ConvertEventHandler ConvertEventHandler ConvertEventHandler ConvertEventHandler Delegate

Definizione

Rappresenta il metodo che gestirà gli eventi Parse e Format di un controllo 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);
type ConvertEventHandler = delegate of obj * ConvertEventArgs -> unit
Public Delegate Sub ConvertEventHandler(sender As Object, e As ConvertEventArgs)

Parametri

sender
Object Object Object Object

Origine dell'evento.The source of the event.

e
ConvertEventArgs ConvertEventArgs ConvertEventArgs ConvertEventArgs

Oggetto ConvertEventArgs che contiene i dati dell'evento.A ConvertEventArgs that contains the event data.

Ereditarietà
ConvertEventHandlerConvertEventHandlerConvertEventHandlerConvertEventHandler

Esempi

Il codice seguenteThe following code

Nell'esempio viene Bindingcreato un oggetto ConvertEventHandler , viene aggiunto un Parse delegato Format a entrambi gli eventi e Binding e viene BindingsCollection aggiunto all' TextBox oggetto di un DataBindings controllo tramite la proprietà.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. Il DecimalToCurrency delegato dell'evento, aggiunto Format all'evento, formatta il valore associato (un Decimal tipo) come valuta usando il ToString metodo.The DecimalToCurrency event delegate, added to the Format event, formats the bound value (a Decimal type) as currency using the ToString method. Il CurrencyToDecimal delegato dell'evento, aggiunto Parse all'evento, converte il valore visualizzato dal controllo di Decimal nuovo nel 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 

Commenti

Quando si crea un delegato ConvertEventHandler, si identifica il metodo che gestirà l'evento.When you create a ConvertEventHandler delegate, you identify the method that will handle the event. Per associare l'evento al gestore eventi in uso, aggiungere all'evento un'istanza del delegato.To associate the event with your event handler, add an instance of the delegate to the event. Il gestore eventi viene chiamato ogni volta che si verifica l'evento, a meno che non venga rimosso il delegato.The event handler is called whenever the event occurs, unless you remove the delegate. Per ulteriori informazioni sui delegati del gestore eventi, vedere gestione e generazione di eventi.For more information about event-handler delegates, see Handling and Raising Events.

Metodi di estensione

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato.Gets an object that represents the method represented by the specified delegate.

Si applica a