private void RemoveItems(IEnumerable <T> itemsToRemove, ObservedCollection <T> observedCollection)
{
foreach (var item in itemsToRemove)
{
RemovePrivate(item, observedCollection);
}
}
private void AddItems(IEnumerable <T> items, ObservedCollection <T> observedCollection)
{
if (observedCollection.AddFilter == null)
{
foreach (T item in items)
{
AddPrivate(item, observedCollection);
}
}
}
/// <summary>
/// Decrements an item's reference count and if it's reached zero, removes it from the main collection.
/// </summary>
private void RemovePrivate(T item, ObservedCollection <T> observedCollection)
{
var observedItem = _observedItems.FirstOrDefault(i => i.Item == item);
if (observedItem != null)
{
observedItem.Sources.Remove(observedCollection);
if (observedItem.Sources.Count > 0)
{
return;
}
}
Remove(item);
}
/// <summary>
/// Adds an item to the merged collection and increments its reference count.
/// </summary>
private void AddPrivate(T item, ObservedCollection <T> observedCollection)
{
if (!Contains(item))
{
Add(item);
}
var observedItem = _observedItems.FirstOrDefault(i => i.Item == item);
if (observedItem == null)
{
observedItem = new ObservedItem <T>(item);
_observedItems.Add(observedItem);
}
observedItem.Sources.Add(observedCollection);
}
/// <summary>
/// Registers an ObservableCollection and adds all filtered members to the MergedObservableCollection.
/// </summary>
/// <param name="collection">The collection to observe for additions and deletions.</param>
public void RegisterObservedCollection(INotifyCollectionChanged collection)
{
var observedCollection = _observedCollections.FirstOrDefault(oc => oc.ObservableCollection == collection);
if (observedCollection == null)
{
observedCollection = new ObservedCollection <T>
{
ObservableCollection = collection
};
_observedCollections.Add(observedCollection);
collection.CollectionChanged += observedCollection_CollectionChanged;
var items = collection as IEnumerable;
if (items != null)
{
AddItems(items.Cast <T>(), observedCollection);
}
}
}
