[iOS,Android] Handle Appearing/Disappearing on CarouselPage

Xamarin.Forms.Controls/ControlGalleryPages/AppearingGalleryPage.cs

@@ -98,6 +98,7 @@ public AppearingPage (int id)
 					Children = {
 						new Label { Text = $"Hello Appearing {_theId} page" },
 						new Button { Text = "Push new Page", Command = new Command ( async () => { await Navigation.PushAsync( new AppearingPage(2)); }) },
+						new Button { Text = "Add new Page", Command = new Command ( () => { (Parent as CarouselPage).Children.Add( new AppearingPage(3)); }) },
 						new Button { Text = "Pop page", Command = new Command ( async () => { await Navigation.PopAsync(); }) },
 						new Button { Text = "Pop to root", Command = new Command ( async () => { await Navigation.PopToRootAsync(); }) },
 						new Button { Text = "Change Main Page", Command = new Command ( () => { 

Xamarin.Forms.Platform.Android/AppCompat/CarouselPageRenderer.cs

@@ -11,6 +11,7 @@ public class CarouselPageRenderer : VisualElementRenderer<CarouselPage>, ViewPag
 	{
 		bool _disposed;
 		FormsViewPager _viewPager;
+		Page _previousPage;
 
 		public CarouselPageRenderer(Context context) : base(context)
 		{
@@ -36,6 +37,12 @@ void ViewPager.IOnPageChangeListener.OnPageScrollStateChanged(int state)
 		void ViewPager.IOnPageChangeListener.OnPageSelected(int position)
 		{
 			Element.CurrentPage = Element.Children[position];
+			if (_previousPage != Element.CurrentPage)
+			{
+				_previousPage?.SendDisappearing();
+				_previousPage = Element.CurrentPage;
+			}
+			Element.CurrentPage.SendAppearing();
 		}
 
 		protected override void Dispose(bool disposing)
@@ -62,6 +69,8 @@ protected override void Dispose(bool disposing)
 					_viewPager = null;
 				}
 
+				_previousPage = null;
+
 				if (Element != null)
 					PageController.InternalChildren.CollectionChanged -= OnChildrenCollectionChanged;
 			}
@@ -72,12 +81,18 @@ protected override void Dispose(bool disposing)
 		protected override void OnAttachedToWindow()
 		{
 			base.OnAttachedToWindow();
+			if (Parent is PageContainer pageContainer && (pageContainer.IsInFragment || pageContainer.Visibility == ViewStates.Gone))
+				return;
 			PageController.SendAppearing();
+			Element.CurrentPage?.SendAppearing();
 		}
 
 		protected override void OnDetachedFromWindow()
 		{
 			base.OnDetachedFromWindow();
+			if (Parent is PageContainer pageContainer && pageContainer.IsInFragment)
+				return;
+			Element.CurrentPage?.SendDisappearing();
 			PageController.SendDisappearing();
 		}
 
@@ -107,7 +122,10 @@ protected override void OnElementChanged(ElementChangedEventArgs<CarouselPage> e
 				ViewGroup.AddView(pager);
 				CarouselPage carouselPage = e.NewElement;
 				if (carouselPage.CurrentPage != null)
+				{
+					_previousPage = carouselPage.CurrentPage;
 					ScrollToCurrentPage();
+				}
 
 				((IPageController)carouselPage).InternalChildren.CollectionChanged += OnChildrenCollectionChanged;
 			}

Xamarin.Forms.Platform.Android/Renderers/CarouselPageRenderer.cs

@@ -9,6 +9,7 @@ namespace Xamarin.Forms.Platform.Android
 	public class CarouselPageRenderer : VisualElementRenderer<CarouselPage>
 	{
 		ViewPager _viewPager;
+		Page _previousPage;
 
 		public CarouselPageRenderer(Context context) : base(context)
 		{
@@ -27,6 +28,8 @@ protected override void Dispose(bool disposing)
 		{
 			if (disposing && _viewPager != null)
 			{
+				_previousPage = null;
+
 				if (_viewPager.Adapter != null)
 					_viewPager.Adapter.Dispose();
 				_viewPager.Dispose();
@@ -44,12 +47,18 @@ protected override void OnAttachedToWindow()
 
 			adapter.UpdateCurrentItem();
 
+			if (Parent is PageContainer pageContainer && (pageContainer.IsInFragment || pageContainer.Visibility == ViewStates.Gone))
+				return;
 			PageController.SendAppearing();
+			Element.CurrentPage?.SendAppearing();
 		}
 
 		protected override void OnDetachedFromWindow()
 		{
 			base.OnDetachedFromWindow();
+			if (Parent is PageContainer pageContainer && pageContainer.IsInFragment)
+				return;
+			Element.CurrentPage?.SendDisappearing();
 			PageController.SendDisappearing();
 		}
 
@@ -66,9 +75,14 @@ protected override void OnElementChanged(ElementChangedEventArgs<CarouselPage> e
 
 			_viewPager = new ViewPager(Context);
 
+
 			AddView(_viewPager);
 
 			_viewPager.OffscreenPageLimit = int.MaxValue;
+
+			if (Element.CurrentPage != null)
+				_previousPage = Element.CurrentPage;
+
 		}
 
 		protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
@@ -105,6 +119,12 @@ void UpdateCurrentItem()
 				return;
 
 			_viewPager.CurrentItem = index;
+			if (_previousPage != Element.CurrentPage)
+			{
+				_previousPage?.SendDisappearing();
+				_previousPage = Element.CurrentPage;
+			}
+			Element.CurrentPage.SendAppearing();
 		}
 	}
 }

Xamarin.Forms.Platform.iOS/Renderers/CarouselPageRenderer.cs

@@ -19,13 +19,15 @@ public class CarouselPageRenderer : UIViewController, IVisualElementRenderer
 		bool _ignoreNativeScrolling;
 		UIScrollView _scrollView;
 		VisualElementTracker _tracker;
+		Page _previousPage;
 
 		public CarouselPageRenderer()
 		{
 		}
 
 		IElementController ElementController => Element as IElementController;
 
+
 		protected CarouselPage Carousel
 		{
 			get { return (CarouselPage)Element; }
@@ -63,6 +65,8 @@ public void SetElement(VisualElement element)
 
 			if (element != null)
 				element.SendViewInitialized(NativeView);
+
+			_previousPage = Carousel?.CurrentPage;
 		}
 
 		public void SetElementSize(Size size)
@@ -167,6 +171,8 @@ protected override void Dispose(bool disposing)
 		{
 			if (disposing && !_disposed)
 			{
+				_previousPage = null;
+
 				if (_scrollView != null)
 					_scrollView.DecelerationEnded -= OnDecelerationEnded;
 
@@ -259,8 +265,15 @@ void OnDecelerationEnded(object sender, EventArgs eventArgs)
 		{
 			if (_ignoreNativeScrolling || SelectedIndex >= ElementController.LogicalChildren.Count)
 				return;
-
-			Carousel.CurrentPage = (ContentPage)ElementController.LogicalChildren[SelectedIndex];
+
+			var currentPage = (ContentPage)ElementController.LogicalChildren[SelectedIndex];
+			if (_previousPage != currentPage)
+			{
+				_previousPage?.SendDisappearing();
+				_previousPage = currentPage;
+			}
+			Carousel.CurrentPage = currentPage;
+			currentPage.SendAppearing();
 		}
 
 		void OnPagesChanged(object sender, NotifyCollectionChangedEventArgs e)

Xamarin.Forms.Platform.iOS/Renderers/PageRenderer.cs

@@ -94,8 +94,12 @@ public override void ViewDidAppear(bool animated)
 				return;
 
 			_appeared = true;
-			Page.SendAppearing();
 			UpdateStatusBarPrefersHidden();
+
+			if (Element.Parent is CarouselPage)
+				return;
+
+			Page.SendAppearing();
 		}
 
 		public override void ViewDidDisappear(bool animated)
@@ -106,6 +110,10 @@ public override void ViewDidDisappear(bool animated)
 				return;
 
 			_appeared = false;
+
+			if (Element.Parent is CarouselPage)
+				return;
+
 			Page.SendDisappearing();
 		}