private void HandleCollectionChange(object sender, NotifyCollectionChangedEventArgs args)
{
if (_watcherList != null)
{
if (args.Action == NotifyCollectionChangedAction.Remove || args.Action == NotifyCollectionChangedAction.Replace || args.Action == NotifyCollectionChangedAction.Move)
{
if (args.OldItems.Count > 1)
{
throw new NotSupportedException("Multi-value collection change notifications are not supported.");
}
foreach (var item in args.OldItems.OfType <T>())
{
_watcherList.Remove(args.OldStartingIndex);
}
}
if (args.Action == NotifyCollectionChangedAction.Add || args.Action == NotifyCollectionChangedAction.Replace || args.Action == NotifyCollectionChangedAction.Move)
{
if (args.NewItems.Count > 1)
{
throw new NotSupportedException("Multi-value collection change notifications are not supported.");
}
foreach (var item in args.NewItems.OfType <T>())
{
_watcherList.Add(args.NewStartingIndex, item);
}
}
if (args.Action == NotifyCollectionChangedAction.Reset)
{
_watcherList.Reset(_collection);
}
}
OnCollectionChanged(args);
}
public void ReplaceCollection(IReadOnlyList <T> collection)
{
if (_collection is INotifyCollectionChanged)
{
CollectionChangedEventManager.RemoveHandler(_collection as INotifyCollectionChanged, HandleCollectionChange);
}
_collection = collection;
_watcherList?.Reset(_collection ?? Enumerable.Empty <T>());
if (_collection is INotifyCollectionChanged)
{
CollectionChangedEventManager.AddHandler(_collection as INotifyCollectionChanged, HandleCollectionChange);
}
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}