Create Captcha with Refresh Button in Asp.Net
Here I will explain
how to create captcha in asp.net using c# with refresh button
First we take a page which name is GenerateCaptcha.aspx
<%@ Page Language="C#"
AutoEventWireup="true"
CodeFile="GenerateCaptcha.aspx.cs"
Inherits="GenerateCaptcha"
%>
<!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>
</div>
</form>
</body>
</html>
Code with GenerateCaptcha.aspx.cs………………………
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
//using this namespace
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
public partial class GenerateCaptcha
: System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs
e)
{
Response.Clear();
// Initializes a new instance of the System.Drawing.Bitmap class
with the specified size (width,height).
Bitmap bmp = new Bitmap(100, 30);
RectangleF rec = new RectangleF(15, 7, 0, 0);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.White);
g.SmoothingMode
= SmoothingMode.AntiAlias;
g.InterpolationMode
= InterpolationMode.HighQualityBicubic;
//Gets or set a value specifying how pixels are offset during
rendering of this System.Drawing.Graphics.
g.PixelOffsetMode
= PixelOffsetMode.HighQuality;
// Draws the specified text
string in the specified rectangle with the specified System.Drawing.Brush and
System.Drawing.Font objects.
g.DrawString(Session["captcha"].ToString(), new Font("Verdana", 12, FontStyle.Regular),
Brushes.Red, rec);
// Draws a rectangle specified by a coordinate pair, a width, and
a height (pen,x-coordinate,y-coordinate,width,height)
g.DrawRectangle(new Pen(Color.Green), 1, 1, 98, 28);
// Forces execution of all
pending graphics operations and returns immediately without waiting for the
operations to finish.
g.Flush();
Response.ContentType
= "image/jpeg";
bmp.Save(Response.OutputStream,
ImageFormat.Jpeg);
// Releases all resources used by this System.Drawing.Graphics
with Dispose.
g.Dispose();
bmp.Dispose();
}
}
We take another web page which name is Registration.aspx.cs
<%@ Page Language="C#"
AutoEventWireup="true"
CodeFile="Registration.aspx.cs"
Inherits="Registration"
%>
<!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">
<table style="border: solid 1px black; padding: 2px; position: relative; top: 10px;" align="center">
<tr><td colspan="2">
<asp:ScriptManager ID="ScriptManager1"
runat="server"></asp:ScriptManager></td></tr>
<tr><td colspan="2" align="center"><b>Captcha
Concept in Asp.Net</b></td></tr>
<tr><td>Name</td><td><asp:TextBox ID="txtname" runat="server" ></asp:TextBox></td></tr>
<tr><td>EmailId</td><td><asp:TextBox ID="txtemailid" runat="server" ></asp:TextBox></td></tr>
<tr><td>Password</td><td><asp:TextBox ID="txtpassword" runat="server"
TextMode="Password" ></asp:TextBox></td></tr>
TextMode="Password" ></asp:TextBox></td></tr>
<tr><td>Confirm Password</td><td><asp:TextBox ID="txtcpassword" runat="server"
TextMode="Password" ></asp:TextBox></td></tr>
TextMode="Password" ></asp:TextBox></td></tr>
<tr><td>Enter Below Code :</td><td><asp:TextBox ID="txtcaptcha" runat="server" ></asp:TextBox></td></tr>
<tr><td></td><td valign="middle">
<asp:UpdatePanel ID="updatepanel1"
runat="server"
ChildrenAsTriggers="False"
UpdateMode="Conditional">
<ContentTemplate>
<table>
<tr><td style="height: 40px; width:100px;"><asp:Image ID="imgCaptcha" runat="server" /></td>
<td valign="middle"><asp:LinkButton ID="linkbutton" runat="server" onclick="LinkRefresh_Click" >Refresh</asp:LinkButton></td></tr>
</table>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="linkbutton"
/>
</Triggers>
</asp:UpdatePanel>
</td></tr>
<tr><td align="center"
colspan="2">
<asp:Button ID="btnsave"
runat="server"
Text="Register"
OnClick="btnRegister_Click"
/></td></tr>
<tr><td colspan="2" valign="middle"><asp:Label ID="lblmessage" runat="server" Visible="false"></asp:Label></td></tr>
</table>
</form>
</body>
</html>
Code with Registration.aspx.cs………………………
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Text;
using System.Drawing;
public partial class Registration
: System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs
e)
{
if(!IsPostBack)
FillCapctha();
}
void FillCapctha()
{
try
{
Random random = new Random();
string combination = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
StringBuilder captcha = new StringBuilder();
//no 7= no of letter
show in Captcha Box
for (int i = 0; i
< 7; i++)
captcha.Append(combination[random.Next(combination.Length)]);
Session["captcha"] = captcha.ToString();
imgCaptcha.ImageUrl
= "GenerateCaptcha.aspx?" + DateTime.Now.Ticks.ToString();
}
catch(Exception
ex)
{
lblmessage.Visible
= true;
lblmessage.ForeColor
= Color.Red;
lblmessage.Text
=ex.Message;
}
}
protected void
btnRegister_Click(object sender, EventArgs e)
{
if (Session["captcha"].ToString()
!= txtcaptcha.Text)
{
lblmessage.Visible
= true;
lblmessage.ForeColor
= Color.Red;
lblmessage.Text
= "Invalid Captcha Code";
}
else
{
lblmessage.Visible
= true;
lblmessage.ForeColor
= Color.Green;
lblmessage.Text
= "Valid Captcha Code";
}
FillCapctha();
}
protected void
LinkRefresh_Click(object sender, EventArgs e)
{
FillCapctha();
}
}
thnku so much sirji... i need it...thnx... it is very very useful nowadays...
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