Winform之GDI绘制验证码_.NET_编程开发_程序员俱乐部

主要功能：点击验证码可更换，输入验证码进行登陆

需要导入命名空间System.Drawing;

产生五位的随机字符串：

1　　　　　　　　Random random = new Random();
2             //产生5个随机字符串
3             str = null;
4             for (int i = 0; i < 5; i++)
5             {
6                 int j = random.Next(64, 90);
7                 str = str + (char)j;
8             }

画字符串

 1             //创建图片
 2             Bitmap bmp = new Bitmap(120,30);
 3             //创建GDI对象
 4             Graphics g = Graphics.FromImage(bmp);
 5             //循环画字符串
 6             for (int i = 0; i < str.Length; i++)
 7             {
 8                 Point p = new Point(i*20,0);
 9                 //随机字体
10                 string[] fonts = { "宋体", "黑体", "微软雅黑", "隶属", "仿宋", };
11                 //随机颜色
12                 Color[] colors = { Color.Red, Color.Aquamarine, Color.Blue, Color.Yellow, Color.YellowGreen };
13                 //画字符串
14                 g.DrawString(str[i].ToString(), new Font(fonts[random.Next(0, fonts.Length)], 20, FontStyle.Bold), new SolidBrush(colors[random.Next(0, colors.Length)]), p);
15             }                

到这里效果如下：

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" alt="" />

这时候我们在加入一些线条：

1 　　　　　　　for (int i = 0; i < 20; i++)
2             {
3                 Point p1 = new Point(random.Next(0, bmp.Width), random.Next(0, bmp.Height));
4                 Point p2 = new Point(random.Next(0, bmp.Width), random.Next(0, bmp.Height));
5                 g.DrawLine(new Pen(Color.Green), p1, p2);
6             }

在画一些像素点：

1            //画像素点
2             for (int i = 0; i < 500; i++)
3             {
4                 Point p = new Point(random.Next(0, bmp.Width), random.Next(0, bmp.Height));
5                 bmp.SetPixel(p.X, p.Y, Color.Black);
6             }                

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大致就这样了，没什么技术含量！

源码地址：http://pan.baidu.com/s/1gdgYqpt