WebForm 上传图片加水印！
界面：
1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
2
3 <!DOCTYPE html>
4
5 <html xmlns="http://www.w3.org/1999/xhtml">
6 <head runat="server">
7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
8 <title></title>
9 <style type="text/css">
10 #Image1 {
11 width: 500px;
12 }
13 </style>
14 </head>
15 <body>
16 <form id="form1" runat="server">
17 <div>
18 <asp:FileUpload ID="FileUpload1" runat="server" />
19 <asp:Button ID="Button1" runat="server" Text="上传" />
20 <br />
21 <asp:Image ID="Image1" runat="server" />
22 </div>
23 </form>
24 </body>
25 </html>
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后台：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Web;
5 using System.Web.UI;
6 using System.Web.UI.WebControls;
7 using System.Drawing;
8
9 public partial class _Default : System.Web.UI.Page
10 {
11 protected void Page_Load(object sender, EventArgs e)
12 {
13 Button1.Click += Button1_Click;
14 }
15
16 void Button1_Click(object sender, EventArgs e)
17 {
18 //画布
19 System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);
20
21 Graphics g = Graphics.FromImage(img);
22 //水印内容
23 string s = "汉企奇点网络0928";
24 Font f = new Font("微软雅黑",20);//字体
25 Brush b = new SolidBrush(Color.Red);//颜色
26 //所在画布位置
27 PointF p = new PointF(20,20);
28 PointF p1 = new PointF(100, 100);
29 PointF p2 = new PointF(400, 100);
30 PointF p3 = new PointF(250, 200);
31
32 g.DrawString(s, f, b, p);
33 g.DrawString(s, f, b, p1);
34 g.DrawString(s, f, b, p2);
35 g.DrawString(s, f, b, p3);
36
37 string sss = "images/"+DateTime.Now.ToString("yyyyMMddhhmmssms")+FileUpload1.FileName;
38 //保存位置
39 img.Save(Server.MapPath(sss));
40 //显示图片
41 Image1.ImageUrl = sss;
42 }
43 }
图片验证码：
单独为验证码图片创建一个窗体，界面上什么都不用写，在后台中绘制
protected void Page_Load(object sender, EventArgs e)
{
Bitmap img = new Bitmap(80, 40);
Graphics g = Graphics.FromImage(img);
Random r = new Random();
//创建一个颜色集合 或者也可以通过RGBA颜色直接随机生成
List<Color> clist = new List<Color>();
clist.Add(Color.Yellow);
clist.Add(Color.Green);
clist.Add(Color.Blue);
clist.Add(Color.Pink);
clist.Add(Color.Orange);
clist.Add(Color.Black);
//绘制背景色
g.FillRectangle(new SolidBrush(clist[r.Next(0, clist.Count)]), 0, 0, 80, 40);
//循环随机绘制干扰线
for (int i = 0; i < 10; i++)
{
Color ccc = clist[r.Next(0, clist.Count)];
Pen ppp = new Pen(new SolidBrush(ccc), r.Next(1, 5));
g.DrawLine(ppp, new PointF(r.Next(0, 80), r.Next(0, 40)), new PointF(r.Next(0, 80), r.Next(0, 40)));
}
//准备一些字母数字
string all = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
string s = "";
//从上面随机出四个字符拼接
for (int i = 0; i < 4; i++)
{
int a = r.Next(all.Length);
s += all.Substring(a, 1);
}
//存入Session
Session["YZM"] = s;
//绘制出验证码
g.DrawString(s, new Font("微软雅黑", 16), new SolidBrush(Color.Red), new PointF(3, 3));
//通过流把绘制好的验证码输出出去
img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png);
Response.End();
}
验证：
void Button1_Click(object sender, EventArgs e)
{
string t1 = TextBox1.Text;
string t2 = Session["YZM"].ToString();
if (t1.ToUpper() == t2.ToUpper())
{
Label1.Text = "验证成功！";
}
else
{
Label1.Text = "验证失败！";
}
}
当验证码不清晰时，点击验证码图片重新生成一个，写在JS里：
<script type="text/javascript">
var a = 0;
document.getElementById("Image1").onclick = function () {
this.setAttribute("src", "yzm.aspx?id=" + a);
a++;
}
</script>
