/// <summary>
 /// 保存
 /// </summary>
 public void Save(Enum.DwgVersion ver = Enum.DwgVersion.AC1024)
 {
     if (IsNewDWG)
     {
         database.SaveAs(dwgPath, (DwgVersion)ver);
     }
     else
     {
         database.Save();
     }
 }
        /// <summary>
        /// 在指定路径创建一个dwg文件。并返回DWGHelper
        /// </summary>
        /// <param name="dwgPath"></param>
        /// <returns></returns>
        static public DWGHelper CreateDWGHelper(string dwgPath, Enum.DwgVersion ver = Enum.DwgVersion.AC1024)
        {
            DWGHelper helper = null;

            if (dwgPath.ToLower().EndsWith(".dwg"))
            {
                if (File.Exists(dwgPath))
                {
                    throw new System.Exception("文件已存在!");
                }
                else
                {
                    helper = new DWGHelper(dwgPath);
                    helper.SaveAs(dwgPath, (DwgVersion)ver);
                }
            }
            else
            {
                throw new System.Exception("文件格式错误,只支持dwg格式的文件!");
            }
            return(helper);
        }