OverscrollGlow for mainThread-{BLINK CHANGES}

Source/core/frame/LocalFrame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 696 matching lines @@
 bool LocalFrame::shouldReuseDefaultView(const KURL& url) const
 {
     return loader().stateMachine()->isDisplayingInitialEmptyDocument() && document()->isSecureTransitionTo(url);
 }
 
 void LocalFrame::removeSpellingMarkersUnderWords(const Vector<String>& words)
 {
     spellChecker().removeSpellingMarkersUnderWords(words);
 }
 
-static bool scrollAreaOnBothAxes(const FloatSize& delta, ScrollableArea& view)
+static ScrollResult scrollAreaOnBothAxes(const FloatSize& delta, ScrollableArea& view)
 {
-    bool scrolledHorizontal = view.scroll(ScrollLeft, ScrollByPrecisePixel, delta.width());
-    bool scrolledVertical = view.scroll(ScrollUp, ScrollByPrecisePixel, delta.height());
-    return scrolledHorizontal || scrolledVertical;
+    ScrollResultOneDimensional horizontal = view.scroll(ScrollLeft, ScrollByPrecisePixel, delta.width());
+    ScrollResultOneDimensional vertical = view.scroll(ScrollUp, ScrollByPrecisePixel, delta.height());
+    return ScrollResult(horizontal.didScroll, vertical.didScroll, horizontal.unusedScrollDelta, vertical.unusedScrollDelta);
 }
 
-// Returns true if a scroll occurred.
-bool LocalFrame::applyScrollDelta(const FloatSize& delta, bool isScrollBegin)
+ScrollResult LocalFrame::applyScrollDelta(const FloatSize& delta, bool isScrollBegin)
 {
     if (isScrollBegin)
         host()->topControls().scrollBegin();
 
     if (!view() || delta.isZero())
-        return false;
+        return ScrollResult(false, false, delta.width(), delta.height());
 
     FloatSize remainingDelta = delta;
 
     // If this is main frame, allow top controls to scroll first.
     if (shouldScrollTopControls(delta))
         remainingDelta = host()->topControls().scrollBy(remainingDelta);
 
     if (remainingDelta.isZero())
-        return true;
+        return ScrollResult(delta.width(), delta.height(), 0.0f, 0.0f);

[MuVen, 2015/06/02 09:04:00]

Even this returns didScrollX, didScrollY. ple let me know your input.

[majidvp, 2015/06/02 17:00:31]

This looks reasonable.

[MuVen, 2015/06/03 09:32:18]

Done.

 
-    bool consumed = remainingDelta != delta;
+    ScrollResult result = scrollAreaOnBothAxes(remainingDelta, *view()->scrollableArea());
 
-    if (scrollAreaOnBothAxes(remainingDelta, *view()->scrollableArea()))
-        return true;
+    if (result.didScroll())
+        return result;

[majidvp, 2015/06/02 17:00:31]

I believe this is no longer correct. Consider this situation where the top
control consumes vertical scroll and the view consumes horizontal scroll. The
final result should have didScroll true for both orientation which is not the
case with this logic.

You can get rid of this conditional and instead use the two computations below.

[MuVen, 2015/06/03 09:32:18]

Done.

 
-    return consumed;
+    result.didScrollX = remainingDelta.width() != delta.width();
+    result.didScrollY = remainingDelta.height() != delta.height();

[majidvp, 2015/06/02 17:00:31]

If you get rid of the conditional above and replace these with

result.didScrollX = result.didScrollX || (remainingDelta.width() !=
delta.width())
...

[MuVen, 2015/06/03 09:32:18]

Done.

+    return result;
 }
 
 bool LocalFrame::shouldScrollTopControls(const FloatSize& delta) const
 {
     if (!isMainFrame())
         return false;
 
     // Always give the delta to the top controls if the scroll is in
     // the direction to show the top controls. If it's in the
     // direction to hide the top controls, only give the delta to the
@@ skipping 55 matching lines @@
     , m_textZoomFactor(parentTextZoomFactor(this))
     , m_inViewSourceMode(false)
 {
     if (isLocalRoot())
         m_instrumentingAgents = InstrumentingAgents::create();
     else
         m_instrumentingAgents = localFrameRoot()->m_instrumentingAgents;
 }
 
 } // namespace blink