基于单文档的画图程序
可以画直线 矩形 圆形 椭圆等
线型、粗细、颜色可任意设置,
也可选择有无填充色,可保存文件,并打开-Paint program based on single document can draw a straight line rectangle circle ellipse and line style, thickness, color can be arbitrarily set, can also choose whether the fill color, save the file, and open the