笔记11：GDI 制作数字验证码
大二学长让我学下GDI绘制验证码，然后自己就试了试了。找了点视频看了下。
现在会画直线，矩形，字符串，制作验证码
一、绘制一条直线
1 private void button1_Click(object sender, EventArgs e) 2 { 3 Graphics g = this.CreateGraphics(); //实例化 4 Pen pen = new Pen(Color.Black); //创建一只笔，颜色 5 Point p1 = new Point(20, 30); //两点确定一条直线 6 Point p2 = new Point(100,200); 7 g.DrawLine(pen,p1,p2); //画直线了 8 }
二、绘制一个矩形，一个字符串
1 private void button2_Click(object sender, EventArgs e) 2 { 3 Graphics j = this.CreateGraphics(); 4 Pen pen = new Pen(Color.YellowGreen); 5 6 j.DrawRectangle(pen,20,20,250,250); //矩形 7 j.DrawString("管星，还蛮不错的！",new Font("宋体",20,FontStyle.Bold),Brushes.Red,50,50); //字符串 8 }
三、制作验证码，和字符串升级版
1 string yanzheng = ""; 2 public void huantu() 3 { 4 //随机生成一个，四个数字的字符串 5 Random r = new Random(); 6 string str = ""; 7 for (int i = 0; i < 4; i++) 8 { 9 str = str + r.Next(0, 10).ToString(); 10 } 11 yanzheng = str; 12 //创建GDI对象 13 Bitmap bmp = new Bitmap(100, 30); 14 Graphics g = Graphics.FromImage(bmp); 15 int n = 10; 16 //将数字画进图片中，随机的字体，随机的颜色 17 for (int i = 0; i < 4; i++) 18 { 19 string[] fonts = { "微软雅黑", "宋体", "幼圆", "黑体", "仿宋" }; 20 Color[] colors = { Color.PowderBlue, Color.Green, Color.Blue, Color.Black, Color.Red }; 21 g.DrawString(str[i].ToString(), new Font(fonts[r.Next(0, 5)], 20, FontStyle.Bold), new SolidBrush(colors[r.Next(0, 5)]), n, 0); 22 n += 20; 23 } 24 //加干扰的点， 25 for (int i = 0; i < 500; i++) 26 { 27 Point p = new Point(r.Next(0, bmp.Width), r.Next(0, bmp.Height)); 28 bmp.SetPixel(p.X, p.Y, Color.Black); 29 } 30 //将图片镶嵌picturebox中 31 pictureBox1.Image = bmp; 32 } 33 //看不清，换一张 34 private void button2_Click(object sender, EventArgs e) 35 { 36 huantu(); 37 } 38 private void button1_Click(object sender, EventArgs e) 39 { 40 if (yanzheng==this.textBox1.Text) 41 { 42 MessageBox.Show("您输入的验证码正确！","消息提示"); 43 } 44 else 45 { 46 MessageBox.Show("您输入的验证码不正确！", "消息提示"); 47 } 48 } 49 } 50 }