Add preloader support for picture based source selection

Source/core/html/parser/HTMLPreloadScanner.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009 Torch Mobile, Inc. http://www.torchmobile.com/
  * Copyright (C) 2010 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 90 matching lines @@
     return mediaQueryEvaluator.eval(mediaQueries.get());
 }
 
 class TokenPreloadScanner::StartTagScanner {
 public:
     StartTagScanner(const StringImpl* tagImpl, PassRefPtr<MediaValues> mediaValues)
         : m_tagImpl(tagImpl)
         , m_linkIsStyleSheet(false)
         , m_matchedMediaAttribute(true)
         , m_inputIsImage(false)
-        , m_imgSourceSize(0)
+        , m_sourceSize(0)
         , m_sourceSizeSet(false)
         , m_isCORSEnabled(false)
         , m_allowCredentials(DoNotAllowStoredCredentials)
         , m_mediaValues(mediaValues)
     {
-        if (!match(m_tagImpl, imgTag)
-            && !match(m_tagImpl, inputTag)
+        if (match(m_tagImpl, imgTag)
+            || match(m_tagImpl, sourceTag)) {
+            if (RuntimeEnabledFeatures::pictureSizesEnabled())
+                m_sourceSize = SizesAttributeParser::findEffectiveSize(String(), m_mediaValues);
+            return;
+        }
+        if ( !match(m_tagImpl, inputTag)
             && !match(m_tagImpl, linkTag)
             && !match(m_tagImpl, scriptTag))
             m_tagImpl = 0;
-        if (RuntimeEnabledFeatures::pictureSizesEnabled())
-            m_imgSourceSize = SizesAttributeParser::findEffectiveSize(String(), m_mediaValues);
     }
 
     enum URLReplacement {
         AllowURLReplacement,
         DisallowURLReplacement
     };
 
     void processAttributes(const HTMLToken::AttributeList& attributes)
     {
         ASSERT(isMainThread());
         if (!m_tagImpl)
             return;
         for (HTMLToken::AttributeList::const_iterator iter = attributes.begin(); iter != attributes.end(); ++iter) {
             AtomicString attributeName(iter->name);
             String attributeValue = StringImpl::create8BitIfPossible(iter->value);
             processAttribute(attributeName, attributeValue);
         }
     }
 
     void processAttributes(const Vector<CompactHTMLToken::Attribute>& attributes)
     {
         if (!m_tagImpl)
             return;
         for (Vector<CompactHTMLToken::Attribute>::const_iterator iter = attributes.begin(); iter != attributes.end(); ++iter)
             processAttribute(iter->name, iter->value);
     }
 
+    void handlePictureSourceURL(Vector<String>& pictureSourceURLStack)
+    {
+        if (pictureSourceURLStack.isEmpty())
+            return;
+
+        if (match(m_tagImpl, sourceTag) && pictureSourceURLStack.last().isEmpty() && m_matchedMediaAttribute) {
+            pictureSourceURLStack.removeLast();
+            pictureSourceURLStack.append(m_srcsetImageCandidate.toString());
+        } else if (match(m_tagImpl, imgTag) && !pictureSourceURLStack.last().isEmpty()) {
+            setUrlToLoad(pictureSourceURLStack.last(), AllowURLReplacement);
+        }
+    }
+
     PassOwnPtr<PreloadRequest> createPreloadRequest(const KURL& predictedBaseURL, const SegmentedString& source)
     {
         if (!shouldPreload() || !m_matchedMediaAttribute)
             return nullptr;
 
         TRACE_EVENT_INSTANT1("net", "PreloadRequest", "url", m_urlToLoad.ascii());
         TextPosition position = TextPosition(source.currentLine(), source.currentColumn());
         OwnPtr<PreloadRequest> request = PreloadRequest::create(initiatorFor(m_tagImpl), position, m_urlToLoad, predictedBaseURL, resourceType());
         if (isCORSEnabled())
             request->setCrossOriginEnabled(allowStoredCredentials());
         request->setCharset(charset());
         return request.release();
     }
 
 private:
     template<typename NameType>
+    void processScriptAttribute(const NameType& attributeName, const String& attributeValue)
+    {
+        if (match(attributeName, srcAttr))
+            setUrlToLoad(attributeValue, DisallowURLReplacement);
+        else if (match(attributeName, crossoriginAttr))
+            setCrossOriginAllowed(attributeValue);
+    }
+
+    template<typename NameType>
+    void processImgAttribute(const NameType& attributeName, const String& attributeValue)
+    {
+        if (match(attributeName, srcAttr) && m_imgSrcUrl.isNull()) {
+            m_imgSrcUrl = attributeValue;
+            setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_sourceSize, attributeValue, m_srcsetImageCandidate), AllowURLReplacement);
+        } else if (match(attributeName, crossoriginAttr)) {
+            setCrossOriginAllowed(attributeValue);
+        } else if (match(attributeName, srcsetAttr) && m_srcsetImageCandidate.isEmpty()) {
+            m_srcsetAttributeValue = attributeValue;
+            m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_sourceSize, attributeValue);
+            setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_sourceSize, m_imgSrcUrl, m_srcsetImageCandidate), AllowURLReplacement);
+        } else if (RuntimeEnabledFeatures::pictureSizesEnabled() && match(attributeName, sizesAttr) && !m_sourceSizeSet) {
+            m_sourceSize = SizesAttributeParser::findEffectiveSize(attributeValue, m_mediaValues);
+            m_sourceSizeSet = true;
+            if (!m_srcsetImageCandidate.isEmpty()) {
+                m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_sourceSize, m_srcsetAttributeValue);
+                setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_sourceSize, m_imgSrcUrl, m_srcsetImageCandidate), AllowURLReplacement);
+            }
+        }
+    }
+
+    template<typename NameType>
+    void processLinkAttribute(const NameType& attributeName, const String& attributeValue)
+    {
+        if (match(attributeName, hrefAttr))
+            setUrlToLoad(attributeValue, DisallowURLReplacement);
+        else if (match(attributeName, relAttr))
+            m_linkIsStyleSheet = relAttributeIsStyleSheet(attributeValue);
+        else if (match(attributeName, mediaAttr))
+            m_matchedMediaAttribute = mediaAttributeMatches(*m_mediaValues, attributeValue);
+        else if (match(attributeName, crossoriginAttr))
+            setCrossOriginAllowed(attributeValue);
+    }
+
+    template<typename NameType>
+    void processInputAttribute(const NameType& attributeName, const String& attributeValue)
+    {
+        if (match(attributeName, srcAttr))
+            setUrlToLoad(attributeValue, DisallowURLReplacement);
+        else if (match(attributeName, typeAttr))
+            m_inputIsImage = equalIgnoringCase(attributeValue, InputTypeNames::image);
+    }
+
+    template<typename NameType>
+    void processSourceAttribute(const NameType& attributeName, const String& attributeValue)
+    {
+        if (!RuntimeEnabledFeatures::pictureEnabled())
+            return;
+        if (match(attributeName, srcsetAttr) && m_srcsetImageCandidate.isEmpty()) {
+            m_srcsetAttributeValue = attributeValue;
+            m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_sourceSize, attributeValue);
+        } else if (match(attributeName, sizesAttr) && !m_sourceSizeSet) {
+            m_sourceSize = SizesAttributeParser::findEffectiveSize(attributeValue, m_mediaValues);
+            m_sourceSizeSet = true;
+            if (!m_srcsetImageCandidate.isEmpty()) {
+                m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_sourceSize, m_srcsetAttributeValue);
+            }
+        } else if (match(attributeName, mediaAttr)) {
+            m_matchedMediaAttribute = mediaAttributeMatches(*m_mediaValues, attributeValue);
+        }
+    }
+
+    template<typename NameType>
     void processAttribute(const NameType& attributeName, const String& attributeValue)
     {
         if (match(attributeName, charsetAttr))
             m_charset = attributeValue;
 
-        if (match(m_tagImpl, scriptTag)) {
-            if (match(attributeName, srcAttr))
-                setUrlToLoad(attributeValue, DisallowURLReplacement);
-            else if (match(attributeName, crossoriginAttr))
-                setCrossOriginAllowed(attributeValue);
-        } else if (match(m_tagImpl, imgTag)) {
-            if (match(attributeName, srcAttr) && m_imgSrcUrl.isNull()) {
-                m_imgSrcUrl = attributeValue;
-                setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_imgSourceSize, attributeValue, m_srcsetImageCandidate), AllowURLReplacement);
-            } else if (match(attributeName, crossoriginAttr)) {
-                setCrossOriginAllowed(attributeValue);
-            } else if (match(attributeName, srcsetAttr) && m_srcsetImageCandidate.isEmpty()) {
-                m_imgSrcsetAttributeValue = attributeValue;
-                m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_imgSourceSize, attributeValue);
-                setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_imgSourceSize, m_imgSrcUrl, m_srcsetImageCandidate), AllowURLReplacement);
-            } else if (RuntimeEnabledFeatures::pictureSizesEnabled() && match(attributeName, sizesAttr) && !m_sourceSizeSet) {
-                m_imgSourceSize = SizesAttributeParser::findEffectiveSize(attributeValue, m_mediaValues);
-                m_sourceSizeSet = true;
-                if (!m_srcsetImageCandidate.isEmpty()) {
-                    m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_imgSourceSize, m_imgSrcsetAttributeValue);
-                    setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_imgSourceSize, m_imgSrcUrl, m_srcsetImageCandidate), AllowURLReplacement);
-                }
-            }
-        } else if (match(m_tagImpl, linkTag)) {
-            if (match(attributeName, hrefAttr))
-                setUrlToLoad(attributeValue, DisallowURLReplacement);
-            else if (match(attributeName, relAttr))
-                m_linkIsStyleSheet = relAttributeIsStyleSheet(attributeValue);
-            else if (match(attributeName, mediaAttr))
-                m_matchedMediaAttribute = mediaAttributeMatches(*m_mediaValues, attributeValue);
-            else if (match(attributeName, crossoriginAttr))
-                setCrossOriginAllowed(attributeValue);
-        } else if (match(m_tagImpl, inputTag)) {
-            if (match(attributeName, srcAttr))
-                setUrlToLoad(attributeValue, DisallowURLReplacement);
-            else if (match(attributeName, typeAttr))
-                m_inputIsImage = equalIgnoringCase(attributeValue, InputTypeNames::image);
-        }
+        if (match(m_tagImpl, scriptTag))
+            processScriptAttribute(attributeName, attributeValue);
+        else if (match(m_tagImpl, imgTag))
+            processImgAttribute(attributeName, attributeValue);
+        else if (match(m_tagImpl, linkTag))
+            processLinkAttribute(attributeName, attributeValue);
+        else if (match(m_tagImpl, inputTag))
+            processInputAttribute(attributeName, attributeValue);
+        else if (match(m_tagImpl, sourceTag))
+            processSourceAttribute(attributeName, attributeValue);
     }
 
     static bool relAttributeIsStyleSheet(const String& attributeValue)
     {
         LinkRelAttribute rel(attributeValue);
         return rel.isStyleSheet() && !rel.isAlternate() && rel.iconType() == InvalidIcon && !rel.isDNSPrefetch();
     }
 
     void setUrlToLoad(const String& value, URLReplacement replacement)
     {
@@ skipping 58 matching lines @@
     }
 
     const StringImpl* m_tagImpl;
     String m_urlToLoad;
     ImageCandidate m_srcsetImageCandidate;
     String m_charset;
     bool m_linkIsStyleSheet;
     bool m_matchedMediaAttribute;
     bool m_inputIsImage;
     String m_imgSrcUrl;
-    String m_imgSrcsetAttributeValue;
-    unsigned m_imgSourceSize;
+    String m_srcsetAttributeValue;
+    unsigned m_sourceSize;
     bool m_sourceSizeSet;
     bool m_isCORSEnabled;
     StoredCredentials m_allowCredentials;
     RefPtr<MediaValues> m_mediaValues;
 };
 
 TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, PassRefPtr<MediaValues> mediaValues)
     : m_documentURL(documentURL)
     , m_inStyle(false)
     , m_templateCount(0)
     , m_mediaValues(mediaValues)
 {
 }
 
 TokenPreloadScanner::~TokenPreloadScanner()
 {
 }
 
 TokenPreloadScannerCheckpoint TokenPreloadScanner::createCheckpoint()
 {
     TokenPreloadScannerCheckpoint checkpoint = m_checkpoints.size();
-    m_checkpoints.append(Checkpoint(m_predictedBaseElementURL, m_inStyle, m_templateCount));
+    m_checkpoints.append(Checkpoint(m_predictedBaseElementURL, m_inStyle, m_pictureSourceURLStack, m_templateCount));
     return checkpoint;
 }
 
 void TokenPreloadScanner::rewindTo(TokenPreloadScannerCheckpoint checkpointIndex)
 {
     ASSERT(checkpointIndex < m_checkpoints.size()); // If this ASSERT fires, checkpointIndex is invalid.
     const Checkpoint& checkpoint = m_checkpoints[checkpointIndex];
     m_predictedBaseElementURL = checkpoint.predictedBaseElementURL;
     m_inStyle = checkpoint.inStyle;
+    m_pictureSourceURLStack = checkpoint.pictureSourceURLStack;
     m_templateCount = checkpoint.templateCount;
     m_cssScanner.reset();
     m_checkpoints.clear();
 }
 
 void TokenPreloadScanner::scan(const HTMLToken& token, const SegmentedString& source, PreloadRequestStream& requests)
 {
     scanCommon(token, source, requests);
 }
 
@@ skipping 17 matching lines @@
         if (match(tagImpl, templateTag)) {
             if (m_templateCount)
                 --m_templateCount;
             return;
         }
         if (match(tagImpl, styleTag)) {
             if (m_inStyle)
                 m_cssScanner.reset();
             m_inStyle = false;
         }
+        if (match(tagImpl, pictureTag))
+            m_pictureSourceURLStack.removeLast();
         return;
     }
     case HTMLToken::StartTag: {
         if (m_templateCount)
             return;
         const StringImpl* tagImpl = tagImplFor(token.data());
         if (match(tagImpl, templateTag)) {
             ++m_templateCount;
             return;
         }
         if (match(tagImpl, styleTag)) {
             m_inStyle = true;
             return;
         }
         if (match(tagImpl, baseTag)) {
             // The first <base> element is the one that wins.
             if (!m_predictedBaseElementURL.isEmpty())
                 return;
             updatePredictedBaseURL(token);
             return;
         }
+        if (match(tagImpl, pictureTag))
+            m_pictureSourceURLStack.append(String());
 
         StartTagScanner scanner(tagImpl, m_mediaValues);
         scanner.processAttributes(token.attributes());
+        scanner.handlePictureSourceURL(m_pictureSourceURLStack);
         OwnPtr<PreloadRequest> request = scanner.createPreloadRequest(m_predictedBaseElementURL, source);
         if (request)
             requests.append(request.release());
         return;
     }
     default: {
         return;
     }
     }
 }
@@ skipping 37 matching lines @@
         if (m_token.type() == HTMLToken::StartTag)
             m_tokenizer->updateStateFor(attemptStaticStringCreation(m_token.name(), Likely8Bit));
         m_scanner.scan(m_token, m_source, requests);
         m_token.clear();
     }
 
     preloader->takeAndPreload(requests);
 }
 
 }