src/codec/SkMaskSwizzler.cpp

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkCodecPriv.h"
#include "SkColorPriv.h"
#include "SkMaskSwizzler.h"

static SkSwizzler::ResultAlpha swizzle_mask16_to_n32_opaque(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    uint16_t* srcPtr = (uint16_t*) srcRow;
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    for (int i = 0; i < width; i++) {
        uint16_t p = srcPtr[i];
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        dstPtr[i] = SkPackARGB32NoCheck(0xFF, red, green, blue);
    }
    return SkSwizzler::kOpaque_ResultAlpha;
}

static SkSwizzler::ResultAlpha swizzle_mask16_to_n32_unpremul(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    uint16_t* srcPtr = (uint16_t*) srcRow;
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    INIT_RESULT_ALPHA;
    for (int i = 0; i < width; i++) {
        uint16_t p = srcPtr[i];
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        uint8_t alpha = masks->getAlpha(p);
        UPDATE_RESULT_ALPHA(alpha);
        dstPtr[i] = SkPackARGB32NoCheck(alpha, red, green, blue);
    }
    return COMPUTE_RESULT_ALPHA;
}

static SkSwizzler::ResultAlpha swizzle_mask16_to_n32_premul(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    uint16_t* srcPtr = (uint16_t*) srcRow;
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    INIT_RESULT_ALPHA;
    for (int i = 0; i < width; i++) {
        uint16_t p = srcPtr[i];
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        uint8_t alpha = masks->getAlpha(p);
        UPDATE_RESULT_ALPHA(alpha);
        dstPtr[i] = SkPreMultiplyARGB(alpha, red, green, blue);
    }
    return COMPUTE_RESULT_ALPHA;
}

static SkSwizzler::ResultAlpha swizzle_mask24_to_n32_opaque(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    for (int i = 0; i < 3*width; i += 3) {
        uint32_t p = srcRow[i] | (srcRow[i + 1] << 8) | srcRow[i + 2] << 16;
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        dstPtr[i/3] = SkPackARGB32NoCheck(0xFF, red, green, blue);
    }
    return SkSwizzler::kOpaque_ResultAlpha;
}

static SkSwizzler::ResultAlpha swizzle_mask24_to_n32_unpremul(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    INIT_RESULT_ALPHA;
    for (int i = 0; i < 3*width; i += 3) {
        uint32_t p = srcRow[i] | (srcRow[i + 1] << 8) | srcRow[i + 2] << 16;
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        uint8_t alpha = masks->getAlpha(p);
        UPDATE_RESULT_ALPHA(alpha);
        dstPtr[i/3] = SkPackARGB32NoCheck(alpha, red, green, blue);
    }
    return COMPUTE_RESULT_ALPHA;
}

static SkSwizzler::ResultAlpha swizzle_mask24_to_n32_premul(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    INIT_RESULT_ALPHA;
    for (int i = 0; i < 3*width; i += 3) {
        uint32_t p = srcRow[i] | (srcRow[i + 1] << 8) | srcRow[i + 2] << 16;
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        uint8_t alpha = masks->getAlpha(p);
        UPDATE_RESULT_ALPHA(alpha);
        dstPtr[i/3] = SkPreMultiplyARGB(alpha, red, green, blue);
    }
    return COMPUTE_RESULT_ALPHA;
}

static SkSwizzler::ResultAlpha swizzle_mask32_to_n32_opaque(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    uint32_t* srcPtr = (uint32_t*) srcRow;
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    for (int i = 0; i < width; i++) {
        uint32_t p = srcPtr[i];
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        dstPtr[i] = SkPackARGB32NoCheck(0xFF, red, green, blue);
    }
    return SkSwizzler::kOpaque_ResultAlpha;
}

static SkSwizzler::ResultAlpha swizzle_mask32_to_n32_unpremul(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    uint32_t* srcPtr = (uint32_t*) srcRow;
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    INIT_RESULT_ALPHA;
    for (int i = 0; i < width; i++) {
        uint32_t p = srcPtr[i];
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        uint8_t alpha = masks->getAlpha(p);
        UPDATE_RESULT_ALPHA(alpha);
        dstPtr[i] = SkPackARGB32NoCheck(alpha, red, green, blue);
    }
    return COMPUTE_RESULT_ALPHA;
}

static SkSwizzler::ResultAlpha swizzle_mask32_to_n32_premul(
        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {

    // Use the masks to decode to the destination
    uint32_t* srcPtr = (uint32_t*) srcRow;
    SkPMColor* dstPtr = (SkPMColor*) dstRow;
    INIT_RESULT_ALPHA;
    for (int i = 0; i < width; i++) {
        uint32_t p = srcPtr[i];
        uint8_t red = masks->getRed(p);
        uint8_t green = masks->getGreen(p);
        uint8_t blue = masks->getBlue(p);
        uint8_t alpha = masks->getAlpha(p);
        UPDATE_RESULT_ALPHA(alpha);
        dstPtr[i] = SkPreMultiplyARGB(alpha, red, green, blue);
    }
    return COMPUTE_RESULT_ALPHA;
}

/*
 *
 * Create a new mask swizzler
 *
 */
SkMaskSwizzler* SkMaskSwizzler::CreateMaskSwizzler(
        const SkImageInfo& info, void* dst, size_t dstRowBytes, SkMasks* masks,
        uint32_t bitsPerPixel) {

    // Choose the appropriate row procedure
    RowProc proc = NULL;
    switch (bitsPerPixel) {
        case 16:
            switch (info.colorType()) {
                case kN32_SkColorType:
                    switch (info.alphaType()) {
                        case kUnpremul_SkAlphaType:
                            proc = &swizzle_mask16_to_n32_unpremul;
                            break;
                        case kPremul_SkAlphaType:
                            proc = &swizzle_mask16_to_n32_premul;
                            break;
                        case kOpaque_SkAlphaType:
                            proc = &swizzle_mask16_to_n32_opaque;
                            break;
                        default:
                            break;
                    }
                    break;
                default:
                    break;
            }
            break;
        case 24:
            switch (info.colorType()) {
                case kN32_SkColorType:
                    switch (info.alphaType()) {
                        case kUnpremul_SkAlphaType:
                            proc = &swizzle_mask24_to_n32_unpremul;
                            break;
                        case kPremul_SkAlphaType:
                            proc = &swizzle_mask24_to_n32_premul;
                            break;
                        case kOpaque_SkAlphaType:
                            proc = &swizzle_mask24_to_n32_opaque;
                            break;
                        default:
                            break;
                    }
                    break;
                default:
                    break;
            }
            break;
        case 32:
            switch (info.colorType()) {
                case kN32_SkColorType:
                    switch (info.alphaType()) {
                        case kUnpremul_SkAlphaType:
                            proc = &swizzle_mask32_to_n32_unpremul;
                            break;
                        case kPremul_SkAlphaType:
                            proc = &swizzle_mask32_to_n32_premul;
                            break;
                        case kOpaque_SkAlphaType:
                            proc = &swizzle_mask32_to_n32_opaque;
                            break;
                        default:
                            break;
                    }
                    break;
                default:
                    break;
            }
            break;
        default:
            SkASSERT(false);
            return NULL;
    }
    return SkNEW_ARGS(SkMaskSwizzler, (info, dst, dstRowBytes, masks, proc));
}

/*
 *
 * Constructor for mask swizzler
 *
 */
SkMaskSwizzler::SkMaskSwizzler(const SkImageInfo& dstInfo, void* dst,
                               size_t dstRowBytes, SkMasks* masks, RowProc proc)
    : fDstInfo(dstInfo)
    , fDst(dst)
    , fDstRowBytes(dstRowBytes)
    , fMasks(masks)
    , fRowProc(proc)
{}

/*
 *
 * Swizzle the specified row
 *
 */
SkSwizzler::ResultAlpha SkMaskSwizzler::next(const uint8_t* SK_RESTRICT src,
        int y) {
    // Choose the row
    void* row = SkTAddOffset<void>(fDst, y*fDstRowBytes);

    // Decode the row
    return fRowProc(row, src, fDstInfo.width(), fMasks);
}