private async void ScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
var fullHeight = e.ExtentHeight;
var currTop = e.VerticalOffset;
var viewableHeight = e.ViewportHeight;
if (!isLoadingMore && currTop + viewableHeight * 2 >= fullHeight)
{
isLoadingMore = true;
await viewModel.LoadMore();
isLoadingMore = false;
}
}
