本程序实现八种图形的绘图功能，分别是直线，圆弧，贝赛尔曲线，矩形，圆角矩形，椭圆和多边形。绘图步骤如下：

直线：点鼠标左键确定起始点，移动鼠标点左键确定终点。

圆弧：用鼠标左键依次点四点确定圆弧。

贝赛尔曲线：用鼠标左键依次点四点确定贝赛尔曲线。

矩形：点左键确定起始点，拖动鼠标再点左键确定对角点。

圆角矩形：点左键确定起始点，拖动鼠标再点左键确定对角点。

椭圆：点左键确定起始点，拖动鼠标再点左键确定对角点，便作出了与该矩形相切的椭圆。

多边形：点鼠标左键确定起始点，然后依次点各点（所有点的总数为所要做多边形的边数，不超过20边），最后用中键确定，自动封闭图形。-the program eight graphical mapping function is linear, arc, Bessel curve, rectangle, rounded rectangle, oval and polygons. Mapping the following steps : Linear : click the mouse button to determine the threshold, mobile click of the mouse button to determine the end. Arc : the left mouse button followed by 4:00 set point arc. Bessel curve : the left mouse button followed by point 4:00 determine Bessel curve. Rectangular : Left to determine the threshold point, then drag the mouse to point to determine Left Corner. Rounded Rectangle : Left to determine the threshold point, then drag the mouse to point to determine Left Corner. Oval : Left to determine the threshold point, drag the mouse button again to determine right point corner, then made a transaction with the rectangular oval. Polygon