gecko-dev/widget/MouseEvents.h

/* -*- 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/MathAlgorithms.h"
#include "mozilla/dom/DataTransfer.h"
#include "nsCOMPtr.h"
#include "nsIDOMMouseEvent.h"
#include "nsIDOMWheelEvent.h"

/******************************************************************************
 * nsDragDropEventStatus
 ******************************************************************************/

enum nsDragDropEventStatus
{  
  // The event is a enter
  nsDragDropEventStatus_eDragEntered,
  // The event is exit
  nsDragDropEventStatus_eDragExited,
  // The event is drop
  nsDragDropEventStatus_eDrop
};

namespace mozilla {

namespace dom {
  class PBrowserParent;
  class PBrowserChild;
} // namespace dom

/******************************************************************************
 * mozilla::WidgetPointerHelper
 ******************************************************************************/

class WidgetPointerHelper
{
public:
  bool convertToPointer;
  uint32_t pointerId;
  uint32_t tiltX;
  uint32_t tiltY;
  bool retargetedByPointerCapture;

  WidgetPointerHelper() : convertToPointer(true), pointerId(0), tiltX(0), tiltY(0),
                          retargetedByPointerCapture(false) {}

  void AssignPointerHelperData(const WidgetPointerHelper& aEvent)
  {
    convertToPointer = aEvent.convertToPointer;
    pointerId = aEvent.pointerId;
    tiltX = aEvent.tiltX;
    tiltY = aEvent.tiltY;
    retargetedByPointerCapture = aEvent.retargetedByPointerCapture;
  }
};

/******************************************************************************
 * mozilla::WidgetMouseEventBase
 ******************************************************************************/

class WidgetMouseEventBase : public WidgetInputEvent
{
private:
  friend class dom::PBrowserParent;
  friend class dom::PBrowserChild;

protected:
  WidgetMouseEventBase()
    : button(0)
    , buttons(0)
    , pressure(0)
    , hitCluster(false)
    , inputSource(nsIDOMMouseEvent::MOZ_SOURCE_MOUSE)
  {
  }

  WidgetMouseEventBase(bool aIsTrusted, EventMessage aMessage,
                       nsIWidget* aWidget, EventClassID aEventClassID)
    : WidgetInputEvent(aIsTrusted, aMessage, aWidget, aEventClassID)
    , button(0)
    , buttons(0)
    , pressure(0)
    , hitCluster(false)
    , inputSource(nsIDOMMouseEvent::MOZ_SOURCE_MOUSE)
 {
 }

public:
  virtual WidgetMouseEventBase* AsMouseEventBase() override { return this; }

  virtual WidgetEvent* Duplicate() const override
  {
    MOZ_CRASH("WidgetMouseEventBase must not be most-subclass");
  }

  /// The possible related target
  nsCOMPtr<nsISupports> relatedTarget;

  enum buttonType
  {
    eLeftButton   = 0,
    eMiddleButton = 1,
    eRightButton  = 2
  };
  // Pressed button ID of mousedown or mouseup event.
  // This is set only when pressing a button causes the event.
  int16_t button;

  enum buttonsFlag {
    eLeftButtonFlag   = 0x01,
    eRightButtonFlag  = 0x02,
    eMiddleButtonFlag = 0x04,
    // typicall, "back" button being left side of 5-button
    // mice, see "buttons" attribute document of DOM3 Events.
    e4thButtonFlag    = 0x08,
    // typicall, "forward" button being right side of 5-button
    // mice, see "buttons" attribute document of DOM3 Events.
    e5thButtonFlag    = 0x10
  };

  // Flags of all pressed buttons at the event fired.
  // This is set at any mouse event, don't be confused with |button|.
  int16_t buttons;

  // Finger or touch pressure of event. It ranges between 0.0 and 1.0.
  float pressure;
  // Touch near a cluster of links (true)
  bool hitCluster;

  // Possible values at nsIDOMMouseEvent
  uint16_t inputSource;

  // ID of the canvas HitRegion
  nsString region;

  bool IsLeftButtonPressed() const { return !!(buttons & eLeftButtonFlag); }
  bool IsRightButtonPressed() const { return !!(buttons & eRightButtonFlag); }
  bool IsMiddleButtonPressed() const { return !!(buttons & eMiddleButtonFlag); }
  bool Is4thButtonPressed() const { return !!(buttons & e4thButtonFlag); }
  bool Is5thButtonPressed() const { return !!(buttons & e5thButtonFlag); }

  void AssignMouseEventBaseData(const WidgetMouseEventBase& aEvent,
                                bool aCopyTargets)
  {
    AssignInputEventData(aEvent, aCopyTargets);

    relatedTarget = aCopyTargets ? aEvent.relatedTarget : nullptr;
    button = aEvent.button;
    buttons = aEvent.buttons;
    pressure = aEvent.pressure;
    hitCluster = aEvent.hitCluster;
    inputSource = aEvent.inputSource;
  }

  /**
   * Returns true if left click event.
   */
  bool IsLeftClickEvent() const
  {
    return mMessage == eMouseClick && button == eLeftButton;
  }
};

/******************************************************************************
 * mozilla::WidgetMouseEvent
 ******************************************************************************/

class WidgetMouseEvent : public WidgetMouseEventBase, public WidgetPointerHelper
{
private:
  friend class mozilla::dom::PBrowserParent;
  friend class mozilla::dom::PBrowserChild;

public:
  enum reasonType
  {
    eReal,
    eSynthesized
  };

  enum contextType
  {
    eNormal,
    eContextMenuKey
  };

  enum exitType
  {
    eChild,
    eTopLevel
  };

protected:
  WidgetMouseEvent()
    : acceptActivation(false)
    , ignoreRootScrollFrame(false)
    , clickCount(0)
  {
  }

  WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
                   EventClassID aEventClassID, reasonType aReason)
    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, aEventClassID)
    , acceptActivation(false)
    , ignoreRootScrollFrame(false)
    , reason(aReason)
    , context(eNormal)
    , exit(eChild)
    , clickCount(0)
  {
    switch (aMessage) {
      case eMouseEnter:
      case eMouseLeave:
        mFlags.mBubbles = false;
        mFlags.mCancelable = false;
        break;
      default:
        break;
    }
  }

public:
  virtual WidgetMouseEvent* AsMouseEvent() override { return this; }

  WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
                   reasonType aReason, contextType aContext = eNormal) :
    WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eMouseEventClass),
    acceptActivation(false), ignoreRootScrollFrame(false),
    reason(aReason), context(aContext), exit(eChild), clickCount(0)
  {
    switch (aMessage) {
      case eMouseEnter:
      case eMouseLeave:
        mFlags.mBubbles = false;
        mFlags.mCancelable = false;
        break;
      case eContextMenu:
        button = (context == eNormal) ? eRightButton : eLeftButton;
        break;
      default:
        break;
    }
  }

#ifdef DEBUG
  virtual ~WidgetMouseEvent()
  {
    NS_WARN_IF_FALSE(mMessage != eContextMenu ||
                     button ==
                       ((context == eNormal) ? eRightButton : eLeftButton),
                     "Wrong button set to eContextMenu event?");
  }
#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, reason, context);
    result->AssignMouseEventData(*this, true);
    result->mFlags = mFlags;
    return result;
  }

  // Special return code for MOUSE_ACTIVATE to signal.
  // If the target accepts activation (1), or denies it (0).
  bool acceptActivation;
  // Whether the event should ignore scroll frame bounds during dispatch.
  bool ignoreRootScrollFrame;

  reasonType reason : 4;
  contextType context : 4;
  exitType exit;

  /// The number of mouse clicks.
  uint32_t clickCount;

  void AssignMouseEventData(const WidgetMouseEvent& aEvent, bool aCopyTargets)
  {
    AssignMouseEventBaseData(aEvent, aCopyTargets);
    AssignPointerHelperData(aEvent);

    acceptActivation = aEvent.acceptActivation;
    ignoreRootScrollFrame = aEvent.ignoreRootScrollFrame;
    clickCount = aEvent.clickCount;
  }

  /**
   * Returns true if the event is a context menu event caused by key.
   */
  bool IsContextMenuKeyEvent() const
  {
    return mMessage == eContextMenu && context == 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 reason == eReal;
  }
};

/******************************************************************************
 * mozilla::WidgetDragEvent
 ******************************************************************************/

class WidgetDragEvent : public WidgetMouseEvent
{
private:
  friend class mozilla::dom::PBrowserParent;
  friend class mozilla::dom::PBrowserChild;
protected:
  WidgetDragEvent()
    : userCancelled(false)
    , mDefaultPreventedOnContent(false)
  {
  }
public:
  virtual WidgetDragEvent* AsDragEvent() override { return this; }

  WidgetDragEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget)
    : WidgetMouseEvent(aIsTrusted, aMessage, aWidget, eDragEventClass, eReal)
    , userCancelled(false)
    , mDefaultPreventedOnContent(false)
  {
    mFlags.mCancelable =
      (aMessage != eDragExit && aMessage != eDragLeave && aMessage != eDragEnd);
  }

  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);
    result->AssignDragEventData(*this, true);
    result->mFlags = mFlags;
    return result;
  }

  // The dragging data.
  nsCOMPtr<dom::DataTransfer> dataTransfer;

  // If this is true, user has cancelled the drag operation.
  bool userCancelled;
  // If this is true, the drag event's preventDefault() is called on content.
  bool mDefaultPreventedOnContent;

  // XXX Not tested by test_assign_event_data.html
  void AssignDragEventData(const WidgetDragEvent& aEvent, bool aCopyTargets)
  {
    AssignMouseEventData(aEvent, aCopyTargets);

    dataTransfer = aEvent.dataTransfer;
    // XXX userCancelled isn't copied, is this instentionally?
    userCancelled = false;
    mDefaultPreventedOnContent = aEvent.mDefaultPreventedOnContent;
  }
};

/******************************************************************************
 * 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()
    : delta(0)
    , isHorizontal(false)
  {
  }

public:
  virtual WidgetMouseScrollEvent* AsMouseScrollEvent() override
  {
    return this;
  }

  WidgetMouseScrollEvent(bool aIsTrusted, EventMessage aMessage,
                         nsIWidget* aWidget)
    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget,
                           eMouseScrollEventClass)
    , delta(0)
    , isHorizontal(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);
    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
  // nsIDOMUIEvent::SCROLL_PAGE_UP or nsIDOMUIEvent::SCROLL_PAGE_DOWN, the
  // value inducates one page scroll.  If the event message is
  // eLegacyMousePixelScroll, the value indicates scroll amount in pixels.
  int32_t delta;

  // If this is true, it may cause to scroll horizontally.
  // Otherwise, vertically.
  bool isHorizontal;

  void AssignMouseScrollEventData(const WidgetMouseScrollEvent& aEvent,
                                  bool aCopyTargets)
  {
    AssignMouseEventBaseData(aEvent, aCopyTargets);

    delta = aEvent.delta;
    isHorizontal = aEvent.isHorizontal;
  }
};

/******************************************************************************
 * mozilla::WidgetWheelEvent
 ******************************************************************************/

class WidgetWheelEvent : public WidgetMouseEventBase
{
private:
  friend class mozilla::dom::PBrowserParent;
  friend class mozilla::dom::PBrowserChild;

  WidgetWheelEvent()
    : deltaX(0.0)
    , deltaY(0.0)
    , deltaZ(0.0)
    , deltaMode(nsIDOMWheelEvent::DOM_DELTA_PIXEL)
    , customizedByUserPrefs(false)
    , isMomentum(false)
    , mIsNoLineOrPageDelta(false)
    , lineOrPageDeltaX(0)
    , lineOrPageDeltaY(0)
    , scrollType(SCROLL_DEFAULT)
    , overflowDeltaX(0.0)
    , overflowDeltaY(0.0)
    , mViewPortIsOverscrolled(false)
    , mCanTriggerSwipe(false)
    , mAllowToOverrideSystemScrollSpeed(false)
  {
  }

public:
  virtual WidgetWheelEvent* AsWheelEvent() override { return this; }

  WidgetWheelEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget)
    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eWheelEventClass)
    , deltaX(0.0)
    , deltaY(0.0)
    , deltaZ(0.0)
    , deltaMode(nsIDOMWheelEvent::DOM_DELTA_PIXEL)
    , customizedByUserPrefs(false)
    , mayHaveMomentum(false)
    , isMomentum(false)
    , mIsNoLineOrPageDelta(false)
    , lineOrPageDeltaX(0)
    , lineOrPageDeltaY(0)
    , scrollType(SCROLL_DEFAULT)
    , overflowDeltaX(0.0)
    , overflowDeltaY(0.0)
    , mViewPortIsOverscrolled(false)
    , mCanTriggerSwipe(false)
    , mAllowToOverrideSystemScrollSpeed(true)
  {
  }

  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);
    result->AssignWheelEventData(*this, true);
    result->mFlags = mFlags;
    return result;
  }

  // On OS X, 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->overflowDeltaX != 0.0;
  }

  // NOTE: deltaX, deltaY and deltaZ 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 deltaX;
  double deltaY;
  double deltaZ;

  // Should be one of nsIDOMWheelEvent::DOM_DELTA_*
  uint32_t deltaMode;

  // Following members are for internal use only, not for DOM event.

  // If the delta values are computed from prefs, this value is true.
  // Otherwise, i.e., they are computed from native events, false.
  bool customizedByUserPrefs;

  // true if the momentum events directly tied to this event may follow it.
  bool mayHaveMomentum;
  // true if the event is caused by momentum.
  bool isMomentum;

  // If device event handlers don't know when they should set lineOrPageDeltaX
  // and lineOrPageDeltaY, this is true.  Otherwise, false.
  // If mIsNoLineOrPageDelta is true, ESM will generate
  // eLegacyMouseLineOrPageScroll events when accumulated delta values reach
  // a line height.
  bool mIsNoLineOrPageDelta;

  // If widget sets lineOrPageDelta, EventStateManager will dispatch
  // eLegacyMouseLineOrPageScroll event for compatibility.  Note that the delta
  // value means pages if the deltaMode is DOM_DELTA_PAGE, otherwise, lines.
  int32_t lineOrPageDeltaX;
  int32_t lineOrPageDeltaY;

  // 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 (!lineOrPageDeltaX && !lineOrPageDeltaY) {
      return 0;
    }
    if (lineOrPageDeltaY && !lineOrPageDeltaX) {
      return lineOrPageDeltaY;
    }
    if (lineOrPageDeltaX && !lineOrPageDeltaY) {
      return lineOrPageDeltaX;
    }
    if ((lineOrPageDeltaX < 0 && lineOrPageDeltaY > 0) ||
        (lineOrPageDeltaX > 0 && lineOrPageDeltaY < 0)) {
      return 0; // We cannot guess the answer in this case.
    }
    return (Abs(lineOrPageDeltaX) > Abs(lineOrPageDeltaY)) ?
             lineOrPageDeltaX : lineOrPageDeltaY;
  }

  // Scroll type
  // The default value is SCROLL_DEFAULT, which means EventStateManager will
  // select preferred scroll type automatically.
  enum ScrollType
  {
    SCROLL_DEFAULT,
    SCROLL_SYNCHRONOUSLY,
    SCROLL_ASYNCHRONOUSELY,
    SCROLL_SMOOTHLY
  };
  ScrollType scrollType;

  // overflowed delta values for scroll, these values are set by
  // nsEventStateManger.  If the default action of the wheel event isn't scroll,
  // these values always zero.  Otherwise, remaning delta values which are
  // not used by scroll are set.
  // NOTE: deltaX, deltaY and deltaZ may be modified by EventStateManager.
  //       However, overflowDeltaX and overflowDeltaY 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 deltaX and deltaY.
  double overflowDeltaX;
  double overflowDeltaY;

  // 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;

  void AssignWheelEventData(const WidgetWheelEvent& aEvent, bool aCopyTargets)
  {
    AssignMouseEventBaseData(aEvent, aCopyTargets);

    deltaX = aEvent.deltaX;
    deltaY = aEvent.deltaY;
    deltaZ = aEvent.deltaZ;
    deltaMode = aEvent.deltaMode;
    customizedByUserPrefs = aEvent.customizedByUserPrefs;
    mayHaveMomentum = aEvent.mayHaveMomentum;
    isMomentum = aEvent.isMomentum;
    mIsNoLineOrPageDelta = aEvent.mIsNoLineOrPageDelta;
    lineOrPageDeltaX = aEvent.lineOrPageDeltaX;
    lineOrPageDeltaY = aEvent.lineOrPageDeltaY;
    scrollType = aEvent.scrollType;
    overflowDeltaX = aEvent.overflowDeltaX;
    overflowDeltaY = aEvent.overflowDeltaY;
    mViewPortIsOverscrolled = aEvent.mViewPortIsOverscrolled;
    mCanTriggerSwipe = aEvent.mCanTriggerSwipe;
    mAllowToOverrideSystemScrollSpeed =
      aEvent.mAllowToOverrideSystemScrollSpeed;
  }

  // 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;

  WidgetPointerEvent()
    : width(0)
    , height(0)
    , isPrimary(true)
  {
  }

public:
  virtual WidgetPointerEvent* AsPointerEvent() override { return this; }

  WidgetPointerEvent(bool aIsTrusted, EventMessage aMsg, nsIWidget* w)
    : WidgetMouseEvent(aIsTrusted, aMsg, w, ePointerEventClass, eReal)
    , width(0)
    , height(0)
    , isPrimary(true)
  {
    UpdateFlags();
  }

  explicit WidgetPointerEvent(const WidgetMouseEvent& aEvent)
    : WidgetMouseEvent(aEvent)
    , width(0)
    , height(0)
    , isPrimary(true)
  {
    mClass = ePointerEventClass;
    UpdateFlags();
  }

  void UpdateFlags()
  {
    switch (mMessage) {
      case ePointerEnter:
      case ePointerLeave:
        mFlags.mBubbles = false;
        mFlags.mCancelable = false;
        break;
      case ePointerCancel:
      case ePointerGotCapture:
      case ePointerLostCapture:
        mFlags.mCancelable = false;
        break;
      default:
        break;
    }
  }

  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);
    result->AssignPointerEventData(*this, true);
    result->mFlags = mFlags;
    return result;
  }

  uint32_t width;
  uint32_t height;
  bool isPrimary;

  // XXX Not tested by test_assign_event_data.html
  void AssignPointerEventData(const WidgetPointerEvent& aEvent,
                              bool aCopyTargets)
  {
    AssignMouseEventData(aEvent, aCopyTargets);

    width = aEvent.width;
    height = aEvent.height;
    isPrimary = aEvent.isPrimary;
  }
};

} // namespace mozilla

#endif // mozilla_MouseEvents_h__