OverscrollGlow for mainThread-{BLINK CHANGES}

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index f5667d003a275407cf9304ebd526e82dc658e6d1..5dfe1d6e1504e37912e8f51b63bebfad83c29875 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -299,6 +299,8 @@ void EventHandler::clear()
     m_dragTarget = nullptr;
     m_shouldOnlyFireDragOverEvent = false;
     m_mousePositionIsUnknown = true;
+    m_unusedDelta = IntPoint();
+    m_accumulatedRootOverscroll = IntPoint();
     m_lastKnownMousePosition = IntPoint();
     m_lastKnownMouseGlobalPosition = IntPoint();
     m_lastMouseDownUserGestureToken.clear();
@@ -926,7 +928,7 @@ void EventHandler::stopAutoscroll()
         controller->stopAutoscroll();
 }
 
-bool EventHandler::scroll(ScrollDirection direction, ScrollGranularity granularity, Node* startNode, Node** stopNode, float delta, IntPoint absolutePoint)
+bool EventHandler::scroll(ScrollDirection direction, ScrollGranularity granularity, Node* startNode, Node** stopNode, float delta, IntPoint absolutePoint, int* unusedDelta)
 {
     if (!delta)
         return false;
@@ -951,6 +953,11 @@ bool EventHandler::scroll(ScrollDirection direction, ScrollGranularity granulari
         // If we're at the stopNode, we should try to scroll it but we shouldn't bubble past it
         bool shouldStopBubbling = stopNode && *stopNode && curBox->node() == *stopNode;
         bool didScroll = curBox->scroll(physicalDirection, granularity, delta);
+        IntPoint cbUnusedDelta = curBox->unUsedDelta();
+        if (direction == ScrollUp)
+            *unusedDelta = cbUnusedDelta.y();
+        else if (direction == ScrollLeft)
+            *unusedDelta = cbUnusedDelta.x();

[majidvp, 2015/04/23 18:25:08]

Overscroll should happen only if the document's main frame is scrolled and has
any scroll delta remaining. This logic overscrolls for all scrolling elements
which is not correct.

Also, this only covers the case where root layer scrolls. See my other comments
the other two cases where frame view maybe scrolled and thus generate unused
scroll delta.

[MuVen, 2015/04/27 12:53:46]

if (m_frame->isMainFrame()) condition will accumulate delta only on mainframe.
Share your inputs.

 
         if (didScroll && stopNode)
             *stopNode = curBox->node();
@@ -996,6 +1003,21 @@ bool EventHandler::bubblingScroll(ScrollDirection direction, ScrollGranularity g
     return toLocalFrame(parentFrame)->eventHandler().bubblingScroll(direction, granularity, m_frame->deprecatedLocalOwner());
 }
 
+IntPoint EventHandler::unusedDelta() const
+{
+    return m_unusedDelta;
+}
+
+IntPoint EventHandler::accumaltedRootOverScroll() const
+{
+    return m_accumulatedRootOverscroll;
+}
+
+void EventHandler::resetOverScrollParams()
+{
+    m_unusedDelta = m_accumulatedRootOverscroll = IntPoint();

[majidvp, 2015/04/23 18:25:08]

Scroll deltas should use |FloatSize| and not |IntPoint|

[MuVen, 2015/04/27 12:53:46]

Done.

+}
+
 IntPoint EventHandler::lastKnownMousePosition() const
 {
     return m_lastKnownMousePosition;
@@ -2366,7 +2388,6 @@ bool EventHandler::handleGestureScrollEvent(const PlatformGestureEvent& gestureE
         if (eventSwallowed)
             return true;
     }
-
     switch (gestureEvent.type()) {
     case PlatformEvent::GestureScrollBegin:
         return handleGestureScrollBegin(gestureEvent);
@@ -2611,6 +2632,7 @@ bool EventHandler::handleGestureScrollEnd(const PlatformGestureEvent& gestureEve
     }
 
     clearGestureScrollNodes();
+    resetOverScrollParams();
     return false;
 }
 
@@ -2636,7 +2658,6 @@ bool EventHandler::handleGestureScrollBegin(const PlatformGestureEvent& gestureE
             return false;
     }
     ASSERT(m_scrollGestureHandlingNode);
-
     passScrollGestureEventToWidget(gestureEvent, m_scrollGestureHandlingNode->layoutObject());
     if (RuntimeEnabledFeatures::scrollCustomizationEnabled()) {
         m_currentScrollChain.clear();
@@ -2648,6 +2669,8 @@ bool EventHandler::handleGestureScrollBegin(const PlatformGestureEvent& gestureE
         if (m_frame->isMainFrame())
             m_frame->host()->topControls().scrollBegin();
     }
+
+    resetOverScrollParams();
     return true;
 }
 
@@ -2709,13 +2732,17 @@ bool EventHandler::handleGestureScrollUpdate(const PlatformGestureEvent& gesture
                 stopNode = m_previousGestureScrolledNode.get();
 
             // First try to scroll the closest scrollable LayoutBox ancestor of |node|.
+            int uDelta;
+            m_unusedDelta = IntPoint();
             ScrollGranularity granularity = ScrollByPrecisePixel;
-            bool horizontalScroll = scroll(ScrollLeft, granularity, node, &stopNode, delta.width());
+            bool horizontalScroll = scroll(ScrollLeft, granularity, node, &stopNode, delta.width(), IntPoint(), &uDelta);
+            m_unusedDelta.setX(uDelta);
             if (!gestureEvent.preventPropagation())
                 stopNode = nullptr;
-            bool verticalScroll = scroll(ScrollUp, granularity, node, &stopNode, delta.height());
+            bool verticalScroll = scroll(ScrollUp, granularity, node, &stopNode, delta.height(), IntPoint(), &uDelta);
+            m_unusedDelta.setY(uDelta);
             scrolled = horizontalScroll || verticalScroll;
-
+            m_accumulatedRootOverscroll = m_accumulatedRootOverscroll + m_unusedDelta;
             if (gestureEvent.preventPropagation())
                 m_previousGestureScrolledNode = stopNode;
         }