private void Handler(object sender, EventArgs args)
{
var item = (Type)sender;
bool filterApplies = Filter(item);
if (filterApplies)
{
if (!Filtered.Contains(item))
{
var previous = Filtered.LastOrDefault();
if (previous != null)
{
_ignoreSourceChangeEvents = true;
try
{
int idxInsertAfter = Source.IndexOf(previous);
Source.Remove(item);
if (idxInsertAfter < Source.Count)
{
Source.Insert(idxInsertAfter, item);
}
else
{
Source.Add(item);
}
}
finally
{
_ignoreSourceChangeEvents = false;
}
}
Filtered.Add(item);
}
return;
}
else
{
if (Filtered.Contains(item))
{
Filtered.Remove(item);
}
return;
}
}
public bool Contains(T item)
{
return(Filtered.Contains(item));
}