def draw_line(x1, y1, x2, y2)
      @context.drawLine(x1, y1, x2, y2)
    end
def draw_line(x1, y1, x2, y2)
      @context.drawLine(x1, y1, x2, y2)
    end
Draws a line from the point (x1, y1) to the point (x2, y2)