一、水印
1.画布
System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);
2.创建绘制对象，告诉它往哪张图片上绘制
Graphics g = Graphics.FromImage(img);
3.绘制的内容
string s = www.itnba.com;
4.绘制的字体
Font f = new Font("黑体",130);
5.绘制的画刷
Brush b = new SolidBrush(Color.Red);
6.开始绘制
g.DrawString(s, f, b, 5, 5);
二、图片验证码
Bitmap bit = new Bitmap(90, 40);//画布大小
Graphics g = Graphics.FromImage(bit);//创建绘制对象，告诉它往哪张图片上绘制
Random r = new Random();
string s = "";
Color color1 = Color.FromArgb(r.Next(155, 255), r.Next(155, 255), r.Next(155, 255));
g.FillRectangle(new SolidBrush(color1), 0, 0, 90, 40);//画布颜色随机
for (int i = 0; i < 10; i++)//随机画干扰线
{
Color color3 = Color.FromArgb(r.Next(170, 255), r.Next(190, 255), r.Next(170, 255));
Pen pp = new Pen(new SolidBrush(color3), r.Next(0, 5));
g.DrawLine(pp, r.Next(0, 90), r.Next(0, 40), r.Next(0, 90), r.Next(0, 40));
}
string yan = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";//设置随机的验证码，从里面抽取
int wei = 0;
for (int i = 0; i < 4; i++)//取四位验证码，颜色随机
{
string m = yan.Substring(r.Next(0, yan.Length), 1);
s += m;
Color color2 = Color.FromArgb(r.Next(0, 155), r.Next(0, 155), r.Next(0, 155));
int w = r.Next(20, 25);
Font f = new Font("黑体", w);
SolidBrush b = new SolidBrush(color2);
g.DrawString(m, f, b, wei, r.Next(0, 10));
wei += w;
}
Session["YZM"] = s;//把验证码保存到session中
for (int i = 0; i < 251; i++)
{
Color color3 = Color.FromArgb(r.Next(0, 255), r.Next(0, 255), r.Next(0, 255));
Pen pp = new Pen(new SolidBrush(color3), r.Next(0, 5));
int a = r.Next(0, 90);
int b = r.Next(0, 40);
g.DrawLine(pp, a, b, (a + 1), (b + 1));
}
bit.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.End();
验证码：
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<asp:Image ID="Image1" runat="server" ImageUrl="Default2.aspx" />//这里图片路径不是一张图片的话会默认打开
以上所述是小编给大家分享的Web前端开发之水印、图片验证码，希望对大家有所帮助，如果大家有任何疑问欢迎给我留言，小编会及时回复大家的，在此也非常感谢大家对找一找教程网网站的支持！
