两者都需要引入命名空间：using System.Drawing;
一、图片水印
前台Photoshuiyin.aspx代码：
<div> <asp:FileUpload runat="server" /> <asp:Button runat="server" Text="上传" /><br /> <asp:Image runat="server" /> </div>
后台Photoshuiyin.aspx.cs代码：
protected void Page_Load(object sender, EventArgs e) { Button1.Click += Button1_Click; } void Button1_Click(object sender, EventArgs e) { //1、制作画布 System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent); Graphics g = Graphics.FromImage(img); //水印样式：画什么东西 string a = "http://www.itnba.com"; //字体、大小 Font f = new Font("黑体", 30); //颜色 Brush b = new SolidBrush(Color.Red); //0,0——开始画水印的位置 g.DrawString(a, f, b, 0, 0); //保存路径 string path = "images/" + FileUpload1.FileName; img.Save(Server.MapPath(path)); //在image控件中展示 Image1.ImageUrl = path; }
效果展示：
二、图片验证码
前台Photoyanzhengma.aspx代码：
<form runat="server"> <div> 用户名：<asp:TextBox runat="server"></asp:TextBox> <br /> 密码：<asp:TextBox runat="server"></asp:TextBox> <br /> 验证码：<asp:TextBox runat="server"></asp:TextBox> <asp:Image runat="server" ImageUrl="YZM.aspx" /> <asp:Label runat="server" Text="Label"></asp:Label> <br /> <asp:Button runat="server" Text="Button" /> </div> </form> </body> </html> <script type="text/javascript"> var aaa = 1; document.getElementById("Image1").onclick = function () { this.setAttribute("src", "YZM.aspx?id=" + aaa); aaa++; }; </script>
链接页面“YZM.aspx”——无需前台代码，后台代码是：
protected void Page_Load(object sender, EventArgs e) { Random r = new Random(); string aaa = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"; //生成画布 Bitmap img = new Bitmap(80, 30); //画布背景色泛性组合 List<Color> Clist = new List<Color>(); Clist.Add(Color.Yellow); Clist.Add(Color.Green); Clist.Add(Color.Blue); Clist.Add(Color.Aqua); Clist.Add(Color.Orange); Clist.Add(Color.Pink); Graphics g = Graphics.FromImage(img); g.FillRectangle(new SolidBrush(Clist[r.Next(0, Clist.Count)]), 0, 0, 80, 30); //随机生成显示的验证码组合 string str = ""; for (int i = 0; i < 4; i++) { str += aaa.Substring(r.Next(0, aaa.Length), 1); } Session["YZM"] = str; Font f = new Font("黑体", 20); Brush b = new SolidBrush(Color.Red); //生成 g.DrawString(str, f, b, 10, 0); //添加干扰线 for (int i = 0; i < r.Next(6, 20); i++) { Brush bb = new SolidBrush(Clist[r.Next(0, Clist.Count)]); Pen p = new Pen(bb, 1); g.DrawLine(p, r.Next(0, 80), r.Next(0, 30), r.Next(0, 80), r.Next(0, 30)); } //保存完成 img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg); Response.End(); }
效果展示：
以上所述是小编给大家介绍的Asp.net开发之webform图片水印和图片验证码的实现方法，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
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