Silverlight图片验证码生成代码

在Silverlight的登录页面中经常用到输入验证码，怎么生成的呢，其实和.NET生成差不多，以下简单介绍一种：

1、在Silverlight项目下建立一个类IndentifyCodeClass.cs文件

    1）、首先注意添加引用 using System.Windows.Media.Imaging;

    2）、添加一个用来产生验证码的方法
        public string CreateIndentifyCode(int count)
        {
            string allchar = "1,2,3,4,5,6,7,8,9,0,A,a,B,b,C,c,D,d,E,e,F,f," +
                "G,g,H,h,I,i,J,j,K,k,L,l,M,m,N,n,O,o,P,p,Q,q,R,r,S,s," +
                "T,t,U,u,V,v,W,w,X,x,Y,y,Z,z";
            string[] allchararray = allchar.Split(',');
            string randomcode = "";
            int temp = -1;
            Random rand = new Random();
            for (int i = 0; i < count; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(61);
                if (temp == t)
                {
                    return CreateIndentifyCode(count);
                }
                temp = t;
                randomcode += allchararray[t];
            }
            return randomcode;
        }

    3）、添加一个方法，用来产生验证码的背景噪声图片
        Random r = new Random(DateTime.Now.Millisecond);
        public void CreatImage(string Text, Image imgsource, int iw, int ih)
        {
            Grid Gx = new Grid();
            Canvas cv1 = new Canvas();
            for (int i = 0; i < 6; i++)
            {
                Polyline p = new Polyline();
                for (int ix = 0; ix < r.Next(3, 6); ix++)
                {
                    p.Points.Add(new Point(r.NextDouble() * iw,
                        r.NextDouble() * ih));
                }
                byte[] Buffer = new byte[3];
                r.NextBytes(Buffer);
                SolidColorBrush SC = new SolidColorBrush(Color.FromArgb(255,
                    Buffer[0], Buffer[1], Buffer[2]));
                p.Stroke = SC;
                p.StrokeThickness = 0.5;
                cv1.Children.Add(p);
            }
            Canvas cv2 = new Canvas();
            int y = 0;
            int lw = 6;
            double w = (iw - lw) / Text.Length;
            int h = (int)ih;
            foreach (char x in Text)
            {
                byte[] Buffer = new byte[3];
                r.NextBytes(Buffer);
                SolidColorBrush SC = new SolidColorBrush(Color.FromArgb(255,
                    Buffer[0], Buffer[1], Buffer[2]));
                TextBlock t = new TextBlock();
                t.TextAlignment = TextAlignment.Center;
                t.FontSize = r.Next(h - 3, h);
                t.Foreground = SC;
                t.Text = x.ToString();
                t.Projection = new PlaneProjection()
                {
                    RotationX = r.Next(-30, 30),
                    RotationY = r.Next(-30, 30),
                    RotationZ = r.Next(-10, 10)
                };
                cv2.Children.Add(t);
                Canvas.SetLeft(t, lw / 2 + y * w);
                Canvas.SetTop(t, 0);
                y++;
            }
            Gx.Children.Add(cv1);
            Gx.Children.Add(cv2);
            WriteableBitmap W = new WriteableBitmap(Gx, new TransformGroup());
            W.Render(Gx, new TransformGroup());
            imgsource.Source = W;
        }

2、在登录页面的UserControl_Loaded事件中添加如下代码即可：

      IndentifyCodeClass code = new IndentifyCodeClass();

      string generatedCode =  code.CreateIndentifyCode(6);
      code.CreatImage(generatedCode , CheckCodeImage, 150, 30);

3、获取用户在文本框中输入的验证码，然后和产生的验证码进行比较验证。

   ....

     string indentifyCode = this.tbIndentifyCode.Text.trim();

     if(generatedCode !=indentifyCode)

     {

          MessageBox.Show("验证码输入错误！");

          this.tbIndentifyCode.Focus(); //输入焦点聚焦

     }

4、实现验证效果，just try it！