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->mTime = PR_Now();
  33     mEvent->mRefPoint = LayoutDeviceIntPoint(0, 0);
  34     mEvent->AsWheelEvent()->mInputSource =
  35         MouseEvent_Binding::MOZ_SOURCE_UNKNOWN;
  36   }
  37 }
  38
  39 void WheelEvent::InitWheelEvent(
  40     const nsAString& aType, bool aCanBubble, bool aCancelable,
  41     nsGlobalWindowInner* aView, int32_t aDetail, int32_t aScreenX,
  42     int32_t aScreenY, int32_t aClientX, int32_t aClientY, uint16_t aButton,
  43     EventTarget* aRelatedTarget, const nsAString& aModifiersList,
  44     double aDeltaX, double aDeltaY, double aDeltaZ, uint32_t aDeltaMode) {
  45   NS_ENSURE_TRUE_VOID(!mEvent->mFlags.mIsBeingDispatched);
  46
  47   MouseEvent::InitMouseEvent(aType, aCanBubble, aCancelable, aView, aDetail,
  48                              aScreenX, aScreenY, aClientX, aClientY, aButton,
  49                              aRelatedTarget, aModifiersList);
  50
  51   WidgetWheelEvent* wheelEvent = mEvent->AsWheelEvent();
  52   // When specified by the caller (for JS-created events), don't mess with the
  53   // delta mode.
  54   wheelEvent->mDeltaModeCheckingState =
  55       WidgetWheelEvent::DeltaModeCheckingState::Checked;
  56   wheelEvent->mDeltaX = aDeltaX;
  57   wheelEvent->mDeltaY = aDeltaY;
  58   wheelEvent->mDeltaZ = aDeltaZ;
  59   wheelEvent->mDeltaMode = aDeltaMode;
  60   wheelEvent->mAllowToOverrideSystemScrollSpeed = false;
  61 }
  62
  63 int32_t WheelEvent::WheelDeltaX(CallerType aCallerType) {
  64   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
  65   if (ev->mWheelTicksX != 0.0) {
  66     return int32_t(-ev->mWheelTicksX * kNativeTicksToWheelDelta);
  67   }
  68   if (IsTrusted()) {
  69     // We always return pixels regardless of the checking-state.
  70     double pixelDelta =
  71         ev->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL
  72             ? DevToCssPixels(ev->OverriddenDeltaX())
  73             : ev->OverriddenDeltaX() *
  74                   CSSPixel::FromAppUnits(ev->mScrollAmount.width).Rounded();
  75     return int32_t(-std::round(pixelDelta * kTrustedDeltaToWheelDelta));
  76   }
  77   return int32_t(-std::round(DeltaX(aCallerType)));  // This matches Safari.
  78 }
  79
  80 int32_t WheelEvent::WheelDeltaY(CallerType aCallerType) {
  81   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
  82   if (ev->mWheelTicksY != 0.0) {
  83     return int32_t(-ev->mWheelTicksY * kNativeTicksToWheelDelta);
  84   }
  85
  86   if (IsTrusted()) {
  87     double pixelDelta =
  88         ev->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL
  89             ? DevToCssPixels(ev->OverriddenDeltaY())
  90             : ev->OverriddenDeltaY() *
  91                   CSSPixel::FromAppUnits(ev->mScrollAmount.height).Rounded();
  92     return int32_t(-std::round(pixelDelta * kTrustedDeltaToWheelDelta));
  93   }
  94   return int32_t(-std::round(DeltaY(aCallerType)));  // This matches Safari.
  95 }
  96
  97 double WheelEvent::ToWebExposedDelta(WidgetWheelEvent& aWidgetEvent,
  98                                      double aDelta, nscoord aLineOrPageAmount,
  99                                      CallerType aCallerType) {
 100   using DeltaModeCheckingState = WidgetWheelEvent::DeltaModeCheckingState;
 101   if (aCallerType != CallerType::System) {
 102     if (aWidgetEvent.mDeltaModeCheckingState ==
 103         DeltaModeCheckingState::Unknown) {
 104       aWidgetEvent.mDeltaModeCheckingState = DeltaModeCheckingState::Unchecked;
 105     }
 106     if (aWidgetEvent.mDeltaModeCheckingState ==
 107             DeltaModeCheckingState::Unchecked &&
 108         aWidgetEvent.mDeltaMode == WheelEvent_Binding::DOM_DELTA_LINE) {
 109       return aDelta * CSSPixel::FromAppUnits(aLineOrPageAmount).Rounded();
 110     }
 111   }
 112   return DevToCssPixels(aDelta);
 113 }
 114
 115 double WheelEvent::DeltaX(CallerType aCallerType) {
 116   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 117   return ToWebExposedDelta(*ev, ev->OverriddenDeltaX(), ev->mScrollAmount.width,
 118                            aCallerType);
 119 }
 120
 121 double WheelEvent::DeltaY(CallerType aCallerType) {
 122   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 123   return ToWebExposedDelta(*ev, ev->OverriddenDeltaY(),
 124                            ev->mScrollAmount.height, aCallerType);
 125 }
 126
 127 double WheelEvent::DeltaZ(CallerType aCallerType) {
 128   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 129   // XXX Unclear what scroll amount we should use for deltaZ...
 130   auto amount = std::max(ev->mScrollAmount.width, ev->mScrollAmount.height);
 131   return ToWebExposedDelta(*ev, ev->mDeltaZ, amount, aCallerType);
 132 }
 133
 134 uint32_t WheelEvent::DeltaMode(CallerType aCallerType) {
 135   using DeltaModeCheckingState = WidgetWheelEvent::DeltaModeCheckingState;
 136
 137   WidgetWheelEvent* ev = mEvent->AsWheelEvent();
 138   uint32_t mode = ev->mDeltaMode;
 139   if (aCallerType != CallerType::System) {
 140     if (ev->mDeltaModeCheckingState == DeltaModeCheckingState::Unknown) {
 141       ev->mDeltaModeCheckingState = DeltaModeCheckingState::Checked;
 142     } else if (ev->mDeltaModeCheckingState ==
 143                    DeltaModeCheckingState::Unchecked &&
 144                mode == WheelEvent_Binding::DOM_DELTA_LINE) {
 145       return WheelEvent_Binding::DOM_DELTA_PIXEL;
 146     }
 147   }
 148
 149   return mode;
 150 }
 151
 152 already_AddRefed<WheelEvent> WheelEvent::Constructor(
 153     const GlobalObject& aGlobal, const nsAString& aType,
 154     const WheelEventInit& aParam) {
 155   nsCOMPtr<EventTarget> t = do_QueryInterface(aGlobal.GetAsSupports());
 156   RefPtr<WheelEvent> e = new WheelEvent(t, nullptr, nullptr);
 157   bool trusted = e->Init(t);
 158   e->InitWheelEvent(aType, aParam.mBubbles, aParam.mCancelable, aParam.mView,
 159                     aParam.mDetail, aParam.mScreenX, aParam.mScreenY,
 160                     aParam.mClientX, aParam.mClientY, aParam.mButton,
 161                     aParam.mRelatedTarget, u""_ns, aParam.mDeltaX,
 162                     aParam.mDeltaY, aParam.mDeltaZ, aParam.mDeltaMode);
 163   e->InitializeExtraMouseEventDictionaryMembers(aParam);
 164   e->SetTrusted(trusted);
 165   e->SetComposed(aParam.mComposed);
 166   return e.forget();
 167 }
 168
 169 }  // namespace mozilla::dom
 170
 171 using namespace mozilla;
 172 using namespace mozilla::dom;
 173
 174 already_AddRefed<WheelEvent> NS_NewDOMWheelEvent(EventTarget* aOwner,
 175                                                  nsPresContext* aPresContext,
 176                                                  WidgetWheelEvent* aEvent) {
 177   RefPtr<WheelEvent> it = new WheelEvent(aOwner, aPresContext, aEvent);
 178   return it.forget();
 179 }