From 0c402339141d098931744e866689cd277f50f094 Mon Sep 17 00:00:00 2001
From: Kartikaya Gupta <kgupta@mozilla.com>
Date: Thu, 7 Jan 2016 10:39:37 -0500
Subject: [PATCH] Bug 1235994 - Add a flag to wheel events to track if they may
 have momentum following them. r=mstange

--HG--
extra : commitid : EAEUoOFxeOj
---
 widget/InputData.cpp   | 3 +++
 widget/InputData.h     | 2 ++
 widget/MouseEvents.h   | 4 ++++
 widget/nsGUIEventIPC.h | 2 ++
 4 files changed, 11 insertions(+)

diff --git a/widget/InputData.cpp b/widget/InputData.cpp
index 86726e6f9eb3..273c796c77ca 100644
--- a/widget/InputData.cpp
+++ b/widget/InputData.cpp
@@ -307,6 +307,7 @@ PanGestureInput::ToWidgetWheelEvent(nsIWidget* aWidget) const
       PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent));
   wheelEvent.buttons = 0;
   wheelEvent.deltaMode = nsIDOMWheelEvent::DOM_DELTA_PIXEL;
+  wheelEvent.mayHaveMomentum = true; // pan inputs may have momentum
   wheelEvent.isMomentum = IsMomentum();
   wheelEvent.lineOrPageDeltaX = mLineOrPageDeltaX;
   wheelEvent.lineOrPageDeltaY = mLineOrPageDeltaY;
@@ -380,6 +381,7 @@ ScrollWheelInput::ScrollWheelInput(const WidgetWheelEvent& aWheelEvent) :
   mLineOrPageDeltaY(aWheelEvent.lineOrPageDeltaY),
   mUserDeltaMultiplierX(1.0),
   mUserDeltaMultiplierY(1.0),
+  mMayHaveMomentum(aWheelEvent.mayHaveMomentum),
   mIsMomentum(aWheelEvent.isMomentum)
 {
   mOrigin =
@@ -399,6 +401,7 @@ ScrollWheelInput::ToWidgetWheelEvent(nsIWidget* aWidget) const
       PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent));
   wheelEvent.buttons = 0;
   wheelEvent.deltaMode = DeltaModeForDeltaType(mDeltaType);
+  wheelEvent.mayHaveMomentum = mMayHaveMomentum;
   wheelEvent.isMomentum = mIsMomentum;
   wheelEvent.deltaX = mDeltaX;
   wheelEvent.deltaY = mDeltaY;
diff --git a/widget/InputData.h b/widget/InputData.h
index cb9530e98e11..a6191bd764a5 100644
--- a/widget/InputData.h
+++ b/widget/InputData.h
@@ -585,6 +585,7 @@ public:
      mScrollSeriesNumber(0),
      mUserDeltaMultiplierX(1.0),
      mUserDeltaMultiplierY(1.0),
+     mMayHaveMomentum(false),
      mIsMomentum(false)
   {}
 
@@ -628,6 +629,7 @@ public:
   double mUserDeltaMultiplierX;
   double mUserDeltaMultiplierY;
 
+  bool mMayHaveMomentum;
   bool mIsMomentum;
 };
 
diff --git a/widget/MouseEvents.h b/widget/MouseEvents.h
index f4056c67010b..3c123f140b66 100644
--- a/widget/MouseEvents.h
+++ b/widget/MouseEvents.h
@@ -449,6 +449,7 @@ public:
     , deltaZ(0.0)
     , deltaMode(nsIDOMWheelEvent::DOM_DELTA_PIXEL)
     , customizedByUserPrefs(false)
+    , mayHaveMomentum(false)
     , isMomentum(false)
     , mIsNoLineOrPageDelta(false)
     , lineOrPageDeltaX(0)
@@ -499,6 +500,8 @@ public:
   // Otherwise, i.e., they are computed from native events, false.
   bool customizedByUserPrefs;
 
+  // true if the momentum events directly tied to this event may follow it.
+  bool mayHaveMomentum;
   // true if the event is caused by momentum.
   bool isMomentum;
 
@@ -579,6 +582,7 @@ public:
     deltaZ = aEvent.deltaZ;
     deltaMode = aEvent.deltaMode;
     customizedByUserPrefs = aEvent.customizedByUserPrefs;
+    mayHaveMomentum = aEvent.mayHaveMomentum;
     isMomentum = aEvent.isMomentum;
     mIsNoLineOrPageDelta = aEvent.mIsNoLineOrPageDelta;
     lineOrPageDeltaX = aEvent.lineOrPageDeltaX;
diff --git a/widget/nsGUIEventIPC.h b/widget/nsGUIEventIPC.h
index 3662eefeecc8..424b94017872 100644
--- a/widget/nsGUIEventIPC.h
+++ b/widget/nsGUIEventIPC.h
@@ -165,6 +165,7 @@ struct ParamTraits<mozilla::WidgetWheelEvent>
     WriteParam(aMsg, aParam.deltaZ);
     WriteParam(aMsg, aParam.deltaMode);
     WriteParam(aMsg, aParam.customizedByUserPrefs);
+    WriteParam(aMsg, aParam.mayHaveMomentum);
     WriteParam(aMsg, aParam.isMomentum);
     WriteParam(aMsg, aParam.mIsNoLineOrPageDelta);
     WriteParam(aMsg, aParam.lineOrPageDeltaX);
@@ -187,6 +188,7 @@ struct ParamTraits<mozilla::WidgetWheelEvent>
       ReadParam(aMsg, aIter, &aResult->deltaZ) &&
       ReadParam(aMsg, aIter, &aResult->deltaMode) &&
       ReadParam(aMsg, aIter, &aResult->customizedByUserPrefs) &&
+      ReadParam(aMsg, aIter, &aResult->mayHaveMomentum) &&
       ReadParam(aMsg, aIter, &aResult->isMomentum) &&
       ReadParam(aMsg, aIter, &aResult->mIsNoLineOrPageDelta) &&
       ReadParam(aMsg, aIter, &aResult->lineOrPageDeltaX) &&