c#验证码

using System;
using System.Drawing;
using System.Windows.Forms;

namespace aaaa
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
        }

        private int count = 0;
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
        }

        private void button2_Click(object sender, EventArgs e)
        {
//            g.DrawArc(p,new Rectangle(new Point(20,20),new Size(200,200) ),0,180);
//            g.DrawRectangle(p,new Rectangle(new Point(20,20),new Size(200,100) ));
//            g.DrawRectangle(p,30,30,200,200);
        }

        private string Obtain()
        {
            string str = "";
            for (int i = 0; i < 4; i++)
            {
                var n = r.Next(10);
                str += n;
            }
            return str;
        }

        private Font obtainFont(float size)
        {
            Font[] fonts =
            {
                new Font(FontFamily.GenericMonospace, size),
                new Font(FontFamily.GenericSerif, size),
                new Font("微软雅黑",20f,FontStyle.Bold)

            };
            return fonts[r.Next(fonts.Length)];
        }
         private Random r = new Random();
        private Color obtainColor()
        {
            Color[] colors = { Color.Blue, Color.Red, Color.Green };
            return colors[r.Next(colors.Length)];
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
            GetValue();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            GetValue();
        }

        private void GetValue()
        {
            var str = Obtain();
            Bitmap bm = new Bitmap(100, 60);
            Graphics g = Graphics.FromImage(bm);
            Pen p = new Pen(Brushes.Red);
            p.Width = 4;
            for (int i = 0; i < str.Length; i++)
            {
                g.DrawString(str[i] + "", obtainFont(15), new SolidBrush(obtainColor()), new PointF(20 * i, 20));
            }

            var w = bm.Width;
            var h = bm.Height;
            for (int i = 0; i < 10; i++)
            {
                
                g.DrawLine(new Pen(Color.Gold,2f),r.Next(w),r.Next(h),r.Next(w),r.Next(h));

            }
            for (int i = 0; i < 200; i++)
            {
                bm.SetPixel(r.Next(w),r.Next(h),Color.Magenta);
            }
            pictureBox1.Image = bm;
        }
    }
}