/// <summary>
/// Initializes a new instance of the <see cref="ObservableCollectionChangedEventArgs{T}"/> class.
/// </summary>
/// <param name="observableCollectionChange">The observable collection change.</param>
/// <exception cref="System.ArgumentNullException"></exception>
public ObservableCollectionChangedEventArgs(IObservableCollectionChange <T> observableCollectionChange)
{
if (observableCollectionChange == null)
{
throw new ArgumentNullException(nameof(observableCollectionChange));
}
Change = observableCollectionChange;
}
/// <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;
}
}
}
/// <summary>
/// Converts the given <paramref name="observableCollectionChange"/> to its <see cref="NotifyCollectionChangedEventArgs"/> counter part.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="observableCollectionChange">The <see cref="IObservableCollectionChange{T}"/> instance containing the event data.</param>
/// <returns></returns>
/// <exception cref="System.ArgumentNullException"></exception>
public static NotifyCollectionChangedEventArgs ToNotifyCollectionChangedEventArgs <T>(this IObservableCollectionChange <T> observableCollectionChange)
{
if (observableCollectionChange == null)
{
throw new ArgumentNullException(nameof(observableCollectionChange));
}
switch (observableCollectionChange.ChangeType)
{
case ObservableCollectionChangeType.ItemAdded:
return(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, observableCollectionChange.Item));
case ObservableCollectionChangeType.ItemChanged:
return(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, observableCollectionChange.Item, observableCollectionChange.Item));
case ObservableCollectionChangeType.ItemRemoved:
return(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, observableCollectionChange.Item));
case ObservableCollectionChangeType.Reset:
return(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
default:
throw new ArgumentOutOfRangeException(nameof(observableCollectionChange), "This should not happen.");
}
}
