Improved implementation for Carousel automation peer

Author: jamesmcroft

Microsoft.Toolkit.Uwp.SampleApp/Data/PhotoDataItem.cs

@@ -11,5 +11,10 @@ public class PhotoDataItem
         public string Category { get; set; }
 
         public string Thumbnail { get; set; }
+
+        public override string ToString()
+        {
+            return Title;
+        }
     }
 }

Microsoft.Toolkit.Uwp.UI.Controls/Carousel/Carousel.cs

@@ -543,14 +543,6 @@ private void OnCarouselItemSelected(object sender, EventArgs e)
             SelectedItem = ItemFromContainer(item);
         }
 
-        internal IEnumerable<CarouselItem> GetCarouselItems()
-        {
-            return Enumerable
-                .Range(0, Items.Count)
-                .Select(idx => (CarouselItem)ContainerFromIndex(idx))
-                .Where(i => i != null);
-        }
-
         internal void SetSelectedItem(CarouselItem owner)
         {
             var item = ItemFromContainer(owner);

Microsoft.Toolkit.Uwp.UI.Controls/Carousel/CarouselAutomationPeer.cs

@@ -47,10 +47,9 @@ private Carousel OwningCarousel
         /// <returns>An array of UI Automation providers.</returns>
         public IRawElementProviderSimple[] GetSelection()
         {
-            CarouselItem selectedCarouselItem = OwningCarousel.GetCarouselItems().FirstOrDefault(x => x.IsSelected);
-            return selectedCarouselItem != null
-                ? new[] { this.ProviderFromPeer(FromElement(selectedCarouselItem)) }
-                : new IRawElementProviderSimple[] { };
+            return OwningCarousel.ContainerFromItem(this.OwningCarousel.SelectedItem) is CarouselItem selectedCarouselItem
+                       ? new[] { this.ProviderFromPeer(FromElement(selectedCarouselItem)) }
+                       : new IRawElementProviderSimple[] { };
         }
 
         /// <summary>

Microsoft.Toolkit.Uwp.UI.Controls/Carousel/CarouselItem.cs

@@ -23,6 +23,8 @@ public class CarouselItem : SelectorItem
         private const string SelectedState = "Selected";
         private const string NormalState = "Normal";
 
+        private WeakReference<Carousel> parentCarousel;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="CarouselItem"/> class.
         /// </summary>
@@ -34,7 +36,15 @@ public CarouselItem()
             RegisterPropertyChangedCallback(SelectorItem.IsSelectedProperty, OnIsSelectedChanged);
         }
 
-        internal Carousel ParentCarousel { get; set; }
+        internal Carousel ParentCarousel
+        {
+            get
+            {
+                this.parentCarousel.TryGetTarget(out var carousel);
+                return carousel;
+            }
+            set => this.parentCarousel = new WeakReference<Carousel>(value);
+        }
 
         /// <inheritdoc/>
         protected override void OnPointerEntered(PointerRoutedEventArgs e)

Microsoft.Toolkit.Uwp.UI.Controls/Carousel/CarouselItemAutomationPeer.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Linq;
 using Microsoft.Toolkit.Uwp.UI.Controls;
 using Windows.UI.Xaml.Automation.Peers;
 using Windows.UI.Xaml.Automation.Provider;
@@ -56,23 +55,26 @@ public void AddToSelection()
         {
             CarouselItem owner = this.OwnerCarouselItem;
             Carousel parent = owner.ParentCarousel;
-            parent.SetSelectedItem(owner);
+            parent?.SetSelectedItem(owner);
         }
 
         /// <summary>Removes the current element from the collection of selected items.</summary>
         public void RemoveFromSelection()
         {
             CarouselItem owner = this.OwnerCarouselItem;
             Carousel parent = owner.ParentCarousel;
-            parent.SelectedItem = null;
+            if (parent != null)
+            {
+                parent.SelectedItem = null;
+            }
         }
 
         /// <summary>Clears any existing selection and then selects the current element.</summary>
         public void Select()
         {
             CarouselItem owner = this.OwnerCarouselItem;
             Carousel parent = owner.ParentCarousel;
-            parent.SetSelectedItem(owner);
+            parent?.SetSelectedItem(owner);
         }
 
         /// <summary>
@@ -105,12 +107,12 @@ protected override string GetClassNameCore()
         /// </returns>
         protected override string GetNameCore()
         {
-            int? index = this.OwnerCarouselItem.ParentCarousel.GetCarouselItems().ToList().IndexOf(this.OwnerCarouselItem);
+            int? index = this.OwnerCarouselItem.ParentCarousel?.IndexFromContainer(this.OwnerCarouselItem);
 
             string name = base.GetNameCore();
             if (!string.IsNullOrEmpty(name))
             {
-                return $"{name} {index}";
+                return $"{name}";
             }
 
             if (this.OwnerCarouselItem != null && !string.IsNullOrEmpty(this.OwnerCarouselItem.Name))