Implement basic parts of hit regions on canvas2d.

Source/core/html/canvas/HitRegion.h

Index: Source/core/html/canvas/HitRegion.h
diff --git a/Source/core/html/canvas/HitRegion.h b/Source/core/html/canvas/HitRegion.h
new file mode 100644
index 0000000000000000000000000000000000000000..c0d57be5a619042deaaee471462aac38870c3e9b
--- /dev/null
+++ b/Source/core/html/canvas/HitRegion.h
@@ -0,0 +1,95 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef HitRegion_h
+#define HitRegion_h
+
+#include "bindings/v8/Dictionary.h"
+#include "core/dom/Element.h"
+#include "platform/graphics/Path.h"
+#include "platform/heap/Handle.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefPtr.h"
+
+namespace WebCore {
+
+struct HitRegionOptions {
+    STACK_ALLOCATED();
+
+public:
+    String id;
+    RefPtrWillBeMember<Element> control;
+    Path path;
+};
+
+class HitRegion FINAL : public RefCountedWillBeGarbageCollected<HitRegion> {
+public:
+    static PassRefPtrWillBeRawPtr<HitRegion> create(const HitRegionOptions& options)
+    {
+        return adoptRefWillBeNoop(new HitRegion(options));
+    }
+
+    virtual ~HitRegion() { }
+
+    void removePixels(const Path&);
+    void updateAccessibility(Element* canvas);
+
+    bool contains(const LayoutPoint&) const;
+
+    const String& id() const { return m_id; }
+    const Path& path() const { return m_path; }
+    Element* control() const { return m_control.get(); }
+
+    void trace(Visitor*);
+
+private:
+    explicit HitRegion(const HitRegionOptions&);
+
+    String m_id;
+    RefPtrWillBeMember<Element> m_control;
+    Path m_path;
+};
+
+class HitRegionManager FINAL : public NoBaseWillBeGarbageCollected<HitRegionManager> {
+    WTF_MAKE_NONCOPYABLE(HitRegionManager);
+
+public:
+    static PassOwnPtrWillBeRawPtr<HitRegionManager> create() { return adoptPtrWillBeNoop(new HitRegionManager()); }
+    virtual ~HitRegionManager() { }
+
+    void addHitRegion(PassRefPtrWillBeRawPtr<HitRegion>);
+
+    void removeHitRegion(HitRegion*);
+    void removeHitRegionById(const String& id);
+    void removeHitRegionByControl(Element*);
+    void removeHitRegionsInRect(const FloatRect&, const AffineTransform&);
+    void removeAllHitRegions();
+
+    HitRegion* getHitRegionById(const String& id) const;
+    HitRegion* getHitRegionByControl(Element*) const;
+    HitRegion* getHitRegionAtPoint(const LayoutPoint&) const;
+
+    unsigned getHitRegionsCount() const;
+
+    void trace(Visitor*);
+
+private:
+    HitRegionManager() { }
+
+    typedef WillBeHeapListHashSet<RefPtrWillBeMember<HitRegion> > HitRegionList;
+    typedef HitRegionList::const_reverse_iterator HitRegionIterator;
+    typedef WillBeHeapHashMap<String, RefPtrWillBeMember<HitRegion> > HitRegionIdMap;
+    typedef WillBeHeapHashMap<RefPtrWillBeMember<Element>, RefPtrWillBeMember<HitRegion> > HitRegionControlMap;
+
+    HitRegionList m_hitRegionList;
+    HitRegionIdMap m_hitRegionIdMap;
+    HitRegionControlMap m_hitRegionControlMap;
+};
+
+} // namespace WebCore
+
+#endif