src/core/SkBitmapProcState.h

/*
** Copyright 2007, 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 SkBitmapProcState_DEFINED
#define SkBitmapProcState_DEFINED

#include "SkBitmap.h"
#include "SkMatrix.h"

class SkPaint;

struct SkBitmapProcState {

    typedef void (*ShaderProc32)(const SkBitmapProcState&, int x, int y,
                                 SkPMColor[], int count);

    typedef void (*ShaderProc16)(const SkBitmapProcState&, int x, int y,
                                 uint16_t[], int count);

    typedef void (*MatrixProc)(const SkBitmapProcState&,
                               uint32_t bitmapXY[],
                               int count,
                               int x, int y);
    
    typedef void (*SampleProc32)(const SkBitmapProcState&,
                                 const uint32_t[],
                                 int count,
                                 SkPMColor colors[]);

    typedef void (*SampleProc16)(const SkBitmapProcState&,
                                 const uint32_t[],
                                 int count,
                                 uint16_t colors[]);
    
    typedef U16CPU (*FixedTileProc)(SkFixed);   // returns 0..0xFFFF
    typedef U16CPU (*IntTileProc)(int value, int count);   // returns 0..count-1

    // If a shader proc is present, then the corresponding matrix/sample procs
    // are ignored
    ShaderProc32        fShaderProc32;      // chooseProcs
    ShaderProc16        fShaderProc16;      // chooseProcs
    // These are used if the shaderproc is NULL
    MatrixProc          fMatrixProc;        // chooseProcs
    SampleProc32        fSampleProc32;      // chooseProcs
    SampleProc16        fSampleProc16;      // chooseProcs

    const SkBitmap*     fBitmap;            // chooseProcs - orig or mip
    const SkMatrix*     fInvMatrix;         // chooseProcs
    SkMatrix::MapXYProc fInvProc;           // chooseProcs

    FixedTileProc       fTileProcX;         // chooseProcs
    FixedTileProc       fTileProcY;         // chooseProcs
    IntTileProc         fIntTileProcY;      // chooseProcs
    SkFixed             fFilterOneX;
    SkFixed             fFilterOneY;

    SkPMColor           fPaintPMColor;      // chooseProcs - A8 config
    SkFixed             fInvSx;             // chooseProcs
    SkFixed             fInvKy;             // chooseProcs
    uint16_t            fAlphaScale;        // chooseProcs
    uint8_t             fInvType;           // chooseProcs
    uint8_t             fTileModeX;         // CONSTRUCTOR
    uint8_t             fTileModeY;         // CONSTRUCTOR
    SkBool8             fDoFilter;          // chooseProcs

    /** Platforms implement this, and can optionally overwrite only the
        following fields:

        fShaderProc32
        fShaderProc16
        fMatrixProc
        fSampleProc32
        fSampleProc32

        They will already have valid function pointers, so a platform that does
        not have an accelerated version can just leave that field as is. A valid
        implementation can do nothing (see SkBitmapProcState_opts_none.cpp)
     */
    void platformProcs();

    /** Given the size of a buffer, to be used for calling the matrix and
        sample procs, this return the maximum count that can be stored in the
        buffer, taking into account that filtering and scale-vs-affine affect
        this value.
     
        Only valid to call after chooseProcs (setContext) has been called. It is
        safe to call this inside the shader's shadeSpan() method.
     */
    int maxCountForBufferSize(size_t bufferSize) const;

private:
    friend class SkBitmapProcShader;

    SkMatrix            fUnitInvMatrix;     // chooseProcs
    SkBitmap            fOrigBitmap;        // CONSTRUCTOR
    SkBitmap            fMipBitmap;

    MatrixProc chooseMatrixProc(bool trivial_matrix);
    bool chooseProcs(const SkMatrix& inv, const SkPaint&);
};

/*  Macros for packing and unpacking pairs of 16bit values in a 32bit uint.
    Used to allow access to a stream of uint16_t either one at a time, or
    2 at a time by unpacking a uint32_t
 */
#ifdef SK_CPU_BENDIAN
    #define PACK_TWO_SHORTS(pri, sec) ((pri) << 16 | (sec))
    #define UNPACK_PRIMARY_SHORT(packed)    ((uint32_t)(packed) >> 16)
    #define UNPACK_SECONDARY_SHORT(packed)  ((packed) & 0xFFFF)
#else
    #define PACK_TWO_SHORTS(pri, sec) ((pri) | ((sec) << 16))
    #define UNPACK_PRIMARY_SHORT(packed)    ((packed) & 0xFFFF)
    #define UNPACK_SECONDARY_SHORT(packed)  ((uint32_t)(packed) >> 16)
#endif

#ifdef SK_DEBUG
    static inline uint32_t pack_two_shorts(U16CPU pri, U16CPU sec) {
        SkASSERT((uint16_t)pri == pri);
        SkASSERT((uint16_t)sec == sec);
        return PACK_TWO_SHORTS(pri, sec);
    }
#else
    #define pack_two_shorts(pri, sec)   PACK_TWO_SHORTS(pri, sec)
#endif

#endif