Templated indicator view - improvements

src/Controls/src/Core/IndicatorView/IndicatorStackLayout.cs

@@ -98,19 +98,30 @@ internal void ResetIndicatorCount(int oldCount)
 			}
 		}
 
+		protected override void OnInsert(int index, IView view)
+		{
+			base.OnInsert(index, view);
+			ResetIndicatorStylesNonBatch();
+		}
+
+		protected override void OnRemove(int index, IView view)
+		{
+			base.OnRemove(index, view);
+			ResetIndicatorStylesNonBatch();
+		}
+
 		void ResetIndicatorStylesNonBatch()
 		{
 			var indicatorCount = _indicatorView.Count;
 			var childrenCount = Children.Count;
+			var maxVisible = _indicatorView.MaximumVisible;
+			var position = _indicatorView.Position;
+			var selectedIndex = position >= maxVisible ? maxVisible - 1 : position;
 
 			for (int index = 0; index < childrenCount; index++)
 			{
-				var maxVisible = _indicatorView.MaximumVisible;
-				var position = _indicatorView.Position;
-				var selectedIndex = position >= maxVisible ? maxVisible - 1 : position;
 				bool isSelected = index == selectedIndex;
-				var visualElement = Children[index] as VisualElement;
-				if (visualElement is null)
+				if (Children[index] is not VisualElement visualElement)
 				{
 					return;
 				}

src/Controls/tests/TestCases.HostApp/Issues/Issues25598.xaml

@@ -0,0 +1,111 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue25598">
+    <VerticalStackLayout 
+            Padding="30,0"
+            Spacing="25">
+        <Button
+            AutomationId="AddItemButton"
+            Margin="0,20,0,0"
+            Command="{Binding AddRandomItemCommand}"
+            Text="Add Random Item"/>
+
+        <Button
+            AutomationId="RemoveItemButton"
+            Command="{Binding RemoveCurrentItemCommand}"
+            CommandParameter="{Binding Source={x:Reference carouselView}, Path=Position}"
+            Text="Remove Current Item"/>
+        <Grid
+            x:Name="cvGrid"
+            Margin="5,0"
+            RowDefinitions="Auto,50,Auto"
+            BackgroundColor="Transparent"
+            HorizontalOptions="FillAndExpand">
+            <Label
+                Grid.Row="0"
+                FontSize="24"
+                Text="CarouselView + IndicatorView using DataTemplate!"/>
+            <CarouselView
+                x:Name="carouselView"
+                Grid.Row="1"
+                HorizontalOptions="FillAndExpand"
+                IndicatorView="indicatorView"
+                IsScrollAnimated="True"
+                ItemsSource="{Binding Items}"
+                ItemsUpdatingScrollMode="KeepScrollOffset"
+                VerticalOptions="EndAndExpand"
+                VerticalScrollBarVisibility="Default">
+                <CarouselView.ItemTemplate>
+                    <DataTemplate>
+                        <Label
+                            FontSize="18"
+                            HorizontalOptions="Center"
+                            Text="{Binding .}"
+                            VerticalOptions="CenterAndExpand"/>
+                    </DataTemplate>
+                </CarouselView.ItemTemplate>
+            </CarouselView>
+
+            <IndicatorView
+                x:Name="indicatorView"
+                Grid.Row="2"
+                HorizontalOptions="Center"
+                IndicatorColor="White"
+                SelectedIndicatorColor="#2040a0">
+                <IndicatorView.IndicatorTemplate>
+                    <DataTemplate>
+                        <Border
+                            BackgroundColor="Transparent"
+                            HeightRequest="20"
+                            Stroke="Black"
+                            WidthRequest="20">
+                            <Border.StrokeShape>
+                                <RoundRectangle CornerRadius="5"/>
+                            </Border.StrokeShape>
+                        </Border>
+                    </DataTemplate>
+                </IndicatorView.IndicatorTemplate>
+            </IndicatorView>
+        </Grid>
+        <Grid
+            x:Name="cvGrid2"
+            Margin="5,0"
+            RowDefinitions="Auto,50,Auto"
+            BackgroundColor="Transparent"
+            HorizontalOptions="FillAndExpand">
+            <Label
+                Grid.Row="0"
+                FontSize="24"
+                Text="CarouselView + IndicatorView NOT USING DataTemplate!"/>
+            <CarouselView
+                x:Name="carouselView2"
+                Grid.Row="1"
+                HorizontalOptions="FillAndExpand"
+                IndicatorView="indicatorView2"
+                IsScrollAnimated="True"
+                ItemsSource="{Binding Items}"
+                ItemsUpdatingScrollMode="KeepScrollOffset"
+                VerticalOptions="EndAndExpand"
+                VerticalScrollBarVisibility="Default">
+                <CarouselView.ItemTemplate>
+                    <DataTemplate>
+                        <Label
+                            FontSize="18"
+                            HorizontalOptions="Center"
+                            Text="{Binding .}"
+                            VerticalOptions="CenterAndExpand"/>
+                    </DataTemplate>
+                </CarouselView.ItemTemplate>
+            </CarouselView>
+
+            <IndicatorView
+                x:Name="indicatorView2"
+                Grid.Row="2"
+                HorizontalOptions="Center"
+                IndicatorColor="Black"
+                IndicatorsShape="Square"
+                SelectedIndicatorColor="#2040a0"/>
+        </Grid>
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issues25598.xaml.cs

@@ -0,0 +1,42 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.Github, 25598, "IndicatorView with Template won't show when ItemSource reaches 0 Elements", PlatformAffected.Android)]
+	public partial class Issue25598 : ContentPage
+	{
+		public Issue25598()
+		{
+			InitializeComponent();
+			BindingContext = new Issue25598ViewModel();
+		}
+	}
+
+	public class Issue25598ViewModel : ViewModel
+	{
+		int _lastItemIndex = 3;
+
+		private ObservableCollection<string> _items = new() { "Item1", "Item2", "Item3" };
+
+		public ObservableCollection<string> Items
+		{
+			get => _items;
+			set
+			{
+				if (_items != value)
+				{
+					_items = value;
+					OnPropertyChanged(nameof(Items));
+				}
+			}
+		}
+
+		public Command AddRandomItemCommand => new(() => Items.Add($"Item{++_lastItemIndex}"));
+
+		public Command RemoveCurrentItemCommand => new Command<int>(index =>
+		{
+			if (index >= 0 && index < Items.Count)
+				Items.RemoveAt(index);
+		});
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25598.cs

@@ -0,0 +1,28 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue25598 : _IssuesUITest
+	{
+		public Issue25598(TestDevice testDevice) : base(testDevice) { }
+
+		public override string Issue => "IndicatorView with Template won't show when ItemSource reaches 0 Elements";
+
+		[Test]
+		[Category(UITestCategories.IndicatorView)]
+		public void IndicatorWithTemplateShouldBeVisible()
+		{
+			App.WaitForElement("RemoveItemButton");
+
+			for (int i = 0; i < 3; i++)
+				App.Click("RemoveItemButton");
+
+			for (int i = 0; i < 3; i++)
+				App.Click("AddItemButton");
+
+			VerifyScreenshot();
+		}
+	}
+}

src/Core/src/Platform/Android/MauiPageControl.cs

@@ -20,6 +20,8 @@ public class MauiPageControl : LinearLayout
 
 		IIndicatorView? _indicatorView;
 
+		bool _isTemplateIndicator;
+
 		public MauiPageControl(Context? context) : base(context)
 		{
 		}
@@ -37,6 +39,7 @@ public void ResetIndicators()
 		{
 			_pageShape = null;
 			_currentPageShape = null;
+			_isTemplateIndicator = false;
 
 			if ((_indicatorView as ITemplatedIndicatorView)?.IndicatorsLayoutOverride == null)
 				UpdateShapes();
@@ -63,7 +66,7 @@ public void UpdatePosition()
 
 		public void UpdateIndicatorCount()
 		{
-			if (_indicatorView == null || Context == null)
+			if (_indicatorView == null || Context == null || _isTemplateIndicator)
 				return;
 
 			var index = GetIndexFromPosition();
@@ -107,6 +110,7 @@ void UpdateIndicatorTemplate(ILayout? layout)
 				return;
 
 			AView? handler = layout.ToPlatform(_indicatorView.Handler.MauiContext);
+			_isTemplateIndicator = true;
 
 			RemoveAllViews();
 			AddView(handler);
@@ -170,7 +174,11 @@ int GetIndexFromPosition()
 
 		void RemoveViews(int startAt)
 		{
-			for (int i = startAt; i < ChildCount; i++)
+			if (_isTemplateIndicator)
+				return;
+
+			var count = ChildCount;
+			for (int i = startAt; i < count; i++)
 			{
 				var imageView = GetChildAt(ChildCount - 1);
 				imageView?.SetOnClickListener(null);