widget/MouseEvents.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef mozilla_MouseEvents_h__
   7 #define mozilla_MouseEvents_h__
   8
   9 #include <stdint.h>
  10
  11 #include "mozilla/BasicEvents.h"
  12 #include "mozilla/MathAlgorithms.h"
  13 #include "mozilla/dom/DataTransfer.h"
  14 #include "nsCOMPtr.h"
  15
  16 namespace mozilla {
  17
  18 namespace dom {
  19 class PBrowserParent;
  20 class PBrowserChild;
  21 class PBrowserBridgeParent;
  22 }  // namespace dom
  23
  24 class WidgetPointerEvent;
  25 }  // namespace mozilla
  26
  27 namespace mozilla {
  28 class WidgetPointerEventHolder final {
  29  public:
  30   nsTArray<WidgetPointerEvent> mEvents;
  31   NS_INLINE_DECL_REFCOUNTING(WidgetPointerEventHolder)
  32
  33  private:
  34   virtual ~WidgetPointerEventHolder() = default;
  35 };
  36
  37 /******************************************************************************
  38  * mozilla::WidgetPointerHelper
  39  ******************************************************************************/
  40
  41 class WidgetPointerHelper {
  42  public:
  43   uint32_t pointerId;
  44   uint32_t tiltX;
  45   uint32_t tiltY;
  46   uint32_t twist;
  47   float tangentialPressure;
  48   bool convertToPointer;
  49   RefPtr<WidgetPointerEventHolder> mCoalescedWidgetEvents;
  50
  51   WidgetPointerHelper()
  52       : pointerId(0),
  53         tiltX(0),
  54         tiltY(0),
  55         twist(0),
  56         tangentialPressure(0),
  57         convertToPointer(true) {}
  58
  59   WidgetPointerHelper(uint32_t aPointerId, uint32_t aTiltX, uint32_t aTiltY,
  60                       uint32_t aTwist = 0, float aTangentialPressure = 0)
  61       : pointerId(aPointerId),
  62         tiltX(aTiltX),
  63         tiltY(aTiltY),
  64         twist(aTwist),
  65         tangentialPressure(aTangentialPressure),
  66         convertToPointer(true) {}
  67
  68   explicit WidgetPointerHelper(const WidgetPointerHelper& aHelper) = default;
  69
  70   void AssignPointerHelperData(const WidgetPointerHelper& aEvent,
  71                                bool aCopyCoalescedEvents = false) {
  72     pointerId = aEvent.pointerId;
  73     tiltX = aEvent.tiltX;
  74     tiltY = aEvent.tiltY;
  75     twist = aEvent.twist;
  76     tangentialPressure = aEvent.tangentialPressure;
  77     convertToPointer = aEvent.convertToPointer;
  78     if (aCopyCoalescedEvents) {
  79       mCoalescedWidgetEvents = aEvent.mCoalescedWidgetEvents;
  80     }
  81   }
  82 };
  83
  84 /******************************************************************************
  85  * mozilla::WidgetMouseEventBase
  86  ******************************************************************************/
  87
  88 class WidgetMouseEventBase : public WidgetInputEvent {
  89  private:
  90   friend class dom::PBrowserParent;
  91   friend class dom::PBrowserChild;
  92   friend class dom::PBrowserBridgeParent;
  93
  94  protected:
  95   WidgetMouseEventBase()
  96       : mPressure(0),
  97         mButton(0),
  98         mButtons(0),
  99         mInputSource(/* MouseEvent_Binding::MOZ_SOURCE_MOUSE = */ 1) {}
 100   // Including MouseEventBinding.h here leads to an include loop, so
 101   // we have to hardcode MouseEvent_Binding::MOZ_SOURCE_MOUSE.
 102
 103   WidgetMouseEventBase(bool aIsTrusted, EventMessage aMessage,
 104                        nsIWidget* aWidget, EventClassID aEventClassID)
 105       : WidgetInputEvent(aIsTrusted, aMessage, aWidget, aEventClassID),
 106         mPressure(0),
 107         mButton(0),
 108         mButtons(0),
 109         mInputSource(/* MouseEvent_Binding::MOZ_SOURCE_MOUSE = */ 1) {}
 110   // Including MouseEventBinding.h here leads to an include loop, so
 111   // we have to hardcode MouseEvent_Binding::MOZ_SOURCE_MOUSE.
 112
 113  public:
 114   virtual WidgetMouseEventBase* AsMouseEventBase() override { return this; }
 115
 116   virtual WidgetEvent* Duplicate() const override {
 117     MOZ_CRASH("WidgetMouseEventBase must not be most-subclass");
 118   }
 119
 120   // ID of the canvas HitRegion
 121   nsString mRegion;
 122
 123   // Finger or touch pressure of event. It ranges between 0.0 and 1.0.
 124   float mPressure;
 125
 126   // Pressed button ID of mousedown or mouseup event.
 127   // This is set only when pressing a button causes the event.
 128   int16_t mButton;
 129
 130   // Flags of all pressed buttons at the event fired.
 131   // This is set at any mouse event, don't be confused with |mButton|.
 132   int16_t mButtons;
 133
 134   // Possible values a in MouseEvent
 135   uint16_t mInputSource;
 136
 137   bool IsLeftButtonPressed() const {
 138     return !!(mButtons & MouseButtonsFlag::ePrimaryFlag);
 139   }
 140   bool IsRightButtonPressed() const {
 141     return !!(mButtons & MouseButtonsFlag::eSecondaryFlag);
 142   }
 143   bool IsMiddleButtonPressed() const {
 144     return !!(mButtons & MouseButtonsFlag::eMiddleFlag);
 145   }
 146   bool Is4thButtonPressed() const {
 147     return !!(mButtons & MouseButtonsFlag::e4thFlag);
 148   }
 149   bool Is5thButtonPressed() const {
 150     return !!(mButtons & MouseButtonsFlag::e5thFlag);
 151   }
 152
 153   void AssignMouseEventBaseData(const WidgetMouseEventBase& aEvent,
 154                                 bool aCopyTargets) {
 155     AssignInputEventData(aEvent, aCopyTargets);
 156
 157     mButton = aEvent.mButton;
 158     mButtons = aEvent.mButtons;
 159     mPressure = aEvent.mPressure;
 160     mInputSource = aEvent.mInputSource;
 161   }
 162
 163   /**
 164    * Returns true if left click event.
 165    */
 166   bool IsLeftClickEvent() const {
 167     return mMessage == eMouseClick && mButton == MouseButton::ePrimary;
 168   }
 169 };
 170
 171 /******************************************************************************
 172  * mozilla::WidgetMouseEvent
 173  ******************************************************************************/
 174
 175 class WidgetMouseEvent : public WidgetMouseEventBase,
 176                          public WidgetPointerHelper {
 177  private:
 178   friend class dom::PBrowserParent;
 179   friend class dom::PBrowserChild;
 180   friend class dom::PBrowserBridgeParent;
 181
 182  public:
 183   typedef bool ReasonType;
 184   enum Reason : ReasonType { eReal, eSynthesized };
 185
 186   typedef uint8_t ContextMenuTriggerType;
 187   enum ContextMenuTrigger : ContextMenuTriggerType {
 188     eNormal,
 189     eContextMenuKey,
 190     eControlClick
 191   };
 192
 193   typedef uint8_t ExitFromType;
 194   enum ExitFrom : ExitFromType {
 195     ePlatformChild,
 196     ePlatformTopLevel,
 197     ePuppet,
 198     ePuppetParentToPuppetChild
 199   };
 200
 201  protected:
 202   WidgetMouseEvent()
 203       : mReason(eReal),
 204         mContextMenuTrigger(eNormal),
 205         mIgnoreRootScrollFrame(false),
 206         mClickCount(0),
 207         mUseLegacyNonPrimaryDispatch(false) {}
 208
 209   WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
 210                    EventClassID aEventClassID, Reason aReason)
 211       : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, aEventClassID),
 212         mReason(aReason),
 213         mContextMenuTrigger(eNormal),
 214         mIgnoreRootScrollFrame(false),
 215         mClickCount(0),
 216         mUseLegacyNonPrimaryDispatch(false) {}
 217
 218  public:
 219   virtual WidgetMouseEvent* AsMouseEvent() override { return this; }
 220
 221   WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
 222                    Reason aReason,
 223                    ContextMenuTrigger aContextMenuTrigger = eNormal)
 224       : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eMouseEventClass),
 225         mReason(aReason),
 226         mContextMenuTrigger(aContextMenuTrigger),
 227         mIgnoreRootScrollFrame(false),
 228         mClickCount(0),
 229         mUseLegacyNonPrimaryDispatch(false) {
 230     if (aMessage == eContextMenu) {
 231       mButton = (mContextMenuTrigger == eNormal) ? MouseButton::eSecondary
 232                                                  : MouseButton::ePrimary;
 233     }
 234   }
 235
 236 #ifdef DEBUG
 237   virtual ~WidgetMouseEvent() {
 238     NS_WARNING_ASSERTION(
 239         mMessage != eContextMenu ||
 240             (mButton == ((mContextMenuTrigger == eNormal)
 241                              ? MouseButton::eSecondary
 242                              : MouseButton::ePrimary) &&
 243              (mContextMenuTrigger != eControlClick || IsControl())),
 244         "Wrong button set to eContextMenu event?");
 245   }
 246 #endif
 247
 248   virtual WidgetEvent* Duplicate() const override {
 249     MOZ_ASSERT(mClass == eMouseEventClass,
 250                "Duplicate() must be overridden by sub class");
 251     // Not copying widget, it is a weak reference.
 252     WidgetMouseEvent* result = new WidgetMouseEvent(
 253         false, mMessage, nullptr, mReason, mContextMenuTrigger);
 254     result->AssignMouseEventData(*this, true);
 255     result->mFlags = mFlags;
 256     return result;
 257   }
 258
 259   // If during mouseup handling we detect that click event might need to be
 260   // dispatched, this is setup to be the target of the click event.
 261   nsCOMPtr<dom::EventTarget> mClickTarget;
 262
 263   // mReason indicates the reason why the event is fired:
 264   // - Representing mouse operation.
 265   // - Synthesized for emulating mousemove event when the content under the
 266   //   mouse cursor is scrolled.
 267   Reason mReason;
 268
 269   // mContextMenuTrigger is valid only when mMessage is eContextMenu.
 270   // This indicates if the context menu event is caused by context menu key or
 271   // other reasons (typically, a click of right mouse button).
 272   ContextMenuTrigger mContextMenuTrigger;
 273
 274   // mExitFrom contains a value only when mMessage is eMouseExitFromWidget.
 275   // This indicates if the mouse cursor exits from a top level platform widget,
 276   // a child widget or a puppet widget.
 277   Maybe<ExitFrom> mExitFrom;
 278
 279   // Whether the event should ignore scroll frame bounds during dispatch.
 280   bool mIgnoreRootScrollFrame;
 281
 282   // mClickCount may be non-zero value when mMessage is eMouseDown, eMouseUp,
 283   // eMouseClick or eMouseDoubleClick. The number is count of mouse clicks.
 284   // Otherwise, this must be 0.
 285   uint32_t mClickCount;
 286
 287   // Indicates whether the event should dispatch click events for non-primary
 288   // mouse buttons on window and document.
 289   bool mUseLegacyNonPrimaryDispatch;
 290
 291   void AssignMouseEventData(const WidgetMouseEvent& aEvent, bool aCopyTargets) {
 292     AssignMouseEventBaseData(aEvent, aCopyTargets);
 293     AssignPointerHelperData(aEvent, /* aCopyCoalescedEvents */ true);
 294
 295     mExitFrom = aEvent.mExitFrom;
 296     mIgnoreRootScrollFrame = aEvent.mIgnoreRootScrollFrame;
 297     mClickCount = aEvent.mClickCount;
 298     mUseLegacyNonPrimaryDispatch = aEvent.mUseLegacyNonPrimaryDispatch;
 299   }
 300
 301   /**
 302    * Returns true if the event is a context menu event caused by key.
 303    */
 304   bool IsContextMenuKeyEvent() const {
 305     return mMessage == eContextMenu && mContextMenuTrigger == eContextMenuKey;
 306   }
 307
 308   /**
 309    * Returns true if the event is a real mouse event.  Otherwise, i.e., it's
 310    * a synthesized event by scroll or something, returns false.
 311    */
 312   bool IsReal() const { return mReason == eReal; }
 313
 314   /**
 315    * Returns true if middle click paste is enabled.
 316    */
 317   static bool IsMiddleClickPasteEnabled();
 318 };
 319
 320 /******************************************************************************
 321  * mozilla::WidgetDragEvent
 322  ******************************************************************************/
 323
 324 class WidgetDragEvent : public WidgetMouseEvent {
 325  private:
 326   friend class mozilla::dom::PBrowserParent;
 327   friend class mozilla::dom::PBrowserChild;
 328
 329  protected:
 330   WidgetDragEvent()
 331       : mUserCancelled(false), mDefaultPreventedOnContent(false) {}
 332
 333  public:
 334   virtual WidgetDragEvent* AsDragEvent() override { return this; }
 335
 336   WidgetDragEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget)
 337       : WidgetMouseEvent(aIsTrusted, aMessage, aWidget, eDragEventClass, eReal),
 338         mUserCancelled(false),
 339         mDefaultPreventedOnContent(false) {}
 340
 341   virtual WidgetEvent* Duplicate() const override {
 342     MOZ_ASSERT(mClass == eDragEventClass,
 343                "Duplicate() must be overridden by sub class");
 344     // Not copying widget, it is a weak reference.
 345     WidgetDragEvent* result = new WidgetDragEvent(false, mMessage, nullptr);
 346     result->AssignDragEventData(*this, true);
 347     result->mFlags = mFlags;
 348     return result;
 349   }
 350
 351   // The dragging data.
 352   nsCOMPtr<dom::DataTransfer> mDataTransfer;
 353
 354   // If this is true, user has cancelled the drag operation.
 355   bool mUserCancelled;
 356   // If this is true, the drag event's preventDefault() is called on content.
 357   bool mDefaultPreventedOnContent;
 358
 359   // XXX Not tested by test_assign_event_data.html
 360   void AssignDragEventData(const WidgetDragEvent& aEvent, bool aCopyTargets) {
 361     AssignMouseEventData(aEvent, aCopyTargets);
 362
 363     mDataTransfer = aEvent.mDataTransfer;
 364     // XXX mUserCancelled isn't copied, is this intentionally?
 365     mUserCancelled = false;
 366     mDefaultPreventedOnContent = aEvent.mDefaultPreventedOnContent;
 367   }
 368
 369   /**
 370    * Should be called before dispatching the DOM tree if this event is
 371    * synthesized for tests because drop effect is initialized before
 372    * dispatching from widget if it's not synthesized event, but synthesized
 373    * events are not initialized in the path.
 374    */
 375   void InitDropEffectForTests();
 376 };
 377
 378 /******************************************************************************
 379  * mozilla::WidgetMouseScrollEvent
 380  *
 381  * This is used for legacy DOM mouse scroll events, i.e.,
 382  * DOMMouseScroll and MozMousePixelScroll event.  These events are NOT hanbled
 383  * by ESM even if widget dispatches them.  Use new WidgetWheelEvent instead.
 384  ******************************************************************************/
 385
 386 class WidgetMouseScrollEvent : public WidgetMouseEventBase {
 387  private:
 388   WidgetMouseScrollEvent() : mDelta(0), mIsHorizontal(false) {}
 389
 390  public:
 391   virtual WidgetMouseScrollEvent* AsMouseScrollEvent() override { return this; }
 392
 393   WidgetMouseScrollEvent(bool aIsTrusted, EventMessage aMessage,
 394                          nsIWidget* aWidget)
 395       : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget,
 396                              eMouseScrollEventClass),
 397         mDelta(0),
 398         mIsHorizontal(false) {}
 399
 400   virtual WidgetEvent* Duplicate() const override {
 401     MOZ_ASSERT(mClass == eMouseScrollEventClass,
 402                "Duplicate() must be overridden by sub class");
 403     // Not copying widget, it is a weak reference.
 404     WidgetMouseScrollEvent* result =
 405         new WidgetMouseScrollEvent(false, mMessage, nullptr);
 406     result->AssignMouseScrollEventData(*this, true);
 407     result->mFlags = mFlags;
 408     return result;
 409   }
 410
 411   // The delta value of mouse scroll event.
 412   // If the event message is eLegacyMouseLineOrPageScroll, the value indicates
 413   // scroll amount in lines.  However, if the value is
 414   // UIEvent::SCROLL_PAGE_UP or UIEvent::SCROLL_PAGE_DOWN, the
 415   // value inducates one page scroll.  If the event message is
 416   // eLegacyMousePixelScroll, the value indicates scroll amount in pixels.
 417   int32_t mDelta;
 418
 419   // If this is true, it may cause to scroll horizontally.
 420   // Otherwise, vertically.
 421   bool mIsHorizontal;
 422
 423   void AssignMouseScrollEventData(const WidgetMouseScrollEvent& aEvent,
 424                                   bool aCopyTargets) {
 425     AssignMouseEventBaseData(aEvent, aCopyTargets);
 426
 427     mDelta = aEvent.mDelta;
 428     mIsHorizontal = aEvent.mIsHorizontal;
 429   }
 430 };
 431
 432 /******************************************************************************
 433  * mozilla::WidgetWheelEvent
 434  ******************************************************************************/
 435
 436 class WidgetWheelEvent : public WidgetMouseEventBase {
 437  private:
 438   friend class mozilla::dom::PBrowserParent;
 439   friend class mozilla::dom::PBrowserChild;
 440
 441   WidgetWheelEvent()
 442       : mDeltaX(0.0),
 443         mDeltaY(0.0),
 444         mDeltaZ(0.0),
 445         mOverflowDeltaX(0.0),
 446         mOverflowDeltaY(0.0)
 447         // Including WheelEventBinding.h here leads to an include loop, so
 448         // we have to hardcode WheelEvent_Binding::DOM_DELTA_PIXEL.
 449         ,
 450         mDeltaMode(/* WheelEvent_Binding::DOM_DELTA_PIXEL = */ 0),
 451         mLineOrPageDeltaX(0),
 452         mLineOrPageDeltaY(0),
 453         mScrollType(SCROLL_DEFAULT),
 454         mCustomizedByUserPrefs(false),
 455         mMayHaveMomentum(false),
 456         mIsMomentum(false),
 457         mIsNoLineOrPageDelta(false),
 458         mViewPortIsOverscrolled(false),
 459         mCanTriggerSwipe(false),
 460         mAllowToOverrideSystemScrollSpeed(false),
 461         mDeltaValuesHorizontalizedForDefaultHandler(false) {}
 462
 463  public:
 464   virtual WidgetWheelEvent* AsWheelEvent() override { return this; }
 465
 466   WidgetWheelEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget)
 467       : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eWheelEventClass),
 468         mDeltaX(0.0),
 469         mDeltaY(0.0),
 470         mDeltaZ(0.0),
 471         mOverflowDeltaX(0.0),
 472         mOverflowDeltaY(0.0)
 473         // Including WheelEventBinding.h here leads to an include loop, so
 474         // we have to hardcode WheelEvent_Binding::DOM_DELTA_PIXEL.
 475         ,
 476         mDeltaMode(/* WheelEvent_Binding::DOM_DELTA_PIXEL = */ 0),
 477         mLineOrPageDeltaX(0),
 478         mLineOrPageDeltaY(0),
 479         mScrollType(SCROLL_DEFAULT),
 480         mCustomizedByUserPrefs(false),
 481         mMayHaveMomentum(false),
 482         mIsMomentum(false),
 483         mIsNoLineOrPageDelta(false),
 484         mViewPortIsOverscrolled(false),
 485         mCanTriggerSwipe(false),
 486         mAllowToOverrideSystemScrollSpeed(true),
 487         mDeltaValuesHorizontalizedForDefaultHandler(false) {}
 488
 489   virtual WidgetEvent* Duplicate() const override {
 490     MOZ_ASSERT(mClass == eWheelEventClass,
 491                "Duplicate() must be overridden by sub class");
 492     // Not copying widget, it is a weak reference.
 493     WidgetWheelEvent* result = new WidgetWheelEvent(false, mMessage, nullptr);
 494     result->AssignWheelEventData(*this, true);
 495     result->mFlags = mFlags;
 496     return result;
 497   }
 498
 499   // On OS X, scroll gestures that start at the edge of the scrollable range
 500   // can result in a swipe gesture. For the first wheel event of such a
 501   // gesture, call TriggersSwipe() after the event has been processed
 502   // in order to find out whether a swipe should be started.
 503   bool TriggersSwipe() const {
 504     return mCanTriggerSwipe && mViewPortIsOverscrolled &&
 505            this->mOverflowDeltaX != 0.0;
 506   }
 507
 508   // NOTE: mDeltaX, mDeltaY and mDeltaZ may be customized by
 509   //       mousewheel.*.delta_multiplier_* prefs which are applied by
 510   //       EventStateManager.  So, after widget dispatches this event,
 511   //       these delta values may have different values than before.
 512   double mDeltaX;
 513   double mDeltaY;
 514   double mDeltaZ;
 515
 516   enum class DeltaModeCheckingState : uint8_t {
 517     // Neither deltaMode nor the delta values have been accessed.
 518     Unknown,
 519     // The delta values have been accessed, without checking deltaMode first.
 520     Unchecked,
 521     // The deltaMode has been checked.
 522     Checked,
 523   };
 524
 525   // For compat reasons, we might expose a DOM_DELTA_LINE event as
 526   // DOM_DELTA_PIXEL instead. Whether we do that depends on whether the event
 527   // has been asked for the deltaMode before the deltas. If it has, we assume
 528   // that the page will correctly handle DOM_DELTA_LINE. This variable tracks
 529   // that state. See bug 1392460.
 530   DeltaModeCheckingState mDeltaModeCheckingState =
 531       DeltaModeCheckingState::Unknown;
 532
 533   // The amount of scrolling per line or page, without accounting for mouse
 534   // wheel transactions etc.
 535   //
 536   // Computed by EventStateManager::DeltaAccumulator::InitLineOrPageDelta.
 537   nsSize mScrollAmount;
 538
 539   // overflowed delta values for scroll, these values are set by
 540   // EventStateManger.  If the default action of the wheel event isn't scroll,
 541   // these values are always zero.  Otherwise, remaining delta values which are
 542   // not used by scroll are set.
 543   // NOTE: mDeltaX, mDeltaY and mDeltaZ may be modified by EventStateManager.
 544   //       However, mOverflowDeltaX and mOverflowDeltaY indicate unused original
 545   //       delta values which are not applied the delta_multiplier prefs.
 546   //       So, if widget wanted to know the actual direction to be scrolled,
 547   //       it would need to check the mDeltaX and mDeltaY.
 548   double mOverflowDeltaX;
 549   double mOverflowDeltaY;
 550
 551   // Should be one of WheelEvent_Binding::DOM_DELTA_*
 552   uint32_t mDeltaMode;
 553
 554   // If widget sets mLineOrPageDelta, EventStateManager will dispatch
 555   // eLegacyMouseLineOrPageScroll event for compatibility.  Note that the delta
 556   // value means pages if the mDeltaMode is DOM_DELTA_PAGE, otherwise, lines.
 557   int32_t mLineOrPageDeltaX;
 558   int32_t mLineOrPageDeltaY;
 559
 560   // When the default action for an wheel event is moving history or zooming,
 561   // need to chose a delta value for doing it.
 562   int32_t GetPreferredIntDelta() {
 563     if (!mLineOrPageDeltaX && !mLineOrPageDeltaY) {
 564       return 0;
 565     }
 566     if (mLineOrPageDeltaY && !mLineOrPageDeltaX) {
 567       return mLineOrPageDeltaY;
 568     }
 569     if (mLineOrPageDeltaX && !mLineOrPageDeltaY) {
 570       return mLineOrPageDeltaX;
 571     }
 572     if ((mLineOrPageDeltaX < 0 && mLineOrPageDeltaY > 0) ||
 573         (mLineOrPageDeltaX > 0 && mLineOrPageDeltaY < 0)) {
 574       return 0;  // We cannot guess the answer in this case.
 575     }
 576     return (Abs(mLineOrPageDeltaX) > Abs(mLineOrPageDeltaY))
 577                ? mLineOrPageDeltaX
 578                : mLineOrPageDeltaY;
 579   }
 580
 581   // Scroll type
 582   // The default value is SCROLL_DEFAULT, which means EventStateManager will
 583   // select preferred scroll type automatically.
 584   enum ScrollType : uint8_t {
 585     SCROLL_DEFAULT,
 586     SCROLL_SYNCHRONOUSLY,
 587     SCROLL_ASYNCHRONOUSELY,
 588     SCROLL_SMOOTHLY
 589   };
 590   ScrollType mScrollType;
 591
 592   // If the delta values are computed from prefs, this value is true.
 593   // Otherwise, i.e., they are computed from native events, false.
 594   bool mCustomizedByUserPrefs;
 595
 596   // true if the momentum events directly tied to this event may follow it.
 597   bool mMayHaveMomentum;
 598   // true if the event is caused by momentum.
 599   bool mIsMomentum;
 600
 601   // If device event handlers don't know when they should set mLineOrPageDeltaX
 602   // and mLineOrPageDeltaY, this is true.  Otherwise, false.
 603   // If mIsNoLineOrPageDelta is true, ESM will generate
 604   // eLegacyMouseLineOrPageScroll events when accumulated delta values reach
 605   // a line height.
 606   bool mIsNoLineOrPageDelta;
 607
 608   // Whether or not the parent of the currently overscrolled frame is the
 609   // ViewPort. This is false in situations when an element on the page is being
 610   // overscrolled (such as a text field), but true when the 'page' is being
 611   // overscrolled.
 612   bool mViewPortIsOverscrolled;
 613
 614   // The wheel event can trigger a swipe to start if it's overscrolling the
 615   // viewport.
 616   bool mCanTriggerSwipe;
 617
 618   // If mAllowToOverrideSystemScrollSpeed is true, the scroll speed may be
 619   // overridden.  Otherwise, the scroll speed won't be overridden even if
 620   // it's enabled by the pref.
 621   bool mAllowToOverrideSystemScrollSpeed;
 622
 623   // After the event's default action handler has adjusted its delta's values
 624   // for horizontalizing a vertical wheel scroll, this variable will be set to
 625   // true.
 626   bool mDeltaValuesHorizontalizedForDefaultHandler;
 627
 628   void AssignWheelEventData(const WidgetWheelEvent& aEvent, bool aCopyTargets) {
 629     AssignMouseEventBaseData(aEvent, aCopyTargets);
 630
 631     mDeltaX = aEvent.mDeltaX;
 632     mDeltaY = aEvent.mDeltaY;
 633     mDeltaZ = aEvent.mDeltaZ;
 634     mDeltaMode = aEvent.mDeltaMode;
 635     mScrollAmount = aEvent.mScrollAmount;
 636     mCustomizedByUserPrefs = aEvent.mCustomizedByUserPrefs;
 637     mMayHaveMomentum = aEvent.mMayHaveMomentum;
 638     mIsMomentum = aEvent.mIsMomentum;
 639     mIsNoLineOrPageDelta = aEvent.mIsNoLineOrPageDelta;
 640     mLineOrPageDeltaX = aEvent.mLineOrPageDeltaX;
 641     mLineOrPageDeltaY = aEvent.mLineOrPageDeltaY;
 642     mScrollType = aEvent.mScrollType;
 643     mOverflowDeltaX = aEvent.mOverflowDeltaX;
 644     mOverflowDeltaY = aEvent.mOverflowDeltaY;
 645     mViewPortIsOverscrolled = aEvent.mViewPortIsOverscrolled;
 646     mCanTriggerSwipe = aEvent.mCanTriggerSwipe;
 647     mAllowToOverrideSystemScrollSpeed =
 648         aEvent.mAllowToOverrideSystemScrollSpeed;
 649     mDeltaValuesHorizontalizedForDefaultHandler =
 650         aEvent.mDeltaValuesHorizontalizedForDefaultHandler;
 651   }
 652
 653   // System scroll speed settings may be too slow at using Gecko.  In such
 654   // case, we should override the scroll speed computed with system settings.
 655   // Following methods return preferred delta values which are multiplied by
 656   // factors specified by prefs.  If system scroll speed shouldn't be
 657   // overridden (e.g., this feature is disabled by pref), they return raw
 658   // delta values.
 659   double OverriddenDeltaX() const;
 660   double OverriddenDeltaY() const;
 661
 662   // Compute the overridden delta value.  This may be useful for suppressing
 663   // too fast scroll by system scroll speed overriding when widget sets
 664   // mAllowToOverrideSystemScrollSpeed.
 665   static double ComputeOverriddenDelta(double aDelta, bool aIsForVertical);
 666
 667  private:
 668   static bool sInitialized;
 669   static bool sIsSystemScrollSpeedOverrideEnabled;
 670   static int32_t sOverrideFactorX;
 671   static int32_t sOverrideFactorY;
 672   static void Initialize();
 673 };
 674
 675 /******************************************************************************
 676  * mozilla::WidgetPointerEvent
 677  ******************************************************************************/
 678
 679 class WidgetPointerEvent : public WidgetMouseEvent {
 680   friend class mozilla::dom::PBrowserParent;
 681   friend class mozilla::dom::PBrowserChild;
 682
 683   WidgetPointerEvent() : mWidth(1), mHeight(1), mIsPrimary(true) {}
 684
 685  public:
 686   virtual WidgetPointerEvent* AsPointerEvent() override { return this; }
 687
 688   WidgetPointerEvent(bool aIsTrusted, EventMessage aMsg, nsIWidget* w)
 689       : WidgetMouseEvent(aIsTrusted, aMsg, w, ePointerEventClass, eReal),
 690         mWidth(1),
 691         mHeight(1),
 692         mIsPrimary(true) {}
 693
 694   explicit WidgetPointerEvent(const WidgetMouseEvent& aEvent)
 695       : WidgetMouseEvent(aEvent), mWidth(1), mHeight(1), mIsPrimary(true) {
 696     mClass = ePointerEventClass;
 697   }
 698
 699   virtual WidgetEvent* Duplicate() const override {
 700     MOZ_ASSERT(mClass == ePointerEventClass,
 701                "Duplicate() must be overridden by sub class");
 702     // Not copying widget, it is a weak reference.
 703     WidgetPointerEvent* result =
 704         new WidgetPointerEvent(false, mMessage, nullptr);
 705     result->AssignPointerEventData(*this, true);
 706     result->mFlags = mFlags;
 707     return result;
 708   }
 709
 710   uint32_t mWidth;
 711   uint32_t mHeight;
 712   bool mIsPrimary;
 713
 714   // XXX Not tested by test_assign_event_data.html
 715   void AssignPointerEventData(const WidgetPointerEvent& aEvent,
 716                               bool aCopyTargets) {
 717     AssignMouseEventData(aEvent, aCopyTargets);
 718
 719     mWidth = aEvent.mWidth;
 720     mHeight = aEvent.mHeight;
 721     mIsPrimary = aEvent.mIsPrimary;
 722   }
 723 };
 724
 725 }  // namespace mozilla
 726
 727 #endif  // mozilla_MouseEvents_h__