Bresenham算法绘制线段并利用“橡皮筋”功能绘制折线 将绘制的折线连接成多边形，并选择种子填充法或扫描线填充法进行填充

鼠标交互生成矩形裁剪框，实现对绘制的折线的裁剪-Bresenham algorithm for drawing line segments using the " rubber band"　feature to draw the line draw the line connected into polygons, and select the method or the scan line seed fill method to fill the mouse filled with interactive cut rectangular box formation to achieve the cutting line on the drawn