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ASP.NET登录验证码解决方案

2019-07-23 21:51 1396 查看

目录

  • #注意
  • #参考
  • 在web项目中,为了防止登录被暴力破解,需要在登录的时候加入验证码验证,思路是:
    1)登录页面打开,向 服务端请求生成验证码图片,并将验证码字符串存入session;
    2)登录时将客户端输入的验证码字符串传到服务端,与session中的验证码进行比较,如果验证码正确,再进行登录验证;

    #验证码效果图

    #代码

    0、html代码

    <img id="CaptchaImg" src="PictureHandler.ashx" title="看不清,点一下!"/>

    1、Handler中调用验证码生成类

    public void ProcessRequest (HttpContext context)
    {
    context.Response.ContentType = "image/jpeg";
    
    Resource.Utility.DrawCaptchaHelper objDrawValidationCode = new Resource.Utility.DrawCaptchaHelper();
    objDrawValidationCode.CaptchaLength = 4;//验证码字符个数
    objDrawValidationCode.IsPixel = true;//随机噪点
    
    objDrawValidationCode.RandomStringCount = 2; //干扰字符个数
    objDrawValidationCode.RandomStringFontSize = 30;//干扰字符字体大小
    
    objDrawValidationCode.FontMinSize = 35;//验证码字体的大小的最小值
    objDrawValidationCode.FontMaxSize = 40;  //验证码字体的大小的最大值
    
    //objDrawValidationCode.GaussianDeviation = 3;    //默认0,不使用高斯模糊算法处理图像。
    //objDrawValidationCode.BrightnessValue = 5;        //明暗度,默认0,是使用明暗度算法处理图像
    
    objDrawValidationCode.LineCount = 1;  //默认3条。
    objDrawValidationCode.BezierCount = 2;//默认3条。
    
    //边框样式
    //objDrawValidationCode.Border = DrawCaptchaHelper.BorderStyle.RoundRectangle;
    
    using (MemoryStream ms = new MemoryStream())
    {
    objDrawValidationCode.CreateImage(ms);
    context.Session["ValidateCode"] = objDrawValidationCode.CaptchaStr;//将验证码字符串存入session,用于登录验证
    //return File(ms.GetBuffer(), "image/jpeg");
    context.Response.BinaryWrite(ms.GetBuffer());
    }
    }

    2、验证码图片绘制生成类

    #region 验证码生成类
    /// <summary>
    /// 验证码生成类
    /// </summary>
    public class DrawCaptchaHelper
    {
    #region 定义和初始化配置字段
    //用户存取验证码字符串
    private string captchaStr = String.Empty;
    /// <summary>
    /// 获取系统生成的随机验证码
    /// </summary>
    public String CaptchaStr
    {
    get { return captchaStr; }
    }
    private Int32 captchaLength = 4;
    /// <summary>
    /// 获取和设置验证码字符串的长度
    /// </summary>
    public Int32 CaptchaLength
    {
    get { return captchaLength; }
    set { captchaLength = value; }
    }
    Graphics dc = null;
    private int bgWidth = 130;
    /// <summary>
    /// 验证码的宽度,默认为130
    /// </summary>
    public Int32 Width
    {
    get { return bgWidth; }
    set { bgWidth = value; }
    }
    
    private int bgHeight = 40;
    /// <summary>
    /// 验证码的高度,默认为40
    /// </summary>
    public Int32 Height
    {
    get { return bgHeight; }
    set { bgHeight = value; }
    }
    
    private int fontMinSize = 15;
    /// <summary>
    /// 验证码字体的最小值,默认为15,建议不小于15像素
    /// </summary>
    public Int32 FontMinSize
    {
    get { return fontMinSize; }
    set { fontMinSize = value; }
    }
    private Int32 fontMaxSize = 20;
    /// <summary>
    /// 验证码字体的最大值,默认为20
    /// </summary>
    public Int32 FontMaxSize
    {
    get { return fontMaxSize; }
    set { fontMaxSize = value; }
    }
    private Color[] fontColor = { };
    /// <summary>
    /// 验证码字体的颜色,默认为系统自动生成字体颜色
    /// </summary>
    public Color[] FontColor
    {
    get { return fontColor; }
    set { fontColor = value; }
    }
    private Color backColor = Color.FromArgb(243, 255, 255);
    /// <summary>
    /// 验证码的背景色,默认为Color.FromArgb(243, 251, 254)
    /// </summary>
    public Color BackgroundColor
    {
    get { return backColor; }
    set { backColor = value; }
    }
    private Int32 bezierCount = 3;
    /// <summary>
    /// 贝塞尔曲线的条数,默认为3条
    /// </summary>
    public Int32 BezierCount
    {
    get { return bezierCount; }
    set { bezierCount = value; }
    }
    private Int32 lineCount = 3;
    /// <summary>
    /// 直线条数,默认为3条
    /// </summary>
    public Int32 LineCount
    {
    get { return lineCount; }
    set { lineCount = value; }
    }
    Random random;
    
    //定义验证码字符及出现频次 ,避免出现 0 o j i l 1 x;
    private String charCollection = "2,3,4,5,6,7,8,9,a,s,d,f,g,h,z,c,v,b,n,m,k,q,w,e,r,t,y,u,p,A,S,D,F,G,H,Z,C,V,B,N,M,K,Q,W,E,R,T,Y,U,P";
    /// <summary>
    /// 随机字符串列表,请使用英文状态下的逗号分隔。
    /// </summary>
    public String CharCollection
    {
    get { return charCollection; }
    set { charCollection = value; }
    }
    private Int32 intCount = 4;
    /// <summary>
    /// 验证码字符串个数,默认为4个字符
    /// </summary>
    public Int32 IntCount
    {
    get { return intCount; }
    set { intCount = value; }
    }
    private Boolean isPixel = true;
    /// <summary>
    /// 是否添加噪点,默认添加,噪点颜色为系统随机生成。
    /// </summary>
    public Boolean IsPixel
    {
    get { return isPixel; }
    set { isPixel = value; }
    }
    /// <summary>
    /// 随机背景字符串的个数
    /// </summary>
    public Int32 RandomStringCount { get; set; }
    private Int32 randomStringFontSize = 10;
    /// <summary>
    /// 随机背景字符串的大小
    /// </summary>
    public Int32 RandomStringFontSize
    {
    get { return randomStringFontSize; }
    set { randomStringFontSize = value; }
    }
    /// <summary>
    /// 边框样式
    /// </summary>
    public enum BorderStyle
    {
    /// <summary>
    /// 无边框
    /// </summary>
    None,
    /// <summary>
    /// 矩形边框
    /// </summary>
    Rectangle,
    /// <summary>
    /// 圆角边框
    /// </summary>
    RoundRectangle
    }
    /// <summary>
    /// 设置或获取边框样式
    /// </summary>
    public BorderStyle Border { get; set; }
    
    private Int32 rotationAngle = 40;
    /// <summary>
    /// 验证码字符串随机转动的角度的最大值
    /// </summary>
    public Int32 RotationAngle
    {
    get { return rotationAngle; }
    set { rotationAngle = value; }
    }
    
    private Point[] strPoint = null;
    
    private Double gaussianDeviation = 0;
    /// <summary>
    /// 对验证码图片进行高斯模糊的阀值,如果设置为0,则不对图片进行高斯模糊,该设置可能会对图片处理的性能有较大影响
    /// </summary>
    public Double GaussianDeviation
    {
    get { return gaussianDeviation; }
    set { gaussianDeviation = value; }
    }
    private Int32 brightnessValue = 0;
    /// <summary>
    /// 对图片进行暗度和亮度的调整,如果该值为0,则不调整。该设置会对图片处理性能有较大影响
    /// </summary>
    public Int32 BrightnessValue
    {
    get { return brightnessValue; }
    set { brightnessValue = value; }
    }
    #endregion
    
    #region wq 新增 边框补(默认1像素)
    int padding = 2;
    public int Padding
    {
    get { return padding; }
    set { padding = value; }
    }
    #endregion
    
    /// <summary>
    /// 构造函数,用于初始化常用变量
    /// </summary>
    public DrawCaptchaHelper()
    {
    random = new Random(Guid.NewGuid().GetHashCode());
    strPoint = new Point[captchaLength + 1];
    if (gaussianDeviation < 0) gaussianDeviation = 0;
    }
    
    /// <summary>
    /// 生成验证码
    /// </summary>
    /// <param name="target">用于存储图片的一般字节序列</param>
    public MemoryStream CreateImage(MemoryStream target)
    {
    //新增 wq ,否则后面报错
    if (strPoint.Length != captchaLength)
    {
    strPoint = new Point[captchaLength + 1];//wq 新增,原因是:构造函数默认初始化5个元素,假如new后,又改了validationCodeCount的数值,则该数字需要重新初始化
    }
    
    //新增 wq    ,否则图片的画布太小
    if (fontMaxSize >= (bgHeight / 5) * 4)
    {
    //throw new ArgumentException("字体最大值参数FontMaxSize与验证码高度相近,这会导致描绘验证码字符串时出错,请重新设置参数!");
    AdjustBitmapSize();
    }
    
    Bitmap bit = new Bitmap(bgWidth + 1, bgHeight + 1);
    //写字符串
    dc = Graphics.FromImage(bit);
    dc.SmoothingMode = SmoothingMode.HighQuality;
    dc.TextRenderingHint = TextRenderingHint.ClearTypeGridFit; ;
    dc.InterpolationMode = InterpolationMode.HighQualityBilinear;
    dc.CompositingQuality = CompositingQuality.HighQuality;
    
    dc.Clear(Color.White);
    //画验证码背景,例如,增加早点,添加曲线和直线等
    dc.DrawImageUnscaled(DrawBackground(), 0, 0);
    
    //绘制验证码
    Bitmap validatecodeImg = DrawRandomString();
    //对随机码图像上的文字进行波形扭曲(扭曲文字方式1)
    validatecodeImg = TwistImage(validatecodeImg, true, 3, 4);
    dc.DrawImageUnscaled(validatecodeImg, 0, 0);
    
    //水波纹效果  文字进行波形扭曲 (扭曲文字方式2)
    //bit = AdjustRippleEffect(bit, 5);
    
    //对图片进行高斯模糊
    if (gaussianDeviation > 0)
    {
    GaussianHelper gau = new GaussianHelper();
    bit = gau.FilterProcessImage(gaussianDeviation, bit);
    }
    //进行暗度和亮度处理
    if (brightnessValue != 0)
    {
    //对图片进行调暗处理
    bit = AdjustBrightness(bit, brightnessValue);
    }
    bit.Save(target, ImageFormat.Gif);
    //brush.Dispose();
    bit.Dispose();
    dc.Dispose();
    return target;
    }
    
    #region 画验证码背景,例如,增加早点,添加曲线和直线等
    /// <summary>
    /// 画验证码背景,例如,增加早点,添加曲线和直线等
    /// </summary>
    /// <returns></returns>
    private Bitmap DrawBackground()
    {
    Bitmap bit = new Bitmap(bgWidth + 1, bgHeight + 1);
    Graphics g = Graphics.FromImage(bit);
    g.SmoothingMode = SmoothingMode.HighQuality;
    
    g.Clear(Color.White);
    Rectangle rectangle = new Rectangle(0, 0, bgWidth, bgHeight);
    Brush brush = new SolidBrush(backColor);
    g.FillRectangle(brush, rectangle);
    
    //画噪点
    if (isPixel)
    {
    g.DrawImageUnscaled(DrawRandomPixel(30), 0, 0);
    }
    //画干扰字符
    g.DrawImageUnscaled(DrawRandBgString(), 0, 0);
    
    //画曲线
    g.DrawImageUnscaled(DrawRandomBezier(bezierCount), 0, 0);
    //画直线
    g.DrawImageUnscaled(DrawRandomLine(lineCount), 0, 0);
    //画字符连接线
    //dc.DrawImageUnscaled(DrawStringline(), 0, 0);
    if (Border == BorderStyle.Rectangle)
    {
    //绘制边框
    g.DrawRectangle(new Pen(Color.FromArgb(90, 87, 46)), 0, 0, bgWidth, bgHeight);
    }
    else if (Border == BorderStyle.RoundRectangle)
    {
    //画圆角
    DrawRoundRectangle(g, rectangle, Color.FromArgb(90, 87, 46), 1, 3);
    }
    else
    {
    //没有边框
    }
    
    return bit;
    
    }
    #endregion
    
    #region 画正弦曲线
    private Bitmap DrawTwist(Bitmap bmp, Int32 tWidth, Int32 tHeight, float angle, Color color)
    {
    //为了方便查看效果,在这里我定义了一个常量。
    //它在定义数组的长度和for循环中都要用到。
    int size = bgWidth;
    
    double[] x = new double[size];
    Bitmap b = new Bitmap(bmp.Width, bmp.Height);
    b.MakeTransparent();
    Graphics graphics = Graphics.FromImage(b);
    Pen pen = new Pen(color);
    
    //画正弦曲线的横轴间距参数。建议所用的值应该是 正数且是2的倍数。
    //在这里采用2。
    int val = 2;
    
    float temp = 0.0f;
    
    //把画布下移100。为什么要这样做,只要你把这一句给注释掉,运行一下代码,
    //你就会明白是为什么?
    graphics.TranslateTransform(0, 100);
    graphics.SmoothingMode = SmoothingMode.HighQuality;
    graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
    for (int i = 0; i < size; i++)
    {
    //改变tWidth,实现正弦曲线宽度的变化。
    //改tHeight,实现正弦曲线高度的变化。
    x[i] = Math.Sin(2 * Math.PI * i / tWidth) * tHeight;
    
    graphics.DrawLine(pen, i * val, temp, i * val + val / 2, (float)x[i]);
    temp = (float)x[i];
    }
    graphics.RotateTransform(60, MatrixOrder.Prepend);
    
    //旋转图片
    // b = KiRotate(b, angle, Color.Transparent);
    return b;
    }
    #endregion
    
    #region 正弦曲线Wave扭曲图片
    /// <summary>
    /// 正弦曲线Wave扭曲图片
    /// </summary>
    /// <param name="srcBmp">图片路径</param>
    /// <param name="bXDir">如果扭曲则选择为True</param>
    /// <param name="dMultValue">波形的幅度倍数,越大扭曲的程度越高,一般为3</param>
    /// <param name="dPhase">波形的起始相位,取值区间[0-2*PI)</param>
    /// <returns></returns>
    public Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
    {
    System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
    double PI2 = 6.283185307179586476925286766559;
    // 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 图片任意角度旋转
    /// <summary>
    /// 图片任意角度旋转
    /// </summary>
    /// <param name="bmp">原始图Bitmap</param>
    /// <param name="angle">旋转角度</param>
    /// <param name="bkColor">背景色</param>
    /// <returns>输出Bitmap</returns>
    public static Bitmap KiRotate(Bitmap bmp, float angle, Color bkColor)
    {
    int w = bmp.Width;
    int h = bmp.Height;
    
    PixelFormat pf;
    
    if (bkColor == Color.Transparent)
    {
    pf = PixelFormat.Format32bppArgb;
    }
    else
    {
    pf = bmp.PixelFormat;
    }
    
    Bitmap tmp = new Bitmap(w, h, pf);
    Graphics g = Graphics.FromImage(tmp);
    g.Clear(bkColor);
    g.DrawImageUnscaled(bmp, 1, 1);
    g.Dispose();
    
    GraphicsPath path = new GraphicsPath();
    path.AddRectangle(new RectangleF(0f, 0f, w, h));
    Matrix mtrx = new Matrix();
    mtrx.Rotate(angle);
    RectangleF rct = path.GetBounds(mtrx);
    
    Bitmap dst = new Bitmap((int)rct.Width, (int)rct.Height, pf);
    g = Graphics.FromImage(dst);
    g.Clear(bkColor);
    g.TranslateTransform(-rct.X, -rct.Y);
    g.RotateTransform(angle);
    g.InterpolationMode = InterpolationMode.HighQualityBilinear;
    g.DrawImageUnscaled(tmp, 0, 0);
    g.Dispose();
    tmp.Dispose();
    
    return dst;
    }
    #endregion
    
    #region 随机生成贝塞尔曲线
    /// <summary>
    /// 随机生成贝塞尔曲线
    /// </summary>
    /// <param name="bmp">一个图片的实例</param>
    /// <param name="lineNum">线条数量</param>
    /// <returns></returns>
    public Bitmap DrawRandomBezier(Int32 lineNum)
    {
    Bitmap b = new Bitmap(bgWidth, bgHeight);
    b.MakeTransparent();
    Graphics g = Graphics.FromImage(b);
    g.Clear(Color.Transparent);
    g.SmoothingMode = SmoothingMode.HighQuality;
    g.PixelOffsetMode = PixelOffsetMode.HighQuality;
    
    GraphicsPath gPath1 = new GraphicsPath();
    Int32 lineRandNum = random.Next(lineNum);
    
    for (int i = 0; i < (lineNum - lineRandNum); i++)
    {
    Pen p = new Pen(GetRandomDeepColor(), 3f);  //wq,增加贝塞尔曲线的线宽参数
    Point[] point = {
    new Point(random.Next(1, (b.Width / 10)), random.Next(1, (b.Height))),
    new Point(random.Next((b.Width / 10) * 2, (b.Width / 10) * 4), random.Next(1, (b.Height))),
    new Point(random.Next((b.Width / 10) * 4, (b.Width / 10) * 6), random.Next(1, (b.Height))),
    new Point(random.Next((b.Width / 10) * 8, b.Width), random.Next(1, (b.Height)))
    };
    
    gPath1.AddBeziers(point);
    g.DrawPath(p, gPath1);
    p.Dispose();
    }
    
    for (int i = 0; i < lineRandNum; i++)
    {
    Pen p = new Pen(GetRandomDeepColor());
    Point[] point = {
    new Point(random.Next(1, b.Width), random.Next(1, b.Height)),
    new Point(random.Next((b.Width / 10) * 2, b.Width), random.Next(1, b.Height)),
    new Point(random.Next((b.Width / 10) * 4, b.Width), random.Next(1, b.Height)),
    new Point(random.Next(1, b.Width), random.Next(1, b.Height))
    };
    gPath1.AddBeziers(point);
    g.DrawPath(p, gPath1);
    p.Dispose();
    }
    return b;
    }
    #endregion
    
    #region 画直线
    /// <summary>
    /// 画直线
    /// </summary>
    /// <param name="bmp">一个bmp实例</param>
    /// <param name="lineNum">线条个数</param>
    /// <returns></returns>
    public Bitmap DrawRandomLine(Int32 lineNum)
    {
    if (lineNum < 0) throw new ArgumentNullException("参数bmp为空!");
    Bitmap b = new Bitmap(bgWidth, bgHeight);
    b.MakeTransparent();
    Graphics g = Graphics.FromImage(b);
    g.Clear(Color.Transparent);
    g.PixelOffsetMode = PixelOffsetMode.HighQuality;
    g.SmoothingMode = SmoothingMode.HighQuality;
    for (int i = 0; i < lineNum; i++)
    {
    Pen p = new Pen(GetRandomDeepColor());
    Point pt1 = new Point(random.Next(1, (b.Width / 5) * 2), random.Next(b.Height));
    Point pt2 = new Point(random.Next((b.Width / 5) * 3, b.Width), random.Next(b.Height));
    g.DrawLine(p, pt1, pt2);
    p.Dispose();
    }
    
    return b;
    }
    #endregion
    
    #region 画随机噪点
    /// <summary>
    /// 画随机噪点
    /// </summary>
    /// <param name="pixNum">噪点的百分比</param>
    /// <returns></returns>
    public Bitmap DrawRandomPixel(Int32 pixNum)
    {
    Bitmap b = new Bitmap(bgWidth, bgHeight);
    b.MakeTransparent();
    Graphics graph = Graphics.FromImage(b);
    graph.SmoothingMode = SmoothingMode.HighQuality;
    graph.InterpolationMode = InterpolationMode.HighQualityBilinear;
    
    //画噪点
    for (int i = 0; i < (bgHeight * bgWidth) / pixNum; i++)
    {
    int x = random.Next(b.Width);
    int y = random.Next(b.Height);
    b.SetPixel(x, y, GetRandomDeepColor());
    //下移坐标重新画点
    if ((x + 1) < b.Width && (y + 1) < b.Height)
    {
    //画图片的前景噪音点
    graph.DrawRectangle(new Pen(Color.Silver), random.Next(b.Width), random.Next(b.Height), 1, 1);
    }
    
    }
    
    return b;
    }
    #endregion
    
    #region 画随机字符串中间连线
    /// <summary>
    /// 画随机字符串中间连线
    /// </summary>
    /// <returns></returns>
    private Bitmap DrawStringline()
    {
    Bitmap b = new Bitmap(bgWidth, bgHeight);
    b.MakeTransparent();
    Graphics g = Graphics.FromImage(b);
    g.SmoothingMode = SmoothingMode.AntiAlias;
    
    Point[] p = new Point[captchaLength];
    for (int i = 0; i < captchaLength; i++)
    {
    p[i] = strPoint[i];
    //throw new Exception(strPoint.Length.ToString());
    }
    // g.DrawBezier(new Pen(GetRandomDeepColor()), strPoint);
    //g.DrawClosedCurve(new Pen(GetRandomDeepColor()), strPoint);
    g.DrawCurve(new Pen(GetRandomDeepColor(), 1), strPoint);
    
    return b;
    }
    #endregion
    
    #region 写入验证码的字符串
    /// <summary>
    /// 写入验证码的字符串
    /// </summary>
    private Bitmap DrawRandomString()
    {
    if (fontMaxSize >= (bgHeight / 5) * 4)
    {
    //throw new ArgumentException("字体最大值参数FontMaxSize与验证码高度相近,这会导致描绘验证码字符串时出错,请重新设置参数!");
    AdjustBitmapSize();
    }
    
    Bitmap b = new Bitmap(bgWidth, bgHeight);
    b.MakeTransparent();
    Graphics g = Graphics.FromImage(b);
    
    g.Clear(Color.Transparent);
    g.PixelOffsetMode = PixelOffsetMode.Half;
    g.SmoothingMode = SmoothingMode.HighQuality;
    g.TextRenderingHint = TextRenderingHint.SingleBitPerPixelGridFit;
    g.InterpolationMode = InterpolationMode.HighQualityBilinear;
    
    char[] chars = GetRandomString(captchaLength).ToCharArray();//拆散字符串成单字符数组
    captchaStr = new string(chars); //这个类的外部,也可以通过这个参数,获取到本次的验证码字符串值。
    
    //设置字体显示格式
    StringFormat format = new StringFormat(StringFormatFlags.NoClip);
    format.Alignment = StringAlignment.Center;
    format.LineAlignment = StringAlignment.Center;
    FontFamily f = new FontFamily(GenericFontFamilies.Monospace);
    
    Int32 charNum = chars.Length;
    
    Point sPoint = new Point();
    Int32 fontSize = 9;
    for (int i = 0; i < captchaLength; i++)
    {
    int findex = random.Next(captchaLength + 1);// random.Next(5);
    //定义字体
    Font textFont = new Font(f, random.Next(fontMinSize, fontMaxSize), FontStyle.Bold);
    //定义画刷,用于写字符串
    //Brush brush = new SolidBrush(GetRandomDeepColor());
    Int32 textFontSize = Convert.ToInt32(textFont.Size);
    fontSize = textFontSize;
    
    var t = (bgWidth / charNum)/2;
    Point point = new Point(random.Next((bgWidth / charNum) * (i) + t - 2, (bgWidth / charNum) * (i + 1) -t+ 2), random.Next(bgHeight / 5 + textFontSize / 2, bgHeight - textFontSize / 2));
    
    //如果当前字符X坐标小于字体的二分之一大小
    if (point.X < textFontSize / 2)
    {
    point.X = point.X + textFontSize / 2;
    }
    //防止文字叠加
    if (i > 0 && (point.X - sPoint.X < (textFontSize / 2 + textFontSize / 2)))
    {
    point.X = point.X + textFontSize;
    }
    //如果当前字符X坐标大于图片宽度,就减去字体的宽度
    if (point.X > (bgWidth - textFontSize / 2))
    {
    point.X = bgWidth - textFontSize / 2;
    }
    
    sPoint = point;
    
    float angle = random.Next(-rotationAngle, rotationAngle);//转动的度数
    g.TranslateTransform(point.X, point.Y);//移动光标到指定位置
    g.RotateTransform(angle);
    
    //设置渐变画刷
    Rectangle myretang = new Rectangle(0, 1, Convert.ToInt32(textFont.Size), Convert.ToInt32(textFont.Size));
    Color c = GetRandomDeepColor();
    LinearGradientBrush mybrush2 = new LinearGradientBrush(myretang, c, GetLightColor(c, 120), random.Next(180));
    
    g.DrawString(chars[i].ToString(), textFont, mybrush2, 1, 1, format);
    
    g.RotateTransform(-angle);//转回去
    g.TranslateTransform(-point.X, -point.Y);//移动光标到指定位置,每个字符紧凑显示,避免被软件识别
    
    strPoint[i] = point;
    
    textFont.Dispose();
    mybrush2.Dispose();
    }
    return b;
    }
    #endregion
    
    #region   新增的矫正验证码的宽高
    private void AdjustBitmapSize()
    {
    int fSize = fontMaxSize;
    int fWidth = fSize + Padding;
    
    int imageWidth = (int)(captchaLength * fWidth) + 4 + Padding * 2;
    int imageHeight = fSize * 2 + Padding;
    bgWidth = imageWidth;
    bgHeight = imageHeight;
    }
    #endregion
    
    #region 画干扰背景文字
    /// <summary>
    /// 画背景干扰文字
    /// </summary>
    /// <returns></returns>
    private Bitmap DrawRandBgString()
    {
    Bitmap b = new Bitmap(bgWidth, bgHeight);
    String[] randStr = { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
    b.MakeTransparent();
    Graphics g = Graphics.FromImage(b);
    
    g.Clear(Color.Transparent);
    g.PixelOffsetMode = PixelOffsetMode.HighQuality;
    g.SmoothingMode = SmoothingMode.HighQuality;
    g.TextRenderingHint = TextRenderingHint.AntiAlias;
    g.InterpolationMode = InterpolationMode.HighQualityBilinear;
    
    //设置字体显示格式
    StringFormat format = new StringFormat(StringFormatFlags.NoClip);
    format.Alignment = StringAlignment.Center;
    format.LineAlignment = StringAlignment.Center;
    
    FontFamily f = new FontFamily(GenericFontFamilies.Serif);
    Font textFont = new Font(f, randomStringFontSize, FontStyle.Underline);
    
    int randAngle = 60; //随机转动角度
    
    for (int i = 0; i < RandomStringCount; i++)
    {
    
    Brush brush = new System.Drawing.SolidBrush(GetRandomLightColor());
    Point pot = new Point(random.Next(randomStringFontSize / 2, bgWidth - randomStringFontSize / 2),
    random.Next(randomStringFontSize / 2, bgHeight - randomStringFontSize/2));
    //随机转动的度数
    float angle = random.Next(-randAngle, randAngle);
    
    //转动画布
    g.RotateTransform(angle);
    g.DrawString(randStr[random.Next(randStr.Length)], textFont, brush, pot, format);
    //转回去,为下一个字符做准备
    g.RotateTransform(-angle);
    //释放资源
    brush.Dispose();
    }
    textFont.Dispose();
    format.Dispose();
    f.Dispose();
    
    return b;
    }
    #endregion
    
    #region 生成随机字符串
    /// <summary>
    /// 生成随机字符串
    /// </summary>
    /// <returns></returns>
    private string GetRandomString(Int32 textLength)
    {
    string[] randomArray = charCollection.Split(','); //将字符串生成数组
    int arrayLength = randomArray.Length;
    string randomString = "";
    for (int i = 0; i < textLength; i++)
    {
    randomString += randomArray[random.Next(0, arrayLength)];
    }
    //Session["CheckCode"] = randomString;
    return randomString; //长度是textLength +1
    }
    #endregion
    
    #region 内部方法:绘制验证码背景
    private void DrawBackground(HatchStyle hatchStyle)
    {
    //设置填充背景时用的笔刷
    HatchBrush hBrush = new HatchBrush(hatchStyle, backColor);
    
    //填充背景图片
    dc.FillRectangle(hBrush, 0, 0, this.bgWidth, this.bgHeight);
    }
    #endregion
    
    #region 根据指定长度,返回随机验证码
    /// <summary>
    /// 根据指定长度,返回随机验证码
    /// </summary>
    /// <param >制定长度</param>
    /// <returns>随即验证码</returns>
    public string Next(int length)
    {
    this.captchaStr = GetRandomCode(length);
    return this.captchaStr;
    }
    #endregion
    
    #region 内部方法:返回指定长度的随机验证码字符串
    /// <summary>
    /// 根据指定大小返回随机验证码
    /// </summary>
    /// <param >字符串长度</param>
    /// <returns>随机字符串</returns>
    private string GetRandomCode(int length)
    {
    StringBuilder sb = new StringBuilder(6);
    
    for (int i = 0; i < length; i++)
    {
    sb.Append(Char.ConvertFromUtf32(RandomAZ09()));
    }
    
    return sb.ToString();
    }
    #endregion
    
    #region 内部方法:产生随机数和随机点
    
    /// <summary>
    /// 产生0-9A-Z的随机字符代码
    /// </summary>
    /// <returns>字符代码</returns>
    private int RandomAZ09()
    {
    int result = 48;
    Random ram = new Random();
    int i = ram.Next(2);
    
    switch (i)
    {
    case 0:
    result = ram.Next(48, 58);
    break;
    case 1:
    result = ram.Next(65, 91);
    break;
    }
    
    return result;
    }
    
    /// <summary>
    /// 返回一个随机点,该随机点范围在验证码背景大小范围内
    /// </summary>
    /// <returns>Point对象</returns>
    private Point RandomPoint()
    {
    Random ram = new Random();
    Point point = new Point(ram.Next(this.bgWidth), ram.Next(this.bgHeight));
    return point;
    }
    #endregion
    
    #region 随机生成颜色值
    /// <summary>
    /// 生成随机深颜色
    /// </summary>
    /// <returns></returns>
    public Color GetRandomDeepColor()
    {
    int nRed, nGreen, nBlue;    // nBlue,nRed  nGreen 相差大一点 nGreen 小一些
    //int high = 255;
    int redLow = 160;
    int greenLow = 100;
    int blueLow = 160;
    nRed = random.Next(redLow);
    nGreen = random.Next(greenLow);
    nBlue = random.Next(blueLow);
    Color color = Color.FromArgb(nRed, nGreen, nBlue);
    return color;
    }
    
    /// <summary>
    /// 生成随机浅颜色
    /// </summary>
    /// <returns>randomColor</returns>
    public Color GetRandomLightColor()
    {
    int nRed, nGreen, nBlue;    //越大颜色越浅
    int low = 180;           //色彩的下限
    int high = 255;          //色彩的上限
    nRed = random.Next(high) % (high - low) + low;
    nGreen = random.Next(high) % (high - low) + low;
    nBlue = random.Next(high) % (high - low) + low;
    Color color = Color.FromArgb(nRed, nGreen, nBlue);
    return color;
    }
    /// <summary>
    /// 生成随机颜色值
    /// </summary>
    /// <returns></returns>
    public Color GetRandomColor()
    {
    int nRed, nGreen, nBlue;    //越大颜色越浅
    int low = 10;           //色彩的下限
    int high = 255;          //色彩的上限
    nRed = random.Next(high) % (high - low) + low;
    nGreen = random.Next(high) % (high - low) + low;
    nBlue = random.Next(high) % (high - low) + low;
    Color color = Color.FromArgb(nRed, nGreen, nBlue);
    return color;
    }
    /// <summary>
    /// 获取与当前颜色值相加后的颜色
    /// </summary>
    /// <param name="c"></param>
    /// <returns></returns>
    public Color GetLightColor(Color c, Int32 value)
    {
    int nRed = c.R, nGreen = c.G, nBlue = c.B;    //越大颜色越浅
    if (nRed + value < 255 && nRed + value > 0)
    {
    nRed = c.R + 40;
    }
    if (nGreen + value < 255 && nGreen + value > 0)
    {
    nGreen = c.G + 40;
    }
    if (nBlue + value < 255 && nBlue + value > 0)
    {
    nBlue = c.B + 40;
    }
    Color color = Color.FromArgb(nRed, nGreen, nBlue);
    return color;
    }
    #endregion
    
    #region 合并图片
    /// <summary>
    /// 合并图片
    /// </summary>
    /// <param name="maps"></param>
    /// <returns></returns>
    private Bitmap MergerImg(params Bitmap[] maps)
    {
    int i = maps.Length;
    if (i == 0)
    throw new Exception("图片数不能够为0");
    //创建要显示的图片对象,根据参数的个数设置宽度
    Bitmap backgroudImg = new Bitmap(i * 12, 16);
    Graphics g = Graphics.FromImage(backgroudImg);
    //清除画布,背景设置为白色
    g.Clear(System.Drawing.Color.White);
    for (int j = 0; j < i; j++)
    {
    //g.DrawImage(maps[j], j * 11, 0, maps[j].Width, maps[j].Height);
    g.DrawImageUnscaled(maps[j], 0, 0);
    }
    g.Dispose();
    return backgroudImg;
    }
    #endregion
    
    #region 生成不重复的随机数,该函数会消耗大量系统资源
    /// <summary>
    /// 生成不重复的随机数,该函数会消耗大量系统资源
    /// </summary>
    /// <returns></returns>
    private static int GetRandomSeed()
    {
    byte[] bytes = new byte[4];
    System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
    rng.GetBytes(bytes);
    return BitConverter.ToInt32(bytes, 0);
    }
    #endregion
    
    #region 缩放图片
    /// <summary>
    /// 缩放图片
    /// </summary>
    /// <param name="bmp">原始Bitmap</param>
    /// <param name="newW">新的宽度</param>
    /// <param name="newH">新的高度</param>
    /// <param name="Mode">缩放质量</param>
    /// <returns>处理以后的图片</returns>
    public static Bitmap KiResizeImage(Bitmap bmp, int newW, int newH, InterpolationMode Mode)
    {
    try
    {
    Bitmap b = new Bitmap(newW, newH);
    Graphics g = Graphics.FromImage(b);
    // 插值算法的质量
    g.InterpolationMode = Mode;
    g.DrawImage(bmp, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, bmp.Width, bmp.Height), GraphicsUnit.Pixel);
    g.Dispose();
    return b;
    }
    catch
    {
    return null;
    }
    }
    #endregion
    
    #region 绘制圆角矩形
    /// <summary>
    /// C# GDI+ 绘制圆角矩形
    /// </summary>
    /// <param name="g">Graphics 对象</param>
    /// <param name="rectangle">Rectangle 对象,圆角矩形区域</param>
    /// <param name="borderColor">边框颜色</param>
    /// <param name="borderWidth">边框宽度</param>
    /// <param name="r">圆角半径</param>
    private static void DrawRoundRectangle(Graphics g, Rectangle rectangle, Color borderColor, float borderWidth, int r)
    {
    // 如要使边缘平滑,请取消下行的注释
    g.SmoothingMode = SmoothingMode.HighQuality;
    
    // 由于边框也需要一定宽度,需要对矩形进行修正
    //rectangle = new Rectangle(rectangle.X, rectangle.Y, rectangle.Width, rectangle.Height);
    Pen p = new Pen(borderColor, borderWidth);
    // 调用 getRoundRectangle 得到圆角矩形的路径,然后再进行绘制
    g.DrawPath(p, getRoundRectangle(rectangle, r));
    }
    #endregion
    
    #region 根据普通矩形得到圆角矩形的路径
    /// <summary>
    /// 根据普通矩形得到圆角矩形的路径
    /// </summary>
    /// <param name="rectangle">原始矩形</param>
    /// <param name="r">半径</param>
    /// <returns>图形路径</returns>
    private static GraphicsPath getRoundRectangle(Rectangle rectangle, int r)
    {
    int l = 2 * r;
    // 把圆角矩形分成八段直线、弧的组合,依次加到路径中
    GraphicsPath gp = new GraphicsPath();
    gp.AddLine(new Point(rectangle.X + r, rectangle.Y), new Point(rectangle.Right - r, rectangle.Y));
    gp.AddArc(new Rectangle(rectangle.Right - l, rectangle.Y, l, l), 270F, 90F);
    
    gp.AddLine(new Point(rectangle.Right, rectangle.Y + r), new Point(rectangle.Right, rectangle.Bottom - r));
    gp.AddArc(new Rectangle(rectangle.Right - l, rectangle.Bottom - l, l, l), 0F, 90F);
    
    gp.AddLine(new Point(rectangle.Right - r, rectangle.Bottom), new Point(rectangle.X + r, rectangle.Bottom));
    gp.AddArc(new Rectangle(rectangle.X, rectangle.Bottom - l, l, l), 90F, 90F);
    
    gp.AddLine(new Point(rectangle.X, rectangle.Bottom - r), new Point(rectangle.X, rectangle.Y + r));
    gp.AddArc(new Rectangle(rectangle.X, rectangle.Y, l, l), 180F, 90F);
    return gp;
    }
    #endregion
    
    #region 柔化
    ///<summary>
    /// 柔化
    /// </summary>
    /// <param name="b">原始图</param>
    /// <returns>输出图</returns>
    public static Bitmap KiBlur(Bitmap b)
    {
    
    if (b == null)
    {
    return null;
    }
    
    int w = b.Width;
    int h = b.Height;
    
    try
    {
    
    Bitmap bmpRtn = new Bitmap(w, h, PixelFormat.Format24bppRgb);
    
    BitmapData srcData = b.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
    BitmapData dstData = bmpRtn.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);
    
    unsafe
    {
    byte* pIn = (byte*)srcData.Scan0.ToPointer();
    byte* pOut = (byte*)dstData.Scan0.ToPointer();
    int stride = srcData.Stride;
    byte* p;
    
    for (int y = 0; y < h; y++)
    {
    for (int x = 0; x < w; x++)
    {
    //取周围9点的值
    if (x == 0 || x == w - 1 || y == 0 || y == h - 1)
    {
    //不做
    pOut[0] = pIn[0];
    pOut[1] = pIn[1];
    pOut[2] = pIn[2];
    }
    else
    {
    int r1, r2, r3, r4, r5, r6, r7, r8, r9;
    int g1, g2, g3, g4, g5, g6, g7, g8, g9;
    int b1, b2, b3, b4, b5, b6, b7, b8, b9;
    
    float vR, vG, vB;
    
    //左上
    p = pIn - stride - 3;
    r1 = p[2];
    g1 = p[1];
    b1 = p[0];
    
    //正上
    p = pIn - stride;
    r2 = p[2];
    g2 = p[1];
    b2 = p[0];
    
    //右上
    p = pIn - stride + 3;
    r3 = p[2];
    g3 = p[1];
    b3 = p[0];
    
    //左侧
    p = pIn - 3;
    r4 = p[2];
    g4 = p[1];
    b4 = p[0];
    
    //右侧
    p = pIn + 3;
    r5 = p[2];
    g5 = p[1];
    b5 = p[0];
    
    //右下
    p = pIn + stride - 3;
    r6 = p[2];
    g6 = p[1];
    b6 = p[0];
    
    //正下
    p = pIn + stride;
    r7 = p[2];
    g7 = p[1];
    b7 = p[0];
    
    //右下
    p = pIn + stride + 3;
    r8 = p[2];
    g8 = p[1];
    b8 = p[0];
    
    //自己
    p = pIn;
    r9 = p[2];
    g9 = p[1];
    b9 = p[0];
    
    vR = (float)(r1 + r2 + r3 + r4 + r5 + r6 + r7 + r8 + r9);
    vG = (float)(g1 + g2 + g3 + g4 + g5 + g6 + g7 + g8 + g9);
    vB = (float)(b1 + b2 + b3 + b4 + b5 + b6 + b7 + b8 + b9);
    
    vR /= 9;
    vG /= 9;
    vB /= 9;
    
    pOut[0] = (byte)vB;
    pOut[1] = (byte)vG;
    pOut[2] = (byte)vR;
    
    }
    
    pIn += 3;
    pOut += 3;
    }// end of x
    
    pIn += srcData.Stride - w * 3;
    pOut += srcData.Stride - w * 3;
    } // end of y
    }
    
    b.UnlockBits(srcData);
    bmpRtn.UnlockBits(dstData);
    
    return bmpRtn;
    }
    catch
    {
    return null;
    }
    
    } // end of KiBlur
    #endregion
    
    #region 滤镜
    /// <summary>
    /// 红色滤镜
    /// </summary>
    /// <param name="bitmap">Bitmap</param>
    /// <param name="threshold">阀值 -255~255</param>
    /// <returns></returns>
    public System.Drawing.Bitmap AdjustToRed(System.Drawing.Bitmap bitmap, int threshold)
    {
    for (int y = 0; y < bitmap.Height; y++)
    {
    for (int x = 0; x < bitmap.Width; x++)
    {
    // 取得每一個 pixel
    var pixel = bitmap.GetPixel(x, y);
    var pR = pixel.R + threshold;
    pR = Math.Max(pR, 0);
    pR = Math.Min(255, pR);
    // 將改過的 RGB 寫回
    // 只寫入紅色的值 , G B 都放零
    System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, 0, 0);
    bitmap.SetPixel(x, y, newColor);
    }
    }
    // 回傳結果
    return bitmap;
    }
    
    /// <summary>
    /// 绿色滤镜
    /// </summary>
    /// <param name="bitmap">一个图片实例</param>
    /// <param name="threshold">阀值 -255~+255</param>
    /// <returns></returns>
    public System.Drawing.Bitmap AdjustToGreen(System.Drawing.Bitmap bitmap, int threshold)
    {
    for (int y = 0; y < bitmap.Height; y++)
    {
    for (int x = 0; x < bitmap.Width; x++)
    {
    // 取得每一個 pixel
    var pixel = bitmap.GetPixel(x, y);
    //判斷是否超過255 如果超過就是255
    var pG = pixel.G + threshold;
    //如果小於0就為0
    if (pG > 255) pG = 255;
    if (pG < 0) pG = 0;
    // 將改過的 RGB 寫回
    // 只寫入綠色的值 , R B 都放零
    System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, 0, pG, 0);
    bitmap.SetPixel(x, y, newColor);
    }
    }
    // 回傳結果
    return bitmap;
    }
    /// <summary>
    /// 蓝色滤镜
    /// </summary>
    /// <param name="bitmap">一个图片实例</param>
    /// <param name="threshold">阀值 -255~255</param>
    /// <returns></returns>
    public System.Drawing.Bitmap AdjustToBlue(System.Drawing.Bitmap bitmap, int threshold)
    {
    for (int y = 0; y < bitmap.Height; y++)
    {
    for (int x = 0; x < bitmap.Width; x++)
    {
    // 取得每一個 pixel
    var pixel = bitmap.GetPixel(x, y);
    //判斷是否超過255 如果超過就是255
    var pB = pixel.B + threshold;
    //如果小於0就為0
    if (pB > 255) pB = 255;
    if (pB < 0) pB = 0;
    // 將改過的 RGB 寫回
    // 只寫入藍色的值 , R G 都放零
    System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, 0, 0, pB);
    bitmap.SetPixel(x, y, newColor);
    }
    }
    // 回傳結果
    return bitmap;
    }
    /// <summary>
    /// 调整 RGB 色调
    /// </summary>
    /// <param name="bitmap"></param>
    /// <param name="thresholdRed">红色阀值</param>
    /// <param name="thresholdBlue">蓝色阀值</param>
    /// <param name="thresholdGreen">绿色阀值</param>
    /// <returns></returns>
    public System.Drawing.Bitmap AdjustToCustomColor(System.Drawing.Bitmap bitmap, int thresholdRed, int thresholdGreen, int thresholdBlue)
    {
    for (int y = 0; y < bitmap.Height; y++)
    {
    for (int x = 0; x < bitmap.Width; x++)
    {
    // 取得每一個 pixel
    var pixel = bitmap.GetPixel(x, y);
    //判斷是否超過255 如果超過就是255
    var pG = pixel.G + thresholdGreen;
    //如果小於0就為0
    if (pG > 255) pG = 255;
    if (pG < 0) pG = 0;
    //判斷是否超過255 如果超過就是255
    var pR = pixel.R + thresholdRed;
    //如果小於0就為0
    if (pR > 255) pR = 255;
    if (pR < 0) pR = 0;
    //判斷是否超過255 如果超過就是255
    var pB = pixel.B + thresholdBlue;
    //如果小於0就為0
    if (pB > 255) pB = 255;
    if (pB < 0) pB = 0;
    // 將改過的 RGB 寫回
    // 只寫入綠色的值 , R B 都放零
    System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, pG, pB);
    bitmap.SetPixel(x, y, newColor);
    }
    }
    return bitmap;
    }
    #endregion
    
    #region 图片去色(图片黑白化)
    /// <summary>
    /// 图片去色(图片黑白化)
    /// </summary>
    /// <param name="original">一个需要处理的图片</param>
    /// <returns></returns>
    public static Bitmap MakeGrayscale(Bitmap original)
    {
    //create a blank bitmap the same size as original
    Bitmap newBitmap = new Bitmap(original.Width, original.Height);
    
    //get a graphics object from the new image
    Graphics g = Graphics.FromImage(newBitmap);
    g.SmoothingMode = SmoothingMode.HighQuality;
    //create the grayscale ColorMatrix
    ColorMatrix colorMatrix = new ColorMatrix(new float[][]
    {
    new float[] {.3f, .3f, .3f, 0, 0},
    new float[] {.59f, .59f, .59f, 0, 0},
    new float[] {.11f, .11f, .11f, 0, 0},
    new float[] {0, 0, 0, 1, 0},
    new float[] {0, 0, 0, 0, 1}
    });
    
    //create some image attributes
    ImageAttributes attributes = new ImageAttributes();
    
    //set the color matrix attribute
    attributes.SetColorMatrix(colorMatrix);
    
    //draw the original image on the new image
    //using the grayscale color matrix
    g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height),
    0, 0, original.Width, original.Height, GraphicsUnit.Pixel, attributes);
    
    //dispose the Graphics object
    g.Dispose();
    return newBitmap;
    }
    #endregion
    
    #region 增加或減少亮度
    /// <summary>
    /// 增加或減少亮度
    /// </summary>
    /// <param name="img">System.Drawing.Image Source </param>
    /// <param name="valBrightness">0~255</param>
    /// <returns></returns>
    public System.Drawing.Bitmap AdjustBrightness(System.Drawing.Image img, int valBrightness)
    {
    // 讀入欲轉換的圖片並轉成為 Bitmap
    System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(img);
    
    for (int y = 0; y < bitmap.Height; y++)
    {
    for (int x = 0; x < bitmap.Width; x++)
    {
    // 取得每一個 pixel
    var pixel = bitmap.GetPixel(x, y);
    
    // 判斷 如果處理過後 255 就設定為 255 如果小於則設定為 0
    var pR = ((pixel.R + valBrightness > 255) ? 255 : pixel.R + valBrightness) < 0 ? 0 : ((pixel.R + valBrightness > 255) ? 255 : pixel.R + valBrightness);
    var pG = ((pixel.G + valBrightness > 255) ? 255 : pixel.G + valBrightness) < 0 ? 0 : ((pixel.G + valBrightness > 255) ? 255 : pixel.G + valBrightness);
    var pB = ((pixel.B + valBrightness > 255) ? 255 : pixel.B + valBrightness) < 0 ? 0 : ((pixel.B + valBrightness > 255) ? 255 : pixel.B + valBrightness);
    
    // 將改過的 RGB 寫回
    System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, pG, pB);
    
    bitmap.SetPixel(x, y, newColor);
    
    }
    }
    // 回傳結果
    return bitmap;
    }
    #endregion
    
    #region 浮雕效果
    /// <summary>
    /// 浮雕效果
    /// </summary>
    /// <param name="src">一个图片实例</param>
    /// <returns></returns>
    public Bitmap AdjustToStone(Bitmap src)
    {
    // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
    BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
    
    unsafe
    {
    // 抓住第一个 Pixel 第一个数值
    byte* p = (byte*)(void*)bitmapData.Scan0;
    
    // 跨步值 - 宽度 *3 可以算出畸零地 之后跳到下一行
    int nOffset = bitmapData.Stride - src.Width * 3;
    
    for (int y = 0; y < src.Height; ++y)
    {
    for (int x = 0; x < src.Width; ++x)
    {
    // 为了理解方便 所以特地在命名
    int r, g, b;
    // 先取得下一个 Pixel
    var q = p + 3;
    r = Math.Abs(p[2] - q[2] + 128);
    r = r < 0 ? 0 : r;
    r = r > 255 ? 255 : r;
    p[2] = (byte)r;
    
    g = Math.Abs(p[1] - q[1] + 128);
    g = g < 0 ? 0 : g;
    g = g > 255 ? 255 : g;
    p[1] = (byte)g;
    
    b = Math.Abs(p[0] - q[0] + 128);
    b = b < 0 ? 0 : b;
    b = b > 255 ? 255 : b;
    p[0] = (byte)b;
    
    // 跳去下一个 Pixel
    p += 3;
    
    }
    // 跨越畸零地
    p += nOffset;
    }
    }
    src.UnlockBits(bitmapData);
    return src;
    }
    #endregion
    
    #region 水波纹效果
    /// <summary>
    /// 水波纹效果
    /// </summary>
    /// <param name="src"></param>
    /// <param name="nWave">坡度</param>
    /// www.it165.net
    /// <returns></returns>
    public Bitmap AdjustRippleEffect(Bitmap src, short nWave)
    {
    
    int nWidth = src.Width;
    int nHeight = src.Height;
    
    // 透过公式进行水波纹的採样
    
    PointF[,] fp = new PointF[nWidth, nHeight];
    
    Point[,] pt = new Point[nWidth, nHeight];
    
    Point mid = new Point();
    mid.X = nWidth / 2;
    mid.Y = nHeight / 2;
    
    double newX, newY;
    double xo, yo;
    
    //先取样将水波纹座标跟RGB取出
    for (int x = 0; x < nWidth; ++x)
    for (int y = 0; y < nHeight; ++y)
    {
    xo = ((double)nWave * Math.Sin(2.0 * 3.1415 * (float)y / 128.0));
    yo = ((double)nWave * Math.Cos(2.0 * 3.1415 * (float)x / 128.0));
    
    newX = (x + xo);
    newY = (y + yo);
    
    if (newX > 0 && newX < nWidth)
    {
    fp[x, y].X = (float)newX;
    pt[x, y].X = (int)newX;
    }
    else
    {
    fp[x, y].X = (float)0.0;
    pt[x, y].X = 0;
    }
    
    if (newY > 0 && newY < nHeight)
    {
    fp[x, y].Y = (float)newY;
    pt[x, y].Y = (int)newY;
    }
    else
    {
    fp[x, y].Y = (float)0.0;
    pt[x, y].Y = 0;
    }
    }
    
    //进行合成
    Bitmap bSrc = (Bitmap)src.Clone();
    
    // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
    BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite,
    PixelFormat.Format24bppRgb);
    BitmapData bmSrc = bSrc.LockBits(new Rectangle(0, 0, bSrc.Width, bSrc.Height), ImageLockMode.ReadWrite,
    PixelFormat.Format24bppRgb);
    
    int scanline = bitmapData.Stride;
    
    IntPtr Scan0 = bitmapData.Scan0;
    IntPtr SrcScan0 = bmSrc.Scan0;
    
    unsafe
    {
    byte* p = (byte*)(void*)Scan0;
    byte* pSrc = (byte*)(void*)SrcScan0;
    
    int nOffset = bitmapData.Stride - src.Width * 3;
    
    int xOffset, yOffset;
    
    for (int y = 0; y < nHeight; ++y)
    {
    for (int x = 0; x < nWidth; ++x)
    {
    xOffset = pt[x, y].X;
    yOffset = pt[x, y].Y;
    
    if (yOffset >= 0 && yOffset < nHeight && xOffset >= 0 && xOffset < nWidth)
    {
    p[0] = pSrc[(yOffset * scanline) + (xOffset * 3)];
    p[1] = pSrc[(yOffset * scanline) + (xOffset * 3) + 1];
    p[2] = pSrc[(yOffset * scanline) + (xOffset * 3) + 2];
    }
    
    p += 3;
    }
    p += nOffset;
    }
    }
    
    src.UnlockBits(bitmapData);
    bSrc.UnlockBits(bmSrc);
    
    return src;
    }
    #endregion
    
    #region 调整曝光度值
    /// <summary>
    /// 调整曝光度值
    /// </summary>
    /// <param name="src">原图</param>
    /// <param name="r"></param>
    /// <param name="g"></param>
    /// <param name="b"></param>
    /// <returns></returns>
    public Bitmap AdjustGamma(Bitmap src, double r, double g, double b)
    {
    // 判断是不是在0.2~5 之间
    r = Math.Min(Math.Max(0.2, r), 5);
    g = Math.Min(Math.Max(0.2, g), 5);
    b = Math.Min(Math.Max(0.2, b), 5);
    
    // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
    BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
    
    unsafe
    {
    // 抓住第一个 Pixel 第一个数值
    byte* p = (byte*)(void*)bitmapData.Scan0;
    
    // 跨步值 - 宽度 *3 可以算出畸零地 之后跳到下一行
    int nOffset = bitmapData.Stride - src.Width * 3;
    
    for (int y = 0; y < src.Height; y++)
    {
    for (int x = 0; x < src.Width; x++)
    {
    p[2] = (byte)Math.Min(255, (int)((255.0 * Math.Pow(p[2] / 255.0, 1.0 / r)) + 0.5));
    p[1] = (byte)Math.Min(255, (int)((255.0 * Math.Pow(p[1] / 255.0, 1.0 / g)) + 0.5));
    p[0] = (byte)Math.Min(255, (int)((255.0 * Math.Pow(p[0] / 255.0, 1.0 / b)) + 0.5));
    
    // 跳去下一个 Pixel
    p += 3;
    
    }
    // 跨越畸零地
    p += nOffset;
    }
    }
    src.UnlockBits(bitmapData);
    return src;
    
    }
    #endregion
    
    #region 高对比,对过深的颜色调浅,过浅的颜色调深。
    /// <summary>
    /// 高对比,对过深的颜色调浅,过浅的颜色调深。
    /// </summary>
    /// <param name="src"></param>
    /// <param name="effectThreshold"> 高对比程度 -100~100</param>
    /// <returns></returns>
    public Bitmap Contrast(Bitmap src, float effectThreshold)
    {
    
    // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
    BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
    
    // 判断是否在 -100~100
    effectThreshold = effectThreshold < -100 ? -100 : effectThreshold;
    effectThreshold = effectThreshold > 100 ? 100 : effectThreshold;
    
    effectThreshold = (float)((100.0 + effectThreshold) / 100.0);
    effectThreshold *= effectThreshold;
    
    unsafe
    {
    // 抓住第一个 Pixel 第一个数值 www.it165.net
    byte* p = (byte*)(void*)bitmapData.Scan0;
    
    // 跨步值 - 宽度 *3 可以算出畸零地 之后跳到下一行
    int nOffset = bitmapData.Stride - src.Width * 3;
    
    for (int y = 0; y < src.Height; y++)
    {
    for (int x = 0; x < src.Width; x++)
    {
    double buffer = 0;
    
    // 公式  (Red/255)-0.5= 偏离中间值程度
    // ((偏离中间值程度 * 影响范围)+0.4 ) * 255
    buffer = ((((p[2] / 255.0) - 0.5) * effectThreshold) + 0.5) * 255.0;
    buffer = buffer > 255 ? 255 : buffer;
    buffer = buffer < 0 ? 0 : buffer;
    p[2] = (byte)buffer;
    
    buffer = ((((p[1] / 255.0) - 0.5) * effectThreshold) + 0.5) * 255.0;
    buffer = buffer > 255 ? 255 : buffer;
    buffer = buffer < 0 ? 0 : buffer;
    p[1] = (byte)buffer;
    
    buffer = ((((p[0] / 255.0) - 0.5) * effectThreshold) + 0.5) * 255.0;
    buffer = buffer > 255 ? 255 : buffer;
    buffer = buffer < 0 ? 0 : buffer;
    p[0] = (byte)buffer;
    
    // 跳去下一个 Pixel
    p += 3;
    
    }
    // 跨越畸零地
    p += nOffset;
    }
    }
    src.UnlockBits(bitmapData);
    return src;
    
    }
    #endregion
    
    #region 对图片进行雾化效果
    /// <summary>
    /// 对图片进行雾化效果
    /// </summary>
    /// <param name="bmp"></param>
    /// <returns></returns>
    public Bitmap Atomization(Bitmap bmp)
    {
    
    int Height = bmp.Height;
    int Width = bmp.Width;
    Bitmap newBitmap = new Bitmap(Width, Height);
    Bitmap oldBitmap = bmp;
    Color pixel;
    for (int x = 1; x < Width - 1; x++)
    {
    for (int y = 1; y < Height - 1; y++)
    {
    Random MyRandom = new Random(Guid.NewGuid().GetHashCode());
    int k = MyRandom.Next(123456);
    //像素块大小
    int dx = x + k % 19;
    int dy = y + k % 19;
    if (dx >= Width)
    dx = Width - 1;
    if (dy >= Height)
    dy = Height - 1;
    pixel = oldBitmap.GetPixel(dx, dy);
    newBitmap.SetPixel(x, y, pixel);
    }
    }
    return newBitmap;
    }
    #endregion
    
    public MemoryStream test(MemoryStream target)
    {
    Graphics dc = null;
    Bitmap bit = new Bitmap(200, 200);
    //写字符串
    dc = Graphics.FromImage(bit);
    //dc.SmoothingMode = SmoothingMode.HighQuality;
    //dc.TextRenderingHint = TextRenderingHint.ClearTypeGridFit; ;
    //dc.InterpolationMode = InterpolationMode.HighQualityBilinear;
    //dc.CompositingQuality = CompositingQuality.HighQuality;
    
    dc.Clear(Color.White);
    //画验证码背景,例如,增加早点,添加曲线和直线等
    dc.DrawImageUnscaled(DrawBackground(), 0, 0);
    
    bit.Save(target, ImageFormat.Gif);
    //brush.Dispose();
    bit.Dispose();
    dc.Dispose();
    return target;
    
    }
    
    } //END Class DrawValidationCode
    #endregion

    3、高斯模糊算法类

    在验证码生成类中调用了该算法;

    #region 高斯模糊算法
    /// <summary>
    /// 高斯模糊算法
    /// </summary>
    public class GaussianHelper
    {
    public static double[,] Calculate1DSampleKernel(double deviation, int size)
    {
    double[,] ret = new double[size, 1];
    double sum = 0;
    int half = size / 2;
    for (int i = 0; i < size; i++)
    {
    ret[i, 0] = 1 / (Math.Sqrt(2 * Math.PI) * deviation) * Math.Exp(-(i - half) * (i - half) / (2 * deviation * deviation));
    sum += ret[i, 0];
    }
    return ret;
    }
    public static double[,] Calculate1DSampleKernel(double deviation)
    {
    int size = (int)Math.Ceiling(deviation * 3) * 2 + 1;
    return Calculate1DSampleKernel(deviation, size);
    }
    public static double[,] CalculateNormalized1DSampleKernel(double deviation)
    {
    return NormalizeMatrix(Calculate1DSampleKernel(deviation));
    }
    public static double[,] NormalizeMatrix(double[,] matrix)
    {
    double[,] ret = new double[matrix.GetLength(0), matrix.GetLength(1)];
    double sum = 0;
    for (int i = 0; i < ret.GetLength(0); i++)
    {
    for (int j = 0; j < ret.GetLength(1); j++)
    sum += matrix[i, j];
    }
    if (sum != 0)
    {
    for (int i = 0; i < ret.GetLength(0); i++)
    {
    for (int j = 0; j < ret.GetLength(1); j++)
    ret[i, j] = matrix[i, j] / sum;
    }
    }
    return ret;
    }
    public static double[,] GaussianConvolution(double[,] matrix, double deviation)
    {
    double[,] kernel = CalculateNormalized1DSampleKernel(deviation);
    double[,] res1 = new double[matrix.GetLength(0), matrix.GetLength(1)];
    double[,] res2 = new double[matrix.GetLength(0), matrix.GetLength(1)];
    //x-direction
    for (int i = 0; i < matrix.GetLength(0); i++)
    {
    for (int j = 0; j < matrix.GetLength(1); j++)
    res1[i, j] = processPoint(matrix, i, j, kernel, 0);
    }
    //y-direction
    for (int i = 0; i < matrix.GetLength(0); i++)
    {
    for (int j = 0; j < matrix.GetLength(1); j++)
    res2[i, j] = processPoint(res1, i, j, kernel, 1);
    }
    return res2;
    }
    private static double processPoint(double[,] matrix, int x, int y, double[,] kernel, int direction)
    {
    double res = 0;
    int half = kernel.GetLength(0) / 2;
    for (int i = 0; i < kernel.GetLength(0); i++)
    {
    int cox = direction == 0 ? x + i - half : x;
    int coy = direction == 1 ? y + i - half : y;
    if (cox >= 0 && cox < matrix.GetLength(0) && coy >= 0 && coy < matrix.GetLength(1))
    {
    res += matrix[cox, coy] * kernel[i, 0];
    }
    }
    return res;
    }
    /// <summary>
    /// 对颜色值进行灰色处理
    /// </summary>
    /// <param name="cr"></param>
    /// <returns></returns>
    private Color grayscale(Color cr)
    {
    return Color.FromArgb(cr.A, (int)(cr.R * .3 + cr.G * .59 + cr.B * 0.11),
    (int)(cr.R * .3 + cr.G * .59 + cr.B * 0.11),
    (int)(cr.R * .3 + cr.G * .59 + cr.B * 0.11));
    }
    /// <summary>
    /// 对图片进行高斯模糊
    /// </summary>
    /// <param name="d">模糊数值,数值越大模糊越很</param>
    /// <param name="image">一个需要处理的图片</param>
    /// <returns></returns>
    public Bitmap FilterProcessImage(double d, Bitmap image)
    {
    Bitmap ret = new Bitmap(image.Width, image.Height);
    Double[,] matrixR = new Double[image.Width, image.Height];
    Double[,] matrixG = new Double[image.Width, image.Height];
    Double[,] matrixB = new Double[image.Width, image.Height];
    for (int i = 0; i < image.Width; i++)
    {
    for (int j = 0; j < image.Height; j++)
    {
    //matrix[i, j] = grayscale(image.GetPixel(i, j)).R;
    matrixR[i, j] = image.GetPixel(i, j).R;
    matrixG[i, j] = image.GetPixel(i, j).G;
    matrixB[i, j] = image.GetPixel(i, j).B;
    }
    }
    matrixR = GaussianHelper.GaussianConvolution(matrixR, d);
    matrixG = GaussianHelper.GaussianConvolution(matrixG, d);
    matrixB = GaussianHelper.GaussianConvolution(matrixB, d);
    for (int i = 0; i < image.Width; i++)
    {
    for (int j = 0; j < image.Height; j++)
    {
    Int32 R = (int)Math.Min(255, matrixR[i, j]);
    Int32 G = (int)Math.Min(255, matrixG[i, j]);
    Int32 B = (int)Math.Min(255, matrixB[i, j]);
    ret.SetPixel(i, j, Color.FromArgb(R, G, B));
    }
    }
    return ret;
    }
    
    }
    #endregion

    #注意

    因代码中涉及到与C++的dll交互,需要将类所在的程序集设置 “允许不安全代码”,否则会编译失败;

    #参考

    https://www.cnblogs.com/wangqiideal/articles/9238787.html

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