Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 812 insertions, 0 deletions

diff --git a/widget/MouseEvents.h b/widget/MouseEvents.h
new file mode 100644
index 0000000000..d29b406524
--- /dev/null
+++ b/widget/MouseEvents.h
@@ -0,0 +1,812 @@
+/* -*- 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 mozilla_MouseEvents_h__
+#define mozilla_MouseEvents_h__
+
+#include <stdint.h>
+
+#include "mozilla/BasicEvents.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/dom/DataTransfer.h"
+#include "mozilla/ipc/IPCForwards.h"
+#include "nsCOMPtr.h"
+
+namespace mozilla {
+
+namespace dom {
+class PBrowserParent;
+class PBrowserChild;
+class PBrowserBridgeParent;
+}  // namespace dom
+
+class WidgetPointerEvent;
+}  // namespace mozilla
+
+namespace mozilla {
+class WidgetPointerEventHolder final {
+ public:
+  nsTArray<WidgetPointerEvent> mEvents;
+  NS_INLINE_DECL_REFCOUNTING(WidgetPointerEventHolder)
+
+ private:
+  virtual ~WidgetPointerEventHolder() = default;
+};
+
+/******************************************************************************
+ * mozilla::WidgetPointerHelper
+ ******************************************************************************/
+
+class WidgetPointerHelper {
+ public:
+  uint32_t pointerId;
+  int32_t tiltX;
+  int32_t tiltY;
+  int32_t twist;
+  float tangentialPressure;
+  bool convertToPointer;
+  RefPtr<WidgetPointerEventHolder> mCoalescedWidgetEvents;
+
+  WidgetPointerHelper()
+      : pointerId(0),
+        tiltX(0),
+        tiltY(0),
+        twist(0),
+        tangentialPressure(0),
+        convertToPointer(true) {}
+
+  WidgetPointerHelper(uint32_t aPointerId, uint32_t aTiltX, uint32_t aTiltY,
+                      uint32_t aTwist = 0, float aTangentialPressure = 0)
+      : pointerId(aPointerId),
+        tiltX(aTiltX),
+        tiltY(aTiltY),
+        twist(aTwist),
+        tangentialPressure(aTangentialPressure),
+        convertToPointer(true) {}
+
+  explicit WidgetPointerHelper(const WidgetPointerHelper& aHelper) = default;
+
+  void AssignPointerHelperData(const WidgetPointerHelper& aEvent,
+                               bool aCopyCoalescedEvents = false) {
+    pointerId = aEvent.pointerId;
+    tiltX = aEvent.tiltX;
+    tiltY = aEvent.tiltY;
+    twist = aEvent.twist;
+    tangentialPressure = aEvent.tangentialPressure;
+    convertToPointer = aEvent.convertToPointer;
+    if (aCopyCoalescedEvents) {
+      mCoalescedWidgetEvents = aEvent.mCoalescedWidgetEvents;
+    }
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetMouseEventBase
+ ******************************************************************************/
+
+class WidgetMouseEventBase : public WidgetInputEvent {
+ private:
+  friend class dom::PBrowserParent;
+  friend class dom::PBrowserChild;
+  friend class dom::PBrowserBridgeParent;
+  ALLOW_DEPRECATED_READPARAM
+
+ protected:
+  WidgetMouseEventBase()
+      : mPressure(0),
+        mButton(0),
+        mButtons(0),
+        mInputSource(/* MouseEvent_Binding::MOZ_SOURCE_MOUSE = */ 1) {}
+  // Including MouseEventBinding.h here leads to an include loop, so
+  // we have to hardcode MouseEvent_Binding::MOZ_SOURCE_MOUSE.
+
+  WidgetMouseEventBase(bool aIsTrusted, EventMessage aMessage,
+                       nsIWidget* aWidget, EventClassID aEventClassID,
+                       const WidgetEventTime* aTime = nullptr)
+      : WidgetInputEvent(aIsTrusted, aMessage, aWidget, aEventClassID, aTime),
+        mPressure(0),
+        mButton(0),
+        mButtons(0),
+        mInputSource(/* MouseEvent_Binding::MOZ_SOURCE_MOUSE = */ 1) {}
+  // Including MouseEventBinding.h here leads to an include loop, so
+  // we have to hardcode MouseEvent_Binding::MOZ_SOURCE_MOUSE.
+
+ public:
+  virtual WidgetMouseEventBase* AsMouseEventBase() override { return this; }
+
+  virtual WidgetEvent* Duplicate() const override {
+    MOZ_CRASH("WidgetMouseEventBase must not be most-subclass");
+  }
+
+  // Finger or touch pressure of event. It ranges between 0.0 and 1.0.
+  float mPressure;
+
+  // Pressed button ID of mousedown or mouseup event.
+  // This is set only when pressing a button causes the event.
+  int16_t mButton;
+
+  // Flags of all pressed buttons at the event fired.
+  // This is set at any mouse event, don't be confused with |mButton|.
+  int16_t mButtons;
+
+  // Possible values a in MouseEvent
+  uint16_t mInputSource;
+
+  bool IsLeftButtonPressed() const {
+    return !!(mButtons & MouseButtonsFlag::ePrimaryFlag);
+  }
+  bool IsRightButtonPressed() const {
+    return !!(mButtons & MouseButtonsFlag::eSecondaryFlag);
+  }
+  bool IsMiddleButtonPressed() const {
+    return !!(mButtons & MouseButtonsFlag::eMiddleFlag);
+  }
+  bool Is4thButtonPressed() const {
+    return !!(mButtons & MouseButtonsFlag::e4thFlag);
+  }
+  bool Is5thButtonPressed() const {
+    return !!(mButtons & MouseButtonsFlag::e5thFlag);
+  }
+
+  void AssignMouseEventBaseData(const WidgetMouseEventBase& aEvent,
+                                bool aCopyTargets) {
+    AssignInputEventData(aEvent, aCopyTargets);
+
+    mButton = aEvent.mButton;
+    mButtons = aEvent.mButtons;
+    mPressure = aEvent.mPressure;
+    mInputSource = aEvent.mInputSource;
+  }
+
+  /**
+   * Returns true if left click event.
+   */
+  bool IsLeftClickEvent() const {
+    return mMessage == eMouseClick && mButton == MouseButton::ePrimary;
+  }
+
+  /**
+   * Returns true if this event changes a button state to "pressed".
+   */
+  [[nodiscard]] bool IsPressingButton() const {
+    MOZ_ASSERT(IsTrusted());
+    if (mClass == eMouseEventClass) {
+      return mMessage == eMouseDown;
+    }
+    if (mButton == MouseButton::eNotPressed) {
+      return false;
+    }
+    // If this is an ePointerDown event whose mButton is not "not pressed", this
+    // is a button pressing event.
+    if (mMessage == ePointerDown) {
+      return true;
+    }
+    // If 2 or more buttons are pressed at same time, they are sent with
+    // pointermove rather than pointerdown.  Therefore, let's check whether
+    // mButtons contains the proper flag for the pressing button.
+    const bool buttonsContainButton = !!(
+        mButtons & MouseButtonsFlagToChange(static_cast<MouseButton>(mButton)));
+    return mMessage == ePointerMove && buttonsContainButton;
+  }
+
+  /**
+   * Returns true if this event changes a button state to "released".
+   */
+  [[nodiscard]] bool IsReleasingButton() const {
+    MOZ_ASSERT(IsTrusted());
+    if (mClass == eMouseEventClass) {
+      return mMessage == eMouseUp;
+    }
+    if (mButton == MouseButton::eNotPressed) {
+      return false;
+    }
+    // If this is an ePointerUp event whose mButton is not "not pressed", this
+    // is a button release event.
+    if (mMessage == ePointerUp) {
+      return true;
+    }
+    // If the releasing button is not the last button of pressing buttons, web
+    // apps notified by pointermove rather than pointerup.  Therefore, let's
+    // check whether mButtons loses the proper flag for the releasing button.
+    const bool buttonsLoseTheButton = !(
+        mButtons & MouseButtonsFlagToChange(static_cast<MouseButton>(mButton)));
+    return mMessage == ePointerMove && buttonsLoseTheButton;
+  }
+
+  /**
+   * Returns true if the input source supports hover state like a mouse.
+   */
+  [[nodiscard]] bool InputSourceSupportsHover() const;
+};
+
+/******************************************************************************
+ * mozilla::WidgetMouseEvent
+ ******************************************************************************/
+
+class WidgetMouseEvent : public WidgetMouseEventBase,
+                         public WidgetPointerHelper {
+ private:
+  friend class dom::PBrowserParent;
+  friend class dom::PBrowserChild;
+  friend class dom::PBrowserBridgeParent;
+  ALLOW_DEPRECATED_READPARAM
+
+ public:
+  typedef bool ReasonType;
+  enum Reason : ReasonType { eReal, eSynthesized };
+
+  typedef uint8_t ContextMenuTriggerType;
+  enum ContextMenuTrigger : ContextMenuTriggerType {
+    eNormal,
+    eContextMenuKey,
+    eControlClick
+  };
+
+  typedef uint8_t ExitFromType;
+  enum ExitFrom : ExitFromType {
+    ePlatformChild,
+    ePlatformTopLevel,
+    ePuppet,
+    ePuppetParentToPuppetChild
+  };
+
+ protected:
+  WidgetMouseEvent()
+      : mReason(eReal),
+        mContextMenuTrigger(eNormal),
+        mClickCount(0),
+        mIgnoreRootScrollFrame(false),
+        mClickEventPrevented(false) {}
+
+  WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
+                   EventClassID aEventClassID, Reason aReason,
+                   const WidgetEventTime* aTime = nullptr)
+      : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, aEventClassID,
+                             aTime),
+        mReason(aReason),
+        mContextMenuTrigger(eNormal),
+        mClickCount(0),
+        mIgnoreRootScrollFrame(false),
+        mClickEventPrevented(false) {}
+
+#ifdef DEBUG
+  void AssertContextMenuEventButtonConsistency() const;
+#endif
+
+ public:
+  virtual WidgetMouseEvent* AsMouseEvent() override { return this; }
+
+  WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
+                   Reason aReason,
+                   ContextMenuTrigger aContextMenuTrigger = eNormal,
+                   const WidgetEventTime* aTime = nullptr)
+      : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eMouseEventClass,
+                             aTime),
+        mReason(aReason),
+        mContextMenuTrigger(aContextMenuTrigger),
+        mClickCount(0),
+        mIgnoreRootScrollFrame(false),
+        mClickEventPrevented(false) {
+    if (aMessage == eContextMenu) {
+      mButton = (mContextMenuTrigger == eNormal) ? MouseButton::eSecondary
+                                                 : MouseButton::ePrimary;
+    }
+  }
+
+#ifdef DEBUG
+  virtual ~WidgetMouseEvent() { AssertContextMenuEventButtonConsistency(); }
+#endif
+
+  virtual WidgetEvent* Duplicate() const override {
+    MOZ_ASSERT(mClass == eMouseEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetMouseEvent* result = new WidgetMouseEvent(
+        false, mMessage, nullptr, mReason, mContextMenuTrigger, this);
+    result->AssignMouseEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // If during mouseup handling we detect that click event might need to be
+  // dispatched, this is setup to be the target of the click event.
+  nsCOMPtr<dom::EventTarget> mClickTarget;
+
+  // mReason indicates the reason why the event is fired:
+  // - Representing mouse operation.
+  // - Synthesized for emulating mousemove event when the content under the
+  //   mouse cursor is scrolled.
+  Reason mReason;
+
+  // mContextMenuTrigger is valid only when mMessage is eContextMenu.
+  // This indicates if the context menu event is caused by context menu key or
+  // other reasons (typically, a click of right mouse button).
+  ContextMenuTrigger mContextMenuTrigger;
+
+  // mExitFrom contains a value only when mMessage is eMouseExitFromWidget.
+  // This indicates if the mouse cursor exits from a top level platform widget,
+  // a child widget or a puppet widget.
+  Maybe<ExitFrom> mExitFrom;
+
+  // mClickCount may be non-zero value when mMessage is eMouseDown, eMouseUp,
+  // eMouseClick or eMouseDoubleClick. The number is count of mouse clicks.
+  // Otherwise, this must be 0.
+  uint32_t mClickCount;
+
+  // Whether the event should ignore scroll frame bounds during dispatch.
+  bool mIgnoreRootScrollFrame;
+
+  // Whether the event shouldn't cause click event.
+  bool mClickEventPrevented;
+
+  void AssignMouseEventData(const WidgetMouseEvent& aEvent, bool aCopyTargets) {
+    AssignMouseEventBaseData(aEvent, aCopyTargets);
+    AssignPointerHelperData(aEvent, /* aCopyCoalescedEvents */ true);
+
+    mExitFrom = aEvent.mExitFrom;
+    mClickCount = aEvent.mClickCount;
+    mIgnoreRootScrollFrame = aEvent.mIgnoreRootScrollFrame;
+    mClickEventPrevented = aEvent.mClickEventPrevented;
+  }
+
+  /**
+   * Returns true if the event is a context menu event caused by key.
+   */
+  bool IsContextMenuKeyEvent() const {
+    return mMessage == eContextMenu && mContextMenuTrigger == eContextMenuKey;
+  }
+
+  /**
+   * Returns true if the event is a real mouse event.  Otherwise, i.e., it's
+   * a synthesized event by scroll or something, returns false.
+   */
+  bool IsReal() const { return mReason == eReal; }
+
+  /**
+   * Returns true if middle click paste is enabled.
+   */
+  static bool IsMiddleClickPasteEnabled();
+};
+
+/******************************************************************************
+ * mozilla::WidgetDragEvent
+ ******************************************************************************/
+
+class WidgetDragEvent : public WidgetMouseEvent {
+ private:
+  friend class mozilla::dom::PBrowserParent;
+  friend class mozilla::dom::PBrowserChild;
+  ALLOW_DEPRECATED_READPARAM
+
+ protected:
+  WidgetDragEvent()
+      : mUserCancelled(false),
+        mDefaultPreventedOnContent(false),
+        mInHTMLEditorEventListener(false) {}
+
+ public:
+  virtual WidgetDragEvent* AsDragEvent() override { return this; }
+
+  WidgetDragEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
+                  const WidgetEventTime* aTime = nullptr)
+      : WidgetMouseEvent(aIsTrusted, aMessage, aWidget, eDragEventClass, eReal,
+                         aTime),
+        mUserCancelled(false),
+        mDefaultPreventedOnContent(false),
+        mInHTMLEditorEventListener(false) {}
+
+  virtual WidgetEvent* Duplicate() const override {
+    MOZ_ASSERT(mClass == eDragEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetDragEvent* result =
+        new WidgetDragEvent(false, mMessage, nullptr, this);
+    result->AssignDragEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // The dragging data.
+  nsCOMPtr<dom::DataTransfer> mDataTransfer;
+
+  // If this is true, user has cancelled the drag operation.
+  bool mUserCancelled;
+  // If this is true, the drag event's preventDefault() is called on content.
+  bool mDefaultPreventedOnContent;
+  // If this event is currently being handled by HTMLEditorEventListener.
+  bool mInHTMLEditorEventListener;
+
+  // XXX Not tested by test_assign_event_data.html
+  void AssignDragEventData(const WidgetDragEvent& aEvent, bool aCopyTargets) {
+    AssignMouseEventData(aEvent, aCopyTargets);
+
+    mDataTransfer = aEvent.mDataTransfer;
+    // XXX mUserCancelled isn't copied, is this intentionally?
+    mUserCancelled = false;
+    mDefaultPreventedOnContent = aEvent.mDefaultPreventedOnContent;
+    // XXX mInHTMLEditorEventListener isn't copied, is this intentionally?
+    mInHTMLEditorEventListener = false;
+  }
+
+  bool CanConvertToInputData() const {
+    return mMessage == eDragStart || mMessage == eDragEnd;
+  }
+
+  /**
+   * Should be called before dispatching the DOM tree if this event is
+   * synthesized for tests because drop effect is initialized before
+   * dispatching from widget if it's not synthesized event, but synthesized
+   * events are not initialized in the path.
+   */
+  void InitDropEffectForTests();
+};
+
+/******************************************************************************
+ * mozilla::WidgetMouseScrollEvent
+ *
+ * This is used for legacy DOM mouse scroll events, i.e.,
+ * DOMMouseScroll and MozMousePixelScroll event.  These events are NOT hanbled
+ * by ESM even if widget dispatches them.  Use new WidgetWheelEvent instead.
+ ******************************************************************************/
+
+class WidgetMouseScrollEvent : public WidgetMouseEventBase {
+ private:
+  WidgetMouseScrollEvent() : mDelta(0), mIsHorizontal(false) {}
+
+ public:
+  virtual WidgetMouseScrollEvent* AsMouseScrollEvent() override { return this; }
+
+  WidgetMouseScrollEvent(bool aIsTrusted, EventMessage aMessage,
+                         nsIWidget* aWidget,
+                         const WidgetEventTime* aTime = nullptr)
+      : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget,
+                             eMouseScrollEventClass, aTime),
+        mDelta(0),
+        mIsHorizontal(false) {}
+
+  virtual WidgetEvent* Duplicate() const override {
+    MOZ_ASSERT(mClass == eMouseScrollEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetMouseScrollEvent* result =
+        new WidgetMouseScrollEvent(false, mMessage, nullptr, this);
+    result->AssignMouseScrollEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // The delta value of mouse scroll event.
+  // If the event message is eLegacyMouseLineOrPageScroll, the value indicates
+  // scroll amount in lines.  However, if the value is
+  // UIEvent::SCROLL_PAGE_UP or UIEvent::SCROLL_PAGE_DOWN, the
+  // value inducates one page scroll.  If the event message is
+  // eLegacyMousePixelScroll, the value indicates scroll amount in pixels.
+  int32_t mDelta;
+
+  // If this is true, it may cause to scroll horizontally.
+  // Otherwise, vertically.
+  bool mIsHorizontal;
+
+  void AssignMouseScrollEventData(const WidgetMouseScrollEvent& aEvent,
+                                  bool aCopyTargets) {
+    AssignMouseEventBaseData(aEvent, aCopyTargets);
+
+    mDelta = aEvent.mDelta;
+    mIsHorizontal = aEvent.mIsHorizontal;
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetWheelEvent
+ ******************************************************************************/
+
+class WidgetWheelEvent : public WidgetMouseEventBase {
+ private:
+  friend class mozilla::dom::PBrowserParent;
+  friend class mozilla::dom::PBrowserChild;
+  ALLOW_DEPRECATED_READPARAM
+
+  WidgetWheelEvent()
+      : mDeltaX(0.0),
+        mDeltaY(0.0),
+        mDeltaZ(0.0),
+        mOverflowDeltaX(0.0),
+        mOverflowDeltaY(0.0)
+        // Including WheelEventBinding.h here leads to an include loop, so
+        // we have to hardcode WheelEvent_Binding::DOM_DELTA_PIXEL.
+        ,
+        mDeltaMode(/* WheelEvent_Binding::DOM_DELTA_PIXEL = */ 0),
+        mLineOrPageDeltaX(0),
+        mLineOrPageDeltaY(0),
+        mScrollType(SCROLL_DEFAULT),
+        mCustomizedByUserPrefs(false),
+        mMayHaveMomentum(false),
+        mIsMomentum(false),
+        mIsNoLineOrPageDelta(false),
+        mViewPortIsOverscrolled(false),
+        mCanTriggerSwipe(false),
+        mAllowToOverrideSystemScrollSpeed(false),
+        mDeltaValuesHorizontalizedForDefaultHandler(false) {}
+
+ public:
+  virtual WidgetWheelEvent* AsWheelEvent() override { return this; }
+
+  WidgetWheelEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
+                   const WidgetEventTime* aTime = nullptr)
+      : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eWheelEventClass,
+                             aTime),
+        mDeltaX(0.0),
+        mDeltaY(0.0),
+        mDeltaZ(0.0),
+        mOverflowDeltaX(0.0),
+        mOverflowDeltaY(0.0)
+        // Including WheelEventBinding.h here leads to an include loop, so
+        // we have to hardcode WheelEvent_Binding::DOM_DELTA_PIXEL.
+        ,
+        mDeltaMode(/* WheelEvent_Binding::DOM_DELTA_PIXEL = */ 0),
+        mLineOrPageDeltaX(0),
+        mLineOrPageDeltaY(0),
+        mScrollType(SCROLL_DEFAULT),
+        mCustomizedByUserPrefs(false),
+        mMayHaveMomentum(false),
+        mIsMomentum(false),
+        mIsNoLineOrPageDelta(false),
+        mViewPortIsOverscrolled(false),
+        mCanTriggerSwipe(false),
+        mAllowToOverrideSystemScrollSpeed(true),
+        mDeltaValuesHorizontalizedForDefaultHandler(false) {}
+
+  virtual WidgetEvent* Duplicate() const override {
+    MOZ_ASSERT(mClass == eWheelEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetWheelEvent* result =
+        new WidgetWheelEvent(false, mMessage, nullptr, this);
+    result->AssignWheelEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // Scroll gestures that start at the edge of the scrollable range can result
+  // in a swipe gesture. For the first wheel event of such a gesture, call
+  // TriggersSwipe() after the event has been processed in order to find out
+  // whether a swipe should be started.
+  bool TriggersSwipe() const {
+    return mCanTriggerSwipe && mViewPortIsOverscrolled &&
+           this->mOverflowDeltaX != 0.0;
+  }
+
+  // NOTE: mDeltaX, mDeltaY and mDeltaZ may be customized by
+  //       mousewheel.*.delta_multiplier_* prefs which are applied by
+  //       EventStateManager.  So, after widget dispatches this event,
+  //       these delta values may have different values than before.
+  double mDeltaX;
+  double mDeltaY;
+  double mDeltaZ;
+
+  // The mousewheel tick counts.
+  double mWheelTicksX = 0.0;
+  double mWheelTicksY = 0.0;
+
+  enum class DeltaModeCheckingState : uint8_t {
+    // Neither deltaMode nor the delta values have been accessed.
+    Unknown,
+    // The delta values have been accessed, without checking deltaMode first.
+    Unchecked,
+    // The deltaMode has been checked.
+    Checked,
+  };
+
+  // For compat reasons, we might expose a DOM_DELTA_LINE event as
+  // DOM_DELTA_PIXEL instead. Whether we do that depends on whether the event
+  // has been asked for the deltaMode before the deltas. If it has, we assume
+  // that the page will correctly handle DOM_DELTA_LINE. This variable tracks
+  // that state. See bug 1392460.
+  DeltaModeCheckingState mDeltaModeCheckingState =
+      DeltaModeCheckingState::Unknown;
+
+  // The amount of scrolling per line or page, without accounting for mouse
+  // wheel transactions etc.
+  //
+  // Computed by EventStateManager::DeltaAccumulator::InitLineOrPageDelta.
+  nsSize mScrollAmount;
+
+  // overflowed delta values for scroll, these values are set by
+  // EventStateManger.  If the default action of the wheel event isn't scroll,
+  // these values are always zero.  Otherwise, remaining delta values which are
+  // not used by scroll are set.
+  // NOTE: mDeltaX, mDeltaY and mDeltaZ may be modified by EventStateManager.
+  //       However, mOverflowDeltaX and mOverflowDeltaY indicate unused original
+  //       delta values which are not applied the delta_multiplier prefs.
+  //       So, if widget wanted to know the actual direction to be scrolled,
+  //       it would need to check the mDeltaX and mDeltaY.
+  double mOverflowDeltaX;
+  double mOverflowDeltaY;
+
+  // Should be one of WheelEvent_Binding::DOM_DELTA_*
+  uint32_t mDeltaMode;
+
+  // If widget sets mLineOrPageDelta, EventStateManager will dispatch
+  // eLegacyMouseLineOrPageScroll event for compatibility.  Note that the delta
+  // value means pages if the mDeltaMode is DOM_DELTA_PAGE, otherwise, lines.
+  int32_t mLineOrPageDeltaX;
+  int32_t mLineOrPageDeltaY;
+
+  // When the default action for an wheel event is moving history or zooming,
+  // need to chose a delta value for doing it.
+  int32_t GetPreferredIntDelta() {
+    if (!mLineOrPageDeltaX && !mLineOrPageDeltaY) {
+      return 0;
+    }
+    if (mLineOrPageDeltaY && !mLineOrPageDeltaX) {
+      return mLineOrPageDeltaY;
+    }
+    if (mLineOrPageDeltaX && !mLineOrPageDeltaY) {
+      return mLineOrPageDeltaX;
+    }
+    if ((mLineOrPageDeltaX < 0 && mLineOrPageDeltaY > 0) ||
+        (mLineOrPageDeltaX > 0 && mLineOrPageDeltaY < 0)) {
+      return 0;  // We cannot guess the answer in this case.
+    }
+    return (Abs(mLineOrPageDeltaX) > Abs(mLineOrPageDeltaY))
+               ? mLineOrPageDeltaX
+               : mLineOrPageDeltaY;
+  }
+
+  // Scroll type
+  // The default value is SCROLL_DEFAULT, which means EventStateManager will
+  // select preferred scroll type automatically.
+  enum ScrollType : uint8_t {
+    SCROLL_DEFAULT,
+    SCROLL_SYNCHRONOUSLY,
+    SCROLL_ASYNCHRONOUSLY,
+    SCROLL_SMOOTHLY
+  };
+  ScrollType mScrollType;
+
+  // If the delta values are computed from prefs, this value is true.
+  // Otherwise, i.e., they are computed from native events, false.
+  bool mCustomizedByUserPrefs;
+
+  // true if the momentum events directly tied to this event may follow it.
+  bool mMayHaveMomentum;
+  // true if the event is caused by momentum.
+  bool mIsMomentum;
+
+  // If device event handlers don't know when they should set mLineOrPageDeltaX
+  // and mLineOrPageDeltaY, this is true.  Otherwise, false.
+  // If mIsNoLineOrPageDelta is true, ESM will generate
+  // eLegacyMouseLineOrPageScroll events when accumulated delta values reach
+  // a line height.
+  bool mIsNoLineOrPageDelta;
+
+  // Whether or not the parent of the currently overscrolled frame is the
+  // ViewPort. This is false in situations when an element on the page is being
+  // overscrolled (such as a text field), but true when the 'page' is being
+  // overscrolled.
+  bool mViewPortIsOverscrolled;
+
+  // The wheel event can trigger a swipe to start if it's overscrolling the
+  // viewport.
+  bool mCanTriggerSwipe;
+
+  // If mAllowToOverrideSystemScrollSpeed is true, the scroll speed may be
+  // overridden.  Otherwise, the scroll speed won't be overridden even if
+  // it's enabled by the pref.
+  bool mAllowToOverrideSystemScrollSpeed;
+
+  // After the event's default action handler has adjusted its delta's values
+  // for horizontalizing a vertical wheel scroll, this variable will be set to
+  // true.
+  bool mDeltaValuesHorizontalizedForDefaultHandler;
+
+  void AssignWheelEventData(const WidgetWheelEvent& aEvent, bool aCopyTargets) {
+    AssignMouseEventBaseData(aEvent, aCopyTargets);
+
+    mDeltaX = aEvent.mDeltaX;
+    mDeltaY = aEvent.mDeltaY;
+    mDeltaZ = aEvent.mDeltaZ;
+    mDeltaMode = aEvent.mDeltaMode;
+    mScrollAmount = aEvent.mScrollAmount;
+    mCustomizedByUserPrefs = aEvent.mCustomizedByUserPrefs;
+    mMayHaveMomentum = aEvent.mMayHaveMomentum;
+    mIsMomentum = aEvent.mIsMomentum;
+    mIsNoLineOrPageDelta = aEvent.mIsNoLineOrPageDelta;
+    mLineOrPageDeltaX = aEvent.mLineOrPageDeltaX;
+    mLineOrPageDeltaY = aEvent.mLineOrPageDeltaY;
+    mScrollType = aEvent.mScrollType;
+    mOverflowDeltaX = aEvent.mOverflowDeltaX;
+    mOverflowDeltaY = aEvent.mOverflowDeltaY;
+    mViewPortIsOverscrolled = aEvent.mViewPortIsOverscrolled;
+    mCanTriggerSwipe = aEvent.mCanTriggerSwipe;
+    mAllowToOverrideSystemScrollSpeed =
+        aEvent.mAllowToOverrideSystemScrollSpeed;
+    mDeltaValuesHorizontalizedForDefaultHandler =
+        aEvent.mDeltaValuesHorizontalizedForDefaultHandler;
+  }
+
+  // System scroll speed settings may be too slow at using Gecko.  In such
+  // case, we should override the scroll speed computed with system settings.
+  // Following methods return preferred delta values which are multiplied by
+  // factors specified by prefs.  If system scroll speed shouldn't be
+  // overridden (e.g., this feature is disabled by pref), they return raw
+  // delta values.
+  double OverriddenDeltaX() const;
+  double OverriddenDeltaY() const;
+
+  // Compute the overridden delta value.  This may be useful for suppressing
+  // too fast scroll by system scroll speed overriding when widget sets
+  // mAllowToOverrideSystemScrollSpeed.
+  static double ComputeOverriddenDelta(double aDelta, bool aIsForVertical);
+
+ private:
+  static bool sInitialized;
+  static bool sIsSystemScrollSpeedOverrideEnabled;
+  static int32_t sOverrideFactorX;
+  static int32_t sOverrideFactorY;
+  static void Initialize();
+};
+
+/******************************************************************************
+ * mozilla::WidgetPointerEvent
+ ******************************************************************************/
+
+class WidgetPointerEvent : public WidgetMouseEvent {
+  friend class mozilla::dom::PBrowserParent;
+  friend class mozilla::dom::PBrowserChild;
+  ALLOW_DEPRECATED_READPARAM
+
+ public:
+  virtual WidgetPointerEvent* AsPointerEvent() override { return this; }
+
+  WidgetPointerEvent(bool aIsTrusted, EventMessage aMsg, nsIWidget* w,
+                     const WidgetEventTime* aTime = nullptr)
+      : WidgetMouseEvent(aIsTrusted, aMsg, w, ePointerEventClass, eReal, aTime),
+        mWidth(1),
+        mHeight(1),
+        mIsPrimary(true),
+        mFromTouchEvent(false) {}
+
+  explicit WidgetPointerEvent(const WidgetMouseEvent& aEvent)
+      : WidgetMouseEvent(aEvent),
+        mWidth(1),
+        mHeight(1),
+        mIsPrimary(true),
+        mFromTouchEvent(false) {
+    mClass = ePointerEventClass;
+  }
+
+  virtual WidgetEvent* Duplicate() const override {
+    MOZ_ASSERT(mClass == ePointerEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetPointerEvent* result =
+        new WidgetPointerEvent(false, mMessage, nullptr, this);
+    result->AssignPointerEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  int32_t mWidth;
+  int32_t mHeight;
+  bool mIsPrimary;
+  bool mFromTouchEvent;
+
+  // XXX Not tested by test_assign_event_data.html
+  void AssignPointerEventData(const WidgetPointerEvent& aEvent,
+                              bool aCopyTargets) {
+    AssignMouseEventData(aEvent, aCopyTargets);
+
+    mWidth = aEvent.mWidth;
+    mHeight = aEvent.mHeight;
+    mIsPrimary = aEvent.mIsPrimary;
+    mFromTouchEvent = aEvent.mFromTouchEvent;
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_MouseEvents_h__