HtmlInputImage.RenderAttributes-Methode

Rendert die Attribute des HtmlInputImage-Steuerelements in das angegebene HtmlTextWriter-Objekt.

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

Syntax

'Declaration
Protected Overrides Sub RenderAttributes ( _
    writer As HtmlTextWriter _
)
'Usage
Dim writer As HtmlTextWriter

Me.RenderAttributes(writer)

protected override void RenderAttributes (
    HtmlTextWriter writer
)

protected:
virtual void RenderAttributes (
    HtmlTextWriter^ writer
) override

protected void RenderAttributes (
    HtmlTextWriter writer
)

protected override function RenderAttributes (
    writer : HtmlTextWriter
)

Parameter

writer
Der HtmlTextWriter, der den Ausgabestream enthält, der auf dem Client gerendert werden soll.

Ausnahmen

Ausnahmetyp	Bedingung
HttpException	Die Src-Eigenschaft enthält einen fehlerhaften URL.

Hinweise

Die RenderAttributes-Methode löst den in der Src-Eigenschaft festgelegten URL auf, schreibt das onclick-Attribut des gerenderten HtmlInputImage-Steuerelements, sofern die CausesValidation-Eigenschaft den Wert true hat, und ruft abschließend die RenderAttributes-Basismethode auf. Wenn der Wert der Src-Eigenschaft ein fehlerhafter URL ist, wird eine HttpException-Ausnahme ausgelöst.

Die RenderAttributes-Methode wird hauptsächlich von Entwicklern von Steuerelementen zum Erweitern der Funktionalität des HtmlInputImage-Steuerelements verwendet.

Beispiel

Im folgenden Codebeispiel wird das Überschreiben der RenderAttributes-Methode in einem benutzerdefinierten Serversteuerelement veranschaulicht, sodass im HtmlInputImage immer ein bestimmter alternativer Text angezeigt wird, der auch als QuickInfo verfügbar ist.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<script runat="server">

  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

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

  End Sub

  Sub HtmlInputImage1_ServerClick(ByVal sender As Object, ByVal e As ImageClickEventArgs)

    ' Set the inner HTML of the div element.
    Div1.InnerHtml = "Hello server-side world."

  End Sub

</script>

<HTML>
    <HEAD>
        <title>Custom HtmlInputImage - RenderAttributes - Visual Basic Example</title>
    </HEAD>
    <body>
        <form runat="server">
            <h3>Custom HtmlInputImage - RenderAttributes - Visual Basic 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>

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

<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>
    <HEAD>
        <title>Custom HtmlInputImage - RenderAttributes - C# Example</title>
    </HEAD>
    <body>
        <form 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>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
    <HEAD>
        <title>Custom HtmlInputImage - RenderAttributes - VJ# Example</title>
    <script runat="server">
    void Page_Load(Object sender, EventArgs e) 
    {
        HtmlInputImage1.get_Attributes().Add("onclick",
            "alert('Hello client-side world.');");
    } //Page_Load

    void HtmlInputImage1_ServerClick(Object sender, ImageClickEventArgs e) 
    {
        Div1.set_InnerHtml("Hello server-side world.");
    } //HtmlInputImage1_ServerClick
    </script>
    </HEAD>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom HtmlInputImage - RenderAttributes - VJ# Example</h3>
        
          <aspSample:CustomHtmlInputImageRenderAttributes 
            id="HtmlInputImage1" 
            name="HtmlInputImage1"
            runat="server" 
            type="image" 
        src="https://www.microsoft.com/homepage/gif/bnr-microsoft.gif"
        alt="Microsoft"
        onserverclick="HtmlInputImage1_ServerClick" /><br>
     
      <p><DIV 
        id="Div1" 
        runat="server" 
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" 
        ms_positioning="FlowLayout" /></p>
        
        </form>
    </body>
</HTML>

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomHtmlInputImageRenderAttributes
        Inherits System.Web.UI.HtmlControls.HtmlInputImage

        Protected Overrides Sub RenderAttributes(ByVal writer As System.Web.UI.HtmlTextWriter)

            ' Add an Alt attribute to the the HtmlInputImage control.
            writer.Write(" alt='Alternate text from RenderAttributes'")

            ' Call the base class's RenderAttributes method.
            MyBase.RenderAttributes(writer)
        End Sub
    End Class
End Namespace

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);
        }
    }
}

package Samples.AspNet.JSL.Controls;

public class CustomHtmlInputImageRenderAttributes
    extends System.Web.UI.HtmlControls.HtmlInputImage
{
    protected void RenderAttributes(System.Web.UI.HtmlTextWriter writer)
    {
        // Add an ALT attribute to the the HtmlInputImage control.
        writer.Write(" alt='Microsoft'");
        // Call the base's RenderAttributes method.
        super.RenderAttributes(writer);
    } //RenderAttributes
} //CustomHtmlInputImageRenderAttributes

Plattformen

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

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

Siehe auch

Referenz

HtmlInputImage-Klasse
HtmlInputImage-Member
System.Web.UI.HtmlControls-Namespace
CausesValidation
ResolveClientUrl
RenderAttributes

Weitere Ressourcen

HTML-Serversteuerelemente

Last updated on 2007-08-20

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