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; }}