C＃的彩色验证码

private void CreateImage(string checkCode)
{
int iwidth = (int)(checkCode.Length * 15);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 25);
Graphics g = Graphics.FromImage(image);
g.Clear(Color.White);
//定义颜色
Color[] c = {Color.Black,Color.Red,Color.DarkBlue,Color.Green,Color.Orange,Color.Brown,Color.DarkCyan,Color.Purple};
//定义字体 string[] font = {"Verdana","Microsoft Sans Serif","Comic Sans MS","Arial","宋体"};
Random rand = new Random();
//随机输出噪点
for(int i=0;i<50;i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
g.DrawRectangle(new Pen(Color.LightGray, 0),x,y,1,1);
}

//输出不同字体和颜色的验证码字符
for(int i=0;i<checkCode.Length;i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);

Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold);
Brush b = new System.Drawing.SolidBrush(c[cindex]);
int ii=4;
if((i+1)%2==0)
{
ii=2;
}
g.DrawString(checkCode.Substring(i,1), f, b, 3+(i*12), ii);
}
//画一个边框
g.DrawRectangle(new Pen(Color.Black,0),0,0,image.Width-1,image.Height-1);

//输出到浏览器
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg);
Response.ClearContent();
Response.ContentType = "image/Jpeg";
Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}