Allow eviction of ImageBitmaps that are created from ImageElements.

Source/core/page/ImageBitmap.h

 // Copyright 2013 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 ImageBitmap_h
 #define ImageBitmap_h
 
 #include "bindings/v8/ScriptWrappable.h"
-#include "core/dom/ScriptExecutionContext.h"
 #include "core/platform/graphics/BitmapImage.h"
 #include "core/platform/graphics/ImageBuffer.h"
 #include "core/platform/graphics/IntRect.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 
 namespace WebCore {
 
 class HTMLCanvasElement;
 class HTMLImageElement;
 class HTMLVideoElement;
 class ImageData;
-class ImageBitmapCallback;
 
 class ImageBitmap : public RefCounted<ImageBitmap>, public ScriptWrappable {
 
 public:
-    static PassRefPtr<ImageBitmap> create(HTMLImageElement*, IntRect);
-    static PassRefPtr<ImageBitmap> create(HTMLVideoElement*, IntRect);
-    static PassRefPtr<ImageBitmap> create(HTMLCanvasElement*, IntRect);
-    static PassRefPtr<ImageBitmap> create(ImageData*, IntRect);
-    static PassRefPtr<ImageBitmap> create(ImageBitmap*, IntRect);
+    static PassRefPtr<ImageBitmap> create(HTMLImageElement*, const IntRect&);
+    static PassRefPtr<ImageBitmap> create(HTMLVideoElement*, const IntRect&);
+    static PassRefPtr<ImageBitmap> create(HTMLCanvasElement*, const IntRect&);
+    static PassRefPtr<ImageBitmap> create(ImageData*, const IntRect&);
+    static PassRefPtr<ImageBitmap> create(ImageBitmap*, const IntRect&);
 
-    BitmapImage* bitmapImage() const { return m_bitmap.get(); }
+    PassRefPtr<Image> bitmapImage() const;
 
-    int bitmapWidth() const { return m_bitmap->width(); }
-    int bitmapHeight() const { return m_bitmap->height(); }
-    IntSize bitmapSize() const { return m_bitmap->size(); }
+    int bitmapWidth() const { return m_bitmapSize.width(); }
+    int bitmapHeight() const { return m_bitmapSize.height(); }
+    IntSize bitmapSize() const { return m_bitmapSize; }
+
     IntPoint bitmapOffset() const { return m_bitmapOffset; }
 
-    int width() const { return m_size.width(); }
-    int height() const { return m_size.height(); }
-    IntSize size() const { return m_size; }
+    int width() const { return m_cropRect.width(); }
+    int height() const { return m_cropRect.height(); }
+    IntSize size() const { return m_cropRect.size(); }
 
     ~ImageBitmap() { };
 
 private:
-    ImageBitmap(HTMLImageElement*, IntRect);
-    ImageBitmap(HTMLVideoElement*, IntRect);
-    ImageBitmap(HTMLCanvasElement*, IntRect);
-    ImageBitmap(ImageData*, IntRect);
-    ImageBitmap(ImageBitmap*, IntRect);
+    ImageBitmap(HTMLImageElement*, const IntRect&);
+    ImageBitmap(HTMLVideoElement*, const IntRect&);
+    ImageBitmap(HTMLCanvasElement*, const IntRect&);
+    ImageBitmap(ImageData*, const IntRect&);
+    ImageBitmap(ImageBitmap*, const IntRect&);
 
-    RefPtr<BitmapImage> m_bitmap;
+    HTMLImageElement* imageElement() const { return m_imageElement; }
+
+    // The Image and HTMLImageElement are mutually exclusive

[Justin Novosad, 2013/07/19 21:09:53]

Missing period.

+    // ImageBitmaps derived from HTMLImageElements use m_imageElement

[Justin Novosad, 2013/07/19 21:09:53]

"derived" is a loaded term in C++. Say "constructed from" instead

+    // Other ImageBitmaps store an m_bitmap
+    HTMLImageElement* m_imageElement;

[Justin Novosad, 2013/07/19 21:09:53]

You should have a LayoutTest that creates an ImageBitmap from a temporary Image,
the triggers a garbage collect after the temporary image is out of scope.  This
code should fail that test. I think it should pass if you make m_imageElement a
RefPtr

+    RefPtr<Image> m_bitmap;
     OwnPtr<ImageBuffer> m_buffer;
 
     IntPoint m_bitmapOffset; // offset applied to the image when it is drawn to the context
-    IntSize m_size; // user defined size of the ImageBitmap
+    IntSize m_bitmapSize; // actual size of the BitmapImage
+    IntRect m_cropRect;
 };
 
 } // namespace WebCore
 
 #endif // ImageBitmap_h