HtmlInputText.OnPreRender(EventArgs) Método

Referencia

Definición

Espacio de nombres:: System.Web.UI.HtmlControls

Ensamblado:: System.Web.dll

Importante

Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.

Genera el evento PreRender.

protected:
 override void OnPreRender(EventArgs ^ e);

protected public:
 override void OnPreRender(EventArgs ^ e);

protected override void OnPreRender (EventArgs e);

protected internal override void OnPreRender (EventArgs e);

override this.OnPreRender : EventArgs -> unit

Protected Overrides Sub OnPreRender (e As EventArgs)

Protected Friend Overrides Sub OnPreRender (e As EventArgs)

Parámetros

e: EventArgs

Objeto EventArgs que contiene los datos del evento.

Ejemplos

En el ejemplo de código siguiente se muestra cómo invalidar el OnPreRender método para que establezca la MaxLength propiedad en 30 caracteres en un control de servidor personalizado HtmlInputText .

<%@ 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) 
  {
    if (!Page.IsPostBack)
    {
      HtmlInputText1.Value = "Hello HtmlInputText World.";
    }
  }

  void HtmlInputText1_ServerChange(object sender, System.EventArgs e)
  {

    // Diplay the value of the selected HtmlInputText control.
    System.Web.UI.HtmlControls.HtmlInputText htmlInputText1 = (System.Web.UI.HtmlControls.HtmlInputText) sender;
    Div1.InnerHtml = "Change the preceding text to:<br />" + htmlInputText1.Value;

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlInputText OnPreRender Example</title>
  </head>

  <body>
    
    <form id="Form1" method="post" runat="server">

      <h3>Custom HtmlInputText OnPreRender Example</h3>

      <p>Make a change to the text, and then press the ENTER.<br />

      <aspSample:CustomHtmlInputTextOnPreRender 
        id="HtmlInputText1" 
        name="HtmlInputText1" 
        runat="server" 
        type="text"
        size="45"
        style="WIDTH: 305px; HEIGHT: 22px" 
        onserverchange="HtmlInputText1_ServerChange">

      </p>
      <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(sender As Object, e As EventArgs)

    If Not Page.IsPostBack Then

      HtmlInputText1.Value = "Hello HtmlInputText World."

    End If

  End Sub

  Sub HtmlInputText1_ServerChange(sender As Object, e As System.EventArgs)

    Dim htmlInputText1 As System.Web.UI.HtmlControls.HtmlInputText = CType(sender, System.Web.UI.HtmlControls.HtmlInputText)
    Div1.InnerHtml = "Change the preceding text to:<br />" & htmlInputText1.Value

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlInputText OnPreRender Example</title>
  </head>

  <body>
    <form id="Form1" method="post" runat="server">

      <h3>Custom HtmlInputText OnPreRender Example</h3>

      <p>Make a change to the text, and then press the ENTER.<br />

      <aspSample:CustomHtmlInputTextOnPreRender 
        id="HtmlInputText1" 
        name="HtmlInputText1" 
        runat="server" 
        type="text"
        size="45"
        style="WIDTH: 305px; HEIGHT: 22px" 
        onserverchange="HtmlInputText1_ServerChange">

      </p>
      <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 CustomHtmlInputTextOnPreRender : System.Web.UI.HtmlControls.HtmlInputText
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);

            // Set the HtmlInputText object's MaxLength property to 30 characters.
            this.MaxLength = 30;
        }
    }
}

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

    Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)

        ' Call the base class's OnPreRender method.
        MyBase.OnPreRender(e)

        ' Set the HtmlInputText object's MaxLength property to 30 characters.
        Me.MaxLength = 30
    End Sub
End Class

Comentarios

Se OnPreRender llama al método justo antes de representar el HtmlInputText control. El OnPreRender método se usa principalmente por los desarrolladores de controles que amplían la funcionalidad del HtmlInputText control.

Se aplica a

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