Control.OnEnter(EventArgs) Control.OnEnter(EventArgs) Control.OnEnter(EventArgs) Control.OnEnter(EventArgs) Method

Definition

Löst das Enter-Ereignis aus.Raises the Enter event.

protected:
 virtual void OnEnter(EventArgs ^ e);
protected virtual void OnEnter (EventArgs e);
abstract member OnEnter : EventArgs -> unit
override this.OnEnter : EventArgs -> unit
Protected Overridable Sub OnEnter (e As EventArgs)

Parameter

e
EventArgs EventArgs EventArgs EventArgs

Ein EventArgs, das die Ereignisdaten enthält.An EventArgs that contains the event data.

Beispiele

Im folgenden Codebeispiel wird das Enter -Ereignis verwendet, um die Vordergrund-und TextBox Hintergrundfarben eines unter bestimmten Bedingungen zu ändern.The following code example uses the Enter event to change the foreground and background colors of a TextBox under particular conditions.

private:
   void textBox1_Enter( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // If the TextBox contains text, change its foreground and background colors.
      if ( textBox1->Text != String::Empty )
      {
         textBox1->ForeColor = Color::Red;
         textBox1->BackColor = Color::Black;

         // Move the selection pointer to the end of the text of the control.
         textBox1->Select(textBox1->Text->Length,0);
      }
   }

   void textBox1_Leave( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Reset the colors and selection of the TextBox after focus is lost.
      textBox1->ForeColor = Color::Black;
      textBox1->BackColor = Color::White;
      textBox1->Select(0,0);
   }
private void textBox1_Enter(object sender, System.EventArgs e)
{
    // If the TextBox contains text, change its foreground and background colors.
    if (!string.IsNullOrEmpty(textBox1.Text))
    {
        textBox1.ForeColor = Color.Red;
        textBox1.BackColor = Color.Black;
        // Move the selection pointer to the end of the text of the control.
        textBox1.Select(textBox1.Text.Length, 0);
    }
}

private void textBox1_Leave(object sender, System.EventArgs e)
{
    // Reset the colors and selection of the TextBox after focus is lost.
    textBox1.ForeColor = Color.Black;
    textBox1.BackColor = Color.White;
    textBox1.Select(0,0);
}
    Private Sub textBox1_Enter(sender As Object, e As System.EventArgs) Handles textBox1.Enter
        ' If the TextBox contains text, change its foreground and background colors.
        If textBox1.Text <> [String].Empty Then
            textBox1.ForeColor = Color.Red
            textBox1.BackColor = Color.Black
            ' Move the selection pointer to the end of the text of the control.
            textBox1.Select(textBox1.Text.Length, 0)
        End If
    End Sub 'textBox1_Enter
   
   
    Private Sub textBox1_Leave(sender As Object, e As System.EventArgs) Handles textBox1.Leave
        ' Reset the colors and selection of the TextBox after focus is lost.
        textBox1.ForeColor = Color.Black
        textBox1.BackColor = Color.White
        textBox1.Select(0, 0)
    End Sub 'textBox1_Leave
End Class 'Form1 

Hinweise

Durch das Auslösen eines Ereignisses wird der Ereignishandler über einen Delegaten aufgerufen.Raising an event invokes the event handler through a delegate. Weitere Informationen finden Sie unter Behandeln und Auslösen von Ereignissen.For more information, see Handling and Raising Events.

Mit der OnEnter-Methode können auch abgeleitete Klassen das Ereignis ohne Anfügen eines Delegaten behandeln.The OnEnter method also allows derived classes to handle the event without attaching a delegate. Dies ist das bevorzugte Verfahren für die Behandlung des Ereignisses in einer abgeleiteten Klasse.This is the preferred technique for handling the event in a derived class.

Hinweise für Vererber

Wenn Sie OnEnter(EventArgs) in einer abgeleiteten Klasse überschreiben, müssen Sie die OnEnter(EventArgs)-Methode der Basisklasse aufrufen, damit registrierte Delegaten das Ereignis empfangen.When overriding OnEnter(EventArgs) in a derived class, be sure to call the base class's OnEnter(EventArgs) method so that registered delegates receive the event.

Gilt für:

Siehe auch