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HtmlInputImage.OnPreRender Method

Raises the PreRender event.

Namespace:  System.Web.UI.HtmlControls
Assembly:  System.Web (in System.Web.dll)

protected internal override void OnPreRender(
	EventArgs e
)

Parameters

e
Type: System.EventArgs

An EventArgs that contains the event data.

The OnPreRender method is called just prior to rendering the HtmlInputImage control. The OnPreRender method is used primarily by control developers extending the functionality of the HtmlInputImage control.

Notes to Inheritors

When overriding the OnPreRender method in a derived class, be sure to call the base class's OnPreRender method so that registered delegates receive the PreRender event.

The following code example demonstrates how to override the OnPreRender method so that it always displays a custom HtmlInputImage server control with no border.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
  void Page_Load(Object sender, EventArgs e)
  {    

    // Define the onclick attribute of custom HtmlInputImage.
    HtmlInputImage1.Attributes.Add("onclick", "alert('Hello client-side world.');");

  }

  void HtmlInputImage1_ServerClick(Object sender, ImageClickEventArgs e)
  {

    // Set the inner HTML of the DIV element.
    Div1.InnerHtml = "Hello server-side world.";

  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
        <title>Custom HtmlInputImage - Method - C# Example</title>
    </head>
    <body>
        <form id="form1" runat="server">

            <h3>Custom HtmlInputImage - Method - C# Example</h3>

          <aspSample:CustomHtmlInputImageOnPreRender 
            id="HtmlInputImage1" 
        alt="image1.jpg"
            name="HtmlInputImage1"
            runat="server" 
            type="image" 
        src="image1.jpg"
        onserverclick="HtmlInputImage1_ServerClick" />

      <br />
      <br />

      <div 
        id="Div1" 
        runat="server" 
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"/>

        </form>
    </body>
</html>
using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputImageOnPreRender : System.Web.UI.HtmlControls.HtmlInputImage
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method. 
            base.OnPreRender(e);

            // Always display the HtmlInputImage control with no border. 
            this.Border = 0;
        }
    }
}

.NET Framework

Supported in: 4.6, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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