private bool isTzDwg()
 {
     MxDrawSelectionSet ss = new MxDrawSelectionSet();
     ss.AllSelect();
     for (int i = 0; i < ss.Count; i++)
     {
         MxDrawEntity ent = ss.Item(i);
         if (ent is MxDrawProxyEntity)
         {
             MxDrawProxyEntity proxy = (MxDrawProxyEntity)ent;
               MxDrawResbuf ret = proxy.GetProp("ExplodeEx");
               if (ret.Count == 0)
               {
                    continue;
               }
             String sClassName = proxy.originalClassName;
             if(sClassName == "TDbWall"
                 || sClassName == "TDbOpening"
                 || sClassName == "TDbSymbCoord"
                 )
             {
                 return true;
             }

         }
     }
     return false;
 }

 // 调用函数的代码

 if (isTzDwg())
{
        MessageBox.Show("发现天正对象");
}

            MxDrawApplication app = new MxDrawApplication();

            //设置读取函数 读取自定义实体的，entget数据 。
            app.Iniset("DefaultReadContent=-131073");


            MxDrawService ser = new MxDrawService();
            ser.Open("I:\ld.dwg");


            MxDrawSelectionSet ss = new MxDrawSelectionSet();
            ss.AllSelect();

            axMxDrawX1.MakeCurrentOcx();
            for (int i = 0; i < ss.Count; i++)
            {
                MxDrawEntity ent = ss.Item(i);

                if (ent.ObjectName == "McDbProxyEntity")
                {
                    MxDrawProxyEntity proxyEntity = (MxDrawProxyEntity)ent;
                    if (proxyEntity.originalClassName == "AcDbLeader")
                    {
                        MxDrawResbuf ret = proxyEntity.GetProp("EntGet");
                        if (ret != null)
                            ret.PrintData();
                    }

                }
            }
            ser.Close();