Use SizesAttributeParser to get the right srcset resource

Source/core/html/parser/HTMLSrcsetParser.cpp

Index: Source/core/html/parser/HTMLSrcsetParser.cpp
diff --git a/Source/core/html/parser/HTMLSrcsetParser.cpp b/Source/core/html/parser/HTMLSrcsetParser.cpp
index 1fffc5d561e1b182427536901fa24113b009f0df..00b14a489aa0b26a3cc51ffc30084219bfe72750 100644
--- a/Source/core/html/parser/HTMLSrcsetParser.cpp
+++ b/Source/core/html/parser/HTMLSrcsetParser.cpp
@@ -142,7 +142,7 @@ static void parseImageCandidatesFromSrcsetAttribute(const String& attribute, Vec
         parseImageCandidatesFromSrcsetAttribute<UChar>(attribute, attribute.characters16(), attribute.length(), imageCandidates);
 }
 
-static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, int effectiveSize, Vector<ImageCandidate>& imageCandidates)
+static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, unsigned sourceSize, Vector<ImageCandidate>& imageCandidates)
 {
     bool ignoreSrc = false;
     if (imageCandidates.isEmpty())
@@ -151,7 +151,7 @@ static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, int effect
     // http://picture.responsiveimages.org/#normalize-source-densities
     for (Vector<ImageCandidate>::iterator it = imageCandidates.begin(); it != imageCandidates.end(); ++it) {
         if (it->resourceWidth() > 0) {
-            it->setScaleFactor((float)it->resourceWidth() / (float)effectiveSize);
+            it->setScaleFactor((float)it->resourceWidth() / (float)sourceSize);
             ignoreSrc = true;
         }
     }
@@ -174,16 +174,16 @@ static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, int effect
     return imageCandidates[winner];
 }
 
-ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, int effectiveSize, const String& srcsetAttribute)
+ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, unsigned sourceSize, const String& srcsetAttribute)
 {
     Vector<ImageCandidate> imageCandidates;
 
     parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates);
 
-    return pickBestImageCandidate(deviceScaleFactor, effectiveSize, imageCandidates);
+    return pickBestImageCandidate(deviceScaleFactor, sourceSize, imageCandidates);
 }
 
-ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, int effectiveSize, const String& srcAttribute, const String& srcsetAttribute)
+ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, unsigned sourceSize, const String& srcAttribute, const String& srcsetAttribute)
 {
     DescriptorParsingResult defaultResult;
     defaultResult.scaleFactor = 1.0;
@@ -198,13 +198,13 @@ ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, int effe
 
     parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates);
 
-    if (!srcAttribute.isEmpty())
+    if (!srcAttribute.isNull() && !srcAttribute.isEmpty())

[eseidel, 2014/04/20 21:27:43]

!isEmpty should be the same...

         imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), defaultResult, ImageCandidate::SrcOrigin));
 
-    return pickBestImageCandidate(deviceScaleFactor, effectiveSize, imageCandidates);
+    return pickBestImageCandidate(deviceScaleFactor, sourceSize, imageCandidates);
 }
 
-String bestFitSourceForImageAttributes(float deviceScaleFactor, int effectiveSize, const String& srcAttribute, ImageCandidate& srcsetImageCandidate)
+String bestFitSourceForImageAttributes(float deviceScaleFactor, unsigned sourceSize, const String& srcAttribute, ImageCandidate& srcsetImageCandidate)
 {
     DescriptorParsingResult defaultResult;
     defaultResult.scaleFactor = 1.0;
@@ -215,10 +215,10 @@ String bestFitSourceForImageAttributes(float deviceScaleFactor, int effectiveSiz
     Vector<ImageCandidate> imageCandidates;
     imageCandidates.append(srcsetImageCandidate);
 
-    if (!srcAttribute.isEmpty())
+    if (!srcAttribute.isNull() && !srcAttribute.isEmpty())
         imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), defaultResult, ImageCandidate::SrcOrigin));

[eseidel, 2014/04/20 21:27:43]

Same thing, I think you have some confusiong with null vs. empty.

null means the impl is set to 0.  Often used to mean something has never been
set at all.

isEmpty means that either it's null, or that its == "".

The String::emptyString() aka String("") isEmpty(), but is not null.

[Yoav Weiss, 2014/04/20 21:48:03]

For some reason I thought isEmpty is not safe to call when String is NULL. Got
it now.

 
-    return pickBestImageCandidate(deviceScaleFactor, effectiveSize, imageCandidates).toString();
+    return pickBestImageCandidate(deviceScaleFactor, sourceSize, imageCandidates).toString();
 }
 
 }