether
+  // the overscroll-behavior of the scroll frame handling this swipe allows
+  // non-local overscroll behaviors in the horizontal direction (such as
+  // swipe navigation).
+  bool mOverscrollBehaviorAllowsSwipe : 1;
+
+  // true if APZ should do a fling animation after this pan ends, like
+  // it would with touchscreens. (For platforms that don't emit momentum
+  // events.)
+  bool mSimulateMomentum : 1;
+
+  void SetHandledByAPZ(bool aHandled) { mHandledByAPZ = aHandled; }
+  void SetFollowedByMomentum(bool aFollowed) {
+    mFollowedByMomentum = aFollowed;
+  }
+  void SetRequiresContentResponseIfCannotScrollHorizontallyInStartDirection(
+      bool aRequires) {
+    mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection =
+        aRequires;
+  }
+  void SetOverscrollBehaviorAllowsSwipe(bool aAllows) {
+    mOverscrollBehaviorAllowsSwipe = aAllows;
+  }
+  void SetSimulateMomentum(bool aSimulate) { mSimulateMomentum = aSimulate; }
+};
+
+/**
+ * Encapsulation class for pinch events. In general, these will be generated by
+ * a gesture listener by looking at SingleTouchData/MultiTouchInput instances
+ * and determining whether or not the user was trying to do a gesture.
+ */
+class PinchGestureInput : public InputData {
+ protected:
+  friend mozilla::layers::APZInputBridgeChild;
+  friend mozilla::layers::PAPZInputBridgeParent;
+
+  PinchGestureInput();
+
+ public:
+  // clang-format off
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    PinchGestureType, (
+      PINCHGESTURE_START,
+      PINCHGESTURE_SCALE,
+      // The FINGERLIFTED state is used when a touch-based pinch gesture is
+      // terminated by lifting one of the two fingers. The position of the
+      // finger that's still down is populated as the focus point.
+      PINCHGESTURE_FINGERLIFTED,
+      // The END state is used when the pinch gesture is completely terminated.
+      // In this state, the focus point should not be relied upon for having
+      // meaningful data.
+      PINCHGESTURE_END
+  ));
+
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    PinchGestureSource, (
+      UNKNOWN, // Default initialization value. Should never actually be used.
+      TOUCH, // From two-finger pinch gesture
+      ONE_TOUCH, // From one-finger pinch gesture
+      TRACKPAD, // From trackpad pinch gesture
+      MOUSEWHEEL // Synthesized from modifier+mousewheel
+
+      // If adding more items here, increase n_values for the
+      // APZ_ZOOM_PINCHSOURCE Telemetry metric.
+  ));
+  // clang-format on
+
+  // Construct a pinch gesture from a Screen point.
+  PinchGestureInput(PinchGestureType aType, PinchGestureSource aSource,
+                    uint32_t aTime, TimeStamp aTimeStamp,
+                    const ExternalPoint& aScreenOffset,
+                    const ScreenPoint& aFocusPoint, ScreenCoord aCurrentSpan,
+                    ScreenCoord aPreviousSpan, Modifiers aModifiers);
+
+  bool TransformToLocal(const ScreenToParentLayerMatrix4x4& aTransform);
+
+  WidgetWheelEvent ToWidgetEvent(nsIWidget* aWidget) const;
+
+  double ComputeDeltaY(nsIWidget* aWidget) const;
+
+  static gfx::IntPoint GetIntegerDeltaForEvent(bool aIsStart, float x, float y);
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  PinchGestureType mType;
+
+  // Some indication of the input device that generated this pinch gesture.
+  PinchGestureSource mSource;
+
+  // Center point of the pinch gesture. That is, if there are two fingers on the
+  // screen, it is their midpoint. In the case of more than two fingers, the
+  // point is implementation-specific, but can for example be the midpoint
+  // between the very first and very last touch. This is in device pixels and
+  // are the coordinates on the screen of this midpoint.
+  // For PINCHGESTURE_END events, this may hold the last known focus point or
+  // just be empty; in any case for END events it should not be relied upon.
+  // For PINCHGESTURE_FINGERLIFTED events, this holds the point of the finger
+  // that is still down.
+  ScreenPoint mFocusPoint;
+
+  // The screen offset of the root widget. This can be changing along with
+  // the touch interaction, so we sstore it in the event.
+  ExternalPoint mScreenOffset;
+
+  // |mFocusPoint| transformed to the local coordinates of the APZC targeted
+  // by the hit. This is set and used by APZ.
+  ParentLayerPoint mLocalFocusPoint;
+
+  // The distance between the touches responsible for the pinch gesture.
+  ScreenCoord mCurrentSpan;
+
+  // The previous |mCurrentSpan| in the PinchGestureInput preceding this one.
+  // This is only really relevant during a PINCHGESTURE_SCALE because when it is
+  // of this type then there must have been a history of spans.
+  ScreenCoord mPreviousSpan;
+
+  // We accumulate (via GetIntegerDeltaForEvent) the deltaY that would be
+  // computed by ToWidgetEvent, and then whenever we get a whole integer
+  // value we put it in mLineOrPageDeltaY. Since we only ever use deltaY we
+  // don't need a mLineOrPageDeltaX. This field is used to dispatch legacy mouse
+  // events which are only dispatched when the corresponding field on
+  // WidgetWheelEvent is non-zero.
+  int32_t mLineOrPageDeltaY;
+
+  bool mHandledByAPZ;
+};
+
+/**
+ * Encapsulation class for tap events. In general, these will be generated by
+ * a gesture listener by looking at SingleTouchData/MultiTouchInput instances
+ * and determining whether or not the user was trying to do a gesture.
+ */
+class TapGestureInput : public InputData {
+ protected:
+  friend mozilla::layers::APZInputBridgeChild;
+  friend mozilla::layers::PAPZInputBridgeParent;
+
+  TapGestureInput();
+
+ public:
+  // clang-format off
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    TapGestureType, (
+      TAPGESTURE_LONG,
+      TAPGESTURE_LONG_UP,
+      TAPGESTURE_UP,
+      TAPGESTURE_CONFIRMED,
+      TAPGESTURE_DOUBLE,
+      TAPGESTURE_SECOND, // See GeckoContentController::TapType::eSecondTap
+      TAPGESTURE_CANCEL
+  ));
+  // clang-format on
+
+  // Construct a tap gesture from a Screen point.
+  // mLocalPoint remains (0,0) unless it's set later.
+  TapGestureInput(TapGestureType aType, uint32_t aTime, TimeStamp aTimeStamp,
+                  const ScreenIntPoint& aPoint, Modifiers aModifiers);
+
+  // Construct a tap gesture from a ParentLayer point.
+  // mPoint remains (0,0) unless it's set later.
+  TapGestureInput(TapGestureType aType, uint32_t aTime, TimeStamp aTimeStamp,
+                  const ParentLayerPoint& aLocalPoint, Modifiers aModifiers);
+
+  bool TransformToLocal(const ScreenToParentLayerMatrix4x4& aTransform);
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  TapGestureType mType;
+
+  // The location of the tap in screen pixels.
+  ScreenIntPoint mPoint;
+
+  // The location of the tap in the local coordinates of the APZC receiving it.
+  // This is set and used by APZ.
+  ParentLayerPoint mLocalPoint;
+};
+
+// Encapsulation class for scroll-wheel events. These are generated by mice
+// with physical scroll wheels, and on Windows by most touchpads when using
+// scroll gestures.
+class ScrollWheelInput : public InputData {
+ protected:
+  friend mozilla::layers::APZInputBridgeChild;
+  friend mozilla::layers::PAPZInputBridgeParent;
+
+  typedef mozilla::layers::APZWheelAction APZWheelAction;
+
+  ScrollWheelInput();
+
+ public:
+  // clang-format off
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    ScrollDeltaType, (
+      // There are three kinds of scroll delta modes in Gecko: "page", "line"
+      // and "pixel".
+      SCROLLDELTA_LINE,
+      SCROLLDELTA_PAGE,
+      SCROLLDELTA_PIXEL
+  ));
+
+  MOZ_DEFINE_ENUM_AT_CLASS_SCOPE(
+    ScrollMode, (
+      SCROLLMODE_INSTANT,
+      SCROLLMODE_SMOOTH
+    )
+  );
+  // clang-format on
+
+  ScrollWheelInput(uint32_t aTime, TimeStamp aTimeStamp, Modifiers aModifiers,
+                   ScrollMode aScrollMode, ScrollDeltaType aDeltaType,
+                   const ScreenPoint& aOrigin, double aDeltaX, double aDeltaY,
+                   bool aAllowToOverrideSystemScrollSpeed,
+                   WheelDeltaAdjustmentStrategy aWheelDeltaAdjustmentStrategy);
+  explicit ScrollWheelInput(const WidgetWheelEvent& aEvent);
+
+  static ScrollDeltaType DeltaTypeForDeltaMode(uint32_t aDeltaMode);
+  static uint32_t DeltaModeForDeltaType(ScrollDeltaType aDeltaType);
+  static mozilla::ScrollUnit ScrollUnitForDeltaType(ScrollDeltaType aDeltaType);
+
+  WidgetWheelEvent ToWidgetEvent(nsIWidget* aWidget) const;
+  bool TransformToLocal(const ScreenToParentLayerMatrix4x4& aTransform);
+
+  bool IsCustomizedByUserPrefs() const;
+
+  // The following two functions are for auto-dir scrolling. For detailed
+  // information on auto-dir, @see mozilla::WheelDeltaAdjustmentStrategy
+  bool IsAutoDir() const {
+    switch (mWheelDeltaAdjustmentStrategy) {
+      case WheelDeltaAdjustmentStrategy::eAutoDir:
+      case WheelDeltaAdjustmentStrategy::eAutoDirWithRootHonour:
+        return true;
+      default:
+        // Prevent compilation errors generated by -Werror=switch
+        break;
+    }
+    return false;
+  }
+  // Indicates which element this scroll honours if it's an auto-dir scroll.
+  // If true, honour the root element; otherwise, honour the currently scrolling
+  // target.
+  // Note that if IsAutoDir() returns false, then this function also returns
+  // false, but false in this case is meaningless as IsAutoDir() indicates it's
+  // not an auto-dir scroll.
+  // For detailed information on auto-dir,
+  // @see mozilla::WheelDeltaAdjustmentStrategy
+  bool HonoursRoot() const {
+    return WheelDeltaAdjustmentStrategy::eAutoDirWithRootHonour ==
+           mWheelDeltaAdjustmentStrategy;
+  }
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+  ScrollDeltaType mDeltaType;
+  ScrollMode mScrollMode;
+  ScreenPoint mOrigin;
+
+  bool mHandledByAPZ;
+
+  // Deltas are in units corresponding to the delta type. For line deltas, they
+  // are the number of line units to scroll. The number of device pixels for a
+  // horizontal and vertical line unit are in FrameMetrics::mLineScrollAmount.
+  // For pixel deltas, these values are in ScreenCoords.
+  //
+  // The horizontal (X) delta is > 0 for scrolling right and < 0 for scrolling
+  // left. The vertical (Y) delta is < 0 for scrolling up and > 0 for
+  // scrolling down.
+  double mDeltaX;
+  double mDeltaY;
+
+  // The location of the scroll in local coordinates. This is set and used by
+  // APZ.
+  ParentLayerPoint mLocalOrigin;
+
+  // See lineOrPageDeltaX/Y on WidgetWheelEvent.
+  int32_t mLineOrPageDeltaX;
+  int32_t mLineOrPageDeltaY;
+
+  // Indicates the order in which this event was added to a transaction. The
+  // first event is 1; if not a member of a transaction, this is 0.
+  uint32_t mScrollSeriesNumber;
+
+  // User-set delta multipliers.
+  double mUserDeltaMultiplierX;
+  double mUserDeltaMultiplierY;
+
+  bool mMayHaveMomentum;
+  bool mIsMomentum;
+  bool mAllowToOverrideSystemScrollSpeed;
+
+  // Sometimes a wheel event input's wheel delta should be adjusted. This member
+  // specifies how to adjust the wheel delta.
+  WheelDeltaAdjustmentStrategy mWheelDeltaAdjustmentStrategy;
+
+  APZWheelAction mAPZAction;
+};
+
+class KeyboardInput : public InputData {
+ public:
+  typedef mozilla::layers::KeyboardScrollAction KeyboardScrollAction;
+
+  // Note that if you change the first member in this enum(I.e. KEY_DOWN) to one
+  // other member, don't forget to update the minimum value in
+  // ContiguousEnumSerializer for KeyboardEventType in widget/nsGUIEventIPC
+  // accordingly.
+  enum KeyboardEventType {
+    KEY_DOWN,
+    KEY_PRESS,
+    KEY_UP,
+    // Any other key event such as eKeyDownOnPlugin
+    KEY_OTHER,
+
+    // Used as an upper bound for ContiguousEnumSerializer
+    KEY_SENTINEL,
+  };
+
+  explicit KeyboardInput(const WidgetKeyboardEvent& aEvent);
+
+  // Warning, this class is serialized and sent over IPC. Any change to its
+  // fields must be reflected in its ParamTraits<>, in nsGUIEventIPC.h
+
+  KeyboardEventType mType;
+  uint32_t mKeyCode;
+  uint32_t mCharCode;
+  CopyableTArray<ShortcutKeyCandidate> mShortcutCandidates;
+
+  bool mHandledByAPZ;
+
+  // The scroll action to perform on a layer for this keyboard input. This is
+  // only used in APZ and is NOT serialized over IPC.
+  KeyboardScrollAction mAction;
+
+ protected:
+  friend mozilla::layers::APZInputBridgeChild;
+  friend mozilla::layers::PAPZInputBridgeParent;
+
+  KeyboardInput();
+};
+
+}  // namespace mozilla
+
+#endif  // InputData_h__