webform（十）——图片水印和图片验证码

二者都须要引入命名空间：using System.Drawing;

1、图片水印

前台Photoshuiyin.aspx代码：

<div>
    <asp:FileUpload ID="FileUpload1" runat="server" />
        <asp:Button ID="Button1" runat="server" Text="上传" /><br />
        <asp:Image ID="Image1" 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) { //一、制做画布
        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控件中展现
        Image1.ImageUrl = path; }

效果展现：

 

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2、图片验证码

前台Photoyanzhengma.aspx代码：

<form id="form1" runat="server">
    <div> 用户名：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            <br /> 密码：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            <br /> 验证码：<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            <asp:Image ID="Image1" runat="server" ImageUrl="YZM.aspx" />
            <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
            <br />
            <asp:Button ID="Button1" 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>

连接页面“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(); }

效果展现：