# File lib/png/font.rb, line 26
  def coordinates c
    i = LETTERS.index c

    raise ArgumentError, "Can't find #{c.inspect}" unless i

    x = (i % 26) * width
    y = (3 - (i / 26)) * height # start from the top (3rd row)

    return x, y, x+width-1, y+height-1
  end