GDI+ 生成验证码

Posted 2020-10-06

这里我们做一个小应用，就是绘制一个如下图所示的验证码图片。并且点击验证码的时候会自动切换。

实现思路如下：

1. 通过Random生成随机数或字符及验证码
2. 通过验证码内容长度生成指定大小的图片
3. 获取生成图片的Graphics对象
4. 定义验证码字体格式
5. 通过指定字体将验证码绘制到图片
6. 向图片上添加背景噪音线
7. 添加前景噪音点

 1 using System;
 2 using System.Collections.Generic;
 3 using System.ComponentModel;
 4 using System.Data;
 5 using System.Drawing;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Threading.Tasks;
 9 using System.Windows.Forms;
10 
11 namespace 使用GDI绘制验证码
12 {
13     public partial class Form1 : Form
14     {
15         public Form1()
16         {
17             InitializeComponent();
18         }
19 
20 
21         /// <summary>
22         /// 点击更换验证码
23         /// </summary>
24         /// <param name="sender"></param>
25         /// <param name="e"></param>
26         private void pictureBox1_Click(object sender, EventArgs e)
27         {
28             Random r = new Random();
29             string str = null;
30             for (int i = 0; i < 5; i++)
31             {
32                 int rNumber = r.Next(0, 10);
33                 str += rNumber;
34             }
35             //  MessageBox.Show(str);
36             //创建GDI对象
37             Bitmap bmp = new Bitmap(150, 40);
38             Graphics g = Graphics.FromImage(bmp);
39 
40             for (int i = 0; i < 5; i++)
41             {
42                 Point p = new Point(i * 20, 0);
43                 string[] fonts = { "微软雅黑", "宋体", "黑体", "隶书", "仿宋" };
44                 Color[] colors = { Color.Yellow, Color.Blue, Color.Black, Color.Red, Color.Green };
45                 g.DrawString(str[i].ToString(), new Font(fonts[r.Next(0, 5)], 20, FontStyle.Bold), new SolidBrush(colors[r.Next(0, 5)]), p);
46             }
47 
48             for (int i = 0; i < 20; i++)
49             {
50                 Point p1=new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
51                 Point p2=new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
52                 g.DrawLine(new Pen(Brushes.Green), p1, p2);
53             }
54 
55             for (int i = 0; i < 500; i++)
56             {
57                 Point p=new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
58                 bmp.SetPixel(p.X, p.Y, Color.Black);
59             }
60 
61 
62             //将图片镶嵌到PictureBox中
63             pictureBox1.Image = bmp;
64         }
65     }
66 }

View Code

效果如下：