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Control.HelpRequested (Evento)

Se produce cuando el usuario solicita ayuda para un control.

Espacio de nombres: System.Windows.Forms
Ensamblado: System.Windows.Forms (en system.windows.forms.dll)

public event HelpEventHandler HelpRequested
/** @event */
public void add_HelpRequested (HelpEventHandler value)

/** @event */
public void remove_HelpRequested (HelpEventHandler value)

En JScript, se pueden controlar los eventos que define una clase, pero no se pueden definir unos propios.
No aplicable.

Normalmente, el evento HelpRequested se provoca cuando el usuario presiona la tecla F1 o hace clic en un botón de ayuda contextual asociado.

Para obtener más información sobre la forma de controlar eventos, vea Utilizar eventos.

En el ejemplo de código siguiente se muestra cómo controlar el evento HelpRequested con el fin de mostrar contenido de Ayuda personalizado en un formulario que contiene cuatro campos de dirección. El evento HelpRequested se provoca al presionar la tecla F1 con el foco en un campo de dirección, o al utilizar un botón de ayuda contextual y hacer clic con el cursor de ayuda en un campo de dirección. La propiedad Handled se establece en true para indicar que se controla el evento HelpRequested. En este ejemplo también se muestra cómo almacenar el texto de ayuda en la propiedad Control.Tag.

using System;
using System.Drawing;
using System.Windows.Forms;

public class Form1 : System.Windows.Forms.Form
{
    private System.Windows.Forms.TextBox addressTextBox;
    private System.Windows.Forms.Label label2;
    private System.Windows.Forms.TextBox cityTextBox;
    private System.Windows.Forms.Label label3;
    private System.Windows.Forms.TextBox stateTextBox;
    private System.Windows.Forms.TextBox zipTextBox;
    private System.Windows.Forms.Label helpLabel;

    [STAThread]
    static void Main() 
    {
        Application.Run(new Form1());
    }

    public Form1()
    {
        this.addressTextBox = new System.Windows.Forms.TextBox();
        this.helpLabel = new System.Windows.Forms.Label();
        this.label2 = new System.Windows.Forms.Label();
        this.cityTextBox = new System.Windows.Forms.TextBox();
        this.label3 = new System.Windows.Forms.Label();
        this.stateTextBox = new System.Windows.Forms.TextBox();
        this.zipTextBox = new System.Windows.Forms.TextBox();

        // Help Label
        this.helpLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
        this.helpLabel.Location = new System.Drawing.Point(8, 80);
        this.helpLabel.Size = new System.Drawing.Size(272, 72);
        this.helpLabel.Text = "Click on any control to give it focus, and then " +
            "press F1 to display help for that control.  Alternately, you can " +
            "click the help button at the top of the dialog and then click on a control.";

        // Address Label
        this.label2.Location = new System.Drawing.Point(16, 8);
        this.label2.Size = new System.Drawing.Size(100, 16);
        this.label2.Text = "Address:";

        // Comma Label
        this.label3.Location = new System.Drawing.Point(136, 56);
        this.label3.Size = new System.Drawing.Size(16, 16);
        this.label3.Text = ",";

        // Address TextBox
        this.addressTextBox.Location = new System.Drawing.Point(16, 24);
        this.addressTextBox.Size = new System.Drawing.Size(264, 20);
        this.addressTextBox.TabIndex = 0;
        this.addressTextBox.Tag = "Enter the street address in this text box.";
        this.addressTextBox.Text = "";
        this.addressTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // City TextBox
        this.cityTextBox.Location = new System.Drawing.Point(16, 48);
        this.cityTextBox.Size = new System.Drawing.Size(120, 20);
        this.cityTextBox.TabIndex = 3;
        this.cityTextBox.Tag = "Enter the city here.";
        this.cityTextBox.Text = "";
        this.cityTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // State TextBox
        this.stateTextBox.Location = new System.Drawing.Point(152, 48);
        this.stateTextBox.MaxLength = 2;
        this.stateTextBox.Size = new System.Drawing.Size(32, 20);
        this.stateTextBox.TabIndex = 5;
        this.stateTextBox.Tag = "Enter the state in this text box.";
        this.stateTextBox.Text = "";
        this.stateTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // Zip TextBox
        this.zipTextBox.Location = new System.Drawing.Point(192, 48);
        this.zipTextBox.Name = "zipTextBox";
        this.zipTextBox.Size = new System.Drawing.Size(88, 20);
        this.zipTextBox.TabIndex = 6;
        this.zipTextBox.Tag = "Enter the zip code here.";
        this.zipTextBox.Text = "";
        this.zipTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested);

        // Set up how the form should be displayed and add the controls to the form.
        this.ClientSize = new System.Drawing.Size(292, 160);
        this.Controls.AddRange(new System.Windows.Forms.Control[] { this.zipTextBox, 
                                this.stateTextBox, this.label3, this.cityTextBox,  
                                this.label2, this.helpLabel, this.addressTextBox});

        this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        this.HelpButton = true;
        this.MaximizeBox = false;
        this.MinimizeBox = false;
        this.Text = "Help Event Demonstration";    
    }

    private void textBox_HelpRequested(object sender, System.Windows.Forms.HelpEventArgs hlpevent)
    {
        // This event is raised when the F1 key is pressed or the
        // Help cursor is clicked on any of the address fields.
        // The Help text for the field is in the control's
        // Tag property. It is retrieved and displayed in the label.

        Control requestingControl = (Control)sender;
        helpLabel.Text = (string)requestingControl.Tag;
        hlpevent.Handled = true;
    }
}

import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;

public class Form1 extends System.Windows.Forms.Form
{
    private System.Windows.Forms.TextBox addressTextBox;
    private System.Windows.Forms.Label label2;
    private System.Windows.Forms.TextBox cityTextBox;
    private System.Windows.Forms.Label label3;
    private System.Windows.Forms.TextBox stateTextBox;
    private System.Windows.Forms.TextBox zipTextBox;
    private System.Windows.Forms.Label helpLabel;

    /** @attribute STAThread()
     */
    public static void main(String[] args)
    {
        Application.Run(new Form1());
    } //main

    public Form1()
    {
        this.addressTextBox = new System.Windows.Forms.TextBox();
        this.helpLabel = new System.Windows.Forms.Label();
        this.label2 = new System.Windows.Forms.Label();
        this.cityTextBox = new System.Windows.Forms.TextBox();
        this.label3 = new System.Windows.Forms.Label();
        this.stateTextBox = new System.Windows.Forms.TextBox();
        this.zipTextBox = new System.Windows.Forms.TextBox();
        // Help Label
        this.helpLabel.set_BorderStyle(
            System.Windows.Forms.BorderStyle.Fixed3D);
        this.helpLabel.set_Location(new System.Drawing.Point(8, 80));
        this.helpLabel.set_Size(new System.Drawing.Size(272, 72));
        this.helpLabel.set_Text("Click on any control to give it focus, " 
            + "and then press F1 to display help for that control.  " 
            + "Alternately, you can click the help button at the top of " 
            + "the dialog and then click on a control.");
        // Address Label
        this.label2.set_Location(new System.Drawing.Point(16, 8));
        this.label2.set_Size(new System.Drawing.Size(100, 16));
        this.label2.set_Text("Address:");
        // Comma Label
        this.label3.set_Location(new System.Drawing.Point(136, 56));
        this.label3.set_Size(new System.Drawing.Size(16, 16));
        this.label3.set_Text(",");
        // Address TextBox
        this.addressTextBox.set_Location(new System.Drawing.Point(16, 24));
        this.addressTextBox.set_Size(new System.Drawing.Size(264, 20));
        this.addressTextBox.set_TabIndex(0);
        this.addressTextBox.set_Tag("Enter the street address " 
            + "in this text box.");
        this.addressTextBox.set_Text("");
        this.addressTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // City TextBox
        this.cityTextBox.set_Location(new System.Drawing.Point(16, 48));
        this.cityTextBox.set_Size(new System.Drawing.Size(120, 20));
        this.cityTextBox.set_TabIndex(3);
        this.cityTextBox.set_Tag("Enter the city here.");
        this.cityTextBox.set_Text("");
        this.cityTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // State TextBox
        this.stateTextBox.set_Location(new System.Drawing.Point(152, 48));
        this.stateTextBox.set_MaxLength(2);
        this.stateTextBox.set_Size(new System.Drawing.Size(32, 20));
        this.stateTextBox.set_TabIndex(5);
        this.stateTextBox.set_Tag("Enter the state in this text box.");
        this.stateTextBox.set_Text("");
        this.stateTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // Zip TextBox
        this.zipTextBox.set_Location(new System.Drawing.Point(192, 48));
        this.zipTextBox.set_Name("zipTextBox");
        this.zipTextBox.set_Size(new System.Drawing.Size(88, 20));
        this.zipTextBox.set_TabIndex(6);
        this.zipTextBox.set_Tag("Enter the zip code here.");
        this.zipTextBox.set_Text("");
        this.zipTextBox.add_HelpRequested(
            new System.Windows.Forms.HelpEventHandler(
            this.TextBox_HelpRequested));
        // Set up how the form should be displayed and add the controls 
        // to the form.
        this.set_ClientSize(new System.Drawing.Size(292, 160));
        this.get_Controls().AddRange(new System.Windows.Forms.Control[] { 
            this.zipTextBox, this.stateTextBox, this.label3, this.cityTextBox, 
            this.label2, this.helpLabel, this.addressTextBox });

        this.set_FormBorderStyle(
            System.Windows.Forms.FormBorderStyle.FixedDialog);
        this.set_HelpButton(true);
        this.set_MaximizeBox(false);
        this.set_MinimizeBox(false);
        this.set_Text("Help Event Demonstration");
    } //Form1

    private void TextBox_HelpRequested(Object sender, 
        System.Windows.Forms.HelpEventArgs hlpEvent)
    {
        // This event is raised when the F1 key is pressed or the
        // Help cursor is clicked on any of the address fields.
        // The Help text for the field is in the control's
        // Tag property. It is retrieved and displayed in the label.
        Control requestingControl = (Control)sender;
        helpLabel.set_Text((String)requestingControl.get_Tag());
        hlpEvent.set_Handled(true);
    } //TextBox_HelpRequested
} //Form1

Windows 98, Windows 2000 Service Pack 4, Windows CE, Windows Millennium, Windows Mobile para Pocket PC, Windows Server 2003, Windows XP Media Center, Windows XP Professional x64, Windows XP SP2, Windows XP Starter

Microsoft .NET Framework 3.0 es compatible con Windows Vista, Microsoft Windows XP SP2 y Windows Server 2003 SP1.

.NET Framework

Compatible con: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Compatible con: 2.0
Mostrar:
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