public virtual void OnLoaded(object sender, RoutedEventArgs e)
 {
     _notification   = ControlsHelper.FindResource <NotificationViewModel>("Notification");
     _pageTitleView  = ControlsHelper.FindResource <NavigationViewModel>("NavigationView");
     _readerView     = ControlsHelper.Find <System.Windows.Controls.ListView>("FlipViewReader");
     _scroolOfReader = _readerView.Find <ScrollViewer>().FirstOrDefault();
     _scroolOfReader.ScrollChanged += ScroolViwer_ViewChanged;
 }
        private void ScroolViwer_ViewChanged(object sender, ScrollChangedEventArgs e)
        {
            var listViewIntem = _readerView.Find <System.Windows.Controls.ListViewItem>().FirstOrDefault();
            var scroll        = sender as ScrollViewer;
            var posi          = scroll.VerticalOffset;
            var height        = listViewIntem.ActualHeight;
            var index         = Convert.ToInt32(posi / height);

            if (index != _actualPage)
            {
                _actualPage = index;
                _readerViewModel.ActualPage = index;
                SavePage();
            }
        }