本程序的关键技术为文件的串行化，并有相应的文档说明。最终要实现的效果：在单文档程序的客户区域，绘制直线，可以用文件的形式来保持用户的绘制内容。-The key technology for this program documents serialization, and have the corresponding documentation. Ultimately to achieve the effect: In the single-document program customer a