Merge 84422

Source/WebCore/platform/graphics/filters/FilterEffect.cpp

 /*
  * Copyright (C) 2008 Alex Mathews <possessedpenguinbob@gmail.com>
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) Research In Motion Limited 2010. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 100 matching lines @@
 
 PassRefPtr<ByteArray> FilterEffect::asPremultipliedImage(const IntRect& rect)
 {
     RefPtr<ByteArray> imageData = ByteArray::create(rect.width() * rect.height() * 4);
     copyPremultipliedImage(imageData.get(), rect);
     return imageData.release();
 }
 
 inline void FilterEffect::copyImageBytes(ByteArray* source, ByteArray* destination, const IntRect& rect)
 {
-    // Copy the necessary lines.
-    if (rect.x() < 0 || rect.y() < 0 || rect.maxY() > m_absolutePaintRect.width() || rect.maxY() > m_absolutePaintRect.height())
+    // Initialize the destination to transparent black, if not entirely covered by the source.
+    if (rect.x() < 0 || rect.y() < 0 || rect.maxX() > m_absolutePaintRect.width() || rect.maxY() > m_absolutePaintRect.height())
         memset(destination->data(), 0, destination->length());
 
+    // Early return if the rect does not intersect with the source.
+    if (rect.maxX() <= 0 || rect.maxY() <= 0 || rect.x() >= m_absolutePaintRect.width() || rect.y() >= m_absolutePaintRect.height())
+        return;
+
     int xOrigin = rect.x();
     int xDest = 0;
     if (xOrigin < 0) {
         xDest = -xOrigin;
         xOrigin = 0;
     }
     int xEnd = rect.maxX();
     if (xEnd > m_absolutePaintRect.width())
         xEnd = m_absolutePaintRect.width();
 
@@ skipping 120 matching lines @@
 TextStream& FilterEffect::externalRepresentation(TextStream& ts, int) const
 {
     // FIXME: We should dump the subRegions of the filter primitives here later. This isn't
     // possible at the moment, because we need more detailed informations from the target object.
     return ts;
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(FILTERS)