public override void OnScrolled(RecyclerView recyclerView, int dx, int dy)
{
base.OnScrolled(recyclerView, dx, dy);
// TODO: These offsets will be incorrect upon row size or count change.
// They are currently provided in place of LayoutManager's default offset calculation
// because it does not report accurate values in the presence of uneven rows.
// See https://stackoverflow.com/questions/27507715/android-how-to-get-the-current-x-offset-of-recyclerview
_horizontalOffset += dx;
_verticalOffset += dy;
var(First, Center, Last) = GetVisibleItemsIndex(recyclerView);
var itemsViewScrolledEventArgs = new ItemsViewScrolledEventArgs
{
HorizontalDelta = recyclerView.FromPixels(dx),
VerticalDelta = recyclerView.FromPixels(dy),
HorizontalOffset = recyclerView.FromPixels(_horizontalOffset),
VerticalOffset = recyclerView.FromPixels(_verticalOffset),
FirstVisibleItemIndex = First,
CenterItemIndex = Center,
LastVisibleItemIndex = Last
};
_itemsView.SendScrolled(itemsViewScrolledEventArgs);
// Don't send RemainingItemsThresholdReached event for non-linear layout managers
// This can also happen if a layout pass has not happened yet
if (Last == -1)
{
return;
}
switch (_itemsView.RemainingItemsThreshold)
{
case -1:
return;
case 0:
if (Last == ItemsViewAdapter.ItemCount - 1)
{
_itemsView.SendRemainingItemsThresholdReached();
}
break;
default:
if (ItemsViewAdapter.ItemCount - 1 - Last <= _itemsView.RemainingItemsThreshold)
{
_itemsView.SendRemainingItemsThresholdReached();
}
break;
}
}
