该程序完成的是通过使用所提供的链码（一种方向码）来画出链码所表示的轮廓。所画轮廓在原图上是黑色的线。速度快，准确度高-Completion of the program is provided through the use of chain code (a direction code) to draw the outline represented by the chain code. The outline of the original painting is a black line.