src/core/SkBitmapProcState_matrix.h

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkMath.h"
#include "SkMathPriv.h"

#define SCALE_FILTER_NAME       MAKENAME(_filter_scale)

#define PACK_FILTER_X_NAME  MAKENAME(_pack_filter_x)
#define PACK_FILTER_Y_NAME  MAKENAME(_pack_filter_y)

#ifndef PREAMBLE
    #define PREAMBLE(state)
    #define PREAMBLE_PARAM_X
    #define PREAMBLE_PARAM_Y
    #define PREAMBLE_ARG_X
    #define PREAMBLE_ARG_Y
#endif

// declare functions externally to suppress warnings.
void SCALE_FILTER_NAME(const SkBitmapProcState& s,
                              uint32_t xy[], int count, int x, int y);

static inline uint32_t PACK_FILTER_Y_NAME(SkFixed f, unsigned max,
                                          SkFixed one PREAMBLE_PARAM_Y) {
    unsigned i = TILEY_PROCF(f, max);
    i = (i << 4) | EXTRACT_LOW_BITS(f, max);
    return (i << 14) | (TILEY_PROCF((f + one), max));
}

static inline uint32_t PACK_FILTER_X_NAME(SkFixed f, unsigned max,
                                          SkFixed one PREAMBLE_PARAM_X) {
    unsigned i = TILEX_PROCF(f, max);
    i = (i << 4) | EXTRACT_LOW_BITS(f, max);
    return (i << 14) | (TILEX_PROCF((f + one), max));
}

void SCALE_FILTER_NAME(const SkBitmapProcState& s,
                              uint32_t xy[], int count, int x, int y) {
    SkASSERT((s.fInvType & ~(SkMatrix::kTranslate_Mask |
                             SkMatrix::kScale_Mask)) == 0);
    SkASSERT(s.fInvKy == 0);

    PREAMBLE(s);

    const unsigned maxX = s.fPixmap.width() - 1;
    const SkFixed one = s.fFilterOneX;
    const SkFractionalInt dx = s.fInvSxFractionalInt;
    SkFractionalInt fx;

    {
        const SkBitmapProcStateAutoMapper mapper(s, x, y);
        const SkFixed fy = mapper.fixedY();
        const unsigned maxY = s.fPixmap.height() - 1;
        // compute our two Y values up front
        *xy++ = PACK_FILTER_Y_NAME(fy, maxY, s.fFilterOneY PREAMBLE_ARG_Y);
        // now initialize fx
        fx = mapper.fractionalIntX();
    }

#ifdef CHECK_FOR_DECAL
    const SkFixed fixedFx = SkFractionalIntToFixed(fx);
    const SkFixed fixedDx = SkFractionalIntToFixed(dx);
    if (can_truncate_to_fixed_for_decal(fixedFx, fixedDx, count, maxX)) {
        decal_filter_scale(xy, fixedFx, fixedDx, count);
    } else
#endif
    {
        do {
            SkFixed fixedFx = SkFractionalIntToFixed(fx);
            *xy++ = PACK_FILTER_X_NAME(fixedFx, maxX, one PREAMBLE_ARG_X);
            fx += dx;
        } while (--count != 0);
    }
}

#undef MAKENAME
#undef TILEX_PROCF
#undef TILEY_PROCF
#ifdef CHECK_FOR_DECAL
    #undef CHECK_FOR_DECAL
#endif

#undef SCALE_FILTER_NAME

#undef PREAMBLE
#undef PREAMBLE_PARAM_X
#undef PREAMBLE_PARAM_Y
#undef PREAMBLE_ARG_X
#undef PREAMBLE_ARG_Y

#undef EXTRACT_LOW_BITS