Use srcset's resource pixel density to determine intrinsic size

Source/core/html/parser/HTMLSrcsetParser.cpp

 /*
  * Copyright (C) 2013 Google 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:
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@@ skipping 136 matching lines @@
 
 ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, const String& srcsetAttribute)
 {
     Vector<ImageCandidate> imageCandidates;
 
     parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates);
 
     return pickBestImageCandidate(deviceScaleFactor, imageCandidates);
 }
 
-String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, const String& srcsetAttribute)
+String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, const String& srcsetAttribute, float& intrinsicSizeFactor)
 {
     if (srcsetAttribute.isNull())
         return srcAttribute;
 
     Vector<ImageCandidate> imageCandidates;
 
     parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates);
 
     if (!srcAttribute.isEmpty())
         imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), 1.0));
 
-    return pickBestImageCandidate(deviceScaleFactor, imageCandidates).toString();
+    ImageCandidate candidate = pickBestImageCandidate(deviceScaleFactor, imageCandidates);
+    intrinsicSizeFactor = 1 / candidate.scaleFactor();

[pdr., 2013/10/11 05:17:33]

Do we need to check that scaleFactor is non-zero here?

The spec requires this but it doesn't seem to be enforced in HTMLSrcsetParser.

[Yoav Weiss, 2013/10/11 07:22:32]

Yes, we should. Will fix. 

+
+    return candidate.toString();
 }
 
 String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, ImageCandidate& srcsetImageCandidate)
 {
     if (srcsetImageCandidate.isEmpty())
         return srcAttribute;
 
     Vector<ImageCandidate> imageCandidates;
     imageCandidates.append(srcsetImageCandidate);
 
     if (!srcAttribute.isEmpty())
         imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), 1.0));
 
     return pickBestImageCandidate(deviceScaleFactor, imageCandidates).toString();
 }
 
 }