// Used by the renderer to maintain scroll offset when using ItemsUpdatingScrollMode KeepScrollOffset
public void UndoNextScrollAdjustment()
{
// Don't start tracking the scroll offsets until we really need to
if (!_maintainingScrollOffsets)
{
_maintainingScrollOffsets = true;
_recyclerView.AddOnScrollListener(this);
}
_undoNextScrollAdjustment = true;
_lastScrollX = _recyclerView.ComputeHorizontalScrollOffset();
_lastScrollY = _recyclerView.ComputeVerticalScrollOffset();
}
public override void OnScrolled(RecyclerView recyclerView, int dx, int dy)
{
base.OnScrolled(recyclerView, dx, dy);
if (scrolledY == int.MinValue)
{
var child = recyclerView.GetChildAt(0);
var positionFirstItem = recyclerView.GetChildAdapterPosition(child);
var heightDecorator = positionFirstItem == 0 ? 0 : headerView.heightHeader;
var offset = recyclerView.ComputeVerticalScrollOffset();
scrolledY = offset + heightDecorator;
}
else
{
scrolledY += dy;
}
headerView.headerAnimator.OnScroll(-scrolledY);
}
public static bool CanScroll(View view)
{
ScrollView scrollView = view as ScrollView;
if (scrollView != null)
{
View child = scrollView.GetChildAt(0);
if (child == null)
{
return(false);
}
return(scrollView.Height < child.Height + scrollView.PaddingTop + scrollView.PaddingBottom);
}
RecyclerView recyclerView = view as RecyclerView;
if (recyclerView != null)
{
return(recyclerView.ComputeVerticalScrollOffset() != 0);
}
return(true);
}
public void CenterIfNeeded(RecyclerView recyclerView, bool isHorizontal)
{
if (!(recyclerView.GetLayoutManager() is LinearLayoutManager linearLayoutManager))
{
return;
}
var itemSourceCount = _itemsSource.Count;
var firstCompletelyItemVisible = linearLayoutManager.FindFirstCompletelyVisibleItemPosition();
var offSet = recyclerView.ComputeHorizontalScrollOffset();
if (!isHorizontal)
{
offSet = recyclerView.ComputeVerticalScrollOffset();
}
if (firstCompletelyItemVisible == 0)
{
linearLayoutManager.ScrollToPositionWithOffset(itemSourceCount, -offSet);
}
}
public override void OnScrolled(RecyclerView recyclerView, int dx, int dy)
{
base.OnScrolled(recyclerView, dx, dy);
if (scrolledY == int.MinValue)
{
var child = recyclerView.GetChildAt(0);
var positionFirstItem = recyclerView.GetChildAdapterPosition(child);
var heightDecorator = positionFirstItem == 0 ? 0 : headerView.heightHeader;
var offset = recyclerView.ComputeVerticalScrollOffset();
scrolledY = offset + heightDecorator;
}
else
{
scrolledY += dy;
}
headerView.headerAnimator.OnScroll(-scrolledY);
}