dom/events/WheelEvent.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/dom/MouseEventBinding.h"
   8 #include "mozilla/dom/WheelEvent.h"
   9 #include "mozilla/MouseEvents.h"
  10 #include "prtime.h"
  11
  12 namespace mozilla::dom {
  13
  14 WheelEvent::WheelEvent(EventTarget* aOwner, nsPresContext* aPresContext,
  15                        WidgetWheelEvent* aWheelEvent)
  16     : MouseEvent(aOwner, aPresContext,
  17                  aWheelEvent
  18                      ? aWheelEvent
  19                      : new WidgetWheelEvent(false, eVoidEvent, nullptr)),
  20       mAppUnitsPerDevPixel(0) {
  21   if (aWheelEvent) {
  22     mEventIsInternal = false;
  23     // If the delta mode is pixel, the WidgetWheelEvent's delta values are in
  24     // device pixels.  However, JS contents need the delta values in CSS pixels.
  25     // We should store the value of mAppUnitsPerDevPixel here because
  26     // it might be changed by changing zoom or something.
  27     if (aWheelEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL) {
  28       mAppUnitsPerDevPixel = aPresContext->AppUnitsPerDevPixel();
  29     }
  30   } else {
  31     mEventIsInternal = true;
  32     mEvent->mRefPoint = LayoutDeviceIntPoint(0, 0);
  33     mEvent->AsWheelEvent()->mInputSource =
  34         MouseEvent_Binding::MOZ_SOURCE_UNKNOWN;
  35   }
  36 }
  37
  38 void WheelEvent::InitWheelEvent(
  39     const nsAString& aType, bool aCanBubble, bool aCancelable,
  40     nsGlobalWindowInner* aView, int32_t aDetail, int32_t aScreenX,
  41     int32_t aScreenY, int32_t aClientX, int32_t aClientY, uint16_t aButton,
  42     EventTarget* aRelatedTarget, const nsAString& aModifiersList,
  43     double aDeltaX, double aDeltaY, double aDeltaZ, uint32_t aDeltaMode) {
  44   NS_ENSURE_TRUE_VOID(!mEvent->mFlags.mIsBeingDispatched);
  45
  46   MouseEvent::InitMouseEvent(aType, aCanBubble, aCancelable, aView, aDetail,
  47                              aScreenX, aScreenY, aClientX, aClientY, aButton,
  48                              aRelatedTarget, aModifiersList);
  49
  50   WidgetWheelEvent* wheelEvent = mEvent->AsWheelEvent();
  51   // When specified by the caller (for JS-created events), don't mess with the
  52   // delta mode.
  53   wheelEvent->mDeltaModeCheckingState =
  54       WidgetWheelEvent::DeltaModeCheckingState::Checked;
  55   wheelEvent->mDeltaX = aDeltaX;
  56   wheelEvent->mDeltaY = aDeltaY;
  57   wheelEvent->mDeltaZ = aDeltaZ;
  58   wheelEvent->mDeltaMode = aDeltaMode;
  59   wheelEvent->mAllowToOverrideSystemScrollSpeed = false;
  60 }
  61
  62 int32_t WheelEvent::WheelDeltaX(CallerType aCallerType) {
  63   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
  64   if (ev->mWheelTicksX != 0.0) {
  65     return int32_t(-ev->mWheelTicksX * kNativeTicksToWheelDelta);
  66   }
  67   if (IsTrusted()) {
  68     // We always return pixels regardless of the checking-state.
  69     double pixelDelta =
  70         ev->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL
  71             ? DevToCssPixels(ev->OverriddenDeltaX())
  72             : ev->OverriddenDeltaX() *
  73                   CSSPixel::FromAppUnits(ev->mScrollAmount.width).Rounded();
  74     return int32_t(-std::round(pixelDelta * kTrustedDeltaToWheelDelta));
  75   }
  76   return int32_t(-std::round(DeltaX(aCallerType)));  // This matches Safari.
  77 }
  78
  79 int32_t WheelEvent::WheelDeltaY(CallerType aCallerType) {
  80   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
  81   if (ev->mWheelTicksY != 0.0) {
  82     return int32_t(-ev->mWheelTicksY * kNativeTicksToWheelDelta);
  83   }
  84
  85   if (IsTrusted()) {
  86     double pixelDelta =
  87         ev->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL
  88             ? DevToCssPixels(ev->OverriddenDeltaY())
  89             : ev->OverriddenDeltaY() *
  90                   CSSPixel::FromAppUnits(ev->mScrollAmount.height).Rounded();
  91     return int32_t(-std::round(pixelDelta * kTrustedDeltaToWheelDelta));
  92   }
  93   return int32_t(-std::round(DeltaY(aCallerType)));  // This matches Safari.
  94 }
  95
  96 double WheelEvent::ToWebExposedDelta(WidgetWheelEvent& aWidgetEvent,
  97                                      double aDelta, nscoord aLineOrPageAmount,
  98                                      CallerType aCallerType) {
  99   using DeltaModeCheckingState = WidgetWheelEvent::DeltaModeCheckingState;
 100   if (aCallerType != CallerType::System) {
 101     if (aWidgetEvent.mDeltaModeCheckingState ==
 102         DeltaModeCheckingState::Unknown) {
 103       aWidgetEvent.mDeltaModeCheckingState = DeltaModeCheckingState::Unchecked;
 104     }
 105     if (aWidgetEvent.mDeltaModeCheckingState ==
 106             DeltaModeCheckingState::Unchecked &&
 107         aWidgetEvent.mDeltaMode == WheelEvent_Binding::DOM_DELTA_LINE) {
 108       return aDelta * CSSPixel::FromAppUnits(aLineOrPageAmount).Rounded();
 109     }
 110   }
 111   return DevToCssPixels(aDelta);
 112 }
 113
 114 double WheelEvent::DeltaX(CallerType aCallerType) {
 115   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 116   return ToWebExposedDelta(*ev, ev->OverriddenDeltaX(), ev->mScrollAmount.width,
 117                            aCallerType);
 118 }
 119
 120 double WheelEvent::DeltaY(CallerType aCallerType) {
 121   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 122   return ToWebExposedDelta(*ev, ev->OverriddenDeltaY(),
 123                            ev->mScrollAmount.height, aCallerType);
 124 }
 125
 126 double WheelEvent::DeltaZ(CallerType aCallerType) {
 127   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 128   // XXX Unclear what scroll amount we should use for deltaZ...
 129   auto amount = std::max(ev->mScrollAmount.width, ev->mScrollAmount.height);
 130   return ToWebExposedDelta(*ev, ev->mDeltaZ, amount, aCallerType);
 131 }
 132
 133 uint32_t WheelEvent::DeltaMode(CallerType aCallerType) {
 134   using DeltaModeCheckingState = WidgetWheelEvent::DeltaModeCheckingState;
 135
 136   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 137   uint32_t mode = ev->mDeltaMode;
 138   if (aCallerType != CallerType::System) {
 139     if (ev->mDeltaModeCheckingState == DeltaModeCheckingState::Unknown) {
 140       ev->mDeltaModeCheckingState = DeltaModeCheckingState::Checked;
 141     } else if (ev->mDeltaModeCheckingState ==
 142                    DeltaModeCheckingState::Unchecked &&
 143                mode == WheelEvent_Binding::DOM_DELTA_LINE) {
 144       return WheelEvent_Binding::DOM_DELTA_PIXEL;
 145     }
 146   }
 147
 148   return mode;
 149 }
 150
 151 already_AddRefed<WheelEvent> WheelEvent::Constructor(
 152     const GlobalObject& aGlobal, const nsAString& aType,
 153     const WheelEventInit& aParam) {
 154   nsCOMPtr<EventTarget> t = do_QueryInterface(aGlobal.GetAsSupports());
 155   RefPtr<WheelEvent> e = new WheelEvent(t, nullptr, nullptr);
 156   bool trusted = e->Init(t);
 157   e->InitWheelEvent(aType, aParam.mBubbles, aParam.mCancelable, aParam.mView,
 158                     aParam.mDetail, aParam.mScreenX, aParam.mScreenY,
 159                     aParam.mClientX, aParam.mClientY, aParam.mButton,
 160                     aParam.mRelatedTarget, u""_ns, aParam.mDeltaX,
 161                     aParam.mDeltaY, aParam.mDeltaZ, aParam.mDeltaMode);
 162   e->InitializeExtraMouseEventDictionaryMembers(aParam);
 163   e->SetTrusted(trusted);
 164   e->SetComposed(aParam.mComposed);
 165   return e.forget();
 166 }
 167
 168 }  // namespace mozilla::dom
 169
 170 using namespace mozilla;
 171 using namespace mozilla::dom;
 172
 173 already_AddRefed<WheelEvent> NS_NewDOMWheelEvent(EventTarget* aOwner,
 174                                                  nsPresContext* aPresContext,
 175                                                  WidgetWheelEvent* aEvent) {
 176   RefPtr<WheelEvent> it = new WheelEvent(aOwner, aPresContext, aEvent);
 177   return it.forget();
 178 }