WPF做验证码，小部分修改原作者内容

原文地址：http://www.cnblogs.com/tianguook/p/4142346.html

首先感谢aparche大牛的帖子，因为过两天可能要做个登录的页面，因此，需要用到验证码，从而看到了大神的这篇帖子，十分感谢。

产生验证码的类ValidCode

public class ValidCode
    {
        public enum CodeType { Words, Numbers, Characters, Alphas }

        private const double PI = 3.1415926535897932384626433832795;
        private const double PI2 = 6.283185307179586476925286766559;

        private int _len;
        private CodeType _codetype;
        private readonly Single _jianju = (float)18.0;
        private readonly Single _height = (float)24.0;
        private string _checkCode;

        public string CheckCode
        {
            get
            {
                return _checkCode;
            }
        }

        private string returnCode = "";

        public string ReturnCode
        {
            get
            {
                return returnCode;
            }

            set
            {
                returnCode = value;
            }
        }
        /// <summary>
        /// 构造函数
        /// </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;
        }

        private string GenerateNumbers()
        {
            Random random = new Random();
            for (int i = 0; i < _len; i++)
            {
                string num = Convert.ToString(random.Next(10000) % 10);
                ReturnCode += num;
            }
            return ReturnCode.Trim();
        }

        private string GenerateCharacters()
        {
            string num = "";
            Random random = new Random();
            for (int i = 0; i < _len; i++)
            {
                if (random.Next(500) % 2 == 0)
                {
                    num = Convert.ToString((char)(65 + random.Next(10000) % 26));
                }
                else
                {
                    num = Convert.ToString((char)(97 + random.Next(10000) % 26));
                }
                ReturnCode += num;
            }
            return ReturnCode.Trim();
        }

        private string GenerateAlphas()
        {
            string num = "";
            Random random = new Random();
            for (int i = 0; i < _len; i++)
            {
                if (random.Next(500) % 3 == 0)
                {
                    num = Convert.ToString(random.Next(10000) % 10);
                }
                else if (random.Next(500) % 3 == 1)
                {
                    num = Convert.ToString((char)(65 + random.Next(10000) % 26));
                }
                else
                {
                    num = Convert.ToString((char)(97 + random.Next(10000) % 26));
                }
                ReturnCode += num;
            }
            return ReturnCode.Trim();
        }

        private Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
        {
            Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
            //将位图背景填充为白色
            Graphics graph = 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;
        }

        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 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 Font("Times New Roman", 14, 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 MemoryStream();
                image.Save(ms, ImageFormat.Gif);
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
            return ms;
        }
    }

修改内容如下：

1、大小写混合随机出现

　　原文都是用大写出现的，而我们常见的验证码都有大小写同时出现的情况，因此，在代码里多写了一句“num = Convert.ToString((char)(97 + random.Next(10000) % 26));”其中97是a的ASCII值。

2、增加一个返回的属性ReturnCode

　　原文在每段代码里都声明了一个strOut，而最后生成的是图片，如果再去解析图片的话，就得不偿失了，因此，增加一个属性，把相应的部分，进行替换，在调用的时候方便了取数。

调用页面的CS代码，写了一个MouseLeftButtonUp事件，可以在鼠标点击的时候，进行验证码变换。

public partial class MainWindow : Window
    {
        ValidCode validCode;
        public MainWindow()
        {
            InitializeComponent();
            validCode = new ValidCode(4, ValidCode.CodeType.Alphas);
            image1.Source = BitmapFrame.Create(validCode.CreateCheckCodeImage());
        }

        private void image1_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            validCode = new ValidCode(4, ValidCode.CodeType.Alphas);
            image1.Source = BitmapFrame.Create(validCode.CreateCheckCodeImage());
        }

        private void btn1_Click(object sender, RoutedEventArgs e)
        {
            if (txtbox1.Text.ToUpper() == validCode.ReturnCode.ToUpper())
                MessageBox.Show("输入验证码正确");
            else
                MessageBox.Show("输入验证码错误");
        }
    }

实现效果图