using System;
using System.Text;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.IO;
/// <summary>
///ValidateCode 的摘要说明
/// </summary>
namespace ASPNETAJAXWeb.ValidateCode.Page
{public class ValidateCode : System.Web.UI.Page{private const double IMAGELENGTHBASE = 12.5;private const int IMAGEHEIGTH = 22;private const int IMAGELINENUMBER = 25;private const int IMAGEPOINTNUMBER = 100;public static string VALIDATECODEKEY = "VALIDATECODEKEY";private int length = 4;//验证码的数字个数private string code = string.Empty;public ValidateCode(){////TODO: 在此处添加构造函数逻辑//
        }public int Length{get { return length; }set { length = value; }}public string Code{get { return Code; }}/// <summary>/// 创建随机验证码/// </summary>/// <param name="length"></param>/// <returns></returns>public string CreateCode(int length){if (length <= 0)return string.Empty;Random random = new Random();StringBuilder sbCode = new StringBuilder();for (int i = 0; i < length; i++){sbCode.Append(random.Next(0, 10));}code = sbCode.ToString();Session[VALIDATECODEKEY] = code;return code;}/// <summary>/// 创建验证码的图片和验证码/// </summary>/// <param name="code"></param>public void CreateValidateImage(string code){if (string.IsNullOrEmpty(code) == true)return;Session[VALIDATECODEKEY] = code;Bitmap image = new Bitmap((int)Math.Ceiling((code.Length * IMAGELENGTHBASE)), IMAGEHEIGTH);Graphics g = Graphics.FromImage(image);///随机数生成器Random random = new Random();try{g.Clear(Color.White);///绘制图片的干扰线int x1, x2, y1, y2;for (int i = 0; i < IMAGELINENUMBER; i++){x1 = random.Next(image.Width);x2 = random.Next(image.Height);y1 = random.Next(image.Width);y2 = random.Next(image.Height);}///绘制验证码Font font = new Font("TaHoma", 12, FontStyle.Bold | FontStyle.Italic);LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);g.DrawString(code, font, brush, 2.0f, 2.0f);///画图片的前景噪音点int x, y;for (int i = 0; i < IMAGEPOINTNUMBER; i++){x = random.Next(image.Width);y = random.Next(image.Height);///绘制点
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));}///
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);///
                MemoryStream ms = new MemoryStream();image.Save(ms, ImageFormat.Gif);///
                Response.ClearContent();Response.ContentType = "image/Gif";Response.BinaryWrite(ms.ToArray());}finally{g.Dispose();image.Dispose();}}protected override void OnLoad(EventArgs e){CreateValidateImage(length);}public void CreateValidateImage(int length){code = CreateCode(length);CreateValidateImage(code);}}
}