private void UpdatePage(int page, IList results, uint stateWhenRequested, bool previousNextRequest)
{
if (stateWhenRequested != State)
{
// this request may contain out-of-date data, so ignore it
return;
}
bool stillRelevant = _requestedPages.Remove(page);
if (!stillRelevant)
{
return;
}
_fetchedPages.Add(page);
var startIndex = page * _pageSize;
// guard against rogue collection sources returning too many results
var count = Math.Min(results.Count, _pageSize);
for (int i = 0; i < count; i++)
{
var index = startIndex + i;
var virtualItem = VirtualItems[index] ?? (VirtualItems[index] = new VirtualItem <object>(this, index));
if (virtualItem.Item == null || results[i] == null || !_equalityComparer.Equals(virtualItem.Item, results[i]))
{
virtualItem.SupplyValue(results[i]);
}
if (!previousNextRequest || virtualItem.IsAskedByIndex)
{
#if SILVERLIGHT
if (firstTimeIndexZero && i == 0)
{
firstTimeIndexZero = false;
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
else
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove,
VirtualItems[startIndex + i].Item, startIndex + i));
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add,
results[i], startIndex + i));
}
#else
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove,
VirtualItems[startIndex + i].Item, startIndex + i));
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add,
results[i], startIndex + i));
#endif
}
}
if (count > 0)
{
OnItemsRealized(new ItemsRealizedEventArgs(startIndex, count));
}
}
private object getbyIndex(int index, bool byIlist)
{
if (index >= Count)
{
throw new ArgumentOutOfRangeException("index");
}
if (byIlist)
{
RealizeItemRequested(index, true);
}
if (!byIlist)
{
return(null);
}
var itm = VirtualItems[index] ?? (VirtualItems[index] = new VirtualItem <object>(this, index));
itm.IsAskedByIndex = byIlist;
return(itm.Item);
}