C# 生成图片验证码 图片缩略图 水印

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;

namespace Planet.OrcaPos.Common
{
    public class ValidateCode
    {
        //需要导入System.Web与System.Drawing
        public ValidateCode()
        {
        }
        /// <summary>
        /// 验证码的最大长度
        /// </summary>
        public int MaxLength
        {
            get { return 10; }
        }
        /// <summary>
        /// 验证码的最小长度
        /// </summary>
        public int MinLength
        {
            get { return 1; }
        }
        /// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="length">指定验证码的长度</param>
        /// <returns></returns>
        public string CreateValidateCode(int length)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            string validateNumberStr = "";
            //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }

        /// <summary>
        /// 创建验证码的图片
        /// </summary>
        /// <param name="containsPage">要输出到的page对象</param>
        /// <param name="validateNum">验证码</param>
        public void CreateValidateGraphic(string validateCode, HttpContext context)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的干扰线
                for (int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                //渐变.
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validateCode, font, brush, 3, 2);

                //画图片的前景干扰点
                for (int i = 0; i < 100; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                context.Response.Clear();
                context.Response.ContentType = "image/jpeg";
                context.Response.BinaryWrite(stream.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
        /// <summary>
        /// 得到验证码图片的长度
        /// </summary>
        /// <param name="validateNumLength">验证码的长度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
        {
            return (int)(validateNumLength * 12.0);
        }
        /// <summary>
        /// 得到验证码的高度
        /// </summary>
        /// <returns></returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }
    }
}

using System;
using System.Collections;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace Planet.OrcaPos.Common
{
    public class ImageClass
    {
        //需要导入System.Drawing
        public ImageClass()
        { }

        #region 缩略图
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImagePath">源图路径（物理路径）</param>
        /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
        /// <param name="width">缩略图宽度</param>
        /// <param name="height">缩略图高度</param>
        /// <param name="mode">生成缩略图的方式</param>
        public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

            int towidth = width;
            int toheight = height;

            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;

            switch (mode)
            {
                case "HW":  //指定高宽缩放（可能变形）
                    break;
                case "W":   //指定宽，高按比例
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H":   //指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut": //指定高宽裁减（不变形）
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }

            //新建一个bmp图片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(System.Drawing.Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            //第一个：对哪张图片进行操作。
            //二：画多么大。
            //三：画那块区域。
            g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }
        #endregion

        #region 图片水印
        /// <summary>
        /// 图片水印处理方法
        /// </summary>
        /// <param name="path">需要加载水印的图片路径（绝对路径）</param>
        /// <param name="waterpath">水印图片（绝对路径）</param>
        /// <param name="location">水印位置（传送正确的代码）</param>
        public static string ImageWatermark(string path, string waterpath, string location)
        {
            string kz_name = Path.GetExtension(path);
            if (kz_name == ".jpg" || kz_name == ".bmp" || kz_name == ".jpeg")
            {
                DateTime time = DateTime.Now;
                string filename = "" + time.Year.ToString() + time.Month.ToString() + time.Day.ToString() + time.Hour.ToString() + time.Minute.ToString() + time.Second.ToString() + time.Millisecond.ToString();
                Image img = Bitmap.FromFile(path);
                Image waterimg = Image.FromFile(waterpath);
                Graphics g = Graphics.FromImage(img);
                ArrayList loca = GetLocation(location, img, waterimg);
                g.DrawImage(waterimg, new Rectangle(int.Parse(loca[0].ToString()), int.Parse(loca[1].ToString()), waterimg.Width, waterimg.Height));
                waterimg.Dispose();
                g.Dispose();
                string newpath = Path.GetDirectoryName(path) + filename + kz_name;
                img.Save(newpath);
                img.Dispose();
                File.Copy(newpath, path, true);
                if (File.Exists(newpath))
                {
                    File.Delete(newpath);
                }
            }
            return path;
        }

        /// <summary>
        /// 图片水印位置处理方法
        /// </summary>
        /// <param name="location">水印位置</param>
        /// <param name="img">需要添加水印的图片</param>
        /// <param name="waterimg">水印图片</param>
        private static ArrayList GetLocation(string location, Image img, Image waterimg)
        {
            ArrayList loca = new ArrayList();
            int x = 0;
            int y = 0;

            if (location == "LT")
            {
                x = 10;
                y = 10;
            }
            else if (location == "T")
            {
                x = img.Width / 2 - waterimg.Width / 2;
                y = img.Height - waterimg.Height;
            }
            else if (location == "RT")
            {
                x = img.Width - waterimg.Width;
                y = 10;
            }
            else if (location == "LC")
            {
                x = 10;
                y = img.Height / 2 - waterimg.Height / 2;
            }
            else if (location == "C")
            {
                x = img.Width / 2 - waterimg.Width / 2;
                y = img.Height / 2 - waterimg.Height / 2;
            }
            else if (location == "RC")
            {
                x = img.Width - waterimg.Width;
                y = img.Height / 2 - waterimg.Height / 2;
            }
            else if (location == "LB")
            {
                x = 10;
                y = img.Height - waterimg.Height;
            }
            else if (location == "B")
            {
                x = img.Width / 2 - waterimg.Width / 2;
                y = img.Height - waterimg.Height;
            }
            else
            {
                x = img.Width - waterimg.Width;
                y = img.Height - waterimg.Height;
            }
            loca.Add(x);
            loca.Add(y);
            return loca;
        }
        #endregion

        #region 文字水印
        /// <summary>
        /// 文字水印处理方法
        /// </summary>
        /// <param name="path">图片路径（绝对路径）</param>
        /// <param name="size">字体大小</param>
        /// <param name="letter">水印文字</param>
        /// <param name="color">颜色</param>
        /// <param name="location">水印位置</param>
        public static string LetterWatermark(string path, int size, string letter, Color color, string location)
        {
            #region

            string kz_name = Path.GetExtension(path);
            if (kz_name == ".jpg" || kz_name == ".bmp" || kz_name == ".jpeg")
            {
                DateTime time = DateTime.Now;
                string filename = "" + time.Year.ToString() + time.Month.ToString() + time.Day.ToString() + time.Hour.ToString() + time.Minute.ToString() + time.Second.ToString() + time.Millisecond.ToString();
                Image img = Bitmap.FromFile(path);
                Graphics gs = Graphics.FromImage(img);
                ArrayList loca = GetLocation(location, img, size, letter.Length);
                Font font = new Font("宋体", size);
                Brush br = new SolidBrush(color);
                gs.DrawString(letter, font, br, float.Parse(loca[0].ToString()), float.Parse(loca[1].ToString()));
                gs.Dispose();
                string newpath = Path.GetDirectoryName(path) + filename + kz_name;
                img.Save(newpath);
                img.Dispose();
                File.Copy(newpath, path, true);
                if (File.Exists(newpath))
                {
                    File.Delete(newpath);
                }
            }
            return path;

            #endregion
        }

        /// <summary>
        /// 文字水印位置的方法
        /// </summary>
        /// <param name="location">位置代码</param>
        /// <param name="img">图片对象</param>
        /// <param name="width">宽(当水印类型为文字时,传过来的就是字体的大小)</param>
        /// <param name="height">高(当水印类型为文字时,传过来的就是字符的长度)</param>
        private static ArrayList GetLocation(string location, Image img, int width, int height)
        {
            #region

            ArrayList loca = new ArrayList();  //定义数组存储位置
            float x = 10;
            float y = 10;

            if (location == "LT")
            {
                loca.Add(x);
                loca.Add(y);
            }
            else if (location == "T")
            {
                x = img.Width / 2 - (width * height) / 2;
                loca.Add(x);
                loca.Add(y);
            }
            else if (location == "RT")
            {
                x = img.Width - width * height;
            }
            else if (location == "LC")
            {
                y = img.Height / 2;
            }
            else if (location == "C")
            {
                x = img.Width / 2 - (width * height) / 2;
                y = img.Height / 2;
            }
            else if (location == "RC")
            {
                x = img.Width - height;
                y = img.Height / 2;
            }
            else if (location == "LB")
            {
                y = img.Height - width - 5;
            }
            else if (location == "B")
            {
                x = img.Width / 2 - (width * height) / 2;
                y = img.Height - width - 5;
            }
            else
            {
                x = img.Width - width * height;
                y = img.Height - width - 5;
            }
            loca.Add(x);
            loca.Add(y);
            return loca;

            #endregion
        }
        #endregion

        #region 调整光暗
        /// <summary>
        /// 调整光暗
        /// </summary>
        /// <param name="mybm">原始图片</param>
        /// <param name="width">原始图片的长度</param>
        /// <param name="height">原始图片的高度</param>
        /// <param name="val">增加或减少的光暗值</param>
        public Bitmap LDPic(Bitmap mybm, int width, int height, int val)
        {
            Bitmap bm = new Bitmap(width, height);//初始化一个记录经过处理后的图片对象
            int x, y, resultR, resultG, resultB;//x、y是循环次数，后面三个是记录红绿蓝三个值的
            Color pixel;
            for (x = 0; x < width; x++)
            {
                for (y = 0; y < height; y++)
                {
                    pixel = mybm.GetPixel(x, y);//获取当前像素的值
                    resultR = pixel.R + val;//检查红色值会不会超出[0, 255]
                    resultG = pixel.G + val;//检查绿色值会不会超出[0, 255]
                    resultB = pixel.B + val;//检查蓝色值会不会超出[0, 255]
                    bm.SetPixel(x, y, Color.FromArgb(resultR, resultG, resultB));//绘图
                }
            }
            return bm;
        }
        #endregion

        #region 反色处理
        /// <summary>
        /// 反色处理
        /// </summary>
        /// <param name="mybm">原始图片</param>
        /// <param name="width">原始图片的长度</param>
        /// <param name="height">原始图片的高度</param>
        public Bitmap RePic(Bitmap mybm, int width, int height)
        {
            Bitmap bm = new Bitmap(width, height);//初始化一个记录处理后的图片的对象
            int x, y, resultR, resultG, resultB;
            Color pixel;
            for (x = 0; x < width; x++)
            {
                for (y = 0; y < height; y++)
                {
                    pixel = mybm.GetPixel(x, y);//获取当前坐标的像素值
                    resultR = 255 - pixel.R;//反红
                    resultG = 255 - pixel.G;//反绿
                    resultB = 255 - pixel.B;//反蓝
                    bm.SetPixel(x, y, Color.FromArgb(resultR, resultG, resultB));//绘图
                }
            }
            return bm;
        }
        #endregion

        #region 浮雕处理
        /// <summary>
        /// 浮雕处理
        /// </summary>
        /// <param name="oldBitmap">原始图片</param>
        /// <param name="Width">原始图片的长度</param>
        /// <param name="Height">原始图片的高度</param>
        public Bitmap FD(Bitmap oldBitmap, int Width, int Height)
        {
            Bitmap newBitmap = new Bitmap(Width, Height);
            Color color1, color2;
            for (int x = 0; x < Width - 1; x++)
            {
                for (int y = 0; y < Height - 1; y++)
                {
                    int r = 0, g = 0, b = 0;
                    color1 = oldBitmap.GetPixel(x, y);
                    color2 = oldBitmap.GetPixel(x + 1, y + 1);
                    r = Math.Abs(color1.R - color2.R + 128);
                    g = Math.Abs(color1.G - color2.G + 128);
                    b = Math.Abs(color1.B - color2.B + 128);
                    if (r > 255) r = 255;
                    if (r < 0) r = 0;
                    if (g > 255) g = 255;
                    if (g < 0) g = 0;
                    if (b > 255) b = 255;
                    if (b < 0) b = 0;
                    newBitmap.SetPixel(x, y, Color.FromArgb(r, g, b));
                }
            }
            return newBitmap;
        }
        #endregion

        #region 拉伸图片
        /// <summary>
        /// 拉伸图片
        /// </summary>
        /// <param name="bmp">原始图片</param>
        /// <param name="newW">新的宽度</param>
        /// <param name="newH">新的高度</param>
        public static Bitmap ResizeImage(Bitmap bmp, int newW, int newH)
        {
            try
            {
                Bitmap bap = new Bitmap(newW, newH);
                Graphics g = Graphics.FromImage(bap);
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                g.DrawImage(bap, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, bap.Width, bap.Height), GraphicsUnit.Pixel);
                g.Dispose();
                return bap;
            }
            catch
            {
                return null;
            }
        }
        #endregion

        #region 滤色处理
        /// <summary>
        /// 滤色处理
        /// </summary>
        /// <param name="mybm">原始图片</param>
        /// <param name="width">原始图片的长度</param>
        /// <param name="height">原始图片的高度</param>
        public Bitmap FilPic(Bitmap mybm, int width, int height)
        {
            Bitmap bm = new Bitmap(width, height);//初始化一个记录滤色效果的图片对象
            int x, y;
            Color pixel;

            for (x = 0; x < width; x++)
            {
                for (y = 0; y < height; y++)
                {
                    pixel = mybm.GetPixel(x, y);//获取当前坐标的像素值
                    bm.SetPixel(x, y, Color.FromArgb(0, pixel.G, pixel.B));//绘图
                }
            }
            return bm;
        }
        #endregion

        #region 左右翻转
        /// <summary>
        /// 左右翻转
        /// </summary>
        /// <param name="mybm">原始图片</param>
        /// <param name="width">原始图片的长度</param>
        /// <param name="height">原始图片的高度</param>
        public Bitmap RevPicLR(Bitmap mybm, int width, int height)
        {
            Bitmap bm = new Bitmap(width, height);
            int x, y, z; //x,y是循环次数,z是用来记录像素点的x坐标的变化的
            Color pixel;
            for (y = height - 1; y >= 0; y--)
            {
                for (x = width - 1, z = 0; x >= 0; x--)
                {
                    pixel = mybm.GetPixel(x, y);//获取当前像素的值
                    bm.SetPixel(z++, y, Color.FromArgb(pixel.R, pixel.G, pixel.B));//绘图
                }
            }
            return bm;
        }
        #endregion

        #region 上下翻转
        /// <summary>
        /// 上下翻转
        /// </summary>
        /// <param name="mybm">原始图片</param>
        /// <param name="width">原始图片的长度</param>
        /// <param name="height">原始图片的高度</param>
        public Bitmap RevPicUD(Bitmap mybm, int width, int height)
        {
            Bitmap bm = new Bitmap(width, height);
            int x, y, z;
            Color pixel;
            for (x = 0; x < width; x++)
            {
                for (y = height - 1, z = 0; y >= 0; y--)
                {
                    pixel = mybm.GetPixel(x, y);//获取当前像素的值
                    bm.SetPixel(x, z++, Color.FromArgb(pixel.R, pixel.G, pixel.B));//绘图
                }
            }
            return bm;
        }
        #endregion

        #region 压缩图片
        /// <summary>
        /// 压缩到指定尺寸
        /// </summary>
        /// <param name="oldfile">原文件</param>
        /// <param name="newfile">新文件</param>
        public bool Compress(string oldfile, string newfile)
        {
            try
            {
                System.Drawing.Image img = System.Drawing.Image.FromFile(oldfile);
                System.Drawing.Imaging.ImageFormat thisFormat = img.RawFormat;
                Size newSize = new Size(100, 125);
                Bitmap outBmp = new Bitmap(newSize.Width, newSize.Height);
                Graphics g = Graphics.FromImage(outBmp);
                g.CompositingQuality = CompositingQuality.HighQuality;
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                g.DrawImage(img, new Rectangle(0, 0, newSize.Width, newSize.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
                g.Dispose();
                EncoderParameters encoderParams = new EncoderParameters();
                long[] quality = new long[1];
                quality[0] = 100;
                EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
                encoderParams.Param[0] = encoderParam;
                ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegICI = null;
                for (int x = 0; x < arrayICI.Length; x++)
                    if (arrayICI[x].FormatDescription.Equals("JPEG"))
                    {
                        jpegICI = arrayICI[x]; //设置JPEG编码
                        break;
                    }
                img.Dispose();
                if (jpegICI != null) outBmp.Save(newfile, System.Drawing.Imaging.ImageFormat.Jpeg);
                outBmp.Dispose();
                return true;
            }
            catch
            {
                return false;
            }
        }
        #endregion

        #region 图片灰度化
        public Color Gray(Color c)
        {
            int rgb = Convert.ToInt32((double)(((0.3 * c.R) + (0.59 * c.G)) + (0.11 * c.B)));
            return Color.FromArgb(rgb, rgb, rgb);
        }
        #endregion

        #region 转换为黑白图片
        /// <summary>
        /// 转换为黑白图片
        /// </summary>
        /// <param name="mybt">要进行处理的图片</param>
        /// <param name="width">图片的长度</param>
        /// <param name="height">图片的高度</param>
        public Bitmap BWPic(Bitmap mybm, int width, int height)
        {
            Bitmap bm = new Bitmap(width, height);
            int x, y, result; //x,y是循环次数，result是记录处理后的像素值
            Color pixel;
            for (x = 0; x < width; x++)
            {
                for (y = 0; y < height; y++)
                {
                    pixel = mybm.GetPixel(x, y);//获取当前坐标的像素值
                    result = (pixel.R + pixel.G + pixel.B) / 3;//取红绿蓝三色的平均值
                    bm.SetPixel(x, y, Color.FromArgb(result, result, result));
                }
            }
            return bm;
        }
        #endregion

        #region 获取图片中的各帧
        /// <summary>
        /// 获取图片中的各帧
        /// </summary>
        /// <param name="pPath">图片路径</param>
        /// <param name="pSavePath">保存路径</param>
        public void GetFrames(string pPath, string pSavedPath)
        {
            Image gif = Image.FromFile(pPath);
            FrameDimension fd = new FrameDimension(gif.FrameDimensionsList[0]);
            int count = gif.GetFrameCount(fd); //获取帧数(gif图片可能包含多帧，其它格式图片一般仅一帧)
            for (int i = 0; i < count; i++)    //以Jpeg格式保存各帧
            {
                gif.SelectActiveFrame(fd, i);
                gif.Save(pSavedPath + "\\frame_" + i + ".jpg", ImageFormat.Jpeg);
            }
        }
        #endregion
    }
}

using System;using System.Collections.Generic;using System.Drawing;using System.Drawing.Drawing2D;using System.Drawing.Imaging;using System.IO;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Web;
namespace Planet.OrcaPos.Common{    public class ValidateCode    {//需要导入System.Web与System.Drawing        public ValidateCode()        {        }        /// <summary>        /// 验证码的最大长度        /// </summary>        public int MaxLength        {            get { return 10; }        }        /// <summary>        /// 验证码的最小长度        /// </summary>        public int MinLength        {            get { return 1; }        }        /// <summary>        /// 生成验证码        /// </summary>        /// <param name="length">指定验证码的长度</param>        /// <returns></returns>        public string CreateValidateCode(int length)        {            int[] randMembers = new int[length];            int[] validateNums = new int[length];            string validateNumberStr = "";            //生成起始序列值            int seekSeek = unchecked((int)DateTime.Now.Ticks);            Random seekRand = new Random(seekSeek);            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);            int[] seeks = new int[length];            for (int i = 0; i < length; i++)            {                beginSeek += 10000;                seeks[i] = beginSeek;            }            //生成随机数字            for (int i = 0; i < length; i++)            {                Random rand = new Random(seeks[i]);                int pownum = 1 * (int)Math.Pow(10, length);                randMembers[i] = rand.Next(pownum, Int32.MaxValue);            }            //抽取随机数字            for (int i = 0; i < length; i++)            {                string numStr = randMembers[i].ToString();                int numLength = numStr.Length;                Random rand = new Random();                int numPosition = rand.Next(0, numLength - 1);                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));            }            //生成验证码            for (int i = 0; i < length; i++)            {                validateNumberStr += validateNums[i].ToString();            }            return validateNumberStr;        }
        /// <summary>        /// 创建验证码的图片        /// </summary>        /// <param name="containsPage">要输出到的page对象</param>        /// <param name="validateNum">验证码</param>        public void CreateValidateGraphic(string validateCode, HttpContext context)        {            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);            Graphics g = Graphics.FromImage(image);            try            {                //生成随机生成器                Random random = new Random();                //清空图片背景色                g.Clear(Color.White);                //画图片的干扰线                for (int i = 0; i < 25; i++)                {                    int x1 = random.Next(image.Width);                    int x2 = random.Next(image.Width);                    int y1 = random.Next(image.Height);                    int y2 = random.Next(image.Height);                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);                }                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));                //渐变.                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),                 Color.Blue, Color.DarkRed, 1.2f, true);                g.DrawString(validateCode, font, brush, 3, 2);                               //画图片的前景干扰点                for (int i = 0; i < 100; i++)                {                    int x = random.Next(image.Width);                    int y = random.Next(image.Height);                    image.SetPixel(x, y, Color.FromArgb(random.Next()));                }                //画图片的边框线                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);                //保存图片数据                MemoryStream stream = new MemoryStream();                image.Save(stream, ImageFormat.Jpeg);                //输出图片流                context.Response.Clear();                context.Response.ContentType = "image/jpeg";                context.Response.BinaryWrite(stream.ToArray());            }            finally            {                g.Dispose();                image.Dispose();            }        }        /// <summary>        /// 得到验证码图片的长度        /// </summary>        /// <param name="validateNumLength">验证码的长度</param>        /// <returns></returns>        public static int GetImageWidth(int validateNumLength)        {            return (int)(validateNumLength * 12.0);        }        /// <summary>        /// 得到验证码的高度        /// </summary>        /// <returns></returns>        public static double GetImageHeight()        {            return 22.5;        }    }}