ImageButton.OnPreRender Method
Assembly: System.Web (in system.web.dll)
The OnPreRender method is used primarily by control developers when deriving a custom class from the ImageButton control.
The following code example demonstrates how to override the OnPreRender method so that it always displays a thin border in a custom ImageButton server control.
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| The following code sample uses the single-file code model and may not work correctly if copied directly into a code-behind file. The first part of the code sample must be copied into an empty text file that has an .aspx extension. The second part must be in a .cs file (for C#) or a .vb file (for Visual Basic). For more information on the Web Forms code model, see ASP.NET Web Page Code Model. |
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom ImageButton - OnPreRender - VJ# Example</title>
<script runat="server">
void ImageButton1_Command(Object sender, CommandEventArgs e)
{
// Redirect to the Microsoft home page.
get_Response().Redirect("http://www.microsoft.com/");
} //ImageButton1_Command
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom ImageButton - OnPreRender - VJ# Example</h3>
<aspSample:CustomImageButtonOnPreRender
id="ImageButton1"
runat="server"
OnCommand="ImageButton1_Command"
AlternateText="Microsoft Home"
ImageUrl="http://www.microsoft.com/homepage/gif/bnr-microsoft.gif" />
</form>
</body>
</HTML>
...package Samples.AspNet.JSL.Controls;
public class CustomImageButtonOnPreRender
extends System.Web.UI.WebControls.ImageButton
{
protected void OnPreRender(System.EventArgs e)
{
// Run the OnPreRender method on the base class.
super.OnPreRender(e);
// Always display the ImageButton with a thin border.
this.set_BorderWidth(System.Web.UI.WebControls.Unit.Point(1));
} //OnPreRender
} //CustomImageButtonOnPreRender
Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
Note