c#winform图片绘制与图片验证码

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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }  

        private void Form1_Load(object sender, EventArgs e)
        {
            //一张纸 一根笔 一个人 两个点  

        }
        //画直线
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics gp = this.CreateGraphics();
            Pen p = new Pen(Color.Blue);
            Point p1 = new Point(, );
            Point p2 = new Point(, );
            gp.DrawLine(p, p1, p2);
        }  

        //画多线直线
        private void button1_Click(object sender, EventArgs e)
        {
            //创建一个GDI+ 对象
            Graphics g = this.CreateGraphics();
            //创建画笔对象
            Pen pen = new Pen(Color.Blue);
            //创建两个点
            Point p1 = new Point(, );
            Point p2 = new Point(, );
            //在画板中用pen在p1和p2两个点之间画一条直线
            g.DrawLine(pen, p1, p2);
            //pos为point数组，在画板中画多条直线
            Point p3 = new Point(, );
            Point p4 = new Point(, );
            Point[] pos = { p1, p2, p3, p4 };
            g.DrawLines(pen, pos);
        }  

        //画矩形
        private void button2_Click(object sender, EventArgs e)
        {
            //创建GDI+对象
            Graphics gp = this.CreateGraphics();
            //创建矩形对象                左上角度座标                 宽   高
            Rectangle rec = new Rectangle(new Point(, ), new Size(, ));
            gp.DrawRectangle(new Pen(Color.Blue), rec);
        }  

        //填充矩形
        private void button3_Click(object sender, EventArgs e)
        {
            //创建GDI+对象
            Graphics gp = this.CreateGraphics();
            //给定要填充的矩形对象
            Rectangle rec = new Rectangle(new Point(, ), new Size(, ));
            //填充颜色       获取系统颜色     给定要填充的矩形
            gp.FillRectangle(Brushes.DarkGreen, rec);
        }  

        //画扇形，并填充
        private void button4_Click(object sender, EventArgs e)
        {
            //创建GDI+对象
            Graphics gp = this.CreateGraphics();
            //给定要填充的矩形对象
            Rectangle rec = new Rectangle(new Point(, ), new Size(, ));
            //绘制扇形 pen对象             矩形 右角 左角度
            gp.DrawPie(new Pen(Color.Red), rec, , );
            //填充扇形 获取系统对象       矩形 右角 左角度
            gp.FillPie(Brushes.DarkGreen, rec, , );
        }  

        //画文字
        private void button5_Click(object sender, EventArgs e)
        {
            //创建GDI+对象
            Graphics g = this.CreateGraphics();
            //绘制文本   文本         字体样式： 字体    字号 样式粗？斜？...  获取系统颜色       绘制到的座标点
            g.DrawString("中国您好!", new Font("华文行楷", , FontStyle.Italic), Brushes.Red, new Point(, ));
        }  

        //验证码
        private void pictureBox1_Click(object sender, EventArgs e)
        {
            //生成1到9之间的4个随机数
            Random r = new Random();
            string str = "";
            for (int i = ; i < ; i++)
            {
                int rNumber = r.Next(, );
                //累加到空字符串中
                str += rNumber;
            }  

            //创建GDI+对象
            //创建图片对象， 指定 宽 和 高
            Bitmap bm = new Bitmap(,);;
            //从指定的Image对象创建新的Grapics画板
            Graphics g = Graphics.FromImage(bm);  

            //数组存放字体
            string[] fonts = {"黑体","微软雅黑","隶书","楷体"};
            //数组存放颜色
            Color[] colors = {Color.Red,Color.Yellow,Color.Pink,Color.Purple};
            //画字
            for (int i = ; i < ; i++)
            {
                //指定座标
                Point p = new Point(i*,);
                //画文字
                g.DrawString(str[i].ToString(), new Font(fonts[i], , FontStyle.Italic), new SolidBrush(colors[i]),p);  

            }
            //画线
            for (int j = ; j < ; j++)
            {
                Point p1 = new Point(r.Next(,bm.Width),r.Next(bm.Height));
                Point p2 = new Point(r.Next(,bm.Width),r.Next(,bm.Height));
                g.DrawLine(new Pen(Color.Green), p1, p2);
            }
            //画像素点
            for (int i = ; i < ; i++)
            {
                Point p1 = new Point(r.Next(,bm.Width),r.Next(bm.Height));
                Point p2 = new Point(r.Next(,bm.Width),r.Next(,bm.Height));
                bm.SetPixel(p1.X, p1.Y, Color.Black);
            }  

            //将bm这个图片直接镶嵌到pictureBox上
            pictureBox1.Image = bm;
        }
    }
}