C# 产生验证码图片



一、实例并初始化GDI+ 位图

Bitmap image = new Bitmap(int width，int height);

二、实例并初始化绘图画面对象

Graphics g = Graphics.FromImage(image);

1.  清空并已指定的颜色填充背景

g.Clear(Color.White);

2. 画图片的背景噪音线

Point Point_1 = new Point(random.Next(image.Width), random.Next(image.Height));

Point Point_2 = new Point(random.Next(image.Width), random.Next(image.Height));

g.DrawLine(new Pen(Color.Black), Point_1, Point_2);

3.画图片的前景噪音点

Point point = new Point(random.Next(image.Width),random.Next(image.Height));

image.SetPixel(tem_point.X,tem_point.Y, Color.FromArgb(random.Next()));

4.画边框

g.DrawRectangle(new Pen(Color.Red), 0, 0, image.Width - 1, image.Height - 1);

5.画字符串

Font font = new Font("宋体", 12, (FontStyle.Bold));

LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),    Color.Blue, Color.Red, 1.2f, true);

g.DrawString(txt, font, brush, 2, 2);