/// <summary>
/// Allows interested objects to be notified when this property changes.
/// </summary>
public override void RemoveValueChanged(object component, EventHandler handler)
{
if (component == null)
{
throw new ArgumentNullException(nameof(component));
}
if (handler == null)
{
throw new ArgumentNullException(nameof(handler));
}
// If there's an event called <propertyname>Changed, we hooked the caller's
// handler directly up to that on the component, so remove it now.
EventDescriptor changedEvent = ChangedEventValue;
if (changedEvent != null && changedEvent.EventType.IsInstanceOfType(handler))
{
changedEvent.RemoveEventHandler(component, handler);
}
// Otherwise the base class added the handler to its ValueChanged
// event for this component, so let the base class remove it now.
else
{
base.RemoveValueChanged(component, handler);
// Special case: If that was the LAST handler removed for this component, and the component implements
// INotifyPropertyChanged, the property descriptor must STOP listening to the generic PropertyChanged event
if (GetValueChangedHandler(component) == null)
{
EventDescriptor iPropChangedEvent = IPropChangedEventValue;
iPropChangedEvent?.RemoveEventHandler(component, new PropertyChangedEventHandler(OnINotifyPropertyChanged));
}
}
}
public override void RemoveValueChanged(object component, EventHandler handler)
{
if (component == null)
{
throw new ArgumentNullException("component");
}
if (handler == null)
{
throw new ArgumentNullException("handler");
}
EventDescriptor changedEventValue = this.ChangedEventValue;
if ((changedEventValue != null) && changedEventValue.EventType.IsInstanceOfType(handler))
{
changedEventValue.RemoveEventHandler(component, handler);
}
else
{
base.RemoveValueChanged(component, handler);
if (base.GetValueChangedHandler(component) == null)
{
EventDescriptor iPropChangedEventValue = this.IPropChangedEventValue;
if (iPropChangedEventValue != null)
{
iPropChangedEventValue.RemoveEventHandler(component, new PropertyChangedEventHandler(this.OnINotifyPropertyChanged));
}
}
}
}
/// <summary>
/// Returns an observable sequence of events from the specified <paramref name="event"/> descriptor.
/// </summary>
/// <param name="event">The descriptor from which to create an observable sequence of changed notifications.</param>
/// <param name="source">The object to which the <paramref name="event"/> belongs.</param>
/// <returns>An observable sequence of events.</returns>
public static IObservable <EventPattern <EventArgs> > EventRaised(
this EventDescriptor @event,
object source)
{
Contract.Requires(@event != null);
Contract.Requires(source != null);
Contract.Ensures(Contract.Result <IObservable <EventPattern <EventArgs> > >() != null);
return(@event.EventType == typeof(EventHandler)
? Observable.FromEventPattern <EventHandler, EventArgs>(
handler => handler.Invoke,
handler => @event.AddEventHandler(source, handler),
handler => @event.RemoveEventHandler(source, handler))
: new EventProxyObservable(source, @event));
}
