void HandleSourceCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
// Firstly if we are copying the source collection into our filtered list, update
// the copy with the new changes and compute the actual index of our item in the
// sorted/grouped/filtered list.
int actualOldIndex = -1;
int actualNewIndex = -1;
bool originalList = ActiveList == SourceCollection;
if (!originalList)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
foreach (object o in e.NewItems)
{
AddToFilteredAndGroupSorted(o);
}
break;
case NotifyCollectionChangedAction.Remove:
actualOldIndex = IndexOf(e.OldItems [0]);
foreach (object o in e.OldItems)
{
RemoveFromFilteredAndGroup(o);
}
break;
case NotifyCollectionChangedAction.Replace:
foreach (object o in e.OldItems)
{
RemoveFromFilteredAndGroup(o);
}
foreach (object o in e.NewItems)
{
AddToFilteredAndGroupSorted(o);
}
break;
case NotifyCollectionChangedAction.Reset:
filteredList.Clear();
RootGroup.ClearSubtree();
foreach (var o in SourceCollection)
{
AddToFilteredAndGroup(o);
}
break;
}
}
else
{
// Raise the collection changed event
RaiseCollectionChanged(e);
}
IsEmpty = ActiveList.Count == 0;
IsCurrentAfterLast = CurrentPosition == ActiveList.Count || ActiveList.Count == 0;
IsCurrentBeforeFirst = CurrentPosition == -1 || ActiveList.Count == 0;
}