def y=(val)
      left = x + center_x
      top = y + center_y

      if val < 0
        val = 0
      elsif val + image.height >= Window.height
        val = Window.height - image.height
      end
      super(val)

      draw_pen(left, top, x + center_x, y + center_y) if @enable_pen
    end
def y=(val)
      left = x + center_x
      top = y + center_y

      if val < 0
        val = 0
      elsif val + image.height >= Window.height
        val = Window.height - image.height
      end
      super(val)

      draw_pen(left, top, x + center_x, y + center_y) if @enable_pen
    end
Y座標を(  )にする