WinForm生成验证码图片的方法

本文实例讲述了WinForm生成验证码图片的方法。分享给大家供大家参考，具体如下：

1、创建ValidCode类：

public class ValidCode
{
 #region Private Fields
 private const double PI = 3.1415926535897932384626433832795;
 private const double PI2 = 6.283185307179586476925286766559;
 //private readonly int _wordsLen = 4;
 private int _len;
 private CodeType _codetype;
 private readonly Single _jianju = (float)18.0;
 private readonly Single _height = (float)24.0;
 private string _checkCode;
 #endregion
 #region Public Property
 public string CheckCode
 {
  get
  {
   return _checkCode;
  }
 }
 #endregion
 #region Constructors
 /// <summary>
 /// public constructors
 /// </summary>
 /// <param name="len"> 验证码长度 </param>
 /// <param name="ctype"> 验证码类型：字母、数字、字母+ 数字 </param>
 public ValidCode(int len, CodeType ctype)
 {
  this._len = len;
  this._codetype = ctype;
 }
 #endregion
 #region Public Field
 public enum CodeType { Words, Numbers, Characters, Alphas }
 #endregion
 #region Private Methods
 private string GenerateNumbers()
 {
  string strOut = "";
  System.Random random = new Random();
  for (int i = 0; i < _len; i++)
  {
   string num = Convert.ToString(random.Next(10000) ％ 10);
   strOut += num;
  }
  return strOut.Trim();
 }
 private string GenerateCharacters()
 {
  string strOut = "";
  System.Random random = new Random();
  for (int i = 0; i < _len; i++)
  {
   string num = Convert.ToString((char)(65 + random.Next(10000) ％ 26));
   strOut += num;
  }
  return strOut.Trim();
 }
 //
 private string GenerateAlphas()
 {
  string strOut = "";
  string num = "";
  System.Random random = new Random();
  for (int i = 0; i < _len; i++)
  {
   if (random.Next(500) ％ 2 == 0)
   {
    num = Convert.ToString(random.Next(10000) ％ 10);
   }
   else
   {
    num = Convert.ToString((char)(65 + random.Next(10000) ％ 26));
   }
   strOut += num;
  }
  return strOut.Trim();
 }
 private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
 {
  System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
  // 将位图背景填充为白色
  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);
    // 取得当前点的颜色
    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;
 }
 #endregion
 #region Public Methods
 public Stream CreateCheckCodeImage()
 {
  string checkCode;
  switch (_codetype)
  {
   case CodeType.Alphas:
    checkCode = GenerateAlphas();
    break;
   case CodeType.Numbers:
    checkCode = GenerateNumbers();
    break;
   case CodeType.Characters:
    checkCode = GenerateCharacters();
    break;
   default:
    checkCode = GenerateAlphas();
    break;
  }
  this._checkCode = checkCode;
  MemoryStream ms = null;
  //
  if (checkCode == null || checkCode.Trim() == String.Empty)
   return null;
  Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * _jianju)), (int)_height);
  Graphics g = Graphics.FromImage(image);
  try
  {
   Random random = new Random();
   g.Clear(Color.White);
   // 画图片的背景噪音线
   for (int i = 0; i < 18; 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.FromArgb(random.Next()), 1), x1, y1, x2, y2);
   }
   Font font = new System.Drawing.Font("Times New Roman", 14, System.Drawing.FontStyle.Bold);
   LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
   if (_codetype != CodeType.Words)
   {
    for (int i = 0; i < checkCode.Length; i++)
    {
     g.DrawString(checkCode.Substring(i, 1), font, brush, 2 + i * _jianju, 1);
    }
   }
   else
   {
    g.DrawString(checkCode, font, brush, 2, 2);
   }
   // 画图片的前景噪音点
   for (int i = 0; i < 150; i++)
   {
    int x = random.Next(image.Width);
    int y = random.Next(image.Height);
    image.SetPixel(x, y, Color.FromArgb(random.Next()));
   }
   // 画图片的波形滤镜效果
   if (_codetype != CodeType.Words)
   {
    image = TwistImage(image, true, 3, 1);
   }
   // 画图片的边框线
   g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
   ms = new System.IO.MemoryStream();
   image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
  }
  finally
  {
   g.Dispose();
   image.Dispose();
  }
  return ms;
 }
 #endregion
}

2、产生验证码图片代码：

//参数一：产生几个字符的验证码图片 参数二：验证码的形式(数字、字母、数字字母混合都有)
ValidCode validCode = new ValidCode(5, ValidCode.CodeType.Alphas);
this.pictureBox2.Image = Bitmap.FromStream(validCode.CreateCheckCodeImage());

希望本文所述对大家C#程序设计有所帮助。