ASP.NET C# 验证码 支持中文 噪点 弯曲

/// <summary>
        /// 根据指定参数返回BitMap对象
        /// 引用如下：
        /// using System.Drawing;
        /// 调用例子如下：
        ///     eg1、保存为图象文件为
        ///     Bitmap srBmp = srBitmap(srs);
        ///     srBmp.Save(Directory.GetCurrentDirectory() + "\\srs.gif", System.Drawing.Imaging.ImageFormat.Gif);
        ///     srBmp.Dispose();
        ///     eg2。网页中调用方式如下
        ///     Bitmap srBmp = srBitmap(srs);
        ///     System.IO.MemoryStream srMS = new System.IO.MemoryStream();
        ///     srBmp.Save(srMS,System.Drawing.Imaging.ImageFormat.Gif);
        ///     Response.ClearContent();
        ///     Response.ContentType = "image/gif";
        ///     Response.BinaryWrite(srMS.ToArray());
        ///     srBmp.Dispose();
        /// </summary>
        /// <param name="srs"></param>
        /// <returns></returns>
        public static Bitmap srBitmap(string srs)
        {