ASPxCaptcha.ChallengeImageCustomRender Event

Enables you to implement custom logic for rendering the ASPxCaptcha’s challenge image.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v22.1.dll

NuGet Package: DevExpress.Web

Declaration

C#

public event ChallengeImageCustomRenderEventHandler ChallengeImageCustomRender

VB.NET

Public Event ChallengeImageCustomRender As ChallengeImageCustomRenderEventHandler

Event Data

The ChallengeImageCustomRender event's data class is ChallengeImageCustomRenderEventArgs. The following properties provide information specific to this event:

Property	Description
Code	Gets the code generated within the challenge image of the ASPxCaptcha control.
Image	Provides access to a Bitmap object representing the ASPxCaptcha’s challenge image.

Remarks

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.

View Example

Default.aspx

<dx:ASPxCaptcha ID="ASPxCaptcha1" runat="server" 
    OnChallengeImageCustomRender="ASPxCaptcha1_ChallengeImageCustomRender">
</dx:ASPxCaptcha>

Default.aspx.cs

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();
        }
    }
}

Default.aspx.vb

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