使用GDI绘制验证码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 使用GDI绘制验证码B
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 点击更换验证码
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox1_Click(object sender, EventArgs e)
        {
            Random r = new Random();
            string str = null;//随机数字符串
            for (int i = 0; i < 5; i++)
            {
                int rNumber = r.Next(0, 10);
                str += rNumber;
            }
           
            //创建GDI对象
            Bitmap bmp = new Bitmap(150,40);
            Graphics g = Graphics.FromImage(bmp);

            for (int i = 0; i < 5; i++)
            {
                Point p = new Point(i*20,0); //每个数字横坐标要有间隔
                string[] fonts = {"微软雅黑","宋体","黑体","仿宋","新宋体"};
                Color[] colors = {Color.Black,Color.Blue,Color.Pink,Color.Red,Color.Yellow};
                g.DrawString(str[i].ToString(),new Font(fonts[r.Next(0,5)],20,FontStyle.Bold),new SolidBrush(colors[r.Next(0,5)]),p);
            }

            for (int i = 0; i < 20; i++) 
            {
                Point p1 = new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
                Point p2 = new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
                g.DrawLine(new Pen(Brushes.Green),p1,p2);
            }

            for (int i = 0; i < 500; i++)
            {
                Point p = new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
                bmp.SetPixel(p.X, p.Y, Color.Black);
            }

            //将图片镶嵌到PictureBox中
            pictureBox1.Image = bmp;
        }
    }
}