[验证码实现] Captcha 验证码类，一个很个性的验证码类 （转载）

点击下载 Captcha.zip

/// <summary>
/// 类说明：条码生成类
/// 编 码 人：苏飞
/// 联系方式：361983679
/// 更新网站：[url=http://www.sufeinet.com/thread-655-1-1.html]http://www.sufeinet.com/thread-655-1-1.html[/url]
/// </summary>
using System;
using System.Drawing;

public static class Captcha
{
    private static double[] addVector(double[] a, double[] b)
    {
        return new double[] { a[] + b[], a[] + b[], a[] + b[] };
    }

    private static double[] scalarProduct(double[] vector, double scalar)
    {
        return new double[] { vector[] * scalar, vector[] * scalar, vector[] * scalar };
    }

    private static double dotProduct(double[] a, double[] b)
    {
        return a[] * b[] + a[] * b[] + a[] * b[];
    }

    private static double norm(double[] vector)
    {
        return Math.Sqrt(dotProduct(vector, vector));
    }

    private static double[] normalize(double[] vector)
    {
        return scalarProduct(vector, 1.0 / norm(vector));
    }

    private static double[] crossProduct(double[] a, double[] b)
    {
        return new double[]
                {
                    (a[] * b[] - a[] * b[]),
                    (a[] * b[] - a[] * b[]),
                    (a[] * b[] - a[] * b[])
                };
    }

    private static double[] vectorProductIndexed(double[] v, double[] m, int i)
    {
        return new double[]
                {
                    v[i + ] * m[] + v[i + ] * m[] + v[i + ] * m[] + v[i + ] * m[],
                    v[i + ] * m[] + v[i + ] * m[] + v[i + ] * m[] + v[i + ] * m[],
                    v[i + ] * m[] + v[i + ] * m[] + v[i + ] * m[]+ v[i + ] * m[],
                    v[i + ] * m[] + v[i + ] * m[] + v[i + ] * m[]+ v[i + ] * m[]
                };
    }

    private static double[] vectorProduct(double[] v, double[] m)
    {
        return vectorProductIndexed(v, m, );
    }

    private static double[] matrixProduct(double[] a, double[] b)
    {
        double[] o1 = vectorProductIndexed(a, b, );
        double[] o2 = vectorProductIndexed(a, b, );
        double[] o3 = vectorProductIndexed(a, b, );
        double[] o4 = vectorProductIndexed(a, b, );

        return new double[]
                {
                    o1[], o1[], o1[], o1[],
                    o2[], o2[], o2[], o2[],
                    o3[], o3[], o3[], o3[],
                    o4[], o4[], o4[], o4[]
                };
    }

    private static double[] cameraTransform(double[] C, double[] A)
    {
        double[] w = normalize(addVector(C, scalarProduct(A, -)));
        double[] y = new double[] { , ,  };
        double[] u = normalize(crossProduct(y, w));
        double[] v = crossProduct(w, u);
        double[] t = scalarProduct(C, -);

        return new double[]
                {
                    u[], v[], w[], ,
                    u[], v[], w[], ,
                    u[], v[], w[], ,
                    dotProduct(u, t), dotProduct(v, t), dotProduct(w, t),
                };
    }

    private static double[] viewingTransform(double fov, double n, double f)
    {
        fov *= (Math.PI / );
        double cot = 1.0 / Math.Tan(fov / );
        return new double[] { cot, , , , , cot, , , , , (f + n) / (f - n), -, , ,  * f * n / (f - n),  };
    }

    public static Image Generate(string captchaText)
    {
        int fontsize = ;
        Font font = new Font("Arial", fontsize);

        SizeF sizeF;
        using (Graphics g = Graphics.FromImage(new Bitmap(, )))
        {
            sizeF = g.MeasureString(captchaText, font, , StringFormat.GenericDefault);
        }

        int image2d_x = (int)sizeF.Width;
        int image2d_y = (int)(fontsize * 1.3);

        Bitmap image2d = new Bitmap(image2d_x, image2d_y);
        Color black = Color.Black;
        Color white = Color.White;

        using (Graphics g = Graphics.FromImage(image2d))
        {
            g.Clear(black);
            g.DrawString(captchaText, font, Brushes.White, , );
        }

        Random rnd = new Random();
        double[] T = cameraTransform(new double[] { rnd.Next(-, ), -, rnd.Next(, ) }, new double[] { , ,  });
        T = matrixProduct(T, viewingTransform(, , ));

        double[][] coord = new double[image2d_x * image2d_y][];

        int count = ;
        for (int y = ; y < image2d_y; y += )
        {
            for (int x = ; x < image2d_x; x++)
            {
                int xc = x - image2d_x / ;
                int zc = y - image2d_y / ;
                double yc = -(double)(image2d.GetPixel(x, y).ToArgb() & 0xff) /  * ;
                double[] xyz = new double[] { xc, yc, zc,  };
                xyz = vectorProduct(xyz, T);
                coord[count] = xyz;
                count++;
            }
        }

        int image3d_x = ;
        int image3d_y = image3d_x *  / ;
        Bitmap image3d = new Bitmap(image3d_x, image3d_y);
        Color fgcolor = Color.White;
        Color bgcolor = Color.Black;
        using (Graphics g = Graphics.FromImage(image3d))
        {
            g.Clear(bgcolor);
            count = ;
            double scale = 1.75 - (double)image2d_x / ;
            for (int y = ; y < image2d_y; y += )
            {
                for (int x = ; x < image2d_x; x++)
                {
                    if (x > )
                    {
                        double x0 = coord[count - ][] * scale + image3d_x / ;
                        double y0 = coord[count - ][] * scale + image3d_y / ;
                        double x1 = coord[count][] * scale + image3d_x / ;
                        double y1 = coord[count][] * scale + image3d_y / ;
                        g.DrawLine(new Pen(fgcolor), (float)x0, (float)y0, (float)x1, (float)y1);
                    }
                    count++;
                }
            }
        }
        return image3d;
    }
}