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

Definizione

Si verifica quando il controllo perde lo stato attivo.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 
Attributi

Esempi

Nell'esempio di codice seguente viene illustrata la convalida del testo per TextBox1.The following code example demonstrates validating the text for TextBox1. Viene inoltre illustrato come gestire LostFocus l'evento impostando FileDialog.InitialDirectory la proprietà sul testo in TextBox1.It also demonstrates handling the LostFocus event by setting the FileDialog.InitialDirectory property to the text in TextBox1. Nell'esempio di codice è ErrorProvider.GetError stato utilizzato il metodo per verificare la presenza di un errore prima di aprire la finestra di dialogo file.The code example used the ErrorProvider.GetError method to check for an error before opening the file dialog box. Per eseguire questo esempio, incollare il codice seguente in un form contenente un TextBox oggetto TextBox1denominato, OpenFileDialog un OpenFileDialog1oggetto denominato Button , Button1un oggetto denominato ErrorProvider e ErrorProvider1un oggetto denominato.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. Verificare che tutti gli eventi siano associati ai relativi gestori eventi.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

Commenti

Quando si modifica lo stato attivo usando la tastiera (TAB, MAIUSC + TAB e così via), chiamando i Select metodi o SelectNextControl oppure impostando la ContainerControl.ActiveControl proprietà sul form corrente, gli eventi di attivazione si verificano nell'ordine seguente: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

Quando si modifica lo stato attivo tramite il mouse o chiamando il Focus metodo, gli eventi di attivazione si verificano nell'ordine seguente: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

Se la CausesValidation proprietà è impostata su false, gli Validating eventi Validated e vengono eliminati.If the CausesValidation property is set to false, the Validating and Validated events are suppressed.

Se la Cancel CancelEventArgs proprietà di true èimpostataValidating su nel delegato dell' evento,tuttiglieventicheingeneresiverificanodopol'eventovengonoeliminati.ValidatingIf 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.

Nota

Gli GotFocus eventi LostFocus e sono eventi di stato attivo di basso livello collegati ai messaggi di Windows WM_KILLFOCUS e WM_SETFOCUS.The GotFocus and LostFocus events are low-level focus events that are tied to the WM_KILLFOCUS and WM_SETFOCUS Windows messages. Gli GotFocus eventi e LostFocus vengono in genere utilizzati solo quando si UICues aggiornano o si scrivono controlli personalizzati.Typically, the GotFocus and LostFocus events are only used when updating UICues or when writing custom controls. Gli Enter eventi e Leave devono invece essere utilizzati per tutti i controlli ad Form eccezione della classe, che Activated utilizza Deactivate gli eventi e.Instead the Enter and Leave events should be used for all controls except the Form class, which uses the Activated and Deactivate events. Per GotFocus ulteriori informazioni sugli eventi e LostFocus , vedere gli argomenti WM_KILLFOCUS e WM_KILLFOCUS .For more information about the GotFocus and LostFocus events, see the WM_KILLFOCUS and WM_KILLFOCUS topics.

Attenzione

Non tentare di impostare lo stato attivo dall'interno Enterdei GotFocusgestori di LostFocuseventi Validating,, Validated Leave,, o.Do not attempt to set focus from within the Enter, GotFocus, Leave, LostFocus, Validating, or Validated event handlers. Questa operazione può causare l'interruzione della risposta dell'applicazione o del sistema operativo.Doing so can cause your application or the operating system to stop responding. Per ulteriori informazioni, vedere l'argomento WM_KILLFOCUS .For more information, see the WM_KILLFOCUS topic.

Per ulteriori informazioni sulla gestione degli eventi, consultare gestione e generazione di eventi.For more information about handling events, see Handling and Raising Events.

Si applica a

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