C++ SkColorTable::readColors方法代码示例

    virtual Result onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                               const Options&,
                               SkPMColor ctableEntries[], int* ctableCount) override {
        SkMemoryStream stream(fData->data(), fData->size(), false);
        SkAutoTUnref<BareMemoryAllocator> allocator(SkNEW_ARGS(BareMemoryAllocator,
                                                               (info, pixels, rowBytes)));
        fDecoder->setAllocator(allocator);
        fDecoder->setRequireUnpremultipliedColors(kUnpremul_SkAlphaType == info.alphaType());

        SkBitmap bm;
        const SkImageDecoder::Result result = fDecoder->decode(&stream, &bm, info.colorType(),
                                                               SkImageDecoder::kDecodePixels_Mode);
        if (SkImageDecoder::kFailure == result) {
            return kInvalidInput;
        }

        SkASSERT(info.colorType() == bm.info().colorType());

        if (kIndex_8_SkColorType == info.colorType()) {
            SkASSERT(ctableEntries);

            SkColorTable* ctable = bm.getColorTable();
            if (NULL == ctable) {
                return kInvalidConversion;
            }
            const int count = ctable->count();
            memcpy(ctableEntries, ctable->readColors(), count * sizeof(SkPMColor));
            *ctableCount = count;
        }
        if (SkImageDecoder::kPartialSuccess == result) {
            return kIncompleteInput;
        }
        return kSuccess;
    }

/*  Fill out buffer with the compressed format Ganesh expects from a colortable
 based bitmap. [palette (colortable) + indices].

 At the moment Ganesh only supports 8bit version. If Ganesh allowed we others
 we could detect that the colortable.count is <= 16, and then repack the
 indices as nibbles to save RAM, but it would take more time (i.e. a lot
 slower than memcpy), so skipping that for now.

 Ganesh wants a full 256 palette entry, even though Skia's ctable is only as big
 as the colortable.count says it is.
 */
static void build_index8_data(void* buffer, const SkBitmap& bitmap) {
    SkASSERT(kIndex_8_SkColorType == bitmap.colorType());

    SkAutoLockPixels alp(bitmap);
    if (!bitmap.readyToDraw()) {
        SkDEBUGFAIL("bitmap not ready to draw!");
        return;
    }

    SkColorTable* ctable = bitmap.getColorTable();
    char* dst = (char*)buffer;

    const int count = ctable->count();

    SkDstPixelInfo dstPI;
    dstPI.fColorType = kRGBA_8888_SkColorType;
    dstPI.fAlphaType = kPremul_SkAlphaType;
    dstPI.fPixels = buffer;
    dstPI.fRowBytes = count * sizeof(SkPMColor);

    SkSrcPixelInfo srcPI;
    srcPI.fColorType = kN32_SkColorType;
    srcPI.fAlphaType = kPremul_SkAlphaType;
    srcPI.fPixels = ctable->readColors();
    srcPI.fRowBytes = count * sizeof(SkPMColor);

    srcPI.convertPixelsTo(&dstPI, count, 1);

    // always skip a full 256 number of entries, even if we memcpy'd fewer
    dst += 256 * sizeof(GrColor);

    if ((unsigned)bitmap.width() == bitmap.rowBytes()) {
        memcpy(dst, bitmap.getPixels(), bitmap.getSize());
    } else {
        // need to trim off the extra bytes per row
        size_t width = bitmap.width();
        size_t rowBytes = bitmap.rowBytes();
        const char* src = (const char*)bitmap.getPixels();
        for (int y = 0; y < bitmap.height(); y++) {
            memcpy(dst, src, width);
            src += rowBytes;
            dst += width;
        }
    }
}