ASPxCaptcha.ChallengeImageCustomRender Event

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

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v24.2.dll

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

The example below demonstrates how to handle the ChallengeImageCustomRender event to implement a custom challenge image.

Default.aspx

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

Default.aspx.cs

protected void OnChallengeImageCustomRender(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

Protected Sub OnChallengeImageCustomRender(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