1 files changed, 140 insertions, 0 deletions
diff --git a/dom/events/WheelEvent.cpp b/dom/events/WheelEvent.cpp
new file mode 100644
index 0000000000..01aeb5a2f5
--- /dev/null
+++ b/dom/events/WheelEvent.cpp
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/dom/WheelEvent.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "prtime.h"
+
+namespace mozilla::dom {
+
+WheelEvent::WheelEvent(EventTarget* aOwner, nsPresContext* aPresContext,
+                       WidgetWheelEvent* aWheelEvent)
+    : MouseEvent(aOwner, aPresContext,
+                 aWheelEvent
+                     ? aWheelEvent
+                     : new WidgetWheelEvent(false, eVoidEvent, nullptr)),
+      mAppUnitsPerDevPixel(0) {
+  if (StaticPrefs::dom_event_wheel_deltaMode_lines_always_disabled()) {
+    mDeltaModeCheckingState = DeltaModeCheckingState::Unchecked;
+  }
+
+  if (aWheelEvent) {
+    mEventIsInternal = false;
+    // If the delta mode is pixel, the WidgetWheelEvent's delta values are in
+    // device pixels.  However, JS contents need the delta values in CSS pixels.
+    // We should store the value of mAppUnitsPerDevPixel here because
+    // it might be changed by changing zoom or something.
+    if (aWheelEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL) {
+      mAppUnitsPerDevPixel = aPresContext->AppUnitsPerDevPixel();
+    }
+  } else {
+    mEventIsInternal = true;
+    mEvent->mTime = PR_Now();
+    mEvent->mRefPoint = LayoutDeviceIntPoint(0, 0);
+    mEvent->AsWheelEvent()->mInputSource =
+        MouseEvent_Binding::MOZ_SOURCE_UNKNOWN;
+  }
+}
+
+void WheelEvent::InitWheelEvent(
+    const nsAString& aType, bool aCanBubble, bool aCancelable,
+    nsGlobalWindowInner* aView, int32_t aDetail, int32_t aScreenX,
+    int32_t aScreenY, int32_t aClientX, int32_t aClientY, uint16_t aButton,
+    EventTarget* aRelatedTarget, const nsAString& aModifiersList,
+    double aDeltaX, double aDeltaY, double aDeltaZ, uint32_t aDeltaMode) {
+  NS_ENSURE_TRUE_VOID(!mEvent->mFlags.mIsBeingDispatched);
+
+  MouseEvent::InitMouseEvent(aType, aCanBubble, aCancelable, aView, aDetail,
+                             aScreenX, aScreenY, aClientX, aClientY, aButton,
+                             aRelatedTarget, aModifiersList);
+
+  WidgetWheelEvent* wheelEvent = mEvent->AsWheelEvent();
+  wheelEvent->mDeltaX = aDeltaX;
+  wheelEvent->mDeltaY = aDeltaY;
+  wheelEvent->mDeltaZ = aDeltaZ;
+  wheelEvent->mDeltaMode = aDeltaMode;
+}
+
+double WheelEvent::ToWebExposedDelta(const WidgetWheelEvent& aWidgetEvent,
+                                     double aDelta, CallerType aCallerType) {
+  if (aCallerType != CallerType::System) {
+    if (mDeltaModeCheckingState == DeltaModeCheckingState::Unknown) {
+      mDeltaModeCheckingState = DeltaModeCheckingState::Unchecked;
+    }
+    if (mDeltaModeCheckingState == DeltaModeCheckingState::Unchecked &&
+        aWidgetEvent.mDeltaMode == WheelEvent_Binding::DOM_DELTA_LINE &&
+        StaticPrefs::dom_event_wheel_deltaMode_lines_disabled()) {
+      // TODO(emilio, bug 1675949): Consider not using a fixed multiplier here?
+      return aDelta *
+             StaticPrefs::dom_event_wheel_deltaMode_lines_to_pixel_scale();
+    }
+  }
+  if (!mAppUnitsPerDevPixel) {
+    return aDelta;
+  }
+  return aDelta * mAppUnitsPerDevPixel / AppUnitsPerCSSPixel();
+}
+
+double WheelEvent::DeltaX(CallerType aCallerType) {
+  WidgetWheelEvent* ev = mEvent->AsWheelEvent();
+  return ToWebExposedDelta(*ev, ev->mDeltaX, aCallerType);
+}
+
+double WheelEvent::DeltaY(CallerType aCallerType) {
+  WidgetWheelEvent* ev = mEvent->AsWheelEvent();
+  return ToWebExposedDelta(*ev, ev->mDeltaY, aCallerType);
+}
+
+double WheelEvent::DeltaZ(CallerType aCallerType) {
+  WidgetWheelEvent* ev = mEvent->AsWheelEvent();
+  return ToWebExposedDelta(*ev, ev->mDeltaZ, aCallerType);
+}
+
+uint32_t WheelEvent::DeltaMode(CallerType aCallerType) {
+  uint32_t mode = mEvent->AsWheelEvent()->mDeltaMode;
+  if (aCallerType != CallerType::System) {
+    if (mDeltaModeCheckingState == DeltaModeCheckingState::Unknown) {
+      mDeltaModeCheckingState = DeltaModeCheckingState::Checked;
+    } else if (mDeltaModeCheckingState == DeltaModeCheckingState::Unchecked &&
+               mode == WheelEvent_Binding::DOM_DELTA_LINE &&
+               StaticPrefs::dom_event_wheel_deltaMode_lines_disabled()) {
+      return WheelEvent_Binding::DOM_DELTA_PIXEL;
+    }
+  }
+
+  return mode;
+}
+
+already_AddRefed<WheelEvent> WheelEvent::Constructor(
+    const GlobalObject& aGlobal, const nsAString& aType,
+    const WheelEventInit& aParam) {
+  nsCOMPtr<EventTarget> t = do_QueryInterface(aGlobal.GetAsSupports());
+  RefPtr<WheelEvent> e = new WheelEvent(t, nullptr, nullptr);
+  bool trusted = e->Init(t);
+  e->InitWheelEvent(aType, aParam.mBubbles, aParam.mCancelable, aParam.mView,
+                    aParam.mDetail, aParam.mScreenX, aParam.mScreenY,
+                    aParam.mClientX, aParam.mClientY, aParam.mButton,
+                    aParam.mRelatedTarget, u""_ns, aParam.mDeltaX,
+                    aParam.mDeltaY, aParam.mDeltaZ, aParam.mDeltaMode);
+  e->InitializeExtraMouseEventDictionaryMembers(aParam);
+  e->SetTrusted(trusted);
+  e->SetComposed(aParam.mComposed);
+  return e.forget();
+}
+
+}  // namespace mozilla::dom
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+already_AddRefed<WheelEvent> NS_NewDOMWheelEvent(EventTarget* aOwner,
+                                                 nsPresContext* aPresContext,
+                                                 WidgetWheelEvent* aEvent) {
+  RefPtr<WheelEvent> it = new WheelEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
+}