src/core/SkBitmapProcShader.h

/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef SkBitmapProcShader_DEFINED
#define SkBitmapProcShader_DEFINED

#include "SkShader.h"
#include "SkSmallAllocator.h"

struct SkBitmapProcState;
class SkBitmapProvider;

class SkBitmapProcShader : public SkShader {
public:
    SkBitmapProcShader(const SkBitmap& src, TileMode tx, TileMode ty,
                       const SkMatrix* localMatrix = nullptr);

    bool isOpaque() const override;

    size_t contextSize(const ContextRec&) const override { return ContextSize(); }

    SK_TO_STRING_OVERRIDE()
    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBitmapProcShader)

#if SK_SUPPORT_GPU
    const GrFragmentProcessor* asFragmentProcessor(GrContext*, const SkMatrix& viewM,
                                                   const SkMatrix*, SkFilterQuality) const override;
#endif

protected:
    class BitmapProcShaderContext : public SkShader::Context {
    public:
        // The context takes ownership of the state. It will call its destructor
        // but will NOT free the memory.
        BitmapProcShaderContext(const SkShader&, const ContextRec&, SkBitmapProcState*);
        ~BitmapProcShaderContext() override;

        void shadeSpan(int x, int y, SkPMColor dstC[], int count) override;
        ShadeProc asAShadeProc(void** ctx) override;

        uint32_t getFlags() const override { return fFlags; }

    private:
        SkBitmapProcState*  fState;
        uint32_t            fFlags;

        typedef SkShader::Context INHERITED;
    };
    
    void flatten(SkWriteBuffer&) const override;
    Context* onCreateContext(const ContextRec&, void* storage) const override;
    bool onIsABitmap(SkBitmap*, SkMatrix*, TileMode*) const override;

    SkBitmap    fRawBitmap;   // experimental for RLE encoding
    uint8_t     fTileModeX, fTileModeY;

private:
    friend class SkImageShader;

    static size_t ContextSize();
    static Context* MakeContext(const SkShader&, TileMode tmx, TileMode tmy,
                                const SkBitmapProvider&, const ContextRec&, void* storage);

    typedef SkShader INHERITED;
};

// Commonly used allocator. It currently is only used to allocate up to 3 objects. The total
// bytes requested is calculated using one of our large shaders, its context size plus the size of
// an Sk3DBlitter in SkDraw.cpp
// Note that some contexts may contain other contexts (e.g. for compose shaders), but we've not
// yet found a situation where the size below isn't big enough.
typedef SkSmallAllocator<3, 1500> SkTBlitterAllocator;

// If alloc is non-nullptr, it will be used to allocate the returned SkShader, and MUST outlive
// the SkShader.
SkShader* SkCreateBitmapShader(const SkBitmap& src, SkShader::TileMode, SkShader::TileMode,
                               const SkMatrix* localMatrix, SkTBlitterAllocator* alloc);

#endif