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<< Click to Display Table of Contents >> Captcha |
  
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<< Click to Display Table of Contents >> Captcha |
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Tela
Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Image ID="Image1" runat="server" ImageUrl="~/GerarCaptcha.aspx" Height="50px" Width="150px" />
<br />
<br />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="btnTestar" runat="server" OnClick="btnTestar_Click" Text="Testar" />
<br />
</div>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</form>
</body>
</html>
Default.aspx.cs
using System;
using System.Web.UI;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnTestar_Click(object sender, EventArgs e)
{
if (Page.IsValid && (TextBox1.Text == Session["captcha"].ToString()))
{
Label1.Text = "Imagem validada com sucesso!";
}
else
{
Label1.Text = "Imagem incorreta!";
}
}
}
GerarCaptcha.aspx
(nada)
GerarCaptcha.aspx.cs
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Text;
public partial class GerarCaptcha : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
// prepara os componentes de saída para desenho
Bitmap bmp = new Bitmap(100, 20);
Graphics grap = Graphics.FromImage(bmp);
// limpa com cores loca
grap.Clear(Color.BurlyWood);
grap.TextRenderingHint = TextRenderingHint.SystemDefault;
// gera randomicamente letras e números
string senhaCaptcha = "";
Random rand = new Random();
for (int x = 0; x < 6; x++)
{
senhaCaptcha += (char)rand.Next(48, 122); // 48 = zero... 122 = z
}
// grava na variável de sessão
Session.Add("captcha", senhaCaptcha);
// desenha na tela
Font fonte = new Font("Calibri", 14, FontStyle.Italic);
grap.DrawString(senhaCaptcha, fonte, Brushes.OliveDrab, 1, 1);
// manda pro response
Response.ContentType = "image/gif";
bmp.Save(Response.OutputStream, ImageFormat.Gif);
// free willy
grap.Dispose();
fonte.Dispose();
bmp.Dispose();
}
}