OverscrollGlow for mainThread-{BLINK CHANGES}

Source/platform/scroll/ScrollAnimator.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 36 matching lines @@
 }
 
 ScrollAnimator::~ScrollAnimator()
 {
 }
 
 ScrollResultOneDimensional ScrollAnimator::scroll(ScrollbarOrientation orientation, ScrollGranularity, float step, float delta)
 {
     float& currentPos = (orientation == HorizontalScrollbar) ? m_currentPosX : m_currentPosY;
     float newPos = clampScrollPosition(orientation, currentPos + step * delta);
+
     if (currentPos == newPos)
-        return ScrollResultOneDimensional(false);
+        return ScrollResultOneDimensional(false, delta);
 
     float usedDelta = (newPos - currentPos) / step;
     currentPos = newPos;
 
     notifyPositionChanged();
 
     return ScrollResultOneDimensional(true, delta - usedDelta);
 }
 
 void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
 {
     m_currentPosX = offset.x();
     m_currentPosY = offset.y();
     notifyPositionChanged();
 }
 
 ScrollResult ScrollAnimator::handleWheelEvent(const PlatformWheelEvent& e)
 {
     bool canScrollX = m_scrollableArea->userInputScrollable(HorizontalScrollbar)
         && e.railsMode() != PlatformEvent::RailsModeVertical;
     bool canScrollY = m_scrollableArea->userInputScrollable(VerticalScrollbar)
         && e.railsMode() != PlatformEvent::RailsModeHorizontal;
 
     // Accept the event if we are scrollable in that direction and can still
     // scroll any further.
     float deltaX = canScrollX ? e.deltaX() : 0;
     float deltaY = canScrollY ? e.deltaY() : 0;
 
-    ScrollResult result(false);
+    ScrollResult result;
 
 #if !OS(MACOSX)
     ScrollGranularity granularity = e.hasPreciseScrollingDeltas() ? ScrollByPrecisePixel : ScrollByPixel;
 #else
     ScrollGranularity granularity = ScrollByPixel;
 #endif
 
     IntSize maxForwardScrollDelta = m_scrollableArea->maximumScrollPosition() - m_scrollableArea->scrollPosition();
     IntSize maxBackwardScrollDelta = m_scrollableArea->scrollPosition() - m_scrollableArea->minimumScrollPosition();
     if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
-        || (deltaX > 0 && maxBackwardScrollDelta.width() > 0)
-        || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
-        || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
-        result.didScroll = true;
-
+        || (deltaX > 0 && maxBackwardScrollDelta.width() > 0))
+        result.didScrollX = true;
+    if ((deltaY < 0 && maxForwardScrollDelta.height() > 0)
+        || (deltaY > 0 && maxBackwardScrollDelta.height() > 0))
+        result.didScrollY = true;
+    if (result.didScroll()) {
         if (deltaY) {
             if (e.granularity() == ScrollByPageWheelEvent) {
                 bool negative = deltaY < 0;
                 deltaY = m_scrollableArea->pageStep(VerticalScrollbar);
                 if (negative)
                     deltaY = -deltaY;
             }
 
             ScrollResultOneDimensional resultY = scroll(
                 VerticalScrollbar, granularity, m_scrollableArea->pixelStep(VerticalScrollbar), -deltaY);
@@ skipping 49 matching lines @@
 }
 
 float ScrollAnimator::clampScrollPosition(ScrollbarOrientation orientation, float pos)
 {
     float maxScrollPos = m_scrollableArea->maximumScrollPosition(orientation);
     float minScrollPos = m_scrollableArea->minimumScrollPosition(orientation);
     return std::max(std::min(pos, maxScrollPos), minScrollPos);
 }
 
 } // namespace blink