Merge image sizing algorithms

third_party/WebKit/Source/core/style/StyleFetchedImageSet.cpp

 /*
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 75 matching lines @@
 bool StyleFetchedImageSet::isLoaded() const
 {
     return m_bestFitImage->isLoaded();
 }
 
 bool StyleFetchedImageSet::errorOccurred() const
 {
     return m_bestFitImage->errorOccurred();
 }
 
-LayoutSize StyleFetchedImageSet::imageSize(const LayoutObject* layoutObject, float multiplier) const
+LayoutSize StyleFetchedImageSet::imageSize(const LayoutObject*, float multiplier, const LayoutSize& defaultObjectSize) const
 {
-    LayoutSize scaledImageSize = m_bestFitImage->imageSize(LayoutObject::shouldRespectImageOrientation(layoutObject), multiplier);
-    scaledImageSize.scale(1 / m_imageScaleFactor);
-    return scaledImageSize;
+    if (m_bestFitImage->image() && m_bestFitImage->image()->isSVGImage())
+        return imageSizeForSVGImage(toSVGImage(m_bestFitImage->image()), multiplier, defaultObjectSize);
+
+    // Image orientation should only be respected for content images,
+    // not decorative ones such as StyleImage (backgrounds,
+    // border-image, etc.)

[Yoav Weiss, 2016/03/07 11:16:07]

Here too, pointing to a spec and testing functionality change would be good.

Otherwise, I believe you would need to take m_imageScaleFactor into account in
order to make sure that if `-webkit-image-set(url(1x.jpg) 1x, url(2x.jpg) 2x)`
loads the 2x resource, it won't be displayed at twice the size that it's
supposed to be displayed in.

[davve, 2016/03/07 13:07:38]

You mean add the spec link as a comment? I'll do that.
 
The tests:

fast/hidpi/image-set-background-repeat-without-size.html
fast/hidpi/image-set-border-image-comparison.html

break when the scale factor is compensated for here (since imageSize() now used
for backgrounds and border-image. Previously the background and border-image
code used Image::computeIntrinsicDimensions and did no such compensation).

Do you know of a test that probably would break with my patch?

[davve, 2016/03/07 14:26:10]

I looked into what happens here. The background image painting code
and the border-image painting code already corrected for the
imageScaleFactor. I'll look into removing that and keeping the
correction here, to make imageSize() return the size for layout which
is the sensible size, AFAICT.

+    return m_bestFitImage->imageSize(DoNotRespectImageOrientation, multiplier);
 }
 
 bool StyleFetchedImageSet::imageHasRelativeSize() const
 {
     return m_bestFitImage->imageHasRelativeSize();
 }
 
 void StyleFetchedImageSet::computeIntrinsicDimensions(const LayoutObject*, FloatSize& intrinsicSize, FloatSize& intrinsicRatio)
 {
     m_bestFitImage->computeIntrinsicDimensions(intrinsicSize, intrinsicRatio);
@@ skipping 29 matching lines @@
 }
 
 DEFINE_TRACE(StyleFetchedImageSet)
 {
     visitor->trace(m_bestFitImage);
     visitor->trace(m_imageSetValue);
     StyleImage::trace(visitor);
 }
 
 } // namespace blink