using System;

using System.Collections.Generic;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.IO;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;

using System.Drawing.Text;

public partial class user_Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        CreateImage(GetCheckCode(VCODE_LENGTH));

    }

    protected static int VCODE_LENGTH = ;

    //产生图片 宽度：_WIDTH, 高度：_HEIGHT

    private static readonly int _WIDTH = , _HEIGHT = ;

    //字体集

    private static readonly string[] _FONT_FAMIly = { "Broadway", "Arial", "Arial Black", "Courier New", "Showcard Gothic", "Algerian", "Wide Latin", "Bernard MT Condensed", "Cooper Black" };

    //字体大小集

    private static readonly int[] _FONT_SIZE = { , ,  };

    //前景字体颜色集

    private static readonly Color[] _COLOR_FACE = { Color.FromArgb(, , ), Color.FromArgb(, , ), Color.FromArgb(, , ), Color.FromArgb(, , ) };

    //背景颜色集

    private static readonly Color[] _COLOR_BACKGROUND = { Color.FromArgb(, , ), Color.FromArgb(, , ), Color.FromArgb(, , ), Color.FromArgb(, , ) };

    //文本布局信息

    private static StringFormat _DL_FORMAT = new StringFormat(StringFormatFlags.NoClip);

    //左右旋转角度

    private static readonly int _ANGLE = ;

    private string GetCheckCode(int codeCount)

    {

        string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";

        string[] allCharArray = allChar.Split(',');

        string randomCode = "";

        int temp = -;

        Random rand = new Random();

        for (int i = ; i < codeCount; i++)

        {

            if (temp != -)

            {

                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));

            }

            int t = rand.Next();

            if (temp == t)

            {

                return GetCheckCode(codeCount);

            }

            temp = t;

            randomCode += allCharArray[t];

        }

        return randomCode;

    }

    private void CreateImage(string code)

    {

        _DL_FORMAT.Alignment = StringAlignment.Center;

        _DL_FORMAT.LineAlignment = StringAlignment.Center;

        long tick = DateTime.Now.Ticks;

        Random Rnd = new Random((int)(tick & 0xffffffffL) | (int)(tick >> ));

        using (Bitmap _img = new Bitmap(_WIDTH, _HEIGHT))

        {

            using (Graphics g = Graphics.FromImage(_img))

            {

                g.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;

                Point dot = new Point(, );

                // 定义一个无干扰线区间和一个起始位置

                int nor = Rnd.Next(), rsta = Rnd.Next();

                // 绘制干扰正弦曲线 M:曲线平折度, D:Y轴常量 V:X轴焦距

                int M = Rnd.Next() + , D = Rnd.Next() + , V = Rnd.Next() + ;

                int ColorIndex = Rnd.Next();

                float Px_x = 0.0F;

                float Px_y = Convert.ToSingle(M * Math.Sin(V * Px_x * Math.PI / ) + D);

                float Py_x, Py_y;

                //填充背景

                g.Clear(_COLOR_BACKGROUND[Rnd.Next()]);

                //前景刷子 //背景刷子

                using (Brush _BrushFace = new SolidBrush(_COLOR_FACE[ColorIndex]))

                {

                    #region 绘制正弦线

                    for (int i = ; i < ; i++)

                    {

                        //初始化y点

                        Py_x = Px_x + ;

                        Py_y = Convert.ToSingle(M * Math.Sin(V * Py_x * Math.PI / ) + D);

                        //确定线条颜色

                        if (rsta >= i || i > (rsta + nor))

                            //初始化画笔

                            using (Pen _pen = new Pen(_BrushFace, 1.5f))

                            {

                                //绘制线条

                                g.DrawLine(_pen, Px_x, Px_y, Py_x, Py_y);

                            }

                        //交替x,y坐标点

                        Px_x = Py_x;

                        Px_y = Py_y;

                    }

                    #endregion

                    //初始化光标的开始位置

                    g.TranslateTransform(-, );

                    #region 绘制校验码字符串

                    for (int i = ; i < code.Length; i++)

                    {

                        //随机旋转 角度

                        int angle = Rnd.Next(-_ANGLE, _ANGLE);

                        //移动光标到指定位置

                        g.TranslateTransform(dot.X, dot.Y);

                        //旋转

                        g.RotateTransform(angle);

                        //初始化字体

                        using (Font _font = new Font(_FONT_FAMIly[Rnd.Next(, )], _FONT_SIZE[Rnd.Next(, )]))

                        {

                            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(, , _WIDTH, _HEIGHT), _COLOR_FACE[ColorIndex], Color.Orange, 1.2f, true);

                            //绘制

                            g.DrawString(code[i].ToString(), _font, brush, , , _DL_FORMAT);

                        }

                        //反转

                        g.RotateTransform(-angle);

                        //重新定位光标位置

                        g.TranslateTransform(-, -dot.Y);

                    }

                    #endregion

                }

            }

            using (System.IO.MemoryStream ms = new System.IO.MemoryStream())

            {

                Response.ContentType = "Image/PNG";

                Response.Clear();

                Response.BufferOutput = true;

                _img.Save(ms, ImageFormat.Png);

                ms.Flush();

                Response.BinaryWrite(ms.GetBuffer());

                Response.End();

            }

        }

    }

}