void UnsubscribeCollectionItemsSourceChanged(ItemsViewAdapter <CarouselView, IItemsViewSource> oldItemViewAdapter)
{
if (oldItemViewAdapter != null && oldItemViewAdapter.ItemsSource is ObservableItemsSource oldObservableItemsSource)
{
oldObservableItemsSource.CollectionItemsSourceChanged -= CollectionItemsSourceChanged;
}
}
void SubscribeCollectionItemsSourceChanged(ItemsViewAdapter <CarouselView, IItemsViewSource> oldItemViewAdapter)
{
if (oldItemViewAdapter?.ItemsSource is ObservableItemsSource oldObservableItemsSource)
{
oldObservableItemsSource.CollectionItemsSourceChanged += CollectionItemsSourceChanged;
}
}
int GetIndexFromTemplatedCell(global::Android.Views.View view)
{
int itemIndex = -1;
if (view is ItemContentView templatedCell)
{
var bContext = (templatedCell?.View as VisualElement)?.BindingContext;
itemIndex = ItemsViewAdapter.GetPositionForItem(bContext);
}
return(itemIndex);
}
int GetCarouselViewCurrentIndex(int index)
{
var centeredView = this.GetCenteredView();
if (centeredView is ItemContentView templatedCell)
{
var bContext = (templatedCell?.View as VisualElement)?.BindingContext;
index = ItemsViewAdapter.GetPositionForItem(bContext);
}
else
{
return(-1);
}
return(index);
}
protected override void Dispose(bool disposing)
{
if (_disposed)
{
return;
}
if (disposing)
{
_itemsView = null;
ItemsViewAdapter = null;
}
_disposed = true;
base.Dispose(disposing);
}
protected override void OnMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
if (Carousel.Loop)
{
// If the height or width are unbounded and the user is set to
// Loop then we can't just do an infinite measure.
// Looping works by setting item count to 16384 so if the
// CarV has infinite room it'll generate all 16384 items.
// This code forces the adapter to just measure the first item
// And then that measure is used for the WxH of the CarouselView
// I found that "AtMost" also causes this behavior so
// that's why I'm turning "AtMost" into "Exactly"
if (MeasureSpec.GetMode(widthMeasureSpec) == MeasureSpecMode.AtMost)
{
widthMeasureSpec = MeasureSpecMode.Exactly.MakeMeasureSpec(widthMeasureSpec.GetSize());
}
if (MeasureSpec.GetMode(heightMeasureSpec) == MeasureSpecMode.AtMost)
{
heightMeasureSpec = MeasureSpecMode.Exactly.MakeMeasureSpec(heightMeasureSpec.GetSize());
}
if (MeasureSpec.GetMode(widthMeasureSpec) == MeasureSpecMode.Unspecified ||
MeasureSpec.GetMode(heightMeasureSpec) == MeasureSpecMode.Unspecified)
{
if (ItemsViewAdapter.ItemCount > 0)
{
// Retrieve the first item of the CarouselView and measure it
// This is what we'll use for the CarV WxH if the requested measure
// is for an infinite amount of space
var viewType = ItemsViewAdapter.GetItemViewType(0);
var viewHolder = (ViewHolder)ItemsViewAdapter.CreateViewHolder(this, viewType);
ItemsViewAdapter.BindViewHolder(viewHolder, 0);
viewHolder.ItemView.Measure(widthMeasureSpec, heightMeasureSpec);
widthMeasureSpec = MeasureSpecMode.Exactly.MakeMeasureSpec(viewHolder.ItemView.MeasuredWidth);
heightMeasureSpec = MeasureSpecMode.Exactly.MakeMeasureSpec(viewHolder.ItemView.MeasuredHeight);
}
}
}
base.OnMeasure(widthMeasureSpec, heightMeasureSpec);
}
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 <CarouselView, IItemsViewSource> itemsViewAdapter, CarouselViewLoopManager carouselViewLoopManager) : base((CarouselView)itemsView, itemsViewAdapter, true)
{
_carouselView = itemsView as CarouselView;
_carouselViewLoopManager = carouselViewLoopManager;
}
public RecyclerViewScrollListener(TItemsView itemsView, ItemsViewAdapter <TItemsView, TItemsViewSource> itemsViewAdapter, bool getCenteredItemOnXAndY)
{
_itemsView = itemsView;
ItemsViewAdapter = itemsViewAdapter;
_getCenteredItemOnXAndY = getCenteredItemOnXAndY;
}
public RecyclerViewScrollListener(TItemsView itemsView, ItemsViewAdapter <TItemsView, TItemsViewSource> itemsViewAdapter) : this(itemsView, itemsViewAdapter, false)
{
}
internal void UpdateAdapter(ItemsViewAdapter <TItemsView, TItemsViewSource> itemsViewAdapter)
{
ItemsViewAdapter = itemsViewAdapter;
}