C#一款比較美觀的驗證碼

    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.Imaging;


public partial class ValidateCode : System.Web.UI.Page  
{  
    private int letterWidth = 16;//單個字體的寬度范圍  
    private int letterHeight = 22;//單個字體的高度范圍  
    private int letterCount = 4;//驗證碼位數  
    private char[] chars = "0123456789".ToCharArray();  
    private string[] fonts = { "Arial", "Georgia" };  
    /// <summary>  
    /// 產生波形濾鏡效果  
    /// </summary>  
    private const double PI = 3.1415926535897932384626433832795;  
    private const double PI2 = 6.283185307179586476925286766559;  
    protected void Page_Load(object sender, EventArgs e)  
    {  
        //防止網頁后退--禁止緩存      
        Response.Expires = 0;  
        Response.Buffer = true;  
        Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);  
        Response.AddHeader("pragma", "no-cache");  
        Response.CacheControl = "no-cache";  
        string str_ValidateCode = GetRandomNumberString(letterCount);  
        HttpCookie objCookie = new HttpCookie("ValidateCode");  
        objCookie.Value = str_ValidateCode;  
        objCookie.Path = "/";  
        objCookie.Expires = DateTime.Now.AddSeconds(1200);  
        Response.Cookies.Add(objCookie);  
        CreateImage(str_ValidateCode);  

    }  
    public void CreateImage(string checkCode)  
    {  
        int int_ImageWidth = checkCode.Length * letterWidth;  
        Random newRandom = new Random();  
        Bitmap image = new Bitmap(int_ImageWidth, letterHeight);  
        Graphics g = Graphics.FromImage(image);  
        //生成隨機生成器  
        Random random = new Random();  
        //白色背景  
        g.Clear(Color.White);  
        //畫圖片的背景噪音線  
        for (int i = 0; i < 10; 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);  
        }  

        //畫圖片的前景噪音點  
        for (int i = 0; i < 10; i++)  
        {  
            int x = random.Next(image.Width);  
            int y = random.Next(image.Height);  

            image.SetPixel(x, y, Color.FromArgb(random.Next()));  
        }  
        //隨機字體和顏色的驗證碼字符  

        int findex;  
        for (int int_index = 0; int_index < checkCode.Length; int_index++)  
        {  
            findex = newRandom.Next(fonts.Length - 1);  
            string str_char = checkCode.Substring(int_index, 1);  
            Brush newBrush = new SolidBrush(GetRandomColor());  
            Point thePos = new Point(int_index * letterWidth + 1 + newRandom.Next(3), 1 + newRandom.Next(3));//5+1+a+s+p+x  
            g.DrawString(str_char, new Font(fonts[findex], 12, FontStyle.Bold), newBrush, thePos);  
        }  
        //灰色邊框  
        g.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, (letterHeight - 1));  
        //圖片扭曲  
        //image = TwistImage(image, true, 3, 4);  
        //將生成的圖片發回客戶端  
        MemoryStream ms = new MemoryStream();  
        image.Save(ms, ImageFormat.Png);  
        Response.ClearContent(); //需要輸出圖象信息 要修改HTTP頭   
        Response.ContentType = "image/Png";  
        Response.BinaryWrite(ms.ToArray());  
        g.Dispose();  
        image.Dispose();  
    }  
    /// <summary>  
    /// 正弦曲線Wave扭曲圖片  
    /// </summary>  
    /// <param name="srcBmp">圖片路徑</param>  
    /// <param name="bXDir">如果扭曲則選擇為True</param>  
    /// <param name="nMultValue">波形的幅度倍數，越大扭曲的程度越高，一般為3</param>  
    /// <param name="dPhase">波形的起始相位，取值區間[0-2*PI)</param>  
    /// <returns></returns>  
    public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)  
    {  
        System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);  
        // 將位圖背景填充為白色  
        System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);  
        graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);  
        graph.Dispose();  
        double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;  

        for (int i = 0; i < destBmp.Width; i++)  
        {  
            for (int j = 0; j < destBmp.Height; j++)  
            {  
                double dx = 0;  
                dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;  
                dx += dPhase;  
                double dy = Math.Sin(dx);  
                // 取得當前點的顏色  
                int nOldX = 0, nOldY = 0;  
                nOldX = bXDir ? i + (int)(dy * dMultValue) : i;  
                nOldY = bXDir ? j : j + (int)(dy * dMultValue);  
                System.Drawing.Color color = srcBmp.GetPixel(i, j);  
                if (nOldX >= 0 && nOldX < destBmp.Width && nOldY >= 0 && nOldY < destBmp.Height)  
                {  
                    destBmp.SetPixel(nOldX, nOldY, color);  
                }  
            }  
        }  
        return destBmp;  
    }  

    public Color GetRandomColor()  
    {  
        Random RandomNum_First = new Random((int)DateTime.Now.Ticks);  
        System.Threading.Thread.Sleep(RandomNum_First.Next(50));  
        Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);  
        int int_Red = RandomNum_First.Next(210);  
        int int_Green = RandomNum_Sencond.Next(180);  
        int int_Blue = (int_Red + int_Green > 300) ? 0 : 400 - int_Red - int_Green;  
        int_Blue = (int_Blue > 255) ? 255 : int_Blue;  
        return Color.FromArgb(int_Red, int_Green, int_Blue);// 5+1+a+s+p+x  
    }  

    //  生成隨機數字字符串  
    public string GetRandomNumberString(int int_NumberLength)  
    {  
        Random random = new Random();  
        string validateCode = string.Empty;  
        for (int i = 0; i < int_NumberLength; i++)  
            validateCode += chars[random.Next(0, chars.Length)].ToString();  
        return validateCode;  
    }  
}  </pre> 



    <img alt="看不清，換一張" title="看不清，換一張" src="ValidateCode.aspx" style="cursor:pointer" onclick="this.src=this.src+'?r='+Math.random()" />