[S.P.] Don't draw frames of animated images that are offscreen.

Source/core/paint/ImagePainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/ImagePainter.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/editing/FrameSelection.h"
@@ skipping 109 matching lines @@
     if (!m_layoutImage.imageResource()->hasImage() || m_layoutImage.imageResource()->errorOccurred())
         return; // FIXME: should we just ASSERT these conditions? (audit all callers).
 
     IntRect alignedRect = pixelSnappedIntRect(rect);
     if (alignedRect.width() <= 0 || alignedRect.height() <= 0)
         return;
 
     RefPtr<Image> image = m_layoutImage.imageResource()->image(alignedRect.width(), alignedRect.height());
     if (!image || image->isNull())
         return;
-
+    fprintf(stderr, "painting image\n");

[Xianzhu, 2015/03/19 22:14:22]

Remove.

[chrishtr, 2015/03/19 22:15:16]

Good catch. Fixed.

     // FIXME: why is interpolation quality selection not included in the Instrumentation reported cost of drawing an image?
     InterpolationQuality interpolationQuality = BoxPainter::chooseInterpolationQuality(m_layoutImage, context, image.get(), image.get(), LayoutSize(alignedRect.size()));
 
     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "PaintImage", "data", InspectorPaintImageEvent::data(m_layoutImage));
 
     InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
     context->setImageInterpolationQuality(interpolationQuality);
     context->drawImage(image.get(), alignedRect, SkXfermode::kSrcOver_Mode, m_layoutImage.shouldRespectImageOrientation());
     context->setImageInterpolationQuality(previousInterpolationQuality);
 }
 
 } // namespace blink