块参照重命名

#region 重命名块参照
        /// <summary>
        /// 重命名块参照
        /// </summary>
        /// <param name="db"> 当前数据库</param>
        /// <param name="oldBlockname">块参照旧名</param>
        /// <param name="newBlockname">块参照新名</param>
        public static void RenameBlock(this Database db, string oldBlockname, string newBlockname)
        {
            using (Transaction trans = db.TransactionManager.StartTransaction())
            {
                //获取当前块表
                BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead, true);
                BlockTableRecord btr = (BlockTableRecord)trans.GetObject(bt["dHead"], OpenMode.ForWrite, true);
                btr.Name = newBlockname;
                trans.Commit();
            }
        }
        #endregion