public NotifyCollectionChangedEventHandler Initialize()
{
_action = null;
_newItems = null;
_oldItems = null;
return((sender, args) =>
{
ObservableCollectionEx <T> wrapper = sender as ObservableCollectionEx <T>;
Debug.Assert(null != wrapper, "Calling object must be ObservableCollectionEx<T>");
Debug.Assert(null != wrapper._notifyInfo, "Calling object must be Delayed wrapper.");
// Setup
_action = args.Action;
switch (_action)
{
case NotifyCollectionChangedAction.Add:
_newItems = new List <T>();
IsCountChanged = true;
wrapper.CollectionChanged = (s, e) =>
{
AssertActionType(e);
foreach (T item in e.NewItems)
{
_newItems.Add(item);
}
};
wrapper.CollectionChanged(sender, args);
break;
case NotifyCollectionChangedAction.Remove:
_oldItems = new List <T>();
IsCountChanged = true;
wrapper.CollectionChanged = (s, e) =>
{
AssertActionType(e);
foreach (T item in e.OldItems)
{
_oldItems.Add(item);
}
};
wrapper.CollectionChanged(sender, args);
break;
case NotifyCollectionChangedAction.Replace:
_newItems = new List <T>();
_oldItems = new List <T>();
wrapper.CollectionChanged = (s, e) =>
{
AssertActionType(e);
foreach (T item in e.NewItems)
{
_newItems.Add(item);
}
foreach (T item in e.OldItems)
{
_oldItems.Add(item);
}
};
wrapper.CollectionChanged(sender, args);
break;
#if !SILVERLIGHT
case NotifyCollectionChangedAction.Move:
_newIndex = args.NewStartingIndex;
_newItems = args.NewItems;
_oldIndex = args.OldStartingIndex;
_oldItems = args.OldItems;
wrapper.CollectionChanged = (s, e) =>
{
throw new InvalidOperationException(
"Due to design of NotifyCollectionChangedEventArgs combination of multiple Move operations is not possible");
};
break;
#endif
case NotifyCollectionChangedAction.Reset:
IsCountChanged = true;
wrapper.CollectionChanged = (s, e) => { AssertActionType(e); };
break;
}
});
}
