using System;

using System.Collections.Generic;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.IO;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;

public partial class user_Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        string checkCode = CreateRandomCode();

        GetImgWithValidateCode(checkCode, , ,);

    }

    ///<summary>

    /// 生成随机字符串

    ///</summary>

    ///<param name="codeCount">字符数量</param>

    ///<returns>随机字符串</returns>

    private string CreateRandomCode(int codeCount)

    {

        string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";

        string[] allCharArray = allChar.Split(',');

        string randomCode = "";

        int temp = -;

        Random rand = new Random();

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

        {

            if (temp != -)

            {

                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));

            }

            int t = rand.Next();

            if (temp == t)

            {

                return CreateRandomCode(codeCount);

            }

            temp = t;

            randomCode += allCharArray[t];

        }

        return randomCode;

    }

    ///<summary>

    /// 创建验证码图片

    ///</summary>

    ///<param name="code">字符串</param>

    ///<param name="width">宽</param>

    ///<param name="height">高</param>

    ///<param name="fontSize">字号</param>

    public void GetImgWithValidateCode(string code, int width, int height, int fontSize)

    {

        Color bgcolor = GetControllableColor();

        Color color = GetControllableColor();

        int charNum = code.Length;

        Bitmap bitMap = null;

        Graphics gph = null;

        //创建内存流

        MemoryStream memStream = new MemoryStream();

        Random random = new Random();

        //创建位图对象

        bitMap = new Bitmap(width, height);

        //根据上面创建的位图对象创建绘图图面

        gph = Graphics.FromImage(bitMap);

        //设定验证码图片背景色

        gph.Clear(bgcolor);

        //产生随机干扰线条

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

        {

            Pen backPen = new Pen(color, );

            int x = ;

            int y = height / ;

            int x2 = width;

            int y2 = random.Next(height);

            gph.DrawLine(backPen, x, y, x2, y2);

        }

        SolidBrush sb = new SolidBrush(color);

        PointF Cpoint1 = new PointF(, );

        Random rnd1 = new Random();

        int x1 = , y1 = ;

        //通过循环,绘制每个字符,

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

        {

            x1 = rnd1.Next() + ((width - ) / code.Length) * i;

            y1 = rnd1.Next(bitMap.Height / );

            Cpoint1 = new PointF(x1, y1);

            Font textFont = new Font("Arial", fontSize, FontStyle.Bold);//字体随机,字号大小30,加粗

            //随机倾斜字符

            Matrix transform = gph.Transform;

            transform.Shear(Convert.ToSingle(rnd1.NextDouble() - 0.5), 0.001f);

            gph.Transform = transform;

            gph.DrawString(code.Substring(i, ), textFont, sb, Cpoint1);

            gph.ResetTransform();

        }

        //画图片的前景噪音点

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

        {

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

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

            bitMap.SetPixel(x, y, Color.White);

        }

        //画图片的边框线

        gph.DrawRectangle(new Pen(Color.Black, ), , , bitMap.Width - , bitMap.Height - );

        try

        {

            bitMap.Save(memStream, ImageFormat.Gif);

        }

        catch (Exception ex)

        {

            Console.WriteLine(ex.Message);

        }

        bitMap.Dispose();

        System.Drawing.Image img = System.Drawing.Image.FromStream(memStream);

        gph.DrawImage(img, , , width, height);

        //img.Save(@"D:\test.jpg", ImageFormat.Jpeg);

        //如果是asp.net 用下面的输出图片

        System.IO.MemoryStream ms = new System.IO.MemoryStream();

        img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

        Response.ClearContent();

        Response.ContentType = "image/Jpeg";

        Response.BinaryWrite(ms.ToArray());

        gph.Dispose();

        img.Dispose();

    }

    ///<summary>

    /// 产生一种 R,G,B 均大于 colorBase 随机颜色，以确保颜色不会过深

    ///</summary>

    ///<param name="colorBase">The color base.</param>

    ///<returns>Color</returns>

    public Color GetControllableColor(int colorBase)

    {

        Color color = Color.Black;

        if (colorBase > )

        {

            return color;

        }

        Random random = new Random();

        color = Color.FromArgb(random.Next() + colorBase, random.Next() + colorBase, random.Next() + colorBase);

        return color;

    }

}