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;
}
}
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 (ItemsViewAdapter?.ItemsSource is ObservableItemsSource observableItemsSource)
{
observableItemsSource.CollectionItemsSourceChanged += CollectionItemsSourceChanged;
}
oldItemViewAdapter?.Dispose();
}
protected virtual void UpdateAdapter()
{
var oldItemViewAdapter = ItemsViewAdapter;
ItemsViewAdapter = new ItemsViewAdapter(ItemsView);
SwapAdapter(ItemsViewAdapter, true);
oldItemViewAdapter?.Dispose();
}
protected override void UpdateItemsSource()
{
// 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
ItemsViewAdapter = new ItemsViewAdapter <ItemsView, IItemsViewSource>(ItemsView,
(view, context) => new SizedItemContentView(context, () => Width, () => Height));
SwapAdapter(ItemsViewAdapter, false);
}
int GetIndexFromTemplatedCell(global::Android.Views.View view)
{
int itemIndex = -1;
if (view is ItemContentView templatedCell)
{
var bContext = templatedCell?.Element?.BindingContext;
itemIndex = ItemsViewAdapter.GetPositionForItem(bContext);
}
return(itemIndex);
}
protected virtual void UpdateAdapter()
{
var oldItemViewAdapter = ItemsViewAdapter;
// Stop watching the old adapter to see if it's empty (if we are watching)
Unwatch(oldItemViewAdapter);
ItemsViewAdapter = new ItemsViewAdapter(ItemsView);
SwapAdapter(ItemsViewAdapter, true);
oldItemViewAdapter?.Dispose();
}
void UpdateAdapter()
{
var oldItemViewAdapter = ItemsViewAdapter;
ItemsViewAdapter = CreateAdapter();
if (GetAdapter() != _emptyViewAdapter)
{
SwapAdapter(ItemsViewAdapter, true);
}
oldItemViewAdapter?.Dispose();
}
protected virtual void UpdateItemsSource()
{
if (ItemsView == null)
{
return;
}
// Stop watching the old adapter to see if it's empty (if we _are_ watching)
Unwatch(GetAdapter());
ItemsViewAdapter = new ItemsViewAdapter(ItemsView, Context);
SwapAdapter(ItemsViewAdapter, false);
UpdateEmptyView();
}
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;
ItemsViewAdapter = new ItemsViewAdapter <ItemsView, IItemsViewSource>(ItemsView,
(view, context) => new SizedItemContentView(Context, GetItemWidth, GetItemHeight));
SwapAdapter(ItemsViewAdapter, false);
oldItemViewAdapter?.Dispose();
}
void MarkItemSelected(object selectedItem)
{
var position = ItemsViewAdapter.GetPositionForItem(selectedItem);
var selectedHolder = FindViewHolderForAdapterPosition(position);
if (selectedHolder == null)
{
return;
}
if (selectedHolder is SelectableViewHolder selectable)
{
selectable.IsSelected = true;
}
}
int GetCarouselViewCurrentIndex(int index)
{
var centeredView = this.GetCenteredView();
if (centeredView is ItemContentView templatedCell)
{
var bContext = templatedCell?.Element?.BindingContext;
index = ItemsViewAdapter.GetPositionForItem(bContext);
}
else
{
return(-1);
}
return(index);
}
protected override int DetermineTargetPosition(ScrollToRequestEventArgs args)
{
if (args.Mode == ScrollToMode.Element)
{
return(ItemsViewAdapter.GetPositionForItem(args.Item));
}
if (!Carousel.Loop)
{
return(args.Index);
}
if (_carouselViewLoopManager == null)
{
return(-1);
}
var carouselPosition = GetCarouselViewCurrentIndex(Carousel.Position);
var getGoIndex = _carouselViewLoopManager.GetGoToIndex(this, carouselPosition, args.Index);
return(getGoIndex);
}
public CarouselViewOnScrollListener(ItemsView itemsView, ItemsViewAdapter <ItemsView, IItemsViewSource> itemsViewAdapter, CarouselViewLoopManager carouselViewLoopManager) : base(itemsView, itemsViewAdapter, true)
{
_carouselView = itemsView as FormsCarouselView;
_carouselViewLoopManager = carouselViewLoopManager;
}
public CarouselViewOnScrollListener(ItemsView itemsView, ItemsViewAdapter <ItemsView, IItemsViewSource> itemsViewAdapter) : base(itemsView, itemsViewAdapter)
{
}
protected virtual void UpdateAdapter()
{
ItemsViewAdapter = new ItemsViewAdapter(ItemsView);
SwapAdapter(ItemsViewAdapter, true);
}
