交互式绘图，用橡皮筋法来绘制直线，圆，矩形框。-Interactive graphics, with the rubber band method to draw a straight line, circle, rectangle.

绘制基本图形,二维曲线，辅助操作，三维曲线，图形修饰处理，交互式绘图工具等(Drawing basic graphics, two-dimensional curve, auxiliary operation, three-dimensional curve, graphic modification processing, interactive drawing tools, etc)