public RawPixel(RawMap <T> map) : this(map, 0, 0, map.Width *map.Height) { }
public RawPixel(RawMap <T> map, int x, int y) : this(map, x, y, map.Width *map.Height) { }
public RawPixel(RawMap <T> map, int x, int y, int limit) { _map = map; _limit = limit; _index = y * map.Width + x; }