Moving GraphicsContext and dependencies from core to platform.

Source/core/platform/graphics/ImageDecodingStore.h

-/*
- * Copyright (C) 2012 Google Inc. 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.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef ImageDecodingStore_h
-#define ImageDecodingStore_h
-
-#include "SkSize.h"
-#include "SkTypes.h"
-#include "core/platform/graphics/DiscardablePixelRef.h"
-#include "core/platform/image-decoders/ImageDecoder.h"
-#include "platform/graphics/ScaledImageFragment.h"
-#include "platform/graphics/SkSizeHash.h"
-
-#include "wtf/DoublyLinkedList.h"
-#include "wtf/HashSet.h"
-#include "wtf/OwnPtr.h"
-#include "wtf/PassOwnPtr.h"
-#include "wtf/ThreadingPrimitives.h"
-#include "wtf/Vector.h"
-
-namespace WebCore {
-
-class ImageFrameGenerator;
-class SharedBuffer;
-
-// FUNCTION
-//
-// ImageDecodingStore is a class used to manage image cache objects. There are two
-// types of cache objects stored:
-//
-// 1. Image objects
-//    Each image object belongs to one frame decoded and/or resampled from an image
-//    file. The image object can be complete or partial. Complete means the image
-//    is fully decoded and will not mutate in future decoding passes. It can have
-//    multiple concurrent users. A partial image object has only one user.
-//
-// 2. Decoder objects
-//    A decoder object contains an image decoder. This allows decoding to resume
-//    from previous states. There can be one user per one decoder object at any
-//    time.
-//
-// EXTERNAL OBJECTS
-//
-// ScaledImageFragment
-//   A cached image object. Contains the bitmap and information about the bitmap
-//   image.
-//
-// ImageDecoder
-//   A decoder object. It is used to decode raw data into bitmap images.
-//
-// ImageFrameGenerator
-//   This is a direct user of this cache. Responsible for generating bitmap images
-//   using an ImageDecoder. It contains encoded image data and is used to represent
-//   one image file. It is used to index image and decoder objects in the cache.
-//
-// LazyDecodingPixelRef
-//   A read only user of this cache.
-//
-// THREAD SAFETY
-//
-// All public methods can be used on any thread.
-
-class ImageDecodingStore {
-public:
-    static PassOwnPtr<ImageDecodingStore> create() { return adoptPtr(new ImageDecodingStore); }
-    ~ImageDecodingStore();
-
-    static ImageDecodingStore* instance();
-    static void initializeOnce();
-    static void shutdown();
-
-    // Access a complete cached image object. A complete cached image object is
-    // indexed by the origin (ImageFrameGenerator), scaled size and frame index
-    // within the image file.
-    // Return true if the cache object is found.
-    // Return false if the cache object cannot be found or it is incomplete.
-    bool lockCache(const ImageFrameGenerator*, const SkISize& scaledSize, size_t index, const ScaledImageFragment**);
-    void unlockCache(const ImageFrameGenerator*, const ScaledImageFragment*);
-    const ScaledImageFragment* insertAndLockCache(const ImageFrameGenerator*, PassOwnPtr<ScaledImageFragment>);
-
-    // Access a cached decoder object. A decoder is indexed by origin (ImageFrameGenerator)
-    // and scaled size. Return true if the cached object is found.
-    bool lockDecoder(const ImageFrameGenerator*, const SkISize& scaledSize, ImageDecoder**);
-    void unlockDecoder(const ImageFrameGenerator*, const ImageDecoder*);
-    void insertDecoder(const ImageFrameGenerator*, PassOwnPtr<ImageDecoder>, bool isDiscardable);
-    void removeDecoder(const ImageFrameGenerator*, const ImageDecoder*);
-
-    // Locks the cache for safety, but does not attempt to lock the object we're checking for.
-    bool isCached(const ImageFrameGenerator*, const SkISize& scaledSize, size_t index);
-
-    // Remove all cache entries indexed by ImageFrameGenerator.
-    void removeCacheIndexedByGenerator(const ImageFrameGenerator*);
-
-    void clear();
-    void setCacheLimitInBytes(size_t);
-    size_t memoryUsageInBytes();
-    int cacheEntries();
-    int imageCacheEntries();
-    int decoderCacheEntries();
-
-private:
-    // Image cache entry is identified by:
-    // 1. Pointer to ImageFrameGenerator.
-    // 2. Size of the image.
-    // 3. Frame index.
-    // 4. Frame generation. Increments on each progressive decode.
-    //
-    // The use of generation ID is to allow multiple versions of an image frame
-    // be stored in the cache. Each generation comes from a progressive decode.
-    //
-    // Decoder entries are identified by (1) and (2) only.
-    typedef std::pair<const ImageFrameGenerator*, SkISize> DecoderCacheKey;
-    typedef std::pair<size_t, size_t> IndexAndGeneration;
-    typedef std::pair<DecoderCacheKey, IndexAndGeneration> ImageCacheKey;
-
-    // Base class for all cache entries.
-    class CacheEntry : public DoublyLinkedListNode<CacheEntry> {
-        friend class WTF::DoublyLinkedListNode<CacheEntry>;
-    public:
-        enum CacheType {
-            TypeImage,
-            TypeDecoder,
-        };
-
-        CacheEntry(const ImageFrameGenerator* generator, int useCount, bool isDiscardable)
-            : m_generator(generator)
-            , m_useCount(useCount)
-            , m_isDiscardable(isDiscardable)
-            , m_prev(0)
-            , m_next(0)
-        {
-        }
-
-        virtual ~CacheEntry()
-        {
-            ASSERT(!m_useCount);
-        }
-
-        const ImageFrameGenerator* generator() const { return m_generator; }
-        int useCount() const { return m_useCount; }
-        void incrementUseCount() { ++m_useCount; }
-        void decrementUseCount() { --m_useCount; ASSERT(m_useCount >= 0); }
-        bool isDiscardable() const { return m_isDiscardable; }
-
-        // FIXME: getSafeSize() returns size in bytes truncated to a 32-bits integer.
-        //        Find a way to get the size in 64-bits.
-        virtual size_t memoryUsageInBytes() const = 0;
-        virtual CacheType type() const = 0;
-
-    protected:
-        const ImageFrameGenerator* m_generator;
-        int m_useCount;
-        bool m_isDiscardable;
-
-    private:
-        CacheEntry* m_prev;
-        CacheEntry* m_next;
-    };
-
-    class ImageCacheEntry : public CacheEntry {
-    public:
-        static PassOwnPtr<ImageCacheEntry> createAndUse(const ImageFrameGenerator* generator, PassOwnPtr<ScaledImageFragment> image)
-        {
-            return adoptPtr(new ImageCacheEntry(generator, 1, image));
-        }
-
-        ImageCacheEntry(const ImageFrameGenerator* generator, int count, PassOwnPtr<ScaledImageFragment> image)
-            : CacheEntry(generator, count, DiscardablePixelRef::isDiscardable(image->bitmap().pixelRef()))
-            , m_cachedImage(image)
-        {
-        }
-
-        // FIXME: getSafeSize() returns size in bytes truncated to a 32-bits integer.
-        //        Find a way to get the size in 64-bits.
-        virtual size_t memoryUsageInBytes() const { return cachedImage()->bitmap().getSafeSize(); }
-        virtual CacheType type() const { return TypeImage; }
-
-        static ImageCacheKey makeCacheKey(const ImageFrameGenerator* generator, const SkISize& size, size_t index, size_t generation)
-        {
-            return std::make_pair(std::make_pair(generator, size), std::make_pair(index, generation));
-        }
-        ImageCacheKey cacheKey() const { return makeCacheKey(m_generator, m_cachedImage->scaledSize(), m_cachedImage->index(), m_cachedImage->generation()); }
-        const ScaledImageFragment* cachedImage() const { return m_cachedImage.get(); }
-        ScaledImageFragment* cachedImage() { return m_cachedImage.get(); }
-
-    private:
-        OwnPtr<ScaledImageFragment> m_cachedImage;
-    };
-
-    class DecoderCacheEntry : public CacheEntry {
-    public:
-        static PassOwnPtr<DecoderCacheEntry> create(const ImageFrameGenerator* generator, PassOwnPtr<ImageDecoder> decoder, bool isDiscardable)
-        {
-            return adoptPtr(new DecoderCacheEntry(generator, 0, decoder, isDiscardable));
-        }
-
-        DecoderCacheEntry(const ImageFrameGenerator* generator, int count, PassOwnPtr<ImageDecoder> decoder, bool isDiscardable)
-            : CacheEntry(generator, count, isDiscardable)
-            , m_cachedDecoder(decoder)
-            , m_size(SkISize::Make(m_cachedDecoder->decodedSize().width(), m_cachedDecoder->decodedSize().height()))
-        {
-        }
-
-        virtual size_t memoryUsageInBytes() const { return m_size.width() * m_size.height() * 4; }
-        virtual CacheType type() const { return TypeDecoder; }
-
-        static DecoderCacheKey makeCacheKey(const ImageFrameGenerator* generator, const SkISize& size)
-        {
-            return std::make_pair(generator, size);
-        }
-        static DecoderCacheKey makeCacheKey(const ImageFrameGenerator* generator, const ImageDecoder* decoder)
-        {
-            return std::make_pair(generator, SkISize::Make(decoder->decodedSize().width(), decoder->decodedSize().height()));
-        }
-        DecoderCacheKey cacheKey() const { return makeCacheKey(m_generator, m_size); }
-        ImageDecoder* cachedDecoder() const { return m_cachedDecoder.get(); }
-
-    private:
-        OwnPtr<ImageDecoder> m_cachedDecoder;
-        SkISize m_size;
-    };
-
-    ImageDecodingStore();
-
-    void prune();
-
-    // These helper methods are called while m_mutex is locked.
-
-    // Find and lock a cache entry, and return true on success.
-    // Memory of the cache entry can be discarded, in which case it is saved in
-    // deletionList.
-    bool lockCacheEntryInternal(ImageCacheEntry*, const ScaledImageFragment**, Vector<OwnPtr<CacheEntry> >* deletionList);
-
-    template<class T, class U, class V> void insertCacheInternal(PassOwnPtr<T> cacheEntry, U* cacheMap, V* identifierMap);
-
-    // Helper method to remove a cache entry. Ownership is transferred to
-    // deletionList. Use of Vector<> is handy when removing multiple entries.
-    template<class T, class U, class V> void removeFromCacheInternal(const T* cacheEntry, U* cacheMap, V* identifierMap, Vector<OwnPtr<CacheEntry> >* deletionList);
-
-    // Helper method to remove a cache entry. Uses the templated version base on
-    // the type of cache entry.
-    void removeFromCacheInternal(const CacheEntry*, Vector<OwnPtr<CacheEntry> >* deletionList);
-
-    // Helper method to remove all cache entries associated with a ImageFraneGenerator.
-    // Ownership of cache entries is transferred to deletionList.
-    template<class U, class V> void removeCacheIndexedByGeneratorInternal(U* cacheMap, V* identifierMap, const ImageFrameGenerator*, Vector<OwnPtr<CacheEntry> >* deletionList);
-
-    // Helper method to remove cache entry pointers from the LRU list.
-    void removeFromCacheListInternal(const Vector<OwnPtr<CacheEntry> >& deletionList);
-
-    void incrementMemoryUsage(size_t size) { m_memoryUsageInBytes += size; }
-    void decrementMemoryUsage(size_t size)
-    {
-        ASSERT(m_memoryUsageInBytes >= size);
-        m_memoryUsageInBytes -= size;
-    }
-
-    // A doubly linked list that maintains usage history of cache entries.
-    // This is used for eviction of old entries.
-    // Head of this list is the least recently used cache entry.
-    // Tail of this list is the most recently used cache entry.
-    DoublyLinkedList<CacheEntry> m_orderedCacheList;
-
-    // A lookup table for all image cache objects. Owns all image cache objects.
-    typedef HashMap<ImageCacheKey, OwnPtr<ImageCacheEntry> > ImageCacheMap;
-    ImageCacheMap m_imageCacheMap;
-
-    // A lookup table for all decoder cache objects. Owns all decoder cache objects.
-    typedef HashMap<DecoderCacheKey, OwnPtr<DecoderCacheEntry> > DecoderCacheMap;
-    DecoderCacheMap m_decoderCacheMap;
-
-    // A lookup table to map ImageFrameGenerator to all associated image
-    // cache keys.
-    typedef HashSet<ImageCacheKey> ImageCacheKeySet;
-    typedef HashMap<const ImageFrameGenerator*, ImageCacheKeySet> ImageCacheKeyMap;
-    ImageCacheKeyMap m_imageCacheKeyMap;
-
-    // A lookup table to map ImageFrameGenerator to all associated
-    // decoder cache keys.
-    typedef HashSet<DecoderCacheKey> DecoderCacheKeySet;
-    typedef HashMap<const ImageFrameGenerator*, DecoderCacheKeySet> DecoderCacheKeyMap;
-    DecoderCacheKeyMap m_decoderCacheKeyMap;
-
-    size_t m_cacheLimitInBytes;
-    size_t m_memoryUsageInBytes;
-
-    // Protect concurrent access to these members:
-    //   m_orderedCacheList
-    //   m_imageCacheMap, m_decoderCacheMap and all CacheEntrys stored in it
-    //   m_imageCacheKeyMap
-    //   m_decoderCacheKeyMap
-    //   m_cacheLimitInBytes
-    //   m_memoryUsageInBytes
-    // This mutex also protects calls to underlying skBitmap's
-    // lockPixels()/unlockPixels() as they are not threadsafe.
-    Mutex m_mutex;
-};
-
-} // namespace WebCore
-
-#endif