[Android] IndicatorView with DataTemplate (custom image) does not render correctly when ItemsSource change

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

@@ -84,11 +84,6 @@ internal void ResetIndicatorCount(int oldCount)
 					oldCount = 0;
 				}
 
-				if (oldCount > _indicatorView.Count)
-				{
-					return;
-				}
-
 				BindIndicatorItems();
 			}
 			finally

src/Controls/tests/TestCases.HostApp/Issues/Issue21980.cs

@@ -0,0 +1,61 @@
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, "21980", "IndicatorView with DataTemplate (custom image) does not render correctly when ItemsSource change.", PlatformAffected.Android | PlatformAffected.iOS)]
+	public partial class Issue21980 : ContentPage
+	{
+		public Issue21980()
+		{
+			InitializeComponent(); 
+			BindingContext = new Issue21980ViewModel();
+		}
+	}
+
+	public class Issue21980ViewModel : INotifyPropertyChanged
+	{
+		private readonly IReadOnlyList<string> _imageSource1 = new List<string>
+		{
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+		};
+		private readonly IReadOnlyList<string> _imageSource2 = new List<string>()
+		{
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+			"dotnet_bot.png",
+		};
+
+		private IReadOnlyList<string> _images = [];
+		public IReadOnlyList<string> Images
+		{
+			get => _images;
+			set
+			{
+				_images = value;
+				OnPropertyChanged();
+			}
+		}
+
+		public Command ChangeSourceCommand { get; set; }
+
+		public Issue21980ViewModel()
+		{
+			Images = _imageSource1;
+			ChangeSourceCommand = new Command(() => Images = _imageSource2);
+		}
+
+		public event PropertyChangedEventHandler PropertyChanged;
+
+		void OnPropertyChanged([CallerMemberName] string propertyName = "") =>
+		PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+	}
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue21980.xaml

@@ -0,0 +1,48 @@
+<?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.Issue21980">
+  <ContentPage.Resources>
+    <Style x:Key="IndicatorViewTemplateStyle" TargetType="Image">
+      <Setter Property="VisualStateManager.VisualStateGroups">
+        <VisualStateGroupList>
+          <VisualStateGroup x:Name="CommonStates">
+            <VisualState x:Name="Normal">
+              <VisualState.Setters>
+                <Setter Property="Source" Value="indicator_unselected" />
+              </VisualState.Setters>
+            </VisualState>
+            <VisualState x:Name="Selected">
+              <VisualState.Setters>
+                <Setter Property="Source" Value="indicator_selected" />
+              </VisualState.Setters>
+            </VisualState>
+          </VisualStateGroup>
+        </VisualStateGroupList>
+      </Setter>
+    </Style>
+  </ContentPage.Resources>
+  <VerticalStackLayout>
+    <Grid>
+      <CarouselView ItemsSource="{Binding Images}" IndicatorView="IndicatorView" HorizontalScrollBarVisibility="Never" WidthRequest="300" HeightRequest="450" Grid.Row="0">
+        <CarouselView.ItemTemplate>
+          <DataTemplate>
+            <Grid>
+              <Image Source="{Binding .}" WidthRequest="300" HeightRequest="450"/>
+            </Grid>
+          </DataTemplate>
+        </CarouselView.ItemTemplate>
+      </CarouselView>
+      <Border HorizontalOptions="Center" VerticalOptions="End" Margin="16" Background="Green" Padding="6" StrokeShape="RoundRectangle 12" StrokeThickness="0" Grid.Row="0">
+        <IndicatorView AutomationId="IndicatorView" x:Name="IndicatorView" IndicatorColor="Pink" SelectedIndicatorColor="Black" IndicatorSize="12" Padding="0" HeightRequest="12">
+          <IndicatorView.IndicatorTemplate>
+            <DataTemplate>
+              <Image Aspect="Center" HeightRequest="12" WidthRequest="12" Margin="1,0" Style="{StaticResource IndicatorViewTemplateStyle}" />
+            </DataTemplate>
+          </IndicatorView.IndicatorTemplate>
+        </IndicatorView>
+      </Border>
+    </Grid>
+    <Button x:Name="BtnChangeSource" AutomationId="changeItemsSource" Command="{Binding ChangeSourceCommand}" Text="Change ItemsSource" HorizontalOptions="Center" WidthRequest="200" Margin="0,16"/>
+  </VerticalStackLayout>
+</ContentPage>

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue21980.cs

@@ -0,0 +1,27 @@
+#if ANDROID || IOS
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue21980 : _IssuesUITest
+	{
+		public Issue21980(TestDevice device) : base(device)
+		{
+		}
+
+		public override string Issue => "IndicatorView with DataTemplate (custom image) does not render correctly when ItemsSource change.";
+
+		[Test]
+		[Category(UITestCategories.IndicatorView)]
+		public void IndicatorViewSizeAfterItemsSourceUpdate()
+		{
+			App.WaitForElement("changeItemsSource");
+			App.Click("changeItemsSource");
+			App.WaitForElement("changeItemsSource");
+			VerifyScreenshot();
+		}
+	}
+}
+#endif

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

@@ -99,6 +99,11 @@ public void UpdateIndicatorCount()
 			}
 
 			RemoveViews(count);
+
+			if (_indicatorView is ITemplatedIndicatorView templatedIndicatorView)
+			{
+				UpdateIndicatorTemplate(templatedIndicatorView.IndicatorsLayoutOverride);
+			}
 		}
 
 		void UpdateIndicatorTemplate(ILayout? layout)
@@ -170,9 +175,11 @@ int GetIndexFromPosition()
 
 		void RemoveViews(int startAt)
 		{
-			for (int i = startAt; i < ChildCount; i++)
+			startAt = ChildCount - startAt;
+			int index = ChildCount - 1;
+			for (int i = 0; i < startAt; i++)
 			{
-				var imageView = GetChildAt(ChildCount - 1);
+				var imageView = GetChildAt(index - i);
 				imageView?.SetOnClickListener(null);
 				RemoveView(imageView);
 			}