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 * modification, are permitted provided that the following conditions are
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 * 
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
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#ifndef NativeImageSkia_h
#define NativeImageSkia_h

#include "SkBitmap.h"
#include "SkRect.h"
#include "SkSize.h"
#include <wtf/Forward.h>

namespace WebCore {

// This object is used as the "native image" in our port. When WebKit uses
// "NativeImagePtr", it is a pointer to this type. It has an SkBitmap, and also
// stores a cached resized image.
class NativeImageSkia {
public:
    NativeImageSkia();
    ~NativeImageSkia();

    // This constructor does a shallow copy of the passed-in SkBitmap (ie., it
    // references the same pixel data and bumps the refcount).  Use only when
    // you want sharing semantics.
    NativeImageSkia(const SkBitmap&, float resolutionScale);

    // Returns the number of bytes of image data. This includes the cached
    // resized version if there is one.
    int decodedSize() const;

    // Sets the immutable flag on the bitmap, indicating that the image data
    // will not be modified any further. This is called by the image decoder
    // when all data is complete, used by us to know whether we can cache
    // resized images, and used by Skia for various optimizations.
    void setDataComplete() { m_image.setImmutable(); }

    // Returns true if the entire image has been decoded.
    bool isDataComplete() const { return m_image.isImmutable(); }

    // Get reference to the internal SkBitmap representing this image.
    const SkBitmap& bitmap() const { return m_image; }
    SkBitmap& bitmap() { return m_image; }

    float resolutionScale() const { return m_resolutionScale; }

    // We can keep a resized version of the bitmap cached on this object.
    // This function will return true if there is a cached version of the given
    // scale and subset.
    bool hasResizedBitmap(const SkISize& scaledImageSize, const SkIRect& scaledImageSubset) const;

    // This will return an existing resized image subset, or generate a new one
    // of the specified size and subset and possibly cache it.
    //
    // scaledImageSize
    // Dimensions of the scaled full image.
    //
    // scaledImageSubset
    // Rectangle of the subset in the scaled image.
    SkBitmap resizedBitmap(const SkISize& scaledImageSize, const SkIRect& scaledImageSubset) const;

    void reportMemoryUsage(MemoryObjectInfo*) const;

private:
    // CachedImageInfo is used to uniquely identify cached or requested image
    // resizes.
    // Image resize is identified by the scaled image size and scaled image subset.
    struct CachedImageInfo {
        SkISize scaledImageSize;
        SkIRect scaledImageSubset;

        CachedImageInfo();

        bool isEqual(const SkISize& otherScaledImageSize, const SkIRect& otherScaledImageSubset) const;
        void set(const SkISize& otherScaledImageSize, const SkIRect& otherScaledImageSubset);
        SkIRect rectInSubset(const SkIRect& otherScaledImageRect);
    };

    // Returns true if the given resize operation should either resize the whole
    // image and cache it, or resize just the part it needs and throw the result
    // away.
    //
    // Calling this function may increment a request count that can change the
    // result of subsequent calls.
    //
    // On the one hand, if only a small subset is desired, then we will waste a
    // lot of time resampling the entire thing, so we only want to do exactly
    // what's required. On the other hand, resampling the entire bitmap is
    // better if we're going to be using it more than once (like a bitmap
    // scrolling on and off the screen. Since we only cache when doing the
    // entire thing, it's best to just do it up front.
    bool shouldCacheResampling(const SkISize& scaledImageSize, const SkIRect& scaledImageSubset) const;

    // The original image.
    SkBitmap m_image;
    float m_resolutionScale;

    // The cached bitmap fragment. This is a subset of the scaled version of
    // |m_image|. empty() returns true if there is no cached image.
    mutable SkBitmap m_resizedImage;

    // References how many times that the image size has been requested for
    // the last size.
    //
    // Every time we get a call to shouldCacheResampling, if it matches the
    // m_cachedImageInfo, we'll increment the counter, and if not, we'll reset
    // the counter and save the dimensions.
    //
    // This allows us to see if many requests have been made for the same
    // resized image, we know that we should probably cache it, even if all of
    // those requests individually are small and would not otherwise be cached.
    //
    // We also track scaling information and destination subset for the scaled
    // image. See comments for CachedImageInfo.
    mutable CachedImageInfo m_cachedImageInfo;
    mutable int m_resizeRequests;
};

}
#endif  // NativeImageSkia_h