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 me