Implement a Hit Test Cache.

Source/core/dom/TreeScope.h

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * 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
@@ skipping 11 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef TreeScope_h
 #define TreeScope_h
 
 #include "core/CoreExport.h"
 #include "core/dom/DocumentOrderedMap.h"
+#include "core/layout/HitTestRequest.h"
 #include "platform/heap/Handle.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class ContainerNode;
 class DOMSelection;
 class Document;
 class Element;
 class HTMLLabelElement;
 class HTMLMapElement;
 class HitTestResult;
-class HitTestRequest;
 class IdTargetObserverRegistry;
 class ScopedStyleResolver;
 class Node;
 
 // A class which inherits both Node and TreeScope must call clearRareData() in its destructor
 // so that the Node destructor no longer does problematic NodeList cache manipulation in
 // the destructor.
 class CORE_EXPORT TreeScope : public WillBeGarbageCollectedMixin {
 public:
     TreeScope* parentTreeScope() const { return m_parentTreeScope; }
@@ skipping 15 matching lines @@
         return *m_document;
     }
 
     Node* ancestorInThisScope(Node*) const;
 
     void addImageMap(HTMLMapElement*);
     void removeImageMap(HTMLMapElement*);
     HTMLMapElement* getImageMap(const String& url) const;
 
     Element* elementFromPoint(int x, int y) const;
+    Element* elementFromPointNoCache(int x, int y) const;
     Vector<Element*> elementsFromPoint(int x, int y) const;
 
     // For accessibility.
     bool shouldCacheLabelsByForAttribute() const { return m_labelsByForAttribute; }
     void addLabel(const AtomicString& forAttributeValue, HTMLLabelElement*);
     void removeLabel(const AtomicString& forAttributeValue, HTMLLabelElement*);
     HTMLLabelElement* labelElementForId(const AtomicString& forAttributeValue);
 
     DOMSelection* getSelection() const;
 
@@ skipping 79 matching lines @@
     bool deletionHasBegun();
     void beginDeletion();
 #else
     bool deletionHasBegun() { return false; }
     void beginDeletion() { }
 #endif
 #endif
 
     bool rootNodeHasTreeSharedParent() const;
 
+    Element* hitTestPoint(int x, int y, const HitTestRequest&) const;
+
     RawPtrWillBeMember<ContainerNode> m_rootNode;
     RawPtrWillBeMember<Document> m_document;
     RawPtrWillBeMember<TreeScope> m_parentTreeScope;
 
 #if !ENABLE(OILPAN)
     int m_guardRefCount;
 #endif
 
     OwnPtrWillBeMember<DocumentOrderedMap> m_elementsById;
     OwnPtrWillBeMember<DocumentOrderedMap> m_imageMapsByName;
@@ skipping 12 matching lines @@
     return m_elementsById && m_elementsById->contains(id);
 }
 
 inline bool TreeScope::containsMultipleElementsWithId(const AtomicString& id) const
 {
     return m_elementsById && m_elementsById->containsMultiple(id);
 }
 
 DEFINE_COMPARISON_OPERATORS_WITH_REFERENCES(TreeScope)
 
-HitTestResult hitTestInDocument(const Document*, int x, int y);
+HitTestResult hitTestInDocument(const Document*, int x, int y, const HitTestRequest& = HitTestRequest::ReadOnly | HitTestRequest::Active);

[tdresser, 2015/06/10 13:35:21]

Why take a reference instead of a value here?

[dtapuska, 2015/06/10 14:04:48]

HitTestRequest is a class; so I prefer to pass classes by const reference as I
don't want to imply the sizing of the class itself and what the compiler will
do.

 
 } // namespace blink
 
 #endif // TreeScope_h