Don't invalidate paint on background image change if it's obscured

third_party/WebKit/Source/core/layout/LayoutImage.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011-2012. All rights reserved.
  *
@@ skipping 198 matching lines @@
     if (!LayoutBoxModelObject::boxShadowShouldBeAppliedToBackground(bleedAvoidance))
         return false;
 
     return !const_cast<LayoutImage*>(this)->backgroundIsKnownToBeObscured();
 }
 
 bool LayoutImage::foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned) const
 {
     if (!m_imageResource->hasImage() || m_imageResource->errorOccurred())
         return false;
-    if (m_imageResource->cachedImage() && !m_imageResource->cachedImage()->isLoaded())
+    if (!m_imageResource->cachedImage() || !m_imageResource->cachedImage()->isLoaded())
         return false;
     if (!contentBoxRect().contains(localRect))
         return false;
     EFillBox backgroundClip = style()->backgroundClip();
     // Background paints under borders.
     if (backgroundClip == BorderFillBox && style()->hasBorder() && !style()->borderObscuresBackground())
         return false;
     // Background shows in padding area.
     if ((backgroundClip == BorderFillBox || backgroundClip == PaddingFillBox) && style()->hasPadding())
         return false;
     // Object-position may leave parts of the content box empty, regardless of the value of object-fit.
     if (style()->objectPosition() != ComputedStyle::initialObjectPosition())
         return false;
     // Object-fit may leave parts of the content box empty.
     ObjectFit objectFit = style()->getObjectFit();
     if (objectFit != ObjectFitFill && objectFit != ObjectFitCover)
         return false;
-    if (!m_imageResource->cachedImage())

[chrishtr, 2016/08/09 16:05:17]

?

[Xianzhu, 2016/08/09 18:51:48]

This is combined into the condition at line 219.

[chrishtr, 2016/08/09 22:07:54]

Ah ok.

-        return false;
     // Check for image with alpha.
     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "PaintImage", "data", InspectorPaintImageEvent::data(this, *m_imageResource->cachedImage()));
     return m_imageResource->cachedImage()->getImage()->currentFrameKnownToBeOpaque(Image::PreCacheMetadata);
 }
 
 bool LayoutImage::computeBackgroundIsKnownToBeObscured() const
 {
     if (!styleRef().hasBackground())
         return false;
 
@@ skipping 60 matching lines @@
         return nullptr;
 
     ImageResource* cachedImage = m_imageResource->cachedImage();
     if (cachedImage && cachedImage->getImage() && cachedImage->getImage()->isSVGImage())
         return toSVGImage(cachedImage->getImage())->embeddedReplacedContent();
 
     return nullptr;
 }
 
 } // namespace blink