C++ SkImageInfo::bytesPerPixel方法代码示例

bool SkPixmap::readPixels(const SkImageInfo& requestedDstInfo, void* dstPixels, size_t dstRB,
                          int x, int y) const {
    if (kUnknown_SkColorType == requestedDstInfo.colorType()) {
        return false;
    }
    if (nullptr == dstPixels || dstRB < requestedDstInfo.minRowBytes()) {
        return false;
    }
    if (0 == requestedDstInfo.width() || 0 == requestedDstInfo.height()) {
        return false;
    }
    
    SkIRect srcR = SkIRect::MakeXYWH(x, y, requestedDstInfo.width(), requestedDstInfo.height());
    if (!srcR.intersect(0, 0, this->width(), this->height())) {
        return false;
    }
    
    // the intersect may have shrunk info's logical size
    const SkImageInfo dstInfo = requestedDstInfo.makeWH(srcR.width(), srcR.height());
    
    // if x or y are negative, then we have to adjust pixels
    if (x > 0) {
        x = 0;
    }
    if (y > 0) {
        y = 0;
    }
    // here x,y are either 0 or negative
    dstPixels = ((char*)dstPixels - y * dstRB - x * dstInfo.bytesPerPixel());

    const SkImageInfo srcInfo = this->info().makeWH(dstInfo.width(), dstInfo.height());
    const void* srcPixels = this->addr(srcR.x(), srcR.y());
    return SkPixelInfo::CopyPixels(dstInfo, dstPixels, dstRB,
                                   srcInfo, srcPixels, this->rowBytes(), this->ctable());
}

static void assert_equal(skiatest::Reporter* reporter, SkImage* a, const SkIRect* subsetA,
                         SkImage* b) {
    const int widthA = subsetA ? subsetA->width() : a->width();
    const int heightA = subsetA ? subsetA->height() : a->height();

    REPORTER_ASSERT(reporter, widthA == b->width());
    REPORTER_ASSERT(reporter, heightA == b->height());
#if 0
    // see skbug.com/3965
    bool AO = a->isOpaque();
    bool BO = b->isOpaque();
    REPORTER_ASSERT(reporter, AO == BO);
#endif

    SkImageInfo info = SkImageInfo::MakeN32(widthA, heightA,
                                        a->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
    SkAutoPixmapStorage pmapA, pmapB;
    pmapA.alloc(info);
    pmapB.alloc(info);

    const int srcX = subsetA ? subsetA->x() : 0;
    const int srcY = subsetA ? subsetA->y() : 0;

    REPORTER_ASSERT(reporter, a->readPixels(pmapA, srcX, srcY));
    REPORTER_ASSERT(reporter, b->readPixels(pmapB, 0, 0));

    const size_t widthBytes = widthA * info.bytesPerPixel();
    for (int y = 0; y < heightA; ++y) {
        REPORTER_ASSERT(reporter, !memcmp(pmapA.addr32(0, y), pmapB.addr32(0, y), widthBytes));
    }
}

// If we already have a stored, can we reuse it instead of also storing b?
static bool equivalent(const SkBitmap& a, const SkBitmap& b) {
    if (a.info() != b.info() || a.pixelRefOrigin() != b.pixelRefOrigin()) {
        // Requiring a.info() == b.info() may be overkill in some cases (alphatype mismatch),
        // but it sure makes things easier to reason about below.
        return false;
    }
    if (a.pixelRef() == b.pixelRef()) {
        return true;  // Same shape and same pixels -> same bitmap.
    }

    // From here down we're going to have to look at the bitmap data, so we require pixelRefs().
    if (!a.pixelRef() || !b.pixelRef()) {
        return false;
    }

    // If the bitmaps have encoded data, check first before locking pixels so they don't decode.
    SkAutoTUnref<SkData> encA(a.pixelRef()->refEncodedData()),
                         encB(b.pixelRef()->refEncodedData());
    if (encA && encB) {
        return encA->equals(encB);
    } else if (encA || encB) {
        return false;   // One has encoded data but the other does not.
    }

    // As a last resort, we have to look at the pixels.  This will read back textures.
    SkAutoLockPixels al(a), bl(b);
    const char* ap = (const char*)a.getPixels();
    const char* bp = (const char*)b.getPixels();
    if (ap && bp) {
        // We check row by row; row bytes might differ.
        SkASSERT(a.info() == b.info());          // We checked this above.
        SkASSERT(a.info().bytesPerPixel() > 0);  // If we have pixelRefs, this better be true.
        const SkImageInfo info = a.info();
        const size_t bytesToCompare = info.width() * info.bytesPerPixel();
        for (int row = 0; row < info.height(); row++) {
            if (0 != memcmp(ap, bp, bytesToCompare)) {
                return false;
            }
            ap += a.rowBytes();
            bp += b.rowBytes();
        }
        return true;
    }
    return false;  // Couldn't get pixels for both bitmaps.
}

static bool choose_linear_pipeline(const SkShader::ContextRec& rec, const SkImageInfo& srcInfo) {
    // These src attributes are not supported in the new 4f context (yet)
    //
    if (srcInfo.colorType() != kRGBA_8888_SkColorType
        && srcInfo.colorType() != kBGRA_8888_SkColorType
        && srcInfo.colorType() != kIndex_8_SkColorType) {
        return false;
    }

#if 0   // later we may opt-in to the new code even if the client hasn't requested it...
    // These src attributes are only supported in the new 4f context
    //
    if (srcInfo.isSRGB() ||
        kUnpremul_SkAlphaType == srcInfo.alphaType() ||
        (4 == srcInfo.bytesPerPixel() && kN32_SkColorType != srcInfo.colorType()))
    {
        return true;
    }
#endif

    // If we get here, we can reasonably use either context, respect the caller's preference
    //
    return SkShader::ContextRec::kPM4f_DstType == rec.fPreferredDstType;
}

void SubsetSingleBench::onDraw(const int n, SkCanvas* canvas) {
    // When the color type is kIndex8, we will need to store the color table.  If it is
    // used, it will be initialized by the codec.
    int colorCount;
    SkPMColor colors[256];
    if (fUseCodec) {
        for (int count = 0; count < n; count++) {
            SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(fStream->duplicate()));
            const SkImageInfo info = codec->getInfo().makeColorType(fColorType);
            SkAutoTDeleteArray<uint8_t> row(SkNEW_ARRAY(uint8_t, info.minRowBytes()));
            SkScanlineDecoder* scanlineDecoder = codec->getScanlineDecoder(
                    info, NULL, colors, &colorCount);

            SkBitmap bitmap;
            bitmap.allocPixels(info.makeWH(fSubsetWidth, fSubsetHeight));

            scanlineDecoder->skipScanlines(fOffsetTop);
            uint32_t bpp = info.bytesPerPixel();
            for (uint32_t y = 0; y < fSubsetHeight; y++) {
                scanlineDecoder->getScanlines(row.get(), 1, 0);
                memcpy(bitmap.getAddr(0, y), row.get() + fOffsetLeft * bpp,
                        fSubsetWidth * bpp);
            }
        }
    } else {
        for (int count = 0; count < n; count++) {
            SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
            int width, height;
            decoder->buildTileIndex(fStream->duplicate(), &width, &height);
            SkBitmap bitmap;
            SkIRect rect = SkIRect::MakeXYWH(fOffsetLeft, fOffsetTop, fSubsetWidth,
                    fSubsetHeight);
            decoder->decodeSubset(&bitmap, rect, fColorType);
        }
    }
}

void SubsetZoomBench::onDraw(const int n, SkCanvas* canvas) {
    // When the color type is kIndex8, we will need to store the color table.  If it is
    // used, it will be initialized by the codec.
    int colorCount;
    SkPMColor colors[256];
    if (fUseCodec) {
        for (int count = 0; count < n; count++) {
            SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(
                    SkScanlineDecoder::NewFromStream(fStream->duplicate()));
            const SkImageInfo info = scanlineDecoder->getInfo().makeColorType(fColorType);
            SkAutoTDeleteArray<uint8_t> row(new uint8_t[info.minRowBytes()]);
            scanlineDecoder->start(info, nullptr, colors, &colorCount);

            const int centerX = info.width() / 2;
            const int centerY = info.height() / 2;
            int w = fSubsetWidth;
            int h = fSubsetHeight;
            do {
                const int subsetStartX = SkTMax(0, centerX - w / 2);
                const int subsetStartY = SkTMax(0, centerY - h / 2);
                const int subsetWidth = SkTMin(w, info.width() - subsetStartX);
                const int subsetHeight = SkTMin(h, info.height() - subsetStartY);
                // Note that if we subsetted and scaled in a single step, we could use the
                // same bitmap - as is often done in actual use cases.
                SkBitmap bitmap;
                SkImageInfo subsetInfo = info.makeWH(subsetWidth, subsetHeight);
                alloc_pixels(&bitmap, subsetInfo, colors, colorCount);

                uint32_t bpp = info.bytesPerPixel();
                scanlineDecoder->skipScanlines(subsetStartY);
                for (int y = 0; y < subsetHeight; y++) {
                    scanlineDecoder->getScanlines(row.get(), 1, 0);
                    memcpy(bitmap.getAddr(0, y), row.get() + subsetStartX * bpp,
                            subsetWidth * bpp);
                }
                w <<= 1;
                h <<= 1;
            } while (w < 2 * info.width() || h < 2 * info.height());
        }
    } else {
        for (int count = 0; count < n; count++) {
            int width, height;
            SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
            decoder->buildTileIndex(fStream->duplicate(), &width, &height);

            const int centerX = width / 2;
            const int centerY = height / 2;
            int w = fSubsetWidth;
            int h = fSubsetHeight;
            do {
                const int subsetStartX = SkTMax(0, centerX - w / 2);
                const int subsetStartY = SkTMax(0, centerY - h / 2);
                const int subsetWidth = SkTMin(w, width - subsetStartX);
                const int subsetHeight = SkTMin(h, height - subsetStartY);
                SkBitmap bitmap;
                SkIRect rect = SkIRect::MakeXYWH(subsetStartX, subsetStartY, subsetWidth,
                        subsetHeight);
                decoder->decodeSubset(&bitmap, rect, fColorType);
                w <<= 1;
                h <<= 1;
            } while (w < 2 * width || h < 2 * height);
        }
    }
}

void SubsetTranslateBench::onDraw(const int n, SkCanvas* canvas) {
    // When the color type is kIndex8, we will need to store the color table.  If it is
    // used, it will be initialized by the codec.
    int colorCount;
    SkPMColor colors[256];
    if (fUseCodec) {
        for (int count = 0; count < n; count++) {
            SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(
                    SkScanlineDecoder::NewFromStream(fStream->duplicate()));
            const SkImageInfo info = scanlineDecoder->getInfo().makeColorType(fColorType);
            SkAutoTDeleteArray<uint8_t> row(new uint8_t[info.minRowBytes()]);
            scanlineDecoder->start(info, nullptr, colors, &colorCount);

            SkBitmap bitmap;
            // Note that we use the same bitmap for all of the subsets.
            // It might be larger than necessary for the end subsets.
            SkImageInfo subsetInfo = info.makeWH(fSubsetWidth, fSubsetHeight);
            alloc_pixels(&bitmap, subsetInfo, colors, colorCount);

            for (int x = 0; x < info.width(); x += fSubsetWidth) {
                for (int y = 0; y < info.height(); y += fSubsetHeight) {
                    scanlineDecoder->skipScanlines(y);
                    const uint32_t currSubsetWidth =
                            x + (int) fSubsetWidth > info.width() ?
                            info.width() - x : fSubsetWidth;
                    const uint32_t currSubsetHeight =
                            y + (int) fSubsetHeight > info.height() ?
                            info.height() - y : fSubsetHeight;
                    const uint32_t bpp = info.bytesPerPixel();
                    for (uint32_t y = 0; y < currSubsetHeight; y++) {
                        scanlineDecoder->getScanlines(row.get(), 1, 0);
                        memcpy(bitmap.getAddr(0, y), row.get() + x * bpp,
                                currSubsetWidth * bpp);
                    }
                }
            }
        }
    } else {
        // We create a color table here to satisfy allocPixels() when the output
        // type is kIndex8.  It's okay that this is uninitialized since we never
        // use it.
        SkColorTable* colorTable = new SkColorTable(colors, 0);
        for (int count = 0; count < n; count++) {
            int width, height;
            SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
            decoder->buildTileIndex(fStream->duplicate(), &width, &height);
            SkBitmap bitmap;
            // Note that we use the same bitmap for all of the subsets.
            // It might be larger than necessary for the end subsets.
            // If we do not include this step, decodeSubset() would allocate space
            // for the pixels automatically, but this would not allow us to reuse the
            // same bitmap as the other subsets.  We want to reuse the same bitmap
            // because it gives a more fair comparison with SkCodec and is a common
            // use case of BitmapRegionDecoder.
            bitmap.allocPixels(SkImageInfo::Make(fSubsetWidth, fSubsetHeight,
                    fColorType, kOpaque_SkAlphaType), nullptr, colorTable);

            for (int x = 0; x < width; x += fSubsetWidth) {
                for (int y = 0; y < height; y += fSubsetHeight) {
                    const uint32_t currSubsetWidth = x + (int) fSubsetWidth > width ?
                            width - x : fSubsetWidth;
                    const uint32_t currSubsetHeight = y + (int) fSubsetHeight > height ?
                            height - y : fSubsetHeight;
                    SkIRect rect = SkIRect::MakeXYWH(x, y, currSubsetWidth,
                            currSubsetHeight);
                    decoder->decodeSubset(&bitmap, rect, fColorType);
                }
            }
        }
    }
}

bool SkPixelInfo::CopyPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRB,
                             const SkImageInfo& srcInfo, const void* srcPixels, size_t srcRB,
                             SkColorTable* ctable) {
    if (srcInfo.dimensions() != dstInfo.dimensions()) {
        return false;
    }

    const int width = srcInfo.width();
    const int height = srcInfo.height();

    // Handle fancy alpha swizzling if both are ARGB32
    if (4 == srcInfo.bytesPerPixel() && 4 == dstInfo.bytesPerPixel()) {
        SkDstPixelInfo dstPI;
        dstPI.fColorType = dstInfo.colorType();
        dstPI.fAlphaType = dstInfo.alphaType();
        dstPI.fPixels = dstPixels;
        dstPI.fRowBytes = dstRB;

        SkSrcPixelInfo srcPI;
        srcPI.fColorType = srcInfo.colorType();
        srcPI.fAlphaType = srcInfo.alphaType();
        srcPI.fPixels = srcPixels;
        srcPI.fRowBytes = srcRB;

        return srcPI.convertPixelsTo(&dstPI, width, height);
    }

    // If they agree on colorType and the alphaTypes are compatible, then we just memcpy.
    // Note: we've already taken care of 32bit colortypes above.
    if (srcInfo.colorType() == dstInfo.colorType()) {
        switch (srcInfo.colorType()) {
            case kRGB_565_SkColorType:
            case kAlpha_8_SkColorType:
                break;
            case kIndex_8_SkColorType:
            case kARGB_4444_SkColorType:
                if (srcInfo.alphaType() != dstInfo.alphaType()) {
                    return false;
                }
                break;
            default:
                return false;
        }
        rect_memcpy(dstPixels, dstRB, srcPixels, srcRB, width * srcInfo.bytesPerPixel(), height);
        return true;
    }

    /*
     *  Begin section where we try to change colorTypes along the way. Not all combinations
     *  are supported.
     */

    // Can no longer draw directly into 4444, but we can manually whack it for a few combinations
    if (kARGB_4444_SkColorType == dstInfo.colorType() &&
        (kN32_SkColorType == srcInfo.colorType() || kIndex_8_SkColorType == srcInfo.colorType())) {
        if (srcInfo.alphaType() == kUnpremul_SkAlphaType) {
            // Our method for converting to 4444 assumes premultiplied.
            return false;
        }

        const SkPMColor* table = NULL;
        if (kIndex_8_SkColorType == srcInfo.colorType()) {
            if (NULL == ctable) {
                return false;
            }
            table = ctable->readColors();
        }

        for (int y = 0; y < height; ++y) {
            DITHER_4444_SCAN(y);
            SkPMColor16* SK_RESTRICT dstRow = (SkPMColor16*)dstPixels;
            if (table) {
                const uint8_t* SK_RESTRICT srcRow = (const uint8_t*)srcPixels;
                for (int x = 0; x < width; ++x) {
                    dstRow[x] = SkDitherARGB32To4444(table[srcRow[x]], DITHER_VALUE(x));
                }
            } else {
                const SkPMColor* SK_RESTRICT srcRow = (const SkPMColor*)srcPixels;
                for (int x = 0; x < width; ++x) {
                    dstRow[x] = SkDitherARGB32To4444(srcRow[x], DITHER_VALUE(x));
                }
            }
            dstPixels = (char*)dstPixels + dstRB;
            srcPixels = (const char*)srcPixels + srcRB;
        }
        return true;
    }