HtmlInputImage.RenderAttributes(HtmlTextWriter) Metod

Definition

Namnområde:
System.Web.UI.HtmlControls
Sammansättning:
System.Web.dll

Renderar HtmlInputImage kontrollens attribut till det angivna HtmlTextWriter objektet.

protected:
 override void RenderAttributes(System::Web::UI::HtmlTextWriter ^ writer);
protected override void RenderAttributes(System.Web.UI.HtmlTextWriter writer);
override this.RenderAttributes : System.Web.UI.HtmlTextWriter -> unit
Protected Overrides Sub RenderAttributes (writer As HtmlTextWriter)

Parametrar

writer
HtmlTextWriter

Som HtmlTextWriter innehåller utdataströmmen som ska återges på klienten.

Undantag

HttpException

Egenskapen Src innehåller en felaktigt formaterad URL.

Exempel

Följande kodexempel visar hur du åsidosätter RenderAttributes metoden i en anpassad serverkontroll så att specifik alternativ text, som är tillgänglig som en knappbeskrivning, alltid visas med 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>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" 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">

  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 xmlns="http://www.w3.org/1999/xhtml" >
    <head>
        <title>Custom HtmlInputImage - RenderAttributes - Visual Basic Example</title>
    </head>
    <body>
        <form id="form1" 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>

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 HtmlInputImage control.
            writer.Write(" alt='Alternate text from RenderAttributes'");
            
            // Call the base class's RenderAttributes method.
            base.RenderAttributes(writer);
        }
    }
}

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 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

Kommentarer

Metoden RenderAttributes löser URL-uppsättningen i Src egenskapen, skriver onclick attributet för den renderade HtmlInputImage kontrollen om CausesValidation egenskapen är trueoch anropar slutligen basmetoden RenderAttributes . Om värdet för Src egenskapen är en felaktigt formaterad URL genereras ett HttpException undantag.

Metoden RenderAttributes används främst av kontrollutvecklare som utökar kontrollens HtmlInputImage funktioner.

Gäller för

Se även