1 files changed, 46 insertions, 0 deletions
diff --git a/dom/ipc/CoalescedWheelData.cpp b/dom/ipc/CoalescedWheelData.cpp
new file mode 100644
index 0000000000..c8e23ac86d
--- /dev/null
+++ b/dom/ipc/CoalescedWheelData.cpp
@@ -0,0 +1,46 @@
+/* -*- 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 "base/basictypes.h"
+
+#include "CoalescedWheelData.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+void CoalescedWheelData::Coalesce(const WidgetWheelEvent& aEvent,
+                                  const ScrollableLayerGuid& aGuid,
+                                  const uint64_t& aInputBlockId) {
+  if (IsEmpty()) {
+    mCoalescedInputEvent = MakeUnique<WidgetWheelEvent>(aEvent);
+    mGuid = aGuid;
+    mInputBlockId = aInputBlockId;
+  } else {
+    MOZ_ASSERT(mGuid == aGuid);
+    MOZ_ASSERT(mInputBlockId == aInputBlockId);
+    MOZ_ASSERT(mCoalescedInputEvent->mModifiers == aEvent.mModifiers);
+    MOZ_ASSERT(mCoalescedInputEvent->mDeltaMode == aEvent.mDeltaMode);
+    MOZ_ASSERT(mCoalescedInputEvent->mCanTriggerSwipe ==
+               aEvent.mCanTriggerSwipe);
+    mCoalescedInputEvent->mDeltaX += aEvent.mDeltaX;
+    mCoalescedInputEvent->mDeltaY += aEvent.mDeltaY;
+    mCoalescedInputEvent->mDeltaZ += aEvent.mDeltaZ;
+    mCoalescedInputEvent->mLineOrPageDeltaX += aEvent.mLineOrPageDeltaX;
+    mCoalescedInputEvent->mLineOrPageDeltaY += aEvent.mLineOrPageDeltaY;
+    mCoalescedInputEvent->mTimeStamp = aEvent.mTimeStamp;
+  }
+}
+
+bool CoalescedWheelData::CanCoalesce(const WidgetWheelEvent& aEvent,
+                                     const ScrollableLayerGuid& aGuid,
+                                     const uint64_t& aInputBlockId) {
+  MOZ_ASSERT(!IsEmpty());
+  return !mCoalescedInputEvent ||
+         (mCoalescedInputEvent->mRefPoint == aEvent.mRefPoint &&
+          mCoalescedInputEvent->mModifiers == aEvent.mModifiers &&
+          mCoalescedInputEvent->mDeltaMode == aEvent.mDeltaMode &&
+          mCoalescedInputEvent->mCanTriggerSwipe == aEvent.mCanTriggerSwipe &&
+          mGuid == aGuid && mInputBlockId == aInputBlockId);
+}