Control.LostFocus Evento

Definição

Ocorre quando o controle perde o foco.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 
Atributos

Exemplos

O exemplo de código a seguir demonstra como validar o texto para TextBox1.The following code example demonstrates validating the text for TextBox1. Ele também demonstra como manipular o evento LostFocus definindo a propriedade FileDialog.InitialDirectory como o texto em TextBox1.It also demonstrates handling the LostFocus event by setting the FileDialog.InitialDirectory property to the text in TextBox1. O exemplo de código usou o método ErrorProvider.GetError para verificar se há um erro antes de abrir a caixa de diálogo arquivo.The code example used the ErrorProvider.GetError method to check for an error before opening the file dialog box. Para executar este exemplo, Cole o código a seguir em um formulário que contém um TextBox chamado TextBox1, um OpenFileDialog chamado OpenFileDialog1, um Button chamado Button1e um ErrorProvider chamado 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. Verifique se todos os eventos estão associados aos seus manipuladores de eventos.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

Comentários

Quando você altera o foco usando o teclado (TAB, SHIFT+TAB etc.), chamando os métodos Select ou SelectNextControl, ou definindo a propriedade ContainerControl.ActiveControl como o formulário atual, os eventos de foco ocorrem na seguinte ordem: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 você altera o foco usando o mouse ou chamando o método Focus, os eventos de foco ocorrem na seguinte ordem: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 a propriedade CausesValidation for definida como false, os eventos Validating e Validated serão suprimidos.If the CausesValidation property is set to false, the Validating and Validated events are suppressed.

Se a propriedade Cancel da CancelEventArgs for definida como true no delegado de evento Validating, todos os eventos que normalmente ocorrerão após o evento Validating serão suprimidos.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.

Observação

Os eventos GotFocus e LostFocus são eventos de foco de baixo nível que estão vinculados às mensagens WM_KILLFOCUS e WM_SETFOCUS do Windows.The GotFocus and LostFocus events are low-level focus events that are tied to the WM_KILLFOCUS and WM_SETFOCUS Windows messages. Normalmente, os eventos GotFocus e LostFocus são usados apenas ao atualizar UICues ou ao escrever controles personalizados.Typically, the GotFocus and LostFocus events are only used when updating UICues or when writing custom controls. Em vez disso, os eventos Enter e Leave devem ser usados para todos os controles, exceto para a classe Form, que usa os eventos Activated e Deactivate.Instead the Enter and Leave events should be used for all controls except the Form class, which uses the Activated and Deactivate events. Para obter mais informações sobre os eventos de GotFocus e LostFocus, consulte os tópicos WM_KILLFOCUS e WM_KILLFOCUS .For more information about the GotFocus and LostFocus events, see the WM_KILLFOCUS and WM_KILLFOCUS topics.

Cuidado

Não tente definir o foco de dentro dos manipuladores de eventos Enter, GotFocus, Leave, LostFocus, Validatingou Validated.Do not attempt to set focus from within the Enter, GotFocus, Leave, LostFocus, Validating, or Validated event handlers. Isso pode fazer com que o aplicativo ou o sistema operacional pare de responder.Doing so can cause your application or the operating system to stop responding. Para obter mais informações, consulte o tópico WM_KILLFOCUS .For more information, see the WM_KILLFOCUS topic.

Para obter mais informações sobre como manipular eventos, consulte manipulando e gerando eventos.For more information about handling events, see Handling and Raising Events.

Aplica-se a

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