ASPxCaptcha.ChallengeImageCustomRender Event
Enables you to implement custom logic for rendering the ASPxCaptcha’s challenge image.
Namespace: DevExpress.Web
Assembly: DevExpress.Web.v18.2.dll
Declaration
public event ChallengeImageCustomRenderEventHandler ChallengeImageCustomRender
Public Event ChallengeImageCustomRender As ChallengeImageCustomRenderEventHandler
Event Data
The ChallengeImageCustomRender event occurs before each render of the challenge image.
The parameters of the event argument allow you to obtain the generated code (ChallengeImageCustomRenderEventArgs.Code) and draw a custom image (ChallengeImageCustomRenderEventArgs.Image).
Example
This example demonstrates how the ChallengeImageCustomRender event of the ASPxCaptcha control can be used to implement a custom challenge image.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register Assembly="DevExpress.Web.ASPxEditors.v10.1" Namespace="DevExpress.Web.ASPxEditors"
TagPrefix="dx" %>
<!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>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<dx:ASPxCaptcha ID="ASPxCaptcha1" runat="server" OnChallengeImageCustomRender="ASPxCaptcha1_ChallengeImageCustomRender">
</dx:ASPxCaptcha>
</div>
</form>
</body>
</html>
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using DevExpress.Web.ASPxEditors.Captcha;
using System.Drawing;
public partial class _Default : System.Web.UI.Page {
protected void Page_Load(object sender, EventArgs e) {
}
protected void ASPxCaptcha1_ChallengeImageCustomRender(object sender, ChallengeImageCustomRenderEventArgs e) {
using (Graphics graphics = Graphics.FromImage(e.Image)) {
System.Drawing.Image backgroundImage = System.Drawing.Image.FromFile(Server.MapPath("~/pp.jpg"));
graphics.DrawImage(backgroundImage, 0, 0, e.Image.Width, e.Image.Height);
Font font = new Font("Times New Roman", 40.0f, FontStyle.Bold, GraphicsUnit.Pixel);
graphics.DrawString(e.Code, font, Brushes.Red, new PointF(0.0f, 0.0f));
graphics.Flush();
}
}
}
Imports Microsoft.VisualBasic
Imports System
Imports System.Data
Imports System.Configuration
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Imports DevExpress.Web.ASPxEditors.Captcha
Imports System.Drawing
Partial Public Class _Default
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
End Sub
Protected Sub ASPxCaptcha1_ChallengeImageCustomRender(ByVal sender As Object, ByVal e As ChallengeImageCustomRenderEventArgs)
Using graphics As Graphics = Graphics.FromImage(e.Image)
Dim backgroundImage As System.Drawing.Image = System.Drawing.Image.FromFile(Server.MapPath("~/pp.jpg"))
graphics.DrawImage(backgroundImage, 0, 0, e.Image.Width, e.Image.Height)
Dim font As New Font("Times New Roman", 40.0f, FontStyle.Bold, GraphicsUnit.Pixel)
graphics.DrawString(e.Code, font, Brushes.Red, New PointF(0.0f, 0.0f))
graphics.Flush()
End Using
End Sub
End Class
<%@ Page Language="vb" AutoEventWireup="true" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<%@ Register Assembly="DevExpress.Web.ASPxEditors.v10.1" Namespace="DevExpress.Web.ASPxEditors"
TagPrefix="dx" %>
<!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>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<dx:ASPxCaptcha ID="ASPxCaptcha1" runat="server" OnChallengeImageCustomRender="ASPxCaptcha1_ChallengeImageCustomRender">
</dx:ASPxCaptcha>
</div>
</form>
</body>
</html>
See Also