Control.HelpRequested-Ereignis
Tritt ein, wenn der Benutzer die Hilfe für ein Steuerelement anfordert.
Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)
Syntax
'Declaration
Public Event HelpRequested As HelpEventHandler
'Usage
Dim instance As Control
Dim handler As HelpEventHandler
AddHandler instance.HelpRequested, handler
public event HelpEventHandler HelpRequested
public:
event HelpEventHandler^ HelpRequested {
void add (HelpEventHandler^ value);
void remove (HelpEventHandler^ value);
}
/** @event */
public void add_HelpRequested (HelpEventHandler value)
/** @event */
public void remove_HelpRequested (HelpEventHandler value)
JScript unterstützt die Verwendung von Ereignissen, aber nicht die Deklaration von neuen Ereignissen.
Hinweise
Das HelpRequested-Ereignis wird normalerweise ausgelöst, wenn der Benutzer die F1-Taste betätigt oder wenn auf eine zugeordnete kontextbezogene Schaltfläche geklickt wird.
Weitere Informationen zum Behandeln von Ereignissen finden Sie unter Behandeln von Ereignissen.
Beispiel
Im folgenden Codebeispiel wird die Behandlung des HelpRequested-Ereignisses zum Anzeigen der benutzerdefinierten Hilfe in einem Formular mit vier Adressfeldern veranschaulicht. Das HelpRequested-Ereignis kann auf zwei Arten ausgelöst werden: durch Drücken von F1 mit Fokus in einem Adressfeld oder durch Klicken auf die Schaltfläche für die Direkthilfe und anschließendes Klicken mit dem Hilfecursor in ein Adressfeld. Die Handled-Eigenschaft wird auf True festgelegt, um anzugeben, dass das HelpRequested-Ereignis behandelt wurde. Im Beispiel wird außerdem veranschaulicht, wie der Hilfetext in der Control.Tag-Eigenschaft gespeichert werden kann.
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Public Class Form1
Inherits System.Windows.Forms.Form
Private WithEvents addressTextBox As System.Windows.Forms.TextBox
Private WithEvents label2 As System.Windows.Forms.Label
Private WithEvents cityTextBox As System.Windows.Forms.TextBox
Private WithEvents label3 As System.Windows.Forms.Label
Private WithEvents stateTextBox As System.Windows.Forms.TextBox
Private WithEvents zipTextBox As System.Windows.Forms.TextBox
Private WithEvents helpLabel As System.Windows.Forms.Label
<STAThread()> _
Shared Sub Main()
Application.Run(New Form1)
End Sub 'Main
Public Sub New()
Me.addressTextBox = New System.Windows.Forms.TextBox
Me.helpLabel = New System.Windows.Forms.Label
Me.label2 = New System.Windows.Forms.Label
Me.cityTextBox = New System.Windows.Forms.TextBox
Me.label3 = New System.Windows.Forms.Label
Me.stateTextBox = New System.Windows.Forms.TextBox
Me.zipTextBox = New System.Windows.Forms.TextBox
' Help Label
Me.helpLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
Me.helpLabel.Location = New System.Drawing.Point(8, 80)
Me.helpLabel.Size = New System.Drawing.Size(272, 72)
Me.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
Me.label2.Location = New System.Drawing.Point(16, 8)
Me.label2.Size = New System.Drawing.Size(100, 16)
Me.label2.Text = "Address:"
' Comma Label
Me.label3.Location = New System.Drawing.Point(136, 56)
Me.label3.Size = New System.Drawing.Size(16, 16)
Me.label3.Text = ","
' Address TextBox
Me.addressTextBox.Location = New System.Drawing.Point(16, 24)
Me.addressTextBox.Size = New System.Drawing.Size(264, 20)
Me.addressTextBox.TabIndex = 0
Me.addressTextBox.Tag = "Enter the stree address in this text box."
Me.addressTextBox.Text = ""
' City TextBox
Me.cityTextBox.Location = New System.Drawing.Point(16, 48)
Me.cityTextBox.Size = New System.Drawing.Size(120, 20)
Me.cityTextBox.TabIndex = 3
Me.cityTextBox.Tag = "Enter the city here."
Me.cityTextBox.Text = ""
' State TextBox
Me.stateTextBox.Location = New System.Drawing.Point(152, 48)
Me.stateTextBox.MaxLength = 2
Me.stateTextBox.Size = New System.Drawing.Size(32, 20)
Me.stateTextBox.TabIndex = 5
Me.stateTextBox.Tag = "Enter the state in this text box."
Me.stateTextBox.Text = ""
' Zip TextBox
Me.zipTextBox.Location = New System.Drawing.Point(192, 48)
Me.zipTextBox.Size = New System.Drawing.Size(88, 20)
Me.zipTextBox.TabIndex = 6
Me.zipTextBox.Tag = "Enter the zip code here."
Me.zipTextBox.Text = ""
' Set up how the form should be displayed and add the controls to the form.
Me.ClientSize = New System.Drawing.Size(292, 160)
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.zipTextBox, _
Me.stateTextBox, Me.label3, Me.cityTextBox, _
Me.label2, Me.helpLabel, Me.addressTextBox})
Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog
Me.HelpButton = True
Me.MaximizeBox = False
Me.MinimizeBox = False
Me.Text = "Help Event Demonstration"
End Sub 'New
Private Sub textBox_HelpRequested(ByVal sender As Object, ByVal hlpevent As System.Windows.Forms.HelpEventArgs) Handles addressTextBox.HelpRequested, cityTextBox.HelpRequested, stateTextBox.HelpRequested, zipTextBox.HelpRequested
' 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.
Dim requestingControl As Control = CType(sender, Control)
helpLabel.Text = CStr(requestingControl.Tag)
hlpevent.Handled = True
End Sub 'textBox_HelpRequested
End Class 'Form1
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;
}
}
#using <System.dll>
#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
public ref class Form1: public System::Windows::Forms::Form
{
private:
System::Windows::Forms::TextBox^ addressTextBox;
System::Windows::Forms::Label ^ label2;
System::Windows::Forms::TextBox^ cityTextBox;
System::Windows::Forms::Label ^ label3;
System::Windows::Forms::TextBox^ stateTextBox;
System::Windows::Forms::TextBox^ zipTextBox;
System::Windows::Forms::Label ^ helpLabel;
public:
Form1()
{
this->addressTextBox = gcnew System::Windows::Forms::TextBox;
this->helpLabel = gcnew System::Windows::Forms::Label;
this->label2 = gcnew System::Windows::Forms::Label;
this->cityTextBox = gcnew System::Windows::Forms::TextBox;
this->label3 = gcnew System::Windows::Forms::Label;
this->stateTextBox = gcnew System::Windows::Forms::TextBox;
this->zipTextBox = gcnew System::Windows::Forms::TextBox;
// Help Label
this->helpLabel->BorderStyle = System::Windows::Forms::BorderStyle::Fixed3D;
this->helpLabel->Location = System::Drawing::Point( 8, 80 );
this->helpLabel->Size = 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 = System::Drawing::Point( 16, 8 );
this->label2->Size = System::Drawing::Size( 100, 16 );
this->label2->Text = "Address:";
// Comma Label
this->label3->Location = System::Drawing::Point( 136, 56 );
this->label3->Size = System::Drawing::Size( 16, 16 );
this->label3->Text = ", ";
// Address TextBox
this->addressTextBox->Location = System::Drawing::Point( 16, 24 );
this->addressTextBox->Size = 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 += gcnew System::Windows::Forms::HelpEventHandler( this, &Form1::textBox_HelpRequested );
// City TextBox
this->cityTextBox->Location = System::Drawing::Point( 16, 48 );
this->cityTextBox->Size = System::Drawing::Size( 120, 20 );
this->cityTextBox->TabIndex = 3;
this->cityTextBox->Tag = "Enter the city here.";
this->cityTextBox->Text = "";
this->cityTextBox->HelpRequested += gcnew System::Windows::Forms::HelpEventHandler( this, &Form1::textBox_HelpRequested );
// State TextBox
this->stateTextBox->Location = System::Drawing::Point( 152, 48 );
this->stateTextBox->MaxLength = 2;
this->stateTextBox->Size = 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 += gcnew System::Windows::Forms::HelpEventHandler( this, &Form1::textBox_HelpRequested );
// Zip TextBox
this->zipTextBox->Location = System::Drawing::Point( 192, 48 );
this->zipTextBox->Name = "zipTextBox";
this->zipTextBox->Size = System::Drawing::Size( 88, 20 );
this->zipTextBox->TabIndex = 6;
this->zipTextBox->Tag = "Enter the zip code here.";
this->zipTextBox->Text = "";
this->zipTextBox->HelpRequested += gcnew System::Windows::Forms::HelpEventHandler( this, &Form1::textBox_HelpRequested );
// Set up how the form should be displayed and add the controls to the form.
this->ClientSize = System::Drawing::Size( 292, 160 );
array<System::Windows::Forms::Control^>^temp0 = {this->zipTextBox,this->stateTextBox,this->label3,this->cityTextBox,this->label2,this->helpLabel,this->addressTextBox};
this->Controls->AddRange( temp0 );
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 = dynamic_cast<Control^>(sender);
helpLabel->Text = dynamic_cast<String^>(requestingControl->Tag);
hlpevent->Handled = true;
}
};
[STAThread]
int main()
{
Application::Run( gcnew Form1 );
}
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
Plattformen
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, 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
.NET Compact Framework
Unterstützt in: 2.0
Siehe auch
Referenz
Control-Klasse
Control-Member
System.Windows.Forms-Namespace
OnHelpRequested
HelpProvider
Help