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..7e81c47f90fb405688494a9ead3f3b6451b66308
--- /dev/null
+++ b/Source/core/html/canvas/HitRegion.h
@@ -0,0 +1,86 @@
+// 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 {

[Justin Novosad, 2014/06/02 22:56:13]

GarbageCollected?

[haraken, 2014/06/03 02:15:51]

I think this is always stack-allocated. So you can add:

STACK_ALLOCATED();

and use:

RefPtrWillBeMember<Element> control;

You don't need trace it since oilpan's conservative scanning will find on-stack
pointers.

[zino, 2014/06/06 06:35:16]

Done.

[zino, 2014/06/06 06:35:17]

Done.

+    String id;
+    RefPtrWillBeMember<Element> control;

[Justin Novosad, 2014/06/02 22:56:13]

missing trace method

[zino, 2014/06/06 06:35:17]

Please refer to @haraken's comment.

+    Path path;
+};
+
+class HitRegion FINAL : public RefCountedWillBeGarbageCollectedFinalized<HitRegion> {

[Justin Novosad, 2014/06/02 22:56:13]

I don't think this class needs to be finalized. It does not even have a
destructor.

[haraken, 2014/06/03 02:15:51]

Unfortunately this needs a destructor, since a String (m_id) requires a
finalization. The GC plugin will catch this kind of error when compiling with
enable_oilpan=1.

[zino, 2014/06/06 06:35:17]

Done.

+public:
+    static PassRefPtrWillBeRawPtr<HitRegion> create(const HitRegionOptions& options)
+    {
+        return adoptRef(new HitRegion(options));

[Justin Novosad, 2014/06/02 22:56:13]

adoptRef -> adoptRefWillBeNoop

[zino, 2014/06/06 06:35:17]

Done.

+    }
+
+    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; }
+    const Element* control() const { return m_control.get(); }
+
+private:
+    HitRegion(const HitRegionOptions&);

[haraken, 2014/06/03 02:15:51]

Add explicit.

[zino, 2014/06/06 06:35:17]

Done.

+
+    String m_id;
+    RefPtrWillBeMember<Element> m_control;

[Justin Novosad, 2014/06/02 22:56:13]

missing trace method

[zino, 2014/06/06 06:35:17]

Done.

+    Path m_path;
+};
+
+class HitRegionManager FINAL : public NoBaseWillBeGarbageCollectedFinalized<HitRegionManager> {

[Justin Novosad, 2014/06/02 22:56:13]

Does this class really need to be finalized?

[zino, 2014/06/06 06:35:16]

Done.

+    WTF_MAKE_NONCOPYABLE(HitRegionManager);
+
+public:
+    static PassOwnPtrWillBeRawPtr<HitRegionManager> create() { return adoptPtr(new HitRegionManager()); }
+    virtual ~HitRegionManager() { }

[Justin Novosad, 2014/06/02 22:56:13]

Is this necessary?

[zino, 2014/06/06 06:35:16]

I'm not sure. if it wasn't exist, build error happened. (enable_oilpan=0)

+
+    void addHitRegion(PassRefPtrWillBeRawPtr<HitRegion>);
+
+    void removeHitRegion(HitRegion*);
+    void removeHitRegionById(const String& id);
+    void removeHitRegionByControl(const Element*);
+    void removeHitRegionsInRect(const FloatRect&, const AffineTransform&);
+    void removeAllHitRegions();
+
+    HitRegion* getHitRegionById(const String& id) const;
+    HitRegion* getHitRegionByControl(const Element*) const;
+    HitRegion* getHitRegionAtPoint(const LayoutPoint&) const;
+
+    unsigned getHitRegionsCount() const;
+
+private:
+    HitRegionManager() { }
+
+    typedef WillBeHeapListHashSet< RefPtrWillBeMember<HitRegion> >::const_reverse_iterator HitRegionIterator;

[fs, 2014/06/03 11:47:01]

If you move this after the HitRegionList typedef it'll be simpler (and more
obvious IMHO.)

[zino, 2014/06/06 06:35:17]

Done.
Good catch!
Thank you :)

+    typedef WillBeHeapListHashSet< RefPtrWillBeMember<HitRegion> > HitRegionList;
+    typedef WillBeHeapHashMap< String, RefPtrWillBeMember<HitRegion> > HitRegionIdMap;
+    typedef WillBeHeapHashMap< const Element*, RefPtrWillBeMember<HitRegion> > HitRegionControlMap;

[haraken, 2014/06/03 02:15:51]

How is it guaranteed that the Element raw pointer doesn't become stale?

Also I guess you can use WillBeHeapHashMap<Member<const Element>,
RefPtrWillBeMember<HitRegion>> since this map can have a strong reference to the
Elements.

[zino, 2014/06/06 06:35:16]

Done.

+
+    HitRegionList m_hitRegionList;

[Justin Novosad, 2014/06/02 22:56:13]

This member and the one below need to be traced.

[zino, 2014/06/06 06:35:16]

Done.

+    HitRegionIdMap m_hitRegionIdMap;
+    HitRegionControlMap m_hitRegionControlMap;

[fs, 2014/06/03 11:47:01]

I didn't see this being used for anything (just accounted). Drop until it's
actually used?

[zino, 2014/06/06 06:35:16]

It is actually used in addHitRegions().

Please refer to following the spec:
 - http://www.w3.org/TR/2dcontext/#dom-context-2d-addhitregion
 - 11. If there is a previous region with this control, remove it from the
canvas element's hit region list.

[fs, 2014/06/09 11:06:27]

Ok.

+};
+
+} // namespace WebCore
+
+#endif