using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Security.Cryptography;
using Loachs.Common;
namespace Loachs.Web
{
    public partial class common_tools_verifyimage : System.Web.UI.Page
    {

        private static byte[] randb = new byte[4];
        private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();
        private Matrix m = new Matrix();
        private Bitmap charbmp = new Bitmap(30, 30);

        private Font[] fonts = {
                                        new Font(new FontFamily("Times New Roman"), 16 + Next(3), FontStyle.Regular),
                                        new Font(new FontFamily("Georgia"), 16 + Next(3), FontStyle.Regular),
                                        new Font(new FontFamily("Arial"), 16 + Next(3), FontStyle.Regular),
                                        new Font(new FontFamily("Comic Sans MS"), 16 + Next(3), FontStyle.Regular)
                                     };

        protected void Page_Load(object sender, System.EventArgs e)
        {
            this.CreateCheckCodeImage(GenerateCheckCode());
        }

        /// <summary>
        /// 生成随机数
        /// </summary>
        /// <returns></returns>
        private string GenerateCheckCode()
        {
            //  PageUtils.VerifyCode = checkCode.ToLower();




            int number;
            char code;
            string checkCode = PageUtils.VerifyCode;

            if (!string.IsNullOrEmpty(checkCode))
            {
                return checkCode;
            }
            System.Random random = new Random();
            for (int i = 0; i < 4; i++)
            {
                number = random.Next();
                if (number % 2 == 0)
                {
                    code = (char)('0' + (char)(number % 10));
                }
                else
                {
                    //	code = (char)('a' + (char)(number % 26));
                    code = (char)('0' + (char)(number % 10));
                }
                checkCode += code.ToString();
            }
            //     Response.Cookies.Add(new HttpCookie("VerifyCode", checkCode.ToLower()));
            //  Session[VerifyCode] = checkCode.ToLower();
            PageUtils.VerifyCode = checkCode.ToLower();
            return checkCode;
        }

        /// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="checkCode"></param>
        private void CreateCheckCodeImage(string checkCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty) return;

            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 22.5)), 30);
            Graphics g = Graphics.FromImage(image);

            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;
            g.Clear(Color.White);
            try
            {
                Random random = new Random();		//生成随机生成器
                g.Clear(Color.White);				//清空图片背景色
                for (int i = 0; i < 2; i++)				//画图片的背景噪音线
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
                }

                //输出文字
                //Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
                //System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Gray, Color.Blue, 1.2f, true);
                //g.DrawString(checkCode, font, brush, 2, 2);

                Graphics charg = Graphics.FromImage(charbmp);

                SolidBrush drawBrush = new SolidBrush(Color.FromArgb(Next(100), Next(100), Next(100)));
                float charx = -18;
                for (int i = 0; i < checkCode.Length; i++)
                {
                    m.Reset();
                    m.RotateAt(Next(30) - 25, new PointF(Next(3) + 7, Next(3) + 7));

                    charg.Clear(Color.Transparent);
                    charg.Transform = m;
                    //定义前景色为黑色
                    drawBrush.Color = Color.Black;

                    charx = charx + 20 + Next(2);
                    PointF drawPoint = new PointF(charx, 0.1F);
                    charg.DrawString(checkCode[i].ToString(), fonts[Next(fonts.Length - 1)], drawBrush, new PointF(0, 0));

                    charg.ResetTransform();

                    g.DrawImage(charbmp, drawPoint);
                }


                //画图片的前景噪音点
                for (int i = 0; i < 25; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);

                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }

                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

                //输出
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                Response.ClearContent();
                Response.ContentType = "image/Gif";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

        /// <summary>
        /// 获得下一个随机数
        /// </summary>
        /// <param name="max">最大值</param>
        /// <returns></returns>
        private static int Next(int max)
        {
            rand.GetBytes(randb);
            int value = BitConverter.ToInt32(randb, 0);
            value = value % (max + 1);
            if (value < 0)
                value = -value;
            return value;
        }

        /// <summary>
        /// 获得下一个随机数
        /// </summary>
        /// <param name="min">最小值</param>
        /// <param name="max">最大值</param>
        /// <returns></returns>
        private static int Next(int min, int max)
        {
            int value = Next(max - min) + min;
            return value;
        }
    }
}