CommonDialog.HelpRequest Ereignis

Definition

Namespace:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

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

public:
 event EventHandler ^ HelpRequest;

public event EventHandler? HelpRequest;

member this.HelpRequest : EventHandler 

Public Custom Event HelpRequest As EventHandler 

Ereignistyp

EventHandler

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie ein ColorDialog Objekt initialisiert wird, das die AnyColorEigenschaften festlegt AllowFullOpen . Das ColorDialog -Objekt erlaubt es dem Benutzer nicht, eine benutzerdefinierte Farbe festzulegen, aber es ermöglicht es, den vollständigen Satz von Grundfarben anzuzeigen. Durch Festlegen der SolidColorOnly Eigenschaft auf false können Farben angezeigt werden, die Kombinationen anderer Farben auf Systemen mit 256 oder weniger Farben sind. Das Beispiel zeigt auch das Festlegen der ShowHelp Eigenschaft und das Behandeln eines Ereignisses HelpRequest für ein Dialogfeld. Fügen Sie zum Ausführen des Beispiels den folgenden Code in ein Formular ein, und rufen Sie die InitializeColorDialog -Methode im Konstruktor oder Load der Methode des Formulars auf. Dieses Beispiel erfordert, dass das Click Ereignis der Schaltfläche mit dem im Beispiel definierten Ereignishandler verbunden ist.

// 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.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.
   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

Hinweise

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

Weitere Informationen

• OnHelpRequest(EventArgs)