How can I raise a CollectionChanged event on an ObservableCollection, and pass it the changed items?

Question

I have a class that inherits from ObservableCollection and adds a few additional methods such as AddRange and RemoveRange

My b

Answer 1

I've been looking into it and apparently the CollectionChanged method cannot be raised with multiple items.

So I can call

OnCollectionChanged(new NotifyCollectionChangedEventArgs(
    NotifyCollectionChangedAction.Add, singleItem));

but I can't call

OnCollectionChanged(new NotifyCollectionChangedEventArgs(
    NotifyCollectionChangedAction.Add, listOfItems));

For now what I have done is simply raise the Add event for every item added, but I am still rather unhappy at this since it means I raise the CollectionChanged event for every item in the AddRange method instead of only once.

public void AddRange(IEnumerable collection)
{
    foreach (var i in collection) 
    {
        Items.Add(i);
        OnCollectionChanged(new NotifyCollectionChangedEventArgs(
            NotifyCollectionChangedAction.Add, i));
    }
}