void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
Action action;
if (_list == null)
{
action = Clear;
}
else
{
action = () =>
{
_version++;
OnCollectionChanged(e);
};
}
CollectionSynchronizationContext sync;
if (BindingBase.TryGetSynchronizedCollection(ProxiedEnumerable, out sync))
{
sync.Callback(ProxiedEnumerable, sync.Context, () =>
{
e = e.WithCount(Count);
_dispatcher.DispatchIfRequired(action);
}, false);
}
else
{
e = e.WithCount(Count);
_dispatcher.DispatchIfRequired(action);
}
}
bool TryGetValue(int index, out object value)
{
value = null;
CollectionSynchronizationContext syncContext;
BindingBase.TryGetSynchronizedCollection(ProxiedEnumerable, out syncContext);
if (_list != null)
{
object indexedValue = null;
var inRange = false;
Action getFromList = () =>
{
if (index >= _list.Count)
{
return;
}
indexedValue = _list[index];
inRange = true;
};
if (syncContext != null)
{
syncContext.Callback(ProxiedEnumerable, syncContext.Context, getFromList, false);
}
else
{
getFromList();
}
value = indexedValue;
return(inRange);
}
if (_collection != null && index >= _collection.Count)
{
return(false);
}
if (_items != null)
{
bool found = _items.TryGetValue(index, out value);
if (found || _finished)
{
return(found);
}
}
if (index >= _windowIndex + _windowSize)
{
int newIndex = index - _windowSize / 2;
ClearRange(_windowIndex, newIndex - _windowIndex);
_windowIndex = newIndex;
}
else if (index < _windowIndex)
{
int clearIndex = _windowIndex;
int clearSize = _windowSize;
if (clearIndex <= index + clearSize)
{
int diff = index + clearSize - clearIndex;
clearIndex += diff + 1;
clearSize -= diff;
}
ClearRange(clearIndex, clearSize);
_windowIndex = 0;
var dispose = _enumerator as IDisposable;
if (dispose != null)
{
dispose.Dispose();
}
_enumerator = null;
_enumeratorIndex = 0;
}
if (_enumerator == null)
{
_enumerator = ProxiedEnumerable.GetEnumerator();
}
if (_items == null)
{
_items = new Dictionary <int, object>();
}
var countChanged = false;
int end = _windowIndex + _windowSize;
for (; _enumeratorIndex < end; _enumeratorIndex++)
{
var moved = false;
Action move = () =>
{
try
{
moved = _enumerator.MoveNext();
}
catch (InvalidOperationException ioex)
{
throw new InvalidOperationException("You must call UpdateNonNotifyingList() after updating a list that does not implement INotifyCollectionChanged", ioex);
}
if (!moved)
{
var dispose = _enumerator as IDisposable;
if (dispose != null)
{
dispose.Dispose();
}
_enumerator = null;
_enumeratorIndex = 0;
_finished = true;
}
};
if (syncContext == null)
{
move();
}
else
{
syncContext.Callback(ProxiedEnumerable, syncContext.Context, move, false);
}
if (!moved)
{
break;
}
if (CountIndex(_enumeratorIndex))
{
countChanged = true;
}
if (_enumeratorIndex >= _windowIndex)
{
_items.Add(_enumeratorIndex, _enumerator.Current);
}
}
if (countChanged)
{
OnCountChanged();
}
return(_items.TryGetValue(index, out value));
}