Control.OnTextChanged(EventArgs) Control.OnTextChanged(EventArgs) Control.OnTextChanged(EventArgs) Control.OnTextChanged(EventArgs) Method

Definición

Genera el evento TextChanged.Raises the TextChanged event.

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

Parámetros

e
EventArgs EventArgs EventArgs EventArgs

Objeto EventArgs que contiene los datos del evento.An EventArgs that contains the event data.

Ejemplos

En el ejemplo de código siguiente ForeColor se cambia TextBox el de una clase derivada que muestra los datos de moneda.The following code example changes the ForeColor of a TextBox derived class displaying currency data. En el ejemplo se convierte el texto en un número decimal y se ForeColor cambia Color.Red a si el número es negativo y Color.Black a si el número es positivo.The example converts the text to a decimal number and changes the ForeColor to Color.Red if the number is negative and to Color.Black if the number is positive. Este ejemplo requiere que tenga una clase que derive de la TextBox clase.This example requires that you have a class that derives from the TextBox class.

protected:
   virtual void OnTextChanged( System::EventArgs^ e ) override
   {
      try
      {
         // Convert the text to a Double and determine
         // if it is a negative number.
         if ( Double::Parse( this->Text ) < 0 )
         {
            // If the number is negative, display it in Red.
            this->ForeColor = Color::Red;
         }
         else
         {
            // If the number is not negative, display it in Black.
            this->ForeColor = Color::Black;
         }
      }
      catch ( Exception^ ) 
      {
         // If there is an error, display the
         // text using the system colors.
         this->ForeColor = SystemColors::ControlText;
      }

      TextBox::OnTextChanged( e );
   }
protected override void OnTextChanged(System.EventArgs e)
{
   try
   {
      // Convert the text to a Double and determine
      // if it is a negative number.
      if(double.Parse(this.Text) < 0)
      {
         // If the number is negative, display it in Red.
         this.ForeColor = Color.Red;
      }
      else
      {
         // If the number is not negative, display it in Black.
         this.ForeColor = Color.Black;
      }
   }
   catch
   {
      // If there is an error, display the 
      // text using the system colors.
      this.ForeColor = SystemColors.ControlText;
   }
   
   base.OnTextChanged(e);
}
Protected Overrides Sub OnTextChanged(e As System.EventArgs)
   Try
      ' Convert the text to a Double and determine
      ' if it is a negative number.
      If Double.Parse(Me.Text) < 0 Then
         ' If the number is negative, display it in Red.
         Me.ForeColor = Color.Red
      Else
         ' If the number is not negative, display it in Black.
         Me.ForeColor = Color.Black
      End If
   Catch
      ' If there is an error, display the
      ' text using the system colors.
      Me.ForeColor = SystemColors.ControlText
   End Try

   MyBase.OnTextChanged(e)
End Sub

Comentarios

Cuando se genera un evento, se invoca el controlador de eventos a través de un delegado.Raising an event invokes the event handler through a delegate. Para obtener más información, consulte controlar y provocar eventos.For more information, see Handling and Raising Events.

El OnTextChanged método también permite que las clases derivadas controlen el evento sin asociar un delegado.The OnTextChanged method also enables derived classes to handle the event without attaching a delegate. Ésta es la técnica preferida para controlar el evento en una clase derivada.This is the preferred technique for handling the event in a derived class.

Notas a los desarrolladores de herederos

Al reemplazar OnTextChanged(EventArgs) en una clase derivada, asegúrese de llamar al método OnTextChanged(EventArgs) de la clase base para que los delegados registrados reciban el evento.When overriding OnTextChanged(EventArgs) in a derived class, be sure to call the base class's OnTextChanged(EventArgs) method so that registered delegates receive the event.

Se aplica a

Consulte también: