Function scaleToTexture8bits_generic

Engine/ViewerInstance.cpp:2138–2365

template <typename PIX, int maxValue, bool opaque, bool applyMatte, int rOffset, int gOffset, int bOffset>
void
scaleToTexture8bits_generic(const RectI& roi,
                            const RenderViewerArgs & args,
                            int nComps,
                            ViewerInstance* viewer,
                            const UpdateViewerParams::CachedTile& tile,
                            U32* tileBuffer)
{
    const size_t pixelSize = sizeof(PIX);
    const bool luminance = (args.channels == eDisplayChannelsY);
    Image::ReadAccess acc = Image::ReadAccess( args.inputImage.get() );
    const RectI srcImgBounds = args.inputImage->getBounds();

    if ( (args.renderOnlyRoI && !tile.rect.contains(roi)) || (!args.renderOnlyRoI && !roi.contains(tile.rect)) ) {
        return;
    }
    assert(tile.rect.x2 > tile.rect.x1);

    int dstRowElements;
    U32* dst_pixels;
    if (args.renderOnlyRoI) {
        dstRowElements = tile.rect.width();
        dst_pixels = tileBuffer + (roi.y1 - tile.rect.y1) * dstRowElements + (roi.x1 - tile.rect.x1);
    } else {
        dstRowElements = args.tileRowElements;
        dst_pixels = tileBuffer + (tile.rect.y1 - tile.rectRounded.y1) * args.tileRowElements + (tile.rect.x1 - tile.rectRounded.x1);
    }

    const int y1 = args.renderOnlyRoI ? roi.y1 : tile.rect.y1;
    const int y2 = args.renderOnlyRoI ? roi.y2 : tile.rect.y2;
    const int x1 = args.renderOnlyRoI ? roi.x1 : tile.rect.x1;
    const int x2 = args.renderOnlyRoI ? roi.x2 : tile.rect.x2;
    const PIX* src_pixels = (const PIX*)acc.pixelAt(x1, y1);
    const int srcRowElements = (int)args.inputImage->getRowElements();
    Image::ReadAccessPtr matteAcc;
    if (applyMatte) {
        matteAcc = std::make_shared<Image::ReadAccess>( args.matteImage.get() );
    }

    for (int y = y1; y < y2;
         ++y,
         dst_pixels += dstRowElements) {
        // coverity[dont_call]
        int start = (int)( rand() % (x2 - x1) );


        for (int backward = 0; backward < 2; ++backward) {
            int index = backward ? start - 1 : start;

            assert( backward == 1 || ( index >= 0 && index < (x2 - x1) ) );

            unsigned error_r = 0x80;
            unsigned error_g = 0x80;
            unsigned error_b = 0x80;

            while (index < (x2 - x1) && index >= 0) {
                double r = 0.;
                double g = 0.;