MODULE Bitmap;

PROCEDURE NewImage(height, width: UByte): T RAISES {BadImage} =
  (* To make things easier, limit image size to also
     be UByte (0 to 255), and to have equal dimensions. *)
  BEGIN
    IF height # width THEN
      RAISE BadImage;
    END;
    RETURN NEW(T, height, width);
  END NewImage;

PROCEDURE Fill(VAR pic: T; color: Pixel) =
  BEGIN
    FOR i := FIRST(pic^) TO LAST(pic^) DO
      FOR j := FIRST(pic[0]) TO LAST(pic[0]) DO
        pic[i,j] := color;
      END;
    END;
  END Fill;

PROCEDURE GetPixel(VAR pic: T; point: Point): Pixel RAISES {BadColor} =
  VAR pixel := pic[point.x, point.y];
  BEGIN
    IF pixel = White THEN
      RETURN White;
    ELSIF pixel = Black THEN
      RETURN Black;
    ELSIF pixel = Red THEN
      RETURN Red;
    ELSIF pixel = Green THEN
      RETURN Green;
    ELSIF pixel = Blue THEN
      RETURN Blue;
    ELSIF pixel = Yellow THEN
      RETURN Yellow;
    ELSE
      RAISE BadColor;
    END;
  END GetPixel;

PROCEDURE SetPixel(VAR pic: T; point: Point; color: Pixel) =
  BEGIN
    pic[point.x, point.y] := color;
  END SetPixel;

BEGIN
END Bitmap.