ASP.NET C# 验证码支持中文噪点弯曲

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/// <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)
        {
            //定义图片弯曲的角度
            int srseedangle = 45;
            //定义图象
            Bitmap srBmp = new Bitmap(srs.Length*20,30);
            //画图
            Graphics srGraph = Graphics.FromImage(srBmp);
            //清空图象
            srGraph.Clear(Color.AliceBlue);
            //给图象画边框
            srGraph.DrawRectangle(new Pen(Color.Black,0),0,0,srBmp.Width-1,srBmp.Height-1);
            //定义随即数
            Random srRandom = new Random();
            //定义画笔
            Pen srPen = new Pen(Color.LightGray,0);
            //画噪点
            for (int i = 0; i < 100; i++)
            {
                srGraph.DrawRectangle(srPen,srRandom.Next(1,srBmp.Width-2),srRandom.Next(1,srBmp.Height-2),1,1);
            }
            //将字符串转化为字符数组
            char[] srchars = srs.ToCharArray();
            //封状文本
            StringFormat srFormat = new StringFormat(StringFormatFlags.NoClip);
            //设置文本垂直居中
            srFormat.Alignment = StringAlignment.Center;
            //设置文本水平居中
            srFormat.LineAlignment = StringAlignment.Center;
            //定义字体颜色
            Color[] srColors ={ Color.Black,Color.Red,Color.DarkBlue,Color.Blue,Color.Orange,Color.Brown,Color.DarkCyan,Color.Purple};
            //定义字体
            string[] srFonts ={ "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
            //循环画出每个字符
            for (int i = 0, j = srchars.Length; i < j; i++)
            {
                //定义字体参数分别为字体样式字体大小字体字形
                Font srFont = new Font(srFonts[srRandom.Next(5)], srRandom.Next(12,20), FontStyle.Regular);
                //填充图形
                Brush srBrush = new SolidBrush(srColors[srRandom.Next(7)]);
                //定义坐标
                Point srPoint = new Point(16, 16);
                //定义倾斜角度
                float srangle = srRandom.Next(-srseedangle, srseedangle);
                //倾斜
                srGraph.TranslateTransform(srPoint.X, srPoint.Y);
                srGraph.RotateTransform(srangle);
                //填充字符
                srGraph.DrawString(srchars[i].ToString(),srFont,srBrush,1,1,srFormat);
                //回归正常
                srGraph.RotateTransform(-srangle);
                srGraph.TranslateTransform(2,-srPoint.Y);
            }
            srGraph.Dispose();
            return srBmp;
        }