async void ItemsSource_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
// NewItems contains the item that was added.
// If NewStartingIndex is not -1, then it contains the index where the new item was added.
if (e.Action == NotifyCollectionChangedAction.Add)
{
InsertPage(Element?.ItemsSource.GetItem(e.NewStartingIndex), e.NewStartingIndex);
}
// OldItems contains the item that was removed.
// If OldStartingIndex is not -1, then it contains the index where the old item was removed.
if (e.Action == NotifyCollectionChangedAction.Remove)
{
await RemovePage(e.OldStartingIndex);
}
// OldItems contains the moved item.
// OldStartingIndex contains the index where the item was moved from.
// NewStartingIndex contains the index where the item was moved to.
if (e.Action == NotifyCollectionChangedAction.Move)
{
var Source = ((PageAdapter)viewPager?.Adapter).Source;
if (Element != null && viewPager != null && Source != null)
{
Source.RemoveAt(e.OldStartingIndex);
Source.Insert(e.NewStartingIndex, e.OldItems[e.OldStartingIndex]);
viewPager.Adapter?.NotifyDataSetChanged();
}
}
// NewItems contains the replacement item.
// NewStartingIndex and OldStartingIndex are equal, and if they are not -1,
// then they contain the index where the item was replaced.
if (e.Action == NotifyCollectionChangedAction.Replace)
{
var Source = ((PageAdapter)viewPager?.Adapter).Source;
if (Element != null && viewPager != null && Source != null)
{
Source[e.OldStartingIndex] = e.NewItems[e.NewStartingIndex];
viewPager.Adapter?.NotifyDataSetChanged();
}
}
// No other properties are valid.
if (e.Action == NotifyCollectionChangedAction.Reset)
{
if (Element != null && viewPager != null)
{
SetPosition();
viewPager.Adapter = new PageAdapter(Element);
viewPager.SetCurrentItem(Element.Position, false);
indicators?.SetViewPager(viewPager);
Element.PositionSelected?.Invoke(Element, Element.Position);
}
}
}
void SetIndicators()
{
if (Element.ShowIndicators)
{
SetPosition();
indicators.SetViewPager(viewPager);
// IndicatorsTintColor BP
indicators.SetFillColor(Element.IndicatorsTintColor.ToAndroid());
// CurrentPageIndicatorTintColor BP
indicators.SetPageColor(Element.CurrentPageIndicatorTintColor.ToAndroid());
// IndicatorsShape BP
indicators.SetStyle(Element.IndicatorsShape); // Rounded or Squared
}
else
{
indicators.RemoveAllViews();
}
// ShowIndicators BP
indicators.Visibility = Element.ShowIndicators? AViews.ViewStates.Visible : AViews.ViewStates.Gone;
}