Control.LostFocus Control.LostFocus Control.LostFocus Control.LostFocus Event

Definition

Tritt ein, wenn das Steuerelement den Fokus verliert.Occurs when the control loses focus.

public:
 event EventHandler ^ LostFocus;
[System.ComponentModel.Browsable(false)]
public event EventHandler LostFocus;
member this.LostFocus : EventHandler 
Public Custom Event LostFocus As EventHandler 
Attribute

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, überprüfen den Text für TextBox1.The following code example demonstrates validating the text for TextBox1. Außerdem zeigt es die Behandlung der LostFocus -Ereignisses durch Festlegen der FileDialog.InitialDirectory Eigenschaft, um den Text in TextBox1.It also demonstrates handling the LostFocus event by setting the FileDialog.InitialDirectory property to the text in TextBox1. Das Codebeispiel verwendet die ErrorProvider.GetError Methode für einen Fehler zu überprüfen, bevor Sie das Dialogfeld Datei öffnen.The code example used the ErrorProvider.GetError method to check for an error before opening the file dialog box. Um dieses Beispiel auszuführen, fügen Sie in den folgenden Code in ein Formular enthält ein TextBox mit dem Namen TextBox1, OpenFileDialog mit dem Namen OpenFileDialog1, Button mit dem Namen Button1, und ein ErrorProvider mit dem Namen ErrorProvider1.To run this example, paste the following code into a form containing a TextBox named TextBox1, an OpenFileDialog named OpenFileDialog1, a Button named Button1, and an ErrorProvider named ErrorProvider1. Stellen Sie sicher, dass alle Ereignisse Ereignishandlern zugeordnet sind.Ensure all events are associated with their event handlers.

private:
   void TextBox1_Validating( Object^ sender,
      System::ComponentModel::CancelEventArgs^ e )
   {
      // If nothing is entered,
      // an ArgumentException is caught; if an invalid directory is entered, 
      // a DirectoryNotFoundException is caught. An appropriate error message 
      // is displayed in either case.
      try
      {
         System::IO::DirectoryInfo^ directory = gcnew System::IO::DirectoryInfo( TextBox1->Text );
         directory->GetFiles();
         ErrorProvider1->SetError( TextBox1, "" );
      }
      catch ( System::ArgumentException^ ) 
      {
         ErrorProvider1->SetError( TextBox1, "Please enter a directory" );
      }
      catch ( System::IO::DirectoryNotFoundException^ ) 
      {
         ErrorProvider1->SetError( TextBox1, "The directory does not exist."
         "Try again with a different directory." );
      }
   }

   // This method handles the LostFocus event for TextBox1 by setting the 
   // dialog's InitialDirectory property to the text in TextBox1.
   void TextBox1_LostFocus( Object^ sender, System::EventArgs^ e )
   {
      OpenFileDialog1->InitialDirectory = TextBox1->Text;
   }

   // This method demonstrates using the ErrorProvider.GetError method 
   // to check for an error before opening the dialog box.
   void Button1_Click( System::Object^ sender, System::EventArgs^ e )
   {
      //If there is no error, then open the dialog box.
      if ( ErrorProvider1->GetError( TextBox1 )->Equals( "" ) )
      {
         ::DialogResult dialogResult = OpenFileDialog1->ShowDialog();
      }
   }
private void textBox1_Validating(object sender, 
	System.ComponentModel.CancelEventArgs e)
{
	// If nothing is entered,
	// an ArgumentException is caught; if an invalid directory is entered, 
	// a DirectoryNotFoundException is caught. An appropriate error message 
	// is displayed in either case.
	try
	{
		System.IO.DirectoryInfo directory = 
			new System.IO.DirectoryInfo(textBox1.Text);
		directory.GetFiles();
		errorProvider1.SetError(textBox1, "");

	}
	catch(System.ArgumentException ex1)
	{
		errorProvider1.SetError(textBox1, "Please enter a directory");

	}
	catch(System.IO.DirectoryNotFoundException ex2)
	{
		errorProvider1.SetError(textBox1, "The directory does not exist." +
			"Try again with a different directory.");
	}

}

// This method handles the LostFocus event for textBox1 by setting the 
// dialog's InitialDirectory property to the text in textBox1.
private void textBox1_LostFocus(object sender, System.EventArgs e)
{
	openFileDialog1.InitialDirectory = textBox1.Text;
}

// This method demonstrates using the ErrorProvider.GetError method 
// to check for an error before opening the dialog box.
private void button1_Click(System.Object sender, System.EventArgs e)
{
	//If there is no error, then open the dialog box.
	if (errorProvider1.GetError(textBox1)=="")
	{
		DialogResult dialogResult = openFileDialog1.ShowDialog();
	}
}
Private Sub TextBox1_Validating(ByVal sender As Object, _
ByVal e As System.ComponentModel.CancelEventArgs) _
Handles TextBox1.Validating

    ' If nothing is entered,
    ' an ArgumentException is caught; if an invalid directory is entered, 
    ' a DirectoryNotFoundException is caught. An appropriate error message 
    ' is displayed in either case.
    Try
        Dim directory As New System.IO.DirectoryInfo(TextBox1.Text)
        directory.GetFiles()
        ErrorProvider1.SetError(TextBox1, "")

    Catch ex1 As System.ArgumentException
        ErrorProvider1.SetError(TextBox1, "Please enter a directory")

    Catch ex2 As System.IO.DirectoryNotFoundException
        ErrorProvider1.SetError(TextBox1, _
        "The directory does not exist." & _
        "Try again with a different directory.")
    End Try

End Sub

' This method handles the LostFocus event for TextBox1 by setting the 
' dialog's InitialDirectory property to the text in TextBox1.
Private Sub TextBox1_LostFocus(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles TextBox1.LostFocus
    OpenFileDialog1.InitialDirectory = TextBox1.Text
End Sub


' This method demonstrates using the ErrorProvider.GetError method 
' to check for an error before opening the dialog box.
Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click

    'If there is no error, then open the dialog box.
    If ErrorProvider1.GetError(TextBox1) = "" Then
        Dim dialogResult As DialogResult = OpenFileDialog1.ShowDialog()
    End If

End Sub

Hinweise

Wenn Sie den Fokus ändern, indem Sie mit der Tastatur (Registerkarte, UMSCHALT + TAB, usw.), durch den Aufruf der Select oder SelectNextControl Methoden oder durch Festlegen der ContainerControl.ActiveControl Eigenschaft mit dem aktuellen Formular den Fokusereignisse auftreten, in der folgenden Reihenfolge:When you change the focus by using the keyboard (TAB, SHIFT+TAB, and so on), by calling the Select or SelectNextControl methods, or by setting the ContainerControl.ActiveControl property to the current form, focus events occur in the following order:

  1. Enter

  2. GotFocus

  3. Leave

  4. Validating

  5. Validated

  6. LostFocus

Wenn Sie den Fokus ändern, mit der Maus oder durch Aufrufen der Focus -Methode, den Fokusereignisse auftreten, in der folgenden Reihenfolge:When you change the focus by using the mouse or by calling the Focus method, focus events occur in the following order:

  1. Enter

  2. GotFocus

  3. LostFocus

  4. Leave

  5. Validating

  6. Validated

Wenn die CausesValidation -Eigenschaftensatz auf false, Validating und Validated Ereignisse unterdrückt werden.If the CausesValidation property is set to false, the Validating and Validated events are suppressed.

Wenn die Cancel Eigenschaft der CancelEventArgs nastaven NA hodnotu true in die Validating Ereignisdelegaten, der alle Ereignisse, die in der Regel nach dem auftreten würden die Validating Ereignis werden unterdrückt.If the Cancel property of the CancelEventArgs is set to true in the Validating event delegate, all events that would usually occur after the Validating event are suppressed.

Hinweis

Die GotFocus und LostFocus Ereignisse werden auf niedriger Ebene konzentrieren, die an die Nachrichten WM_KILLFOCUS und WM_SETFOCUS Windows gebunden sind.The GotFocus and LostFocus events are low-level focus events that are tied to the WM_KILLFOCUS and WM_SETFOCUS Windows messages. In der Regel die GotFocus und LostFocus Ereignisse werden nur verwendet, bei der Aktualisierung UICues oder beim Schreiben benutzerdefinierter Steuerelemente.Typically, the GotFocus and LostFocus events are only used when updating UICues or when writing custom controls. Stattdessen die Enter und Leave Ereignisse sollte verwendet werden, für alle Steuerelemente, mit Ausnahme der Form -Klasse verwendet die Activated und Deactivate Ereignisse.Instead the Enter and Leave events should be used for all controls except the Form class, which uses the Activated and Deactivate events. Weitere Informationen zu den GotFocus und LostFocus Ereignisse finden Sie unter den WM_KILLFOCUS und WM_KILLFOCUS Themen.For more information about the GotFocus and LostFocus events, see the WM_KILLFOCUS and WM_KILLFOCUS topics.

Achtung

Versuchen Sie nicht, legen Sie den Fokus aus dem Enter, GotFocus, Leave, LostFocus, Validating, oder Validated -Ereignishandler.Do not attempt to set focus from within the Enter, GotFocus, Leave, LostFocus, Validating, or Validated event handlers. Auf diese Weise kann dazu führen, dass Ihre Anwendung oder das Betriebssystem nicht mehr reagiert.Doing so can cause your application or the operating system to stop responding. Weitere Informationen finden Sie unter den WM_KILLFOCUS Thema.For more information, see the WM_KILLFOCUS topic.

Weitere Informationen zur Behandlung von Ereignissen finden Sie unter behandeln und Auslösen von Ereignissen.For more information about handling events, see Handling and Raising Events.

Gilt für:

Siehe auch