一个可以返回验证码图片的类库源码(C#)

验证码字符个数、生成图片宽度、高度自定均可由构造方法自定，无参构造生成默认字符个数和默认大小的Image,方法 GetImgWithValidateCode()返回生成的验证码图片，方法 IsRight(string inputValCode) 判断用户输入的验证码 inputValCode与图片显示的字符是否一致，不区分大小写

using System;
using System.IO;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace DrawValidateImageLib
{
public class DrawValImg
{
/// <summary>
/// 无参构造
/// </summary>
public DrawValImg() { }
/// <summary>
/// 带有生成字符个数的构造
/// </summary>
/// <param name="charNum">验证码中包含随机字符的个数</param>
public DrawValImg( int charNum)
{
this.CharNum = charNum;
}
/// <summary>
/// 带有验证码图片宽度和高度的构造
/// </summary>
/// <param name="width">验证码图片宽度</param>
/// <param name="height">验证码图片高度</param>
public DrawValImg( int width, int height)
{
this.width = width;
this.height = height;
}
/// <summary>
/// 带有生成字符个数，验证码图片宽度和高度的构造
/// </summary>
/// <param name="charNum">验证码中包含随机字符的个数</param>
/// <param name="width">验证码图片宽度</param>
/// <param name="height">验证码图片高度</param>
public DrawValImg( int charNum, int width, int height)
{
this.CharNum = charNum;
this.width = width;
this.height = height;
}

/// <summary>
/// 验证码中字符个数
/// </summary>
int charNum = 5; //默认字符个数为5

public int CharNum
{
get { return charNum; }
set { charNum = value; }
}
/// <summary>
/// 字号
/// </summary>
int fontSize = 20;

public int FontSize
{
get { return fontSize; }
}
/// <summary>
/// 图片宽度
/// </summary>
int width=200;

public int Width
{
get { return width; }
}

/// <summary>
/// 图片高度
/// </summary>
int height=45;

public int Height
{
get { return height; }
set { height = value; }
}

/// <summary>
/// 随机生成的字符串
/// </summary>
string validStr="";

public string ValidStr
{
get { return validStr; }
set { validStr = value; }
}

/// <summary>
/// 产生指定个数的随机字符串，默认字符个数为5
/// </summary>
void GetValidateCode()
{
Random rd = new Random(); //创建随机数对象

//产生由 charNum 个字母或数字组成的一个字符串
string str = "abcdefghijkmnpqrstuvwyzABCDEFGHJKLMNPQRSTUVWYZ23456789田国兴"; //共57个字符，除 l,o,x,I,O,X,1,0 的所有数字和大写字母
for ( int i = 0; i < charNum; i++)
{
validStr = validStr + str.Substring(rd.Next(57), 1); //返回0到56共57个
}

}

/// <summary>
/// 由随机字符串，随即颜色背景，和随机线条产生的Image
/// </summary>
/// <returns>Image</returns>
public Image GetImgWithValidateCode() //返回 Image
{
//产生随机字符串
GetValidateCode();

//声明一个位图对象
Bitmap bitMap = null;
//声明一个绘图画面
Graphics gph = null;
//创建内存流
MemoryStream memStream = new MemoryStream();

Random random = new Random();

//由给定的需要生成字符串中字符个数 CharNum， 图片宽度 Width 和高度 Height 确定字号 FontSize，
//确保不因字号过大而不能全部显示在图片上
int fontWidth=( int)Math.Round(width/(charNum+2)/1.3);
int fontHeight=( int)Math.Round(height/1.5);
//字号取二者中小者，以确保所有字符能够显示，并且字符的下半部分也能显示
fontSize = fontWidth <= fontHeight ? fontWidth : fontHeight;

//创建位图对象
bitMap = new Bitmap(width+FontSize,height);
//根据上面创建的位图对象创建绘图图面
gph = Graphics.FromImage(bitMap);

//设定验证码图片背景色
gph.Clear(GetControllableColor(200));
//产生随机干扰线条
for ( int i = 0; i < 10; i++)
{
Pen backPen = new Pen(GetControllableColor(100), 2);
//线条起点
int x = random.Next(width);
int y = random.Next(height);
//线条终点
int x2 = random.Next(width);
int y2 = random.Next(height);
//划线
gph.DrawLine(backPen, x, y, x2, y2);
}

//定义一个含10种字体的数组
String[] fontFamily ={ "Arial", "Verdana", "Comic Sans MS", "Impact", "Haettenschweiler",
"Lucida Sans Unicode", "Garamond", "Courier New", "Book Antiqua", "Arial Narrow" };
SolidBrush sb = new SolidBrush(GetControllableColor(0));
//通过循环,绘制每个字符,
for ( int i = 0; i < validStr.Length; i++)
{
Font textFont = new Font(fontFamily[random.Next(10)], fontSize, FontStyle.Bold); //字体随机,字号大小30,加粗

//每次循环绘制一个字符,设置字体格式,画笔颜色,字符相对画布的X坐标,字符相对画布的Y坐标
int space = ( int)Math.Round(( double)((width - fontSize * (CharNum + 2)) / CharNum));
//纵坐标
int y = ( int)Math.Round(( double)((height - fontSize)/3));
gph.DrawString(validStr.Substring(i, 1), textFont, sb, fontSize + i * (fontSize + space), y);
}
//扭曲图片
bitMap=TwistImage(bitMap, true, random.Next(3,5),random.Next(3));

try
{

bitMap.Save(memStream, ImageFormat.Gif);

}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show(ex.Message);
}
//gph.Dispose();
bitMap.Dispose();

Image img = Image.FromStream(memStream);
gph.DrawImage(img, 50, 20, width, 10);

return img;
}
/// <summary>
/// 产生一种 R,G,B 均大于 colorBase 随机颜色，以确保颜色不会过深
/// </summary>
/// <returns>背景色</returns>
Color GetControllableColor( int colorBase)
{
Color color=Color.Black;
if (colorBase > 200)
{
System.Windows.Forms.MessageBox.Show( "可控制颜色参数大于200，颜色默认位黑色");
}
Random random = new Random();
//确保 R,G,B 均大于 colorBase，这样才能保证背景色较浅
color= Color.FromArgb(random.Next(56) + colorBase, random.Next(56) + colorBase, random.Next(56) + colorBase);
return color;
}

/// <summary>
/// 扭曲图片
/// </summary>
/// <param name="srcBmp"></param>
/// <param name="bXDir"></param>
/// <param name="dMultValue"></param>
/// <param name="dPhase"></param>
/// <returns></returns>
Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
{
int leftMargin = 0;
int rightMargin = 0;
int topMargin = 0;
int bottomMargin = 0;
//float PI = 3.14159265358979f;
float PI2 = 6.28318530717959f;
Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
double dBaseAxisLen = bXDir ? Convert.ToDouble(destBmp.Height) : Convert.ToDouble(destBmp.Width);
for ( int i = 0; i < destBmp.Width; i++)
{
for ( int j = 0; j < destBmp.Height; j++)
{
double dx = 0;
dx = bXDir ? PI2 * Convert.ToDouble(j) / dBaseAxisLen : PI2 * Convert.ToDouble(i) / dBaseAxisLen;
dx += dPhase;
double dy = Math.Sin(dx);

//取得当前点的颜色
int nOldX = 0;
int nOldY = 0;
nOldX = bXDir ? i + Convert.ToInt32(dy * dMultValue) : i;
nOldY = bXDir ? j : j + Convert.ToInt32(dy * dMultValue);
System.Drawing.Color color = srcBmp.GetPixel(i, j);
if (nOldX >= leftMargin && nOldX < destBmp.Width - rightMargin && nOldY >= bottomMargin && nOldY < destBmp.Height - topMargin)
{
destBmp.SetPixel(nOldX, nOldY, color);
}
}
}
return destBmp;
}






/// <summary>
/// 判断验证码是否正确
/// </summary>
/// <param name="inputValCode">待判断的验证码</param>
/// <returns>正确返回 true,错误返回 false</returns>
public bool IsRight( string inputValCode)
{

if (validStr.ToUpper().Equals(inputValCode.ToUpper())) //无论输入大小写都转换为大些判断
{
return true;
}
else
{
return false;
}
}

}
}

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