using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
namespace ChineseCode
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        public string txt = "";
        private void Form1_Load(object sender, EventArgs e)
        {
            CreateImage();
        }
        private void CreateImage()
        {
            //获取GB2312编码页（表） 
            Encoding gb = Encoding.GetEncoding("gb2312");
            //调用函数产生4个随机中文汉字编码 
            object[] bytes = CreateCode(4);
            //根据汉字编码的字节数组解码出中文汉字 
            string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])));
            string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));
            string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));
            string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])));
            txt = str1 + str2 + str3 + str4;
            if (txt == null || txt == String.Empty)
            {
                return;
            }
            Bitmap image = new Bitmap((int)Math.Ceiling((txt.Length * 20.5)), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的背景噪音线
                for (int i = 0; i < 2; i++)
                {
                    Point tem_Point_1 = new Point(random.Next(image.Width), random.Next(image.Height));
                    Point tem_Point_2 = new Point(random.Next(image.Width), random.Next(image.Height));
                    g.DrawLine(new Pen(Color.Black), tem_Point_1, tem_Point_2);
                }
                Font font = new Font("宋体", 12, (FontStyle.Bold));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(txt, font, brush, 2, 2);
                //画图片的前景噪音点
                for (int i = 0; i < 100; i++)
                {
                    Point tem_point = new Point(random.Next(image.Width),random.Next(image.Height));
                    image.SetPixel(tem_point.X,tem_point.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);
                pictureBox1.Image = image;
            }
            catch { }
        }

        /**/
        /* 
        此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将 
        四个字节数组存储在object数组中。 
        参数：strlength，代表需要产生的汉字个数 
        */
        public static object[] CreateCode(int strlength)
        { 
            //定义一个字符串数组储存汉字编码的组成元素 
            string[] r=new String [16]{"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"}; 
            Random rnd=new Random(); 
            //定义一个object数组用来 
            object[] bytes=new object[strlength]; 
            /**//*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中 
             每个汉字有四个区位码组成 
             区位码第1位和区位码第2位作为字节数组第一个元素 
             区位码第3位和区位码第4位作为字节数组第二个元素 
            */ 
            for(int i=0;i<strlength;i++) 
            { 
                //区位码第1位 
                int r1=rnd.Next(11,14);
                string str_r1 = r[r1].Trim(); 
                //区位码第2位 
                rnd=new Random(r1*unchecked((int)DateTime.Now.Ticks)+i);//更换随机数发生器的种子避免产生重复值 
                int r2; 
                if (r1==13) 
                    r2=rnd.Next(0,7); 
                else 
                    r2=rnd.Next(0,16); 
                string str_r2 = r[r2].Trim(); 
                //区位码第3位 
                rnd=new Random(r2*unchecked((int)DateTime.Now.Ticks)+i); 
                int r3=rnd.Next(10,16);
                string str_r3 = r[r3].Trim(); 
                //区位码第4位 
                rnd=new Random(r3*unchecked((int)DateTime.Now.Ticks)+i); 
                int r4; 
                if (r3==10) 
                { 
                    r4=rnd.Next(1,16); 
                } 
                else if (r3==15) 
                { 
                    r4=rnd.Next(0,15); 
                } 
                else 
                { 
                    r4=rnd.Next(0,16); 
                }
                string str_r4 = r[r4].Trim(); 
                //定义两个字节变量存储产生的随机汉字区位码 
                byte byte1=Convert.ToByte(str_r1 + str_r2,16); 
                byte byte2=Convert.ToByte(str_r3 + str_r4,16); 
                //将两个字节变量存储在字节数组中 
                byte[] str_r=new byte[]{byte1,byte2}; 
                //将产生的一个汉字的字节数组放入object数组中 
                bytes.SetValue(str_r,i);    
            } 
            return bytes; 
       }

        private void button2_Click(object sender, EventArgs e)
        {
            CreateImage();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (txtCode.Text.Trim() == "")
                return;
            else
            {
                if (txtCode.Text.Trim() == txt)
                {
                    MessageBox.Show("提示：验证码输入正确！","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);
                }
                else
                {
                    MessageBox.Show("提示：验证码输入错误，请重新输入！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
        } 
    }
}
