android_frameworks_base/libs/hwui/ResourceCache.h

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ANDROID_HWUI_RESOURCE_CACHE_H
#define ANDROID_HWUI_RESOURCE_CACHE_H

#include <cutils/compiler.h>

#include <SkBitmap.h>
#include <SkPixelRef.h>

#include <utils/KeyedVector.h>
#include <utils/Singleton.h>

#include <androidfw/ResourceTypes.h>

namespace android {
namespace uirenderer {

class Layer;

/**
 * Type of Resource being cached
 */
enum ResourceType {
    kNinePatch,
};

class ResourceReference {
public:

    ResourceReference(ResourceType type) {
        refCount = 0; destroyed = false; resourceType = type;
    }

    int refCount;
    bool destroyed;
    ResourceType resourceType;
};

class BitmapKey {
public:
    BitmapKey(const SkBitmap* bitmap)
        : mRefCount(1)
        , mBitmapDimensions(bitmap->dimensions())
        , mPixelRefOrigin(bitmap->pixelRefOrigin())
        , mPixelRefStableID(bitmap->pixelRef()->getStableID()) { }

    void operator=(const BitmapKey& other);
    bool operator==(const BitmapKey& other) const;
    bool operator<(const BitmapKey& other) const;

private:
    // This constructor is only used by the KeyedVector implementation
    BitmapKey()
        : mRefCount(-1)
        , mBitmapDimensions(SkISize::Make(0,0))
        , mPixelRefOrigin(SkIPoint::Make(0,0))
        , mPixelRefStableID(0) { }

    // reference count of all HWUI object using this bitmap
    mutable int mRefCount;

    SkISize mBitmapDimensions;
    SkIPoint mPixelRefOrigin;
    uint32_t mPixelRefStableID;

    friend class ResourceCache;
    friend struct android::key_value_pair_t<BitmapKey, SkBitmap*>;
};

class ANDROID_API ResourceCache: public Singleton<ResourceCache> {
    ResourceCache();
    ~ResourceCache();

    friend class Singleton<ResourceCache>;

public:

    /**
     * When using these two methods, make sure to only invoke the *Locked()
     * variants of increment/decrementRefcount(), recyle() and destructor()
     */
    void lock();
    void unlock();

    /**
     * The cache stores a copy of the provided resource or refs an existing resource
     * if the bitmap has previously been inserted and returns the cached copy.
     */
    const SkBitmap* insert(const SkBitmap* resource);

    void incrementRefcount(const Res_png_9patch* resource);

    void decrementRefcount(const SkBitmap* resource);
    void decrementRefcount(const Res_png_9patch* resource);

    void decrementRefcountLocked(const SkBitmap* resource);
    void decrementRefcountLocked(const Res_png_9patch* resource);

    void destructor(Res_png_9patch* resource);

    void destructorLocked(Res_png_9patch* resource);

private:
    void deleteResourceReferenceLocked(const void* resource, ResourceReference* ref);

    void incrementRefcount(void* resource, ResourceType resourceType);
    void incrementRefcountLocked(void* resource, ResourceType resourceType);

    void decrementRefcount(void* resource);
    void decrementRefcountLocked(void* resource);

    void logCache();

    /**
     * Used to increment, decrement, and destroy. Incrementing is generally accessed on the UI
     * thread, but destroying resources may be called from the GC thread, the finalizer thread,
     * or a reference queue finalization thread.
     */
    mutable Mutex mLock;

    KeyedVector<const void*, ResourceReference*>* mCache;
    KeyedVector<BitmapKey, SkBitmap*> mBitmapCache;
};

}; // namespace uirenderer
}; // namespace android

#endif // ANDROID_HWUI_RESOURCE_CACHE_H