HtmlImage.RenderAttributes(HtmlTextWriter) 方法

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)

參數

例外狀況

範例

以下程式碼範例示範如何在自訂伺服器控制項中覆寫該 RenderAttributes 方法，使得以工具提示形式存取的特定替代文字始終與控制項一同 HtmlImage 顯示。

<%@ 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 HtmlImage - RenderAttributes - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlImage - RenderAttributes - C# Example</h3>

      <aspSample:CustomHtmlImageRenderAttributes id="Img1"
        runat="server"
        border="0"
        src="image.jpg" />
    </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">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlImage - RenderAttributes - Visual Basic Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlImage - RenderAttributes - Visual Basic Example</h3>

      <aspSample:CustomHtmlImageRenderAttributes id="Img1"
        runat="server"
        border="0"
        src="image.jpg" />
    </form>
  </body>
</html>

using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlImageRenderAttributes : System.Web.UI.HtmlControls.HtmlImage
    {
        protected override void RenderAttributes(System.Web.UI.HtmlTextWriter writer)
        {
            // Call the base class's RenderAttributes method.
            base.RenderAttributes(writer);
            
            // Write out the HtmlImage control's alt tag.
            writer.Write(" alt=\"Text from custom RenderAttributes method.\"");
        }
    }
}

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls

    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomHtmlImageRenderAttributes
        Inherits System.Web.UI.HtmlControls.HtmlImage

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

            ' Call the base class's RenderAttributes method.
            MyBase.RenderAttributes(writer)

            ' Write out the HtmlImage control's alt tag.
            writer.Write(" alt=""Text from custom RenderAttributes method.""")
        End Sub
    End Class

End Namespace

備註

如果屬性的值 Src 是錯誤的 URL，該 RenderAttributes 方法會拋 HttpException 出例外。

該 RenderAttributes 方法會覆寫基底類別 RenderAttributes 的方法，以寫入 src 渲染控制 HtmlImage 項的屬性。

此 RenderAttributes 方法主要由控制開發者使用，以擴充控制功能 HtmlImage 。

另請參閱

• Src