移除实体应用程序名（xdata）

        /// <summary>
        /// 移除实体应用程序名（xdata） houlinbo QQ420021327
         /// </summary>
        /// <param name="Objid"></param>
        /// <param name="sAppName"></param>
        public void RemoveAppName(Database db, ObjectId objId, string sAppName)
        {
            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                DBObject obj = tr.GetObject(objId, OpenMode.ForWrite);
                ResultBuffer rb = obj.XData;
                if (rb != null)
                {
                    TypedValue[] values = rb.AsArray();
                    for (int i = 0; i < values.Length; i++)
                    {
                        if (values[i].TypeCode ==
                            (int)DxfCode.ExtendedDataRegAppName && values[i].Value.ToString() ==
                            sAppName)
                        {
                            //移除之
                            TypedValue[] values_New ={ new TypedValue((int)DxfCode.ExtendedDataRegAppName, values[i].Value.ToString()) };
                            ResultBuffer rb_New = new ResultBuffer(values_New);
                            obj.UpgradeOpen();
                            obj.XData = rb_New;
                            obj.DowngradeOpen();
                        }
                    }
                }
                tr.Commit();
            }
        }