生成验证码

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class vcode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Page.Response.AppendHeader("Cache-Control", "no-cache");
string verifyCode = System.Guid.NewGuid().ToString().Substring(0,4).ToUpper();

verifyCode = verifyCode.Replace("O", "X").Replace("I", "Z");

Session["vc"] = verifyCode.ToLower();
DrawPic(verifyCode);
GC.Collect();
}

private void CheckReferer()
{
if (Request.ServerVariables["HTTP_REFERER"] != null)
{
if (Request.ServerVariables["HTTP_REFERER"].ToString().Split('/')[2] != Request.ServerVariables["HTTP_HOST"].ToString())
{
Response.Redirect("error/403.html");
}
}
else
{
Response.Redirect("error/403.html");
}
}

private void DrawPic(string vc)
{
int width = 78;
int height = 24;
Bitmap bm = new Bitmap(width, height);
Graphics g;
g = Graphics.FromImage(bm);
g.Clear(Color.White);
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

// pic
Random x = new Random();
int[] a = new int[4];
int[] b = new int[4];
int[] c = new int[4];
// 杂线
for (int i = 0; i < 5; i++)
{
g.DrawLine(Pens.DimGray, x.Next(0, width - 1), x.Next(0, height - 1), x.Next(0, width - 1), x.Next(0, height - 1));
}
for (int i = 0; i < 5; i++)
{
g.DrawLine(Pens.LightGray, x.Next(0, width - 1), x.Next(0, height - 1), x.Next(0, width - 1), x.Next(0, height - 1));
}
a[0] = x.Next(0, 7);
a[1] = x.Next(0, 7);
a[2] = x.Next(0, 7);
a[3] = x.Next(0, 7);
b[0] = x.Next(0, 4);
b[1] = x.Next(0, 4);
b[2] = x.Next(0, 4);
b[3] = x.Next(0, 4);
c[0] = x.Next(0, 8);
c[1] = x.Next(0, 8);
c[2] = x.Next(0, 8);
c[3] = x.Next(0, 8);
//g.DrawRectangle(Pens.DimGray, 0, 0, width - 1, height - 1);
string fonts = "Verdana,Verdana,Arial,Tahoma";
FontStyle[] fs = new FontStyle[4];
fs[0] = FontStyle.Bold;
fs[1] = FontStyle.Bold;
fs[2] = FontStyle.Bold;
fs[3] = FontStyle.Bold;

// 写验证码
int fontSize = 16;
float[] angle = new float[4];
angle[0] = x.Next(0, 20);
angle[1] = x.Next(0, 20);
angle[2] = x.Next(0, 20);
angle[3] = x.Next(0, 20);

string reg = "";
if (Request.QueryString["reg"] != null)
{
reg = Request.QueryString["reg"];
}

for (int i = 0; i < 4; i++)
{
g.TranslateTransform(i * 16 + 1 + c[i] + 0, 0f);
g.RotateTransform(angle[i] - 10f);
if (reg == "p")
{
g.DrawString(vc.Substring(i, 1), new Font(fonts.Split(',')[b[i]], fontSize, fs[b[i]]), Brushes.DarkBlue, new Point(0, 0));
}
else if (reg == "s")
{
g.DrawString(vc.Substring(i, 1), new Font(fonts.Split(',')[b[i]], fontSize, fs[b[i]]), Brushes.Maroon, new Point(0, 0));
}
else
{
g.DrawString(vc.Substring(i, 1), new Font(fonts.Split(',')[b[i]], fontSize, fs[b[i]]), Brushes.DarkGreen, new Point(0, 0));
}
g.ResetTransform();
}

// 变形
//Bitmap bmp = new Bitmap(width, height);
//Disort(bm, ref bmp);
//bm = bmp;

//g.DrawRectangle(Pens.Black, 0, 0, width - 1/2, height - 1/2);
// 杂点
for (int i = 0; i < 10; i++)
{
int startX = x.Next(1, width - 2);
int startY = x.Next(1, height - 2);
g.DrawRectangle(Pens.LightGray, startX, startY, 1, 1);
//g.DrawLine(Pens.Gray, startX + 1, startY + 1, startX + 2, startY + 2);
}
a = null;
b = null;
c = null;
fs = null;
GC.Collect();

bm.Save(Response.OutputStream, ImageFormat.Jpeg);
}

private int ColorRGB(System.Drawing.Color posClr, string RGB)
{
//return (posClr.R * 19595 + posClr.G * 38469 + posClr.B * 7472) >> 16;
if (RGB == "R")
{
return posClr.R;
}
if (RGB == "G")
{
return posClr.G;
}
else
{
return posClr.B;
}
}

/// 扭曲，逐点方式
public void Disort(Bitmap bmpobj, ref Bitmap bmpOut)
{
int[,] rs = new int[bmpobj.Height, bmpobj.Width];
int[,] gs = new int[bmpobj.Height, bmpobj.Width];
int[,] bs = new int[bmpobj.Height, bmpobj.Width];
for (int i = 0; i < bmpobj.Height; i++)
{
for (int j = 0; j < bmpobj.Width; j++)
{
rs[i, j] = ColorRGB(bmpobj.GetPixel(j, i), "R");
gs[i, j] = ColorRGB(bmpobj.GetPixel(j, i), "G");
bs[i, j] = ColorRGB(bmpobj.GetPixel(j, i), "B");
//bmpOut.SetPixel(j, i, Color.FromArgb(r, g, b));
}
}

Random x = new Random();
int mover = 0;
for (int i = 0; i < bmpobj.Height; i++)
{
if (x.Next(0, 10) <= 5)
{
mover--;
}
else
{
mover++;
}
for (int j = 0; j < bmpobj.Width; j++)
{
if (j + mover >= bmpobj.Width)
{
bmpOut.SetPixel(j, i, Color.FromArgb(255, 255, 255));
}
else if (j + mover < 0)
{
bmpOut.SetPixel(j, i, Color.FromArgb(255, 255, 255));
}
else
{
bmpOut.SetPixel(j, i, Color.FromArgb(rs[i, j + mover], gs[i, j + mover], bs[i, j + mover]));
}
}
}
}
}