Canvas2d: fix event.region being null on mouseleave/out events

third_party/WebKit/Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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 169 matching lines @@
 
     void createImageBufferUsingSurfaceForTesting(PassOwnPtr<ImageBufferSurface>);
 
     static void registerRenderingContextFactory(PassOwnPtr<CanvasRenderingContextFactory>);
     void updateExternallyAllocatedMemory() const;
 
     void styleDidChange(const ComputedStyle* oldStyle, const ComputedStyle& newStyle);
 
     void notifyListenersCanvasChanged();
 
+    // For Canvas HitRegions
     bool isSupportedInteractiveCanvasFallback(const Element&);
     std::pair<Element*, String> getControlAndIdIfHitRegionExists(const LayoutPoint&);
+    String getIdFromControl(Element*);

[dtapuska, 2016/04/05 15:57:28]

Is there a requirement that Element be a ptr. Perhaps it would be better to be a
const reference like the isSupportedInteractiveCanvasFallback API..

Can this method be const as well?

[zino, 2016/04/06 11:08:20]

In the current implementation, we are saving the control elements as pointer
type. So, we will finally have to use pointer type to get a hit region
representing control. If needed, we can refactor the related codes to not use
pointer type in follow-up CL.

[dtapuska, 2016/04/06 13:41:25]

That doesn't preclude you from taking the address of the member down in the
HitRegionManager. I'm just looking for a consistent API. It the very least it
should be a const Element*

[zino, 2016/04/06 16:25:38]

Done.

But I used |const_cast| when calling getHitRegionByControl() in
CanvasRenderingContext2D::getIdFromControl().

 
 protected:
     void didMoveToNewDocument(Document& oldDocument) override;
 
 private:
     explicit HTMLCanvasElement(Document&);
 
     using ContextFactoryVector = Vector<OwnPtr<CanvasRenderingContextFactory>>;
     static ContextFactoryVector& renderingContextFactories();
     static CanvasRenderingContextFactory* getRenderingContextFactory(int);
@@ skipping 35 matching lines @@
     mutable bool m_didFailToCreateImageBuffer;
     bool m_imageBufferIsClear;
     OwnPtr<ImageBuffer> m_imageBuffer;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h