Install-Package ZKWeb.System.Drawing

static void ImgTestTwo()

{

    string filename = @"E:\CoreWork\backone.jpg";

    string targetname = @"E:\CoreWork\temp1.jpg";

    Bitmap bitmap = new Bitmap(filename);

    //保持图片的比例不变，缩放图片

    int width = ,

        height = ;

    if (bitmap.Width > bitmap.Height)

    {

        //宽度为大,计算高度

        height = Convert.ToInt32(width * (bitmap.Height * 1.0 / bitmap.Width));

    }

    else

    {

        //高度为大，计算宽度

        width = Convert.ToInt32(height * (bitmap.Width * 1.0 / bitmap.Height));

    }

    Bitmap result = ResizeImage(bitmap, width, height);

    filename = filename.Substring(,filename.LastIndexOf('.'))+".jpg";

    //保存图片,指定保存 格式为Jpeg，占用空间会比较小

    result.Save(targetname,ImageFormat.Jpeg);

    result.Dispose();

    bitmap.Dispose();

}

/// <summary>

///  Resize图片

/// </summary>

/// <param name="bmp">原始Bitmap </param>

/// <param name="newW">新的宽度</param>

/// <param name="newH">新的高度</param>

/// <returns>处理以后的图片</returns>

public static Bitmap ResizeImage(Bitmap bmp, int newW, int newH)

{

    try

    {

        Bitmap b = new Bitmap(newW, newH);

        Graphics g = Graphics.FromImage(b);

        // 插值算法的质量

        //g.InterpolationMode = InterpolationMode.NearestNeighbor;

        g.DrawImage(bmp, new Rectangle(, , newW, newH), new Rectangle(, , bmp.Width, bmp.Height), GraphicsUnit.Pixel);

        g.Dispose();

        return b;

    }

    catch(Exception ex)

    {

        return null;

    }

}

   public class VierificationCodeServices

      {

          /// <summary>

          /// 该方法用于生成指定位数的随机数

          /// </summary>

          /// <param name="VcodeNum">参数是随机数的位数</param>

          /// <returns>返回一个随机数字符串</returns>

          private string RndNum(int VcodeNum)

          {

             //验证码可以显示的字符集合

             string Vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p" +

                 ",q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,P,Q" +

                 ",R,S,T,U,V,W,X,Y,Z";

             string[] VcArray = Vchar.Split(new Char[] { ',' });//拆分成数组

             string code = "";//产生的随机数

             int temp = -;//记录上次随机数值，尽量避避免生产几个一样的随机数  

             Random rand = new Random();

             //采用一个简单的算法以保证生成随机数的不同

             for (int i = ; i < VcodeNum + ; i++)

             {

                 if (temp != -)

                 {

                     rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));//初始化随机类

                 }

                 int t = rand.Next();//获取随机数

                 if (temp != - && temp == t)

                 {

                     return RndNum(VcodeNum);//如果获取的随机数重复，则递归调用

                 }

                 temp = t;//把本次产生的随机数记录起来

                 code += VcArray[t];//随机数的位数加一

             }

             return code;

         }

        /// <summary>

        /// 生成图片验证码

        /// </summary>

        /// <param name="code"></param>

        /// <returns></returns>

        public static MemoryStream ValideCode(string code)

        {

            Bitmap Img = null;

            Graphics g = null;

            Random random = new Random();

            //验证码颜色集合

            Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };

            //验证码字体集合

            string[] fonts = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };

            //定义图像的大小，生成图像的实例

            Img = new Bitmap((int)code.Length * , );

            g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象

            g.Clear(Color.White);//背景设为白色  

            //在随机位置画背景点

            for (int i = ; i < ; i++)

            {

                int x = random.Next(Img.Width);

                int y = random.Next(Img.Height);

                g.DrawRectangle(new Pen(Color.LightGray, ), x, y, , );

            }

            //验证码绘制在g中

            for (int i = ; i < code.Length; i++)

            {

                int cindex = random.Next();//随机颜色索引值

                int findex = random.Next();//随机字体索引值

                Font f = new Font(fonts[findex], , FontStyle.Bold);//字体

                Brush b = new SolidBrush(c[cindex]);//颜色

                int ii = ;

                if ((i + ) %  == )//控制验证码不在同一高度

                {

                    ii = ;

                }

                g.DrawString(code.Substring(i, ), f, b,  + (i * ), ii);//绘制一个验证字符

            }

            MemoryStream ms = new MemoryStream();//生成内存流对象

            Img.Save(ms, ImageFormat.Jpeg);//将此图像以Png图像文件的格式保存到流中

            ms.Seek(, SeekOrigin.Begin);//指针回归

            //回收资源

            g.Dispose();

            Img.Dispose();

            return ms;

        }