ConvertEventHandler Delegado

Definición

Representa el método que controlará los eventos Parse y Format de un control Binding.Represents the method that will handle the Parse and Format events of a Binding.

public delegate void ConvertEventHandler(System::Object ^ sender, ConvertEventArgs ^ e);
public delegate void ConvertEventHandler(object? sender, ConvertEventArgs e);
public delegate void ConvertEventHandler(object sender, ConvertEventArgs e);
type ConvertEventHandler = delegate of obj * ConvertEventArgs -> unit
Public Delegate Sub ConvertEventHandler(sender As Object, e As ConvertEventArgs)

Parámetros

sender
Object

Origen del evento.The source of the event.

e
ConvertEventArgs

Objeto ConvertEventArgs que contiene los datos del evento.A ConvertEventArgs that contains the event data.

Herencia
ConvertEventHandler

Ejemplos

El código siguienteThe following code

en el ejemplo se crea un Binding , se agrega un ConvertEventHandler delegado a los Parse Format eventos y y Binding se agrega a la BindingsCollection de un TextBox control a través de la DataBindings propiedad.example creates a Binding, adds a ConvertEventHandler delegate to both the Parse and Format events, and adds the Binding to the BindingsCollection of a TextBox control through the DataBindings property. El DecimalToCurrency delegado de eventos, que se agrega al Format evento, da formato al valor enlazado (un Decimal tipo) como moneda mediante el ToString método.The DecimalToCurrency event delegate, added to the Format event, formats the bound value (a Decimal type) as currency using the ToString method. El CurrencyToDecimal delegado de eventos, que se agrega al Parse evento, convierte el valor mostrado por el control de nuevo Decimal al tipo.The CurrencyToDecimal event delegate, added to the Parse event, converts the value displayed by the control back to the Decimal type.

private:
   void DecimalToCurrency( Object^ /*sender*/, ConvertEventArgs^ cevent )
   {
      // The method converts only to string type. Test this using the DesiredType.
      if ( cevent->DesiredType != String::typeid )
      {
         return;
      }
      
      // Use the ToString method to format the value as currency ("c").
      cevent->Value = ( (Decimal^)(cevent->Value) )->ToString( "c" );
   }

   void CurrencyToDecimal( Object^ /*sender*/, ConvertEventArgs^ cevent )
   {
      // ' The method converts only to decimal type. 
      if ( cevent->DesiredType != Decimal::typeid )
      {
         return;
      }

      // Converts the string back to decimal using the static ToDecimal method.
      cevent->Value = Convert::ToDecimal( cevent->Value->ToString() );
   }

   void BindControl()
   {
      // Creates the binding first. The OrderAmount is typed as Decimal.
      Binding^ b = gcnew Binding(
         "Text",ds,"customers.custToOrders.OrderAmount" );
      
      // Add the delegates to the events.
      b->Format += gcnew ConvertEventHandler(
         this, &Form1::DecimalToCurrency );
      b->Parse += gcnew ConvertEventHandler(
         this, &Form1::CurrencyToDecimal );
      text1->DataBindings->Add( b );
   }
private void DecimalToCurrency(object sender, ConvertEventArgs cevent)
{
   // The method converts only to string type. Test this using the DesiredType.
   if (cevent.DesiredType != typeof(string)) return;

   // Use the ToString method to format the value as currency ("c").
   cevent.Value = ((decimal) cevent.Value).ToString("c");
}

private void CurrencyToDecimal(object sender, ConvertEventArgs cevent)
{
   // ' The method converts only to decimal type. 
   if (cevent.DesiredType != typeof(decimal)) return;

   // Converts the string back to decimal using the static ToDecimal method.
   cevent.Value = Convert.ToDecimal(cevent.Value.ToString());
}

private void BindControl()
{
   // Creates the binding first. The OrderAmount is typed as Decimal.
   Binding b = new Binding
      ("Text", ds, "customers.custToOrders.OrderAmount");
   // Add the delegates to the events.
   b.Format += new ConvertEventHandler(DecimalToCurrency);
   b.Parse += new ConvertEventHandler(CurrencyToDecimal);
   text1.DataBindings.Add(b);
}

Private Sub DecimalToCurrency(sender As Object, cevent As ConvertEventArgs)
    ' The method converts only to string type. Test this using the DesiredType.
    If cevent.DesiredType IsNot GetType(String) Then
        Return
    End If 
    ' Use the ToString method to format the value as currency ("c").
    cevent.Value = CDec(cevent.Value).ToString("c")
End Sub 


Private Sub CurrencyToDecimal(sender As Object, cevent As ConvertEventArgs)
    ' The method converts only to decimal type. 
    If cevent.DesiredType IsNot GetType(Decimal) Then
        Return
    End If 
    ' Converts the string back to decimal using the static ToDecimal method.
    cevent.Value = Convert.ToDecimal(cevent.Value.ToString())
End Sub 


Private Sub BindControl()
    ' Creates the binding first. The OrderAmount is typed as Decimal.
    Dim b As New Binding("Text", ds, "customers.custToOrders.OrderAmount")
    ' Adds the delegates to the events.
    AddHandler b.Format, AddressOf DecimalToCurrency
    AddHandler b.Parse, AddressOf CurrencyToDecimal
    text1.DataBindings.Add(b)
End Sub 

Comentarios

Cuando se crea un delegado ConvertEventHandler, se identifica el método que controlará el evento.When you create a ConvertEventHandler delegate, you identify the method that will handle the event. Para asociar el evento al controlador, se debe agregar una instancia del delegado al evento.To associate the event with your event handler, add an instance of the delegate to the event. Siempre que se produce el evento, se llama a su controlador, a menos que se quite el delegado.The event handler is called whenever the event occurs, unless you remove the delegate. Para obtener más información sobre los delegados de controladores de eventos, vea controlar y provocar eventos.For more information about event-handler delegates, see Handling and Raising Events.

Métodos de extensión

GetMethodInfo(Delegate)

Obtiene un objeto que representa el método representado por el delegado especificado.Gets an object that represents the method represented by the specified delegate.

Se aplica a