GDI绘制图形的使用_验证码

//创建GDI对象
Graphics g = this.CreateGraphics();// new Graphics();

//创建画笔对象
Pen pen = new Pen(Brushes.Red);

//创建两个点
Point p1 = new Point(30, 50);
Point p2 = new Point(250, 250);
g.DrawLine(pen, p1, p2);

Graphics g = this.CreateGraphics();
g.DrawString("XX是最帅的", new Font("宋体", 20, FontStyle.Underline), Brushes.Black, new Point(300, 300));

点击更换验证码

 private void pictureBox1_Click(object sender, EventArgs e)
        {
            Random r = new Random();
            string str = null;
            for (int i = ; i < ; i++)
            {
                int rNumber = r.Next(, );
                str += rNumber;
            }
            //  MessageBox.Show(str);
            //创建GDI对象
            Bitmap bmp = new Bitmap(, );
            Graphics g = Graphics.FromImage(bmp);

            for (int i = ; i < ; i++)
            {
                Point p = new Point(i * , );
                string[] fonts = { "微软雅黑", "宋体", "黑体", "隶书", "仿宋" };
                Color[] colors = { Color.Yellow, Color.Blue, Color.Black, Color.Red, Color.Green };
                g.DrawString(str[i].ToString(), new Font(fonts[r.Next(, )], , FontStyle.Bold), new SolidBrush(colors[r.Next(, )]), p);
            }

            for (int i = ; i < ; i++)
            {
                Point p1=new Point(r.Next(,bmp.Width),r.Next(,bmp.Height));
                Point p2=new Point(r.Next(,bmp.Width),r.Next(,bmp.Height));
                g.DrawLine(new Pen(Brushes.Green), p1, p2);
            }

            for (int i = ; i < ; i++)
            {
                Point p=new Point(r.Next(,bmp.Width),r.Next(,bmp.Height));
                bmp.SetPixel(p.X, p.Y, Color.Black);//设置像素
            }

            //将图片镶嵌到PictureBox中
            pictureBox1.Image = bmp;
        }