If font is 1, 2, 3, 4 or 5, a built-in font is used (with higher numbers corresponding to larger fonts).
ImageChar() draws the first character of c in the image identified by id with its upper-left at x, y (top left is 0, 0) with the color col. If font is 1, 2, 3, 4 or 5, a built-in font is used (with higher numbers corresponding to larger fonts).