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HtmlInputImage.RenderAttributes Method

Renders the HtmlInputImage control's attributes to the specified HtmlTextWriter object.

Namespace:  System.Web.UI.HtmlControls
Assembly:  System.Web (in System.Web.dll)
protected override void RenderAttributes(
	HtmlTextWriter writer
)

Parameters

writer
Type: System.Web.UI.HtmlTextWriter

The HtmlTextWriter that contains the output stream to render on the client.

ExceptionCondition
HttpException

The Src property contains a malformed URL.

The RenderAttributes method resolves the URL set in the Src property, writes the onclick attribute of the rendered HtmlInputImage control if the CausesValidation property is true, and finally calls the base RenderAttributes method. If the value of the Src property is a malformed URL, an HttpException exception is thrown.

The RenderAttributes method is used primarily by control developers extending the functionality of the HtmlInputImage control.

The following code example demonstrates how to override the RenderAttributes method in a custom server control so that specific alternate text, accessible as a ToolTip, is always displayed with the HtmlInputImage.

<%@ 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)
  {

    // Set the OnClick attribute of the custom HtmlInputImage control.
    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 - RenderAttributes - C# Example</title>
    </head>
    <body>
        <form id="form1" runat="server">
            <h3>Custom HtmlInputImage - RenderAttributes - C# Example</h3>

          <aspSample:CustomHtmlInputImageRenderAttributes 
            id="HtmlInputImage1" 
            name="HtmlInputImage1"
            runat="server" 
            type="image" 
                    src="Image1.jpg"
                    alt="Microsoft"
                    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 CustomHtmlInputImageRenderAttributes : System.Web.UI.HtmlControls.HtmlInputImage
    {
        protected override void RenderAttributes(System.Web.UI.HtmlTextWriter writer)
        {
            // Add an Alt attribute to the the HtmlInputImage control.
            writer.Write(" alt='Alternate text from RenderAttributes'");

            // Call the base class's RenderAttributes method. 
            base.RenderAttributes(writer);
        }
    }
}

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows Phone 8.1, Windows Phone 8, 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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