# File examples/oo-board.rb, line 31
  def draw_squares()
    0.upto(@w / 2) { |x|
      0.upto(@h / 2) { |y|
        (0..1).each { |i|
          rect = [x * @bw * 2 + @bw * i, y * @bh * 2 + @bh * i, @bw, @bh]
          @im.fill_rect rect, @fg
        }
      }
    }
  end