void CheckForEmptySource()
{
var wasEmpty = _isEmpty;
_isEmpty = ItemsSource.ItemCount == 0;
if (_isEmpty)
{
_measurementCells.Clear();
ItemsViewLayout?.ClearCellSizeCache();
}
if (wasEmpty != _isEmpty)
{
UpdateEmptyViewVisibility(_isEmpty);
}
if (wasEmpty && !_isEmpty)
{
// If we're going from empty to having stuff, it's possible that we've never actually measured
// a prototype cell and our itemSize or estimatedItemSize are wrong/unset
// So trigger a constraint update; if we need a measurement, that will make it happen
ItemsViewLayout.ConstrainTo(CollectionView.Bounds.Size);
}
}
public virtual void UpdateItemsSource()
{
_measurementCells.Clear();
ItemsViewLayout?.ClearCellSizeCache();
ItemsSource = CreateItemsViewSource();
CollectionView.ReloadData();
CollectionView.CollectionViewLayout.InvalidateLayout();
}