protected override void UpdateAdapter()
{
// By default the CollectionViewAdapter creates the items at whatever size the template calls for
// But for the Carousel, we want it to create the items to fit the width/height of the viewport
// So we give it an alternate delegate for creating the views
var oldItemViewAdapter = ItemsViewAdapter;
UnsubscribeCollectionItemsSourceChanged(oldItemViewAdapter);
ItemsViewAdapter = new ItemsViewAdapter <ItemsView, IItemsViewSource>(ItemsView,
(view, context) => new SizedItemContentView(Context, GetItemWidth, GetItemHeight));
_gotoPosition = -1;
SwapAdapter(ItemsViewAdapter, false);
if (_oldPosition > 0)
{
UpdateInitialPosition();
}
if (ItemsViewAdapter?.ItemsSource is ObservableItemsSource observableItemsSource)
{
observableItemsSource.CollectionItemsSourceChanged += CollectionItemsSourceChanged;
}
oldItemViewAdapter?.Dispose();
}
void UnsubscribeCollectionItemsSourceChanged(ItemsViewAdapter <ItemsView, IItemsViewSource> oldItemViewAdapter)
{
if (oldItemViewAdapter?.ItemsSource is ObservableItemsSource oldObservableItemsSource)
{
oldObservableItemsSource.CollectionItemsSourceChanged -= CollectionItemsSourceChanged;
}
}
void UpdateNativeSelection()
{
var mode = ItemsView.SelectionMode;
ItemsViewAdapter.ClearNativeSelection();
switch (mode)
{
case SelectionMode.None:
return;
case SelectionMode.Single:
var selectedItem = ItemsView.SelectedItem;
ItemsViewAdapter.MarkNativeSelection(selectedItem);
return;
case SelectionMode.Multiple:
var selectedItems = ItemsView.SelectedItems;
foreach (var item in selectedItems)
{
ItemsViewAdapter.MarkNativeSelection(item);
}
return;
}
}
public CarouselViewOnScrollListener(ItemsView itemsView, ItemsViewAdapter <ItemsView, IItemsViewSource> itemsViewAdapter) : base(itemsView, itemsViewAdapter)
{
}
