SkRasterHandleAllocator.h

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/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef SkRasterHandleAllocator_DEFINED
#define SkRasterHandleAllocator_DEFINED
 
#include "include/core/SkImageInfo.h"
 
class SkBitmap;
class SkCanvas;
class SkMatrix;
 
class SK_API SkRasterHandleAllocator {
public:
    virtual ~SkRasterHandleAllocator() = default;
 
    // The value that is returned to clients of the canvas that has this allocator installed.
    typedef void* Handle;
 
    struct Rec {
        // When the allocation goes out of scope, this proc is called to free everything associated
        // with it: the pixels, the "handle", etc. This is passed the pixel address and fReleaseCtx.
        void    (*fReleaseProc)(void* pixels, void* ctx);
        void*   fReleaseCtx;    // context passed to fReleaseProc
        void*   fPixels;        // pixels for this allocation
        size_t  fRowBytes;      // rowbytes for these pixels
        Handle  fHandle;        // public handle returned by SkCanvas::accessTopRasterHandle()
    };
 
    virtual bool allocHandle(const SkImageInfo&, Rec*) = 0;
 
    virtual void updateHandle(Handle, const SkMatrix&, const SkIRect&) = 0;
 
    static std::unique_ptr<SkCanvas> MakeCanvas(std::unique_ptr<SkRasterHandleAllocator>,
                                                const SkImageInfo&, const Rec* rec = nullptr);
 
protected:
    SkRasterHandleAllocator() = default;
    SkRasterHandleAllocator(const SkRasterHandleAllocator&) = delete;
    SkRasterHandleAllocator& operator=(const SkRasterHandleAllocator&) = delete;
 
private:
    friend class SkBitmapDevice;
 
    Handle allocBitmap(const SkImageInfo&, SkBitmap*);
};
 
#endif