Function getRegion

dgl/src/Cairo.cpp:679–699

}

static cairo_surface_t* getRegion(cairo_surface_t* origsurface, int x, int y, int width, int height) noexcept
{
    const cairo_format_t format = cairo_image_surface_get_format(origsurface);
    DISTRHO_SAFE_ASSERT_RETURN(format != CAIRO_FORMAT_INVALID, nullptr);

    const int bpp = getBytesPerPixel(format);
    DISTRHO_SAFE_ASSERT_RETURN(bpp != 0, nullptr);

    const int fullWidth   = cairo_image_surface_get_width(origsurface);
    const int fullHeight  = cairo_image_surface_get_height(origsurface);
    const int stride      = cairo_image_surface_get_stride(origsurface);
    uchar* const fullData = cairo_image_surface_get_data(origsurface);

    x = (x < fullWidth) ? x : fullWidth;
    y = (y < fullHeight) ? y : fullHeight;
    width = (x + width < fullWidth) ? width : (fullWidth - x);
    height = (x + height < fullHeight) ? height : (fullHeight - x);

    uchar* const data = fullData + (x * bpp + y * stride);
    return cairo_image_surface_create_for_data(data, format, width, height, stride);
}

template <>
void ImageBaseKnob<CairoImage>::onDisplay()