生成图片，保存到指定目录

        /// <summary>
        /// 将指定的联系号码转换成图片
         /// </summary>
        /// <param name="phone">联系号码</param>
        /// <param name="fileSaveDir">生成图片的保存路径</param>
        /// <returns>返回生成的图片的文件名</returns>
        public static string ConvertPhoneToImageAndSave(string phone, string fileSaveDir)
        {
            Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling(15 * 0.76 * phone.Length), 25);
            Graphics g = System.Drawing.Graphics.FromImage(image);
            try
            {
                g.Clear(Color.White);
                Font f = new Font("Arial", 15, FontStyle.Bold);
                SolidBrush brush = new SolidBrush(ColorTranslator.FromHtml("#0A3B7E"));
                g.DrawString(phone, f, brush, 1, 2);
                Guid guid = Guid.NewGuid();
                string fileName = guid.ToString() + ".gif";
                DirectoryInfo dir = new DirectoryInfo(fileSaveDir);
                if (!dir.Exists)
                {
                    dir.Create();
                }
                string fileFullName = dir.FullName + fileName;
                image.Save(fileFullName);
                return fileName;
            }
            catch
            {
                return "";
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }