ImageButton.OnPreRender Method (EventArgs)
Determines whether the image has been clicked prior to rendering on the client.
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 Forms Page Code Model. |
<%@ 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"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Custom ImageButton - OnPreRender - C# Example</title> <script runat="server"> void ImageButton1_Command(Object sender, CommandEventArgs e) { // Redirect to the Microsoft home page. Response.Redirect("http://www.microsoft.com/"); } </script> </head> <body> <form id="Form1" method="post" runat="server"> <h3>Custom ImageButton - OnPreRender - C# 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>
using System; using System.Web; using System.Web.UI.WebControls; using System.Security.Permissions; namespace Samples.AspNet.CS.Controls { [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)] public class CustomImageButtonOnPreRender : ImageButton { protected override void OnPreRender(EventArgs e) { // Run the OnPreRender method on the base class. base.OnPreRender(e); // Always display the ImageButton with a thin border. this.BorderWidth = Unit.Point(1); } } }
Available since 1.1
