Report accurate Overscroll on handleWheel.

Source/core/input/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 1764 matching lines @@
         if (node && !node->dispatchWheelEvent(event))
             RETURN_WHEEL_EVENT_HANDLED();
     }
 
     // We do another check on the frame view because the event handler can run
     // JS which results in the frame getting destroyed.
     view = m_frame->view();
     if (!view)
         return false;
 
-    if (view->scrollableArea()->handleWheel(event).didScroll())
+    ScrollResult scrollResult = view->scrollableArea()->handleWheel(event);
+    if (m_frame->settings() && m_frame->settings()->reportWheelOverscroll())
+        handleOverscroll(scrollResult);
+    if (scrollResult.didScroll())
         RETURN_WHEEL_EVENT_HANDLED();
 
     return false;
 #undef RETURN_WHEEL_EVENT_HANDLED
 }
 
 void EventHandler::defaultWheelEventHandler(Node* startNode, WheelEvent* wheelEvent)
 {
     if (!startNode || !wheelEvent)
         return;
@@ skipping 452 matching lines @@
 }
 
 void EventHandler::resetOverscroll(bool didScrollX, bool didScrollY)
 {
     if (didScrollX)
         m_accumulatedRootOverscroll.setWidth(0);
     if (didScrollY)
         m_accumulatedRootOverscroll.setHeight(0);
 }
 
-void EventHandler::handleOverscroll(const ScrollResult& scrollResult, const PlatformGestureEvent& gestureEvent)
+void EventHandler::handleOverscroll(const ScrollResult& scrollResult, const FloatPoint& position, const FloatSize& velocity)
 {
-    if (m_frame->isMainFrame() && m_frame->view() && m_frame->view()->scrollableArea()) {
-        ScrollableArea* scrollablearea = m_frame->view()->scrollableArea();
-        // Set unusedDelta if axis is scrollable, else set 0 to ensure overflow is not reported on non-scrollable axes.
-        FloatSize unusedDelta(scrollablearea->scrollSize(HorizontalScrollbar) ? scrollResult.unusedScrollDeltaX : 0, scrollablearea->scrollSize(VerticalScrollbar) ? scrollResult.unusedScrollDeltaY : 0);
-        resetOverscroll(scrollResult.didScrollX, scrollResult.didScrollY);
-        if (unusedDelta != FloatSize()) {
-            m_accumulatedRootOverscroll += unusedDelta;
-            FloatPoint position = FloatPoint(gestureEvent.position().x(), gestureEvent.position().y());
-            FloatSize velocity = FloatSize(gestureEvent.velocityX(), gestureEvent.velocityY());
-            m_frame->chromeClient().didOverscroll(unusedDelta, m_accumulatedRootOverscroll, position, velocity);
-        }
+    FloatSize unusedDelta(scrollResult.unusedScrollDeltaX, scrollResult.unusedScrollDeltaY);
+    resetOverscroll(scrollResult.didScrollX, scrollResult.didScrollY);
+    if (unusedDelta != FloatSize()) {
+        m_accumulatedRootOverscroll += unusedDelta;
+        m_frame->chromeClient().didOverscroll(unusedDelta, m_accumulatedRootOverscroll, position, velocity);
     }
 }
 
 bool EventHandler::handleGestureScrollUpdate(const PlatformGestureEvent& gestureEvent)
 {
     ASSERT(gestureEvent.type() == PlatformEvent::GestureScrollUpdate);
 
     FloatSize delta(gestureEvent.deltaX(), gestureEvent.deltaY());
     if (delta.isZero())
         return false;
@@ skipping 66 matching lines @@
             setFrameWasScrolledByUser();
             return true;
         }
     }
 
     if (RuntimeEnabledFeatures::scrollCustomizationEnabled())
         return false;
 
     // Try to scroll the frame view.
     ScrollResult scrollResult = m_frame->applyScrollDelta(delta, false);
-    handleOverscroll(scrollResult, gestureEvent);
+    FloatPoint position = FloatPoint(gestureEvent.position().x(), gestureEvent.position().y());
+    FloatSize velocity = FloatSize(gestureEvent.velocityX(), gestureEvent.velocityY());
+    if (m_frame->isMainFrame() && m_frame->view() && m_frame->view()->scrollableArea()) {
+        ScrollableArea* scrollablearea = m_frame->view()->scrollableArea();
+        // TODO(sataya.m) : In Case of android set unusedDelta to 0 to ensure overflow is not reported
+        // on non-scrollable axis. Move this check to CC to block OverscrollGlow Animation on non-scrollable axes.
+        scrollResult.unusedScrollDeltaX = scrollablearea->scrollSize(HorizontalScrollbar) ? scrollResult.unusedScrollDeltaX : 0;
+        scrollResult.unusedScrollDeltaY = scrollablearea->scrollSize(VerticalScrollbar) ? scrollResult.unusedScrollDeltaY : 0;
+    }
+    handleOverscroll(scrollResult, position, velocity);
     if (scrollResult.didScroll()) {
         setFrameWasScrolledByUser();
         return true;
     }
 
     return false;
 }
 
 void EventHandler::clearGestureScrollState()
 {
@@ skipping 1521 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink