/// <summary>
/// (Temporarily) suppresses item count change notification until the returned <see cref="IDisposable" />
/// has been Disposed.
/// </summary>
/// <param name="signalCurrentCountWhenFinished">
/// if set to <c>true</c> signals a the <see cref="IReadOnlyCollection{T}.Count" />
/// when finished.
/// </param>
/// <returns></returns>
public virtual IDisposable SuppressCountChangeNotifications(bool signalCurrentCountWhenFinished = true)
{
CheckForAndThrowIfDisposed(false);
IsTrackingCountChanges = false;
return(Disposable.Create(() =>
{
IsTrackingCountChanges = true;
if (signalCurrentCountWhenFinished)
{
CountChangesObserver.OnNext(Count);
}
}));
}
/// <summary>
/// Notifies all <see cref="CollectionChanges" /> and <see cref="Resets" /> subscribers and
/// raises the (observable)collection changed events.
/// </summary>
/// <param name="observableCollectionChange">The observable collection change.</param>
protected virtual void NotifyObserversAboutCollectionChanges(IObservableCollectionChange <T> observableCollectionChange)
{
if (observableCollectionChange == null)
{
throw new ArgumentNullException(nameof(observableCollectionChange));
}
CheckForAndThrowIfDisposed();
// go ahead and check whether a Reset or item add, -change, -move or -remove shall be signaled
// .. based on the ThresholdAmountWhenChangesAreNotifiedAsReset value
var actualObservableCollectionChange =
(observableCollectionChange.ChangeType == ObservableCollectionChangeType.Reset ||
IsItemsChangedAmountGreaterThanResetThreshold(1, ThresholdAmountWhenChangesAreNotifiedAsReset))
? ObservableCollectionChange <T> .Reset
: observableCollectionChange;
// raise events and notify about collection changes
if (actualObservableCollectionChange.ChangeType == ObservableCollectionChangeType.ItemAdded ||
actualObservableCollectionChange.ChangeType == ObservableCollectionChangeType.ItemRemoved ||
actualObservableCollectionChange.ChangeType == ObservableCollectionChangeType.Reset)
{
try
{
CountChangesObserver.OnNext(Count);
}
catch (Exception exception)
{
var observerException = new ObserverException(
$"An error occured notifying {nameof(CountChanges)} Observers of this {this.GetType().Name}.",
exception);
ObserverExceptionsObserver.OnNext(observerException);
if (observerException.Handled == false)
{
throw;
}
}
}
try
{
CollectionChangesObserver.OnNext(actualObservableCollectionChange);
}
catch (Exception exception)
{
var observerException = new ObserverException(
$"An error occured notifying {nameof(CollectionChanges)} Observers of this {this.GetType().Name}.",
exception);
ObserverExceptionsObserver.OnNext(observerException);
if (observerException.Handled == false)
{
throw;
}
}
try
{
RaiseCollectionChanged(actualObservableCollectionChange.ToNotifyCollectionChangedEventArgs());
}
catch (Exception exception)
{
var observerException = new ObserverException(
$"An error occured notifying CollectionChanged Subscribers of this {this.GetType().Name}.",
exception);
ObserverExceptionsObserver.OnNext(observerException);
if (observerException.Handled == false)
{
throw;
}
}
}
