利用openGL实现的绘图程序，很小很简单。 可以预先选定颜色，删除选定图形，移动图形，恢复已删除的图形，保存以及打开文件。-Implemented using openGL drawing program, very small and very simple. Can be pre-selected color, remove the selected graphics, mobile graphics, recover deleted graphics, save, and open th