利用C#.net开发的dxf读取程序，对于初学者有较大帮助-The use of C#. Net developed dxf reader, have a greater help for beginners

用于CAD图形编程的一个动态库，遗憾之处是会调用动态库时会弹出对话框，注册后可消除。-CAD graphics programming for a dynamic library, regret is that the dynamic library calls the dialog box will pop up, registration can be eliminated.