CommonDialog.HelpRequest-Ereignis

Tritt ein, wenn der Benutzer in einem Standarddialogfeld auf die Hilfeschaltfläche klickt.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

Syntax

'Declaration
Public Event HelpRequest As EventHandler
'Usage
Dim instance As CommonDialog
Dim handler As EventHandler

AddHandler instance.HelpRequest, handler

public event EventHandler HelpRequest

public:
event EventHandler^ HelpRequest {
    void add (EventHandler^ value);
    void remove (EventHandler^ value);
}

/** @event */
public void add_HelpRequest (EventHandler value)

/** @event */
public void remove_HelpRequest (EventHandler value)

JScript unterstützt die Verwendung von Ereignissen, aber nicht die Deklaration von neuen Ereignissen.

Hinweise

Informationen zum Behandeln von Ereignissen finden Sie unter Behandeln von Ereignissen.

Beispiel

Im folgenden Codebeispiel wird das Initialisieren eines ColorDialog-Objekts veranschaulicht, das die AnyColor-Eigenschaft und die AllowFullOpen-Eigenschaft festlegt. Im ColorDialog-Objekt können Benutzer keine benutzerdefinierte Farbe festlegen. Im Objekt können aber alle vorhandenen Grundfarben angezeigt werden. Wenn die SolidColorOnly-Eigenschaft auf false festgelegt wird, können Farben angezeigt werden, die auf Systemen mit 256 oder weniger Farben Kombinationen anderer Farben darstellen. Im Beispiel wird auch das Festlegen der ShowHelp-Eigenschaft und das Behandeln eines HelpRequest-Ereignisses für ein Dialogfeld veranschaulicht. Zum Ausführen des Beispiels fügen Sie den folgenden Code in ein Formular ein, und rufen Sie die InitializeColorDialog-Methode im Konstruktor oder die Load-Methode des Formulars auf. In diesem Beispiel muss das Click-Ereignis der Schaltfläche mit dem im Beispiel definierten Ereignishandler verbunden sein.

' This method initializes ColorDialog1 to allow any colors, 
' and combination colors on systems with 256 colors or less, 
' but will not allow the user to set custom colors.  The
' dialog will contain the help button.
Private Sub InitializeColorDialog()
    Me.ColorDialog1 = New System.Windows.Forms.ColorDialog
    Me.ColorDialog1.AllowFullOpen = False
    Me.ColorDialog1.AnyColor = True
    Me.ColorDialog1.SolidColorOnly = False
    Me.ColorDialog1.ShowHelp = True
End Sub
  

' This method opens the dialog and checks the DialogResult value. 
' If the result is OK, the text box's background color will be changed 
' to the user-selected color.
Private Sub Button1_Click(ByVal sender As System.Object,  _
    ByVal e As System.EventArgs) Handles Button1.Click
    Dim result As DialogResult = ColorDialog1.ShowDialog()
    If (result.Equals(DialogResult.OK)) Then
        TextBox1.BackColor = ColorDialog1.Color
    End If
End Sub
 
  
' This method is called when the HelpRequest event is raised, 
'which occurs when the user clicks the Help button on the ColorDialog object.
Private Sub ColorDialog1_HelpRequest(ByVal sender As Object, _ 
    ByVal e As System.EventArgs) Handles ColorDialog1.HelpRequest

    MessageBox.Show("Please select a color by clicking it." _
    & "This will change the BackColor property of the TextBox.")
End Sub

// This method initializes ColorDialog1 to allow any colors, 
// and combination colors on systems with 256 colors or less, 
// but will not allow the user to set custom colors.  The
// dialog will contain the help button.
private void InitializeColorDialog()
{
    this.ColorDialog1 = new System.Windows.Forms.ColorDialog();
    this.ColorDialog1.AllowFullOpen = false;
    this.ColorDialog1.AnyColor = true;
    this.ColorDialog1.SolidColorOnly = false;
    this.ColorDialog1.ShowHelp = true;
    
    // Associate the event-handling method with
    // the HelpRequest event.
    this.ColorDialog1.HelpRequest 
        += new System.EventHandler(ColorDialog1_HelpRequest);
}


// This method opens the dialog and checks the DialogResult value. 
// If the result is OK, the text box's background color will be changed 
// to the user-selected color.
private void Button1_Click(System.Object sender, System.EventArgs e)
{
    DialogResult result = ColorDialog1.ShowDialog();
    if (result.Equals(DialogResult.OK))
    {
        TextBox1.BackColor = ColorDialog1.Color;
    }
}

// This method is called when the HelpRequest event is raised, 
//which occurs when the user clicks the Help button on the ColorDialog object.
private void ColorDialog1_HelpRequest(object sender, System.EventArgs e)
{

    MessageBox.Show("Please select a color by clicking it. "
       + "This will change the BackColor property of the TextBox.");
}

// This method initializes ColorDialog1 to allow any colors, 
// and combination colors on systems with 256 colors or less, 
// but will not allow the user to set custom colors.  The
// dialog will contain the help button.
void InitializeColorDialog()
{
   this->ColorDialog1 = gcnew System::Windows::Forms::ColorDialog;
   this->ColorDialog1->AllowFullOpen = false;
   this->ColorDialog1->AnyColor = true;
   this->ColorDialog1->SolidColorOnly = false;
   this->ColorDialog1->ShowHelp = true;
   
   // Associate the event-handling method with
   // the HelpRequest event.
   this->ColorDialog1->HelpRequest +=
      gcnew System::EventHandler( this, &Form1::ColorDialog1_HelpRequest );
}

// This method opens the dialog and checks the DialogResult value. 
// If the result is OK, the text box's background color will be changed 
// to the user-selected color.
void Button1_Click( System::Object^ sender, System::EventArgs^ e )
{
   ::DialogResult result = ColorDialog1->ShowDialog();
   if ( result == ::DialogResult::OK )
   {
      TextBox1->BackColor = ColorDialog1->Color;
   }
}

// This method is called when the HelpRequest event is raised, 
//which occurs when the user clicks the Help button on the ColorDialog object.
void ColorDialog1_HelpRequest( Object^ sender, System::EventArgs^ e )
{
   MessageBox::Show( "Please select a color by clicking it. " +
      "This will change the BackColor property of the TextBox." );
}

// This method initializes colorDialog1 to allow any colors, 
// and combination colors on systems with 256 colors or less, 
// but will not allow the user to set custom colors.  The
// dialog will contain the help button.
private void InitializeColorDialog()
{
    this.colorDialog1 = new System.Windows.Forms.ColorDialog();
    this.colorDialog1.set_AllowFullOpen(false);
    this.colorDialog1.set_AnyColor(true);
    this.colorDialog1.set_SolidColorOnly(false);
    this.colorDialog1.set_ShowHelp(true);
    // Associate the event-handling method with
    // the HelpRequest event.
    this.colorDialog1.add_HelpRequest(new System.EventHandler(
        colorDialog1_HelpRequest));
} //InitializeColorDialog

// This method opens the dialog and checks the DialogResult value. 
// If the result is OK, the text box's background color will be changed 
// to the user-selected color.
private void button1_Click(System.Object sender, System.EventArgs e)
{
    DialogResult result = colorDialog1.ShowDialog();
    if (result.Equals(DialogResult.OK)) {
        textBox1.set_BackColor(colorDialog1.get_Color());
    }
} //button1_Click

// This method is called when the HelpRequest event is raised, 
//which occurs when the user clicks the Help button on the ColorDialog object.
private void colorDialog1_HelpRequest(Object sender, System.EventArgs e)
{
    MessageBox.Show("Please select a color by clicking it. " 
        + "This will change the BackColor property of the TextBox.");
} //colorDialog1_HelpRequest

Plattformen

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, 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

Siehe auch

Referenz

CommonDialog-Klasse
CommonDialog-Member
System.Windows.Forms-Namespace
OnHelpRequest