ASP.NET登录验证码解决方案

目录

• #验证码效果图
• #代码 0、html代码
• 1、Handler中调用验证码生成类
• 2、验证码图片绘制生成类
• 3、高斯模糊算法类

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