OpenDWG,著名的DWG格式破译组织写的一个DWG与DXF之间的转换工具,其官方网站有开源的全部代码可供下载.-OpenDWG, leading DWG format, written in deciphering the organization of a DWG and DXF conversion tool between its official website has all the open source code available for download.

非常实用的shp数据转VCT数据工具，开放源码，大家可以下载学习-The SHP data to VCT data is very useful tool, open source, you can download the study

一种用C#写的画图工具，简单模拟CAD的部分功能，附上源码。(A drawing tool written in C#, a simple simulation of some of the functions of CAD, attached to the source code.)

小菜选择易,很好用的图层选择工具,为lsp源码文件,可以参考自己修改(The choice of easy, very good use of the layer selection tool for the LSP source file, you can refer to the revision of your own)