Clear scrollbar damages in time

Source/core/rendering/RenderBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 1551 matching lines @@
     RenderObject::invalidateTreeIfNeeded(childTreeWalkState);
 }
 
 void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInvalidationState, const RenderLayerModelObject& newPaintInvalidationContainer)
 {
     const LayoutRect oldPaintInvalidationRect = previousPaintInvalidationRect();
     const LayoutPoint oldPositionFromPaintInvalidationContainer = previousPositionFromPaintInvalidationContainer();
     setPreviousPaintInvalidationRect(boundsRectForPaintInvalidation(&newPaintInvalidationContainer, &paintInvalidationState));
     setPreviousPositionFromPaintInvalidationContainer(RenderLayer::positionFromPaintInvalidationContainer(this, &newPaintInvalidationContainer, &paintInvalidationState));
 
+    // Issue paint invalidations for any scrollbars if there is a scrollable area for this renderer.
+    if (enclosingLayer()) {
+        if (RenderLayerScrollableArea* area = enclosingLayer()->scrollableArea()) {
+            if (!view()->doingFullRepaint()) {

[dsinclair, 2014/07/22 19:55:22]

This is really confusing. I wonder if the resetScrollbarDamage shouldn't
actually be happening inside the clearPaintInvalidationState() method instead of
being done in here.

Then this chunk would stay after the invalidatePaintINeeded call.

[Xianzhu, 2014/07/23 00:18:13]

Done.

+                if (area->hasVerticalBarDamage())
+                    invalidatePaintRectangle(area->verticalBarDamage());
+                if (area->hasHorizontalBarDamage())
+                    invalidatePaintRectangle(area->horizontalBarDamage());
+            }
+            area->resetScrollbarDamage();
+        }
+    }
+
     // If we are set to do a full paint invalidation that means the RenderView will be
     // issue paint invalidations. We can then skip issuing of paint invalidations for the child
     // renderers as they'll be covered by the RenderView.
     if (view()->doingFullRepaint())
         return;
 
     if ((onlyNeededPositionedMovementLayout() && compositingState() != PaintsIntoOwnBacking)
         || (shouldDoFullPaintInvalidationIfSelfPaintingLayer()
             && hasLayer()
             && layer()->isSelfPaintingLayer())) {
         setShouldDoFullPaintInvalidation(true);
     }
 
     if (!RenderObject::invalidatePaintIfNeeded(newPaintInvalidationContainer, oldPaintInvalidationRect, oldPositionFromPaintInvalidationContainer, paintInvalidationState))
         invalidatePaintForOverflowIfNeeded();
 
-    // Issue paint invalidations for any scrollbars if there is a scrollable area for this renderer.
-    if (enclosingLayer()) {
-        if (RenderLayerScrollableArea* area = enclosingLayer()->scrollableArea()) {
-            if (area->hasVerticalBarDamage())
-                invalidatePaintRectangle(area->verticalBarDamage());
-            if (area->hasHorizontalBarDamage())
-                invalidatePaintRectangle(area->horizontalBarDamage());
-            area->resetScrollbarDamage();
-        }
-    }
 }
 
 bool RenderBox::pushContentsClip(PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset, ContentsClipBehavior contentsClipBehavior)
 {
     if (paintInfo.phase == PaintPhaseBlockBackground || paintInfo.phase == PaintPhaseSelfOutline || paintInfo.phase == PaintPhaseMask)
         return false;
 
     bool isControlClip = hasControlClip();
     bool isOverflowClip = hasOverflowClip() && !layer()->isSelfPaintingLayer();
 
@@ skipping 3057 matching lines @@
 
         // We need the old border box size only when the box has background or box decorations.
         if (!style()->hasBackground() && !style()->hasBoxDecorations())
             return;
     }
 
     ensureRareData().m_previousBorderBoxSize = size();
 }
 
 } // namespace blink