public unsafe static Color GetColor(this BitmapData data, int x, int y)
        {
            bool  alpha = data.HasAlpha();
            byte *ptr   = data.PtrAt(x, y);

            if (alpha)
            {
                return(Color.FromArgb(ptr[3], ptr[2], ptr[1], ptr[0]));
            }
            else
            {
                return(Color.FromArgb(ptr[2], ptr[1], ptr[0]));
            }
        }
        public unsafe static bool MatchesColor(this BitmapData data, int x, int y, Color color)
        {
            bool  alpha = data.HasAlpha();
            byte *ptr   = data.PtrAt(x, y);

            if (alpha)
            {
                return(color.R == ptr[2] && color.G == ptr[1] &&
                       color.B == ptr[0] && color.A == ptr[3]);
            }
            else
            {
                return(color.R == ptr[2] && color.G == ptr[1] &&
                       color.B == ptr[0] && color.A == 255);
            }
        }
        public unsafe static void SetColor(this BitmapData data, int x, int y, Color color)
        {
            bool  alpha = data.HasAlpha();
            byte *ptr   = data.PtrAt(x, y);

            if (alpha)
            {
                ptr[2] = color.R;
                ptr[1] = color.G;
                ptr[0] = color.B;
                ptr[3] = color.A;
            }
            else
            {
                ptr[2] = color.R;
                ptr[1] = color.G;
                ptr[0] = color.B;
            }
        }
 private unsafe static byte *PtrAt(this BitmapData data, Point point)
 => data.PtrAt(point.X, point.Y);