Accord.Imaging.Filters.CanvasFill.ProcessFilter C# (CSharp) Method

        protected override unsafe void ProcessFilter(UnmanagedImage image)
        {
            int pixelSize = Image.GetPixelFormatSize(image.PixelFormat) / 8;

            // get image width and height
            int width = image.Width;
            int height = image.Height;

            // start (X, Y) point of filling region
            int startX = Math.Max(0, region.X);
            int startY = Math.Max(0, region.Y);

            // check if there is nothing to do
            if ((startX >= width) || (startY >= height))
                return;

            // stop (X, Y) point of filling region
            int stopX = Math.Min(width, region.Right);
            int stopY = Math.Min(height, region.Bottom);

            // check if there is nothing to do
            if ((stopX <= startX) || (stopY <= startY))
                return;

            int stride = image.Stride;

            // do the job
            byte* ptr = (byte*)image.ImageData.ToPointer() + startY * stride + startX * pixelSize;

            if (image.PixelFormat == PixelFormat.Format8bppIndexed)
            {
                // grayscale image
                int fillWidth = stopX - startX;

                for (int y = startY; y < stopY; y++)
                {
                    Accord.SystemTools.SetUnmanagedMemory(ptr, fillGray, fillWidth);
                    ptr += stride;
                }
            }
            else
            {
                // color image
                int offset = stride - (stopX - startX) * pixelSize;

                for (int y = startY; y < stopY; y++)
                {
                    for (int x = startX; x < stopX; x++, ptr += pixelSize)
                    {
                        ptr[RGB.R] = fillRed;
                        ptr[RGB.G] = fillGreen;
                        ptr[RGB.B] = fillBlue;
                    }
                    ptr += offset;
                }
            }
        }
    }