[net11.0][Android] Implement handler based Shell architecture replacing legacy renderers

src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets

@@ -380,6 +380,10 @@
                                       Condition="'$(UseMaterial3)' != ''"
                                       Value="$(UseMaterial3)"
                                       Trim="true" />
+      <RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.UseAndroidShellHandlers"
+                                      Condition="'$(UseAndroidShellHandlers)' != ''"
+                                      Value="$(UseAndroidShellHandlers)"
+                                      Trim="true" />
     </ItemGroup>
   </Target>
 

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellFlyoutRecyclerAdapter.cs

@@ -81,7 +81,7 @@ DataTemplate GetDataTemplate(int viewTypeId)
 
 		public override void OnViewRecycled(Java.Lang.Object holder)
 		{
-			if (holder is ElementViewHolder evh)
+			if (holder is ElementViewHolder evh && _listItems is not null)
 			{
 				// only clear out the Element if the item has been removed
 				bool found = false;
@@ -208,7 +208,9 @@ protected virtual void OnFlyoutItemsChanged(object sender, EventArgs e)
 		protected override void Dispose(bool disposing)
 		{
 			if (_disposed)
+			{
 				return;
+			}
 
 			_disposed = true;
 
@@ -222,8 +224,15 @@ protected override void Dispose(bool disposing)
 
 		internal void Disconnect()
 		{
+			if (_shellContext is null)
+			{
+				return;
+			}
+
 			if (Shell is IShellController scc)
+			{
 				scc.FlyoutItemsChanged -= OnFlyoutItemsChanged;
+			}
 
 			_listItems = null;
 			_selectedCallback = null;

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellFlyoutTemplatedContentRenderer.cs

@@ -1,12 +1,8 @@
 #nullable disable
 using System;
 using System.ComponentModel;
-using System.Threading.Tasks;
 using Android.Content;
 using Android.Graphics.Drawables;
-using Android.Hardware.Lights;
-using Android.Runtime;
-using Android.Util;
 using Android.Views;
 using Android.Widget;
 using AndroidX.CoordinatorLayout.Widget;
@@ -15,12 +11,9 @@
 using AndroidX.RecyclerView.Widget;
 using Google.Android.Material.AppBar;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Maui.Controls.Internals;
-using Microsoft.Maui.Controls.Platform.Compatibility;
 using Microsoft.Maui.Layouts;
 using AView = Android.Views.View;
 using LP = Android.Views.ViewGroup.LayoutParams;
-
 namespace Microsoft.Maui.Controls.Platform.Compatibility
 {
 	public class ShellFlyoutTemplatedContentRenderer : Java.Lang.Object, IShellFlyoutContentRenderer
@@ -211,6 +204,7 @@ protected virtual void LoadView(IShellContext shellContext)
 			MauiWindowInsetListener.SetupViewWithLocalListener(coordinator, _windowsListener);
 
 			UpdateFlyoutHeaderBehavior();
+
 			_shellContext.Shell.PropertyChanged += OnShellPropertyChanged;
 
 			UpdateFlyoutBackground();
@@ -267,31 +261,51 @@ protected void OnElementSelected(Element element)
 
 		protected virtual void OnShellPropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
+			// When using the new ShellHandler (not the compatibility ShellRenderer),
+			// all these properties are already handled by the handler's property mapper.
+			// Responding to PropertyChanged here would cause double updates.
+			if (_shellContext.Shell.Handler is Handlers.ShellHandler)
+			{
+				return;
+			}
+
 			if (e.PropertyName == Shell.FlyoutHeaderBehaviorProperty.PropertyName)
+			{
 				UpdateFlyoutHeaderBehavior();
+			}
 			else if (e.IsOneOf(
 				Shell.FlyoutBackgroundColorProperty,
 				Shell.FlyoutBackgroundProperty,
 				Shell.FlyoutBackgroundImageProperty,
 				Shell.FlyoutBackgroundImageAspectProperty))
+			{
 				UpdateFlyoutBackground();
+			}
 			else if (e.Is(Shell.FlyoutVerticalScrollModeProperty))
+			{
 				UpdateVerticalScrollMode();
+			}
 			else if (e.IsOneOf(
 				Shell.FlyoutHeaderProperty,
 				Shell.FlyoutHeaderTemplateProperty))
+			{
 				UpdateFlyoutHeader();
+			}
 			else if (e.IsOneOf(
 				Shell.FlyoutFooterProperty,
 				Shell.FlyoutFooterTemplateProperty))
+			{
 				UpdateFlyoutFooter();
+			}
 			else if (e.IsOneOf(
 				Shell.FlyoutContentProperty,
 				Shell.FlyoutContentTemplateProperty))
+			{
 				UpdateFlyoutContent();
+			}
 		}
 
-		protected virtual void UpdateFlyoutContent()
+		public virtual void UpdateFlyoutContent()
 		{
 			if (!_rootView.IsAlive())
 				return;
@@ -362,7 +376,7 @@ AView CreateFlyoutContent(ViewGroup rootView)
 			return _contentView.PlatformView;
 		}
 
-		protected virtual void UpdateFlyoutHeader()
+		public virtual void UpdateFlyoutHeader()
 		{
 			if (_headerView != null)
 			{
@@ -374,10 +388,7 @@ protected virtual void UpdateFlyoutHeader()
 				oldHeaderView.Dispose();
 			}
 
-			if (_flyoutHeader != null)
-			{
-				_flyoutHeader.MeasureInvalidated -= OnFlyoutHeaderMeasureInvalidated;
-			}
+			_flyoutHeader?.MeasureInvalidated -= OnFlyoutHeaderMeasureInvalidated;
 
 			_flyoutHeader = ((IShellController)_shellContext.Shell).FlyoutHeader;
 			if (_flyoutHeader != null)
@@ -414,7 +425,7 @@ void OnHeaderViewLayoutChange(object sender, AView.LayoutChangeEventArgs e)
 			UpdateContentPadding();
 		}
 
-		protected virtual void UpdateFlyoutFooter()
+		public virtual void UpdateFlyoutFooter()
 		{
 			if (_footerView != null)
 			{
@@ -427,7 +438,7 @@ protected virtual void UpdateFlyoutFooter()
 
 			var footer = ((IShellController)_shellContext.Shell).FlyoutFooter;
 
-			if (footer == null)
+			if (footer is null)
 			{
 				UpdateContentPadding();
 				return;
@@ -592,18 +603,17 @@ void OnFlyoutViewLayoutChanging()
 			}
 		}
 
-		void UpdateVerticalScrollMode()
+		public virtual void UpdateVerticalScrollMode()
 		{
 			if (_flyoutContentView is RecyclerView rv && rv.GetLayoutManager() is ScrollLayoutManager lm)
 			{
 				lm.ScrollVertically = _shellContext.Shell.FlyoutVerticalScrollMode;
 			}
 		}
 
-		protected virtual void UpdateFlyoutBackground()
+		public virtual void UpdateFlyoutBackground()
 		{
 			var brush = _shellContext.Shell.FlyoutBackground;
-
 			if (Brush.IsNullOrEmpty(brush))
 			{
 				var color = _shellContext.Shell.FlyoutBackgroundColor;
@@ -672,7 +682,7 @@ void UpdateFlyoutBgImageAsync()
 			});
 		}
 
-		protected virtual void UpdateFlyoutHeaderBehavior()
+		public virtual void UpdateFlyoutHeaderBehavior()
 		{
 			if (_headerView == null)
 				return;
@@ -737,8 +747,7 @@ internal void Disconnect()
 			if (_shellContext?.Shell != null)
 				_shellContext.Shell.PropertyChanged -= OnShellPropertyChanged;
 
-			if (_flyoutHeader != null)
-				_flyoutHeader.MeasureInvalidated -= OnFlyoutHeaderMeasureInvalidated;
+			_flyoutHeader?.MeasureInvalidated -= OnFlyoutHeaderMeasureInvalidated;
 
 			_flyoutHeader = null;
 
@@ -775,8 +784,7 @@ protected override void Dispose(bool disposing)
 				if (View != null && View is ShellFlyoutLayout sfl)
 					sfl.LayoutChanging -= OnFlyoutViewLayoutChanging;
 
-				if (_headerView != null)
-					_headerView.LayoutChange -= OnHeaderViewLayoutChange;
+				_headerView?.LayoutChange -= OnHeaderViewLayoutChange;
 
 				_contentView?.View = null;
 
@@ -814,8 +822,7 @@ public HeaderContainer(Context context, View view, IMauiContext mauiContext) : b
 
 			void Initialize(View view)
 			{
-				if (view != null)
-					view.PropertyChanged += OnViewPropertyChanged;
+				view?.PropertyChanged += OnViewPropertyChanged;
 			}
 
 			void OnViewPropertyChanged(object sender, PropertyChangedEventArgs e)
@@ -874,11 +881,8 @@ protected override void Dispose(bool disposing)
 
 			internal void Disconnect()
 			{
-				if (View != null)
-				{
-					View.PropertyChanged -= OnViewPropertyChanged;
-					View = null;
-				}
+				View?.PropertyChanged -= OnViewPropertyChanged;
+				View = null;
 			}
 
 			internal void SetFlyoutHeaderBehavior(FlyoutHeaderBehavior flyoutHeaderBehavior)
@@ -984,4 +988,4 @@ public override bool CanScrollVertically()
 			}
 		}
 	}
-}
+}

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellSearchViewAdapter.cs

@@ -154,6 +154,11 @@ class CustomFilter : Filter
 		{
 			private readonly BaseAdapter _adapter;
 
+			// Required by Android JNI bridge for native handle activation
+			protected CustomFilter(IntPtr javaReference, global::Android.Runtime.JniHandleOwnership transfer) : base(javaReference, transfer)
+			{
+			}
+
 			public CustomFilter(BaseAdapter adapter)
 			{
 				_adapter = adapter;
@@ -169,7 +174,7 @@ protected override FilterResults PerformFiltering(ICharSequence constraint)
 
 			protected override void PublishResults(ICharSequence constraint, FilterResults results)
 			{
-				_adapter.NotifyDataSetChanged();
+				_adapter?.NotifyDataSetChanged();
 			}
 		}
 

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellToolbarAppearanceTracker.cs

@@ -20,6 +20,11 @@ public ShellToolbarAppearanceTracker(IShellContext shellContext)
 
 		public virtual void SetAppearance(AToolbar toolbar, IShellToolbarTracker toolbarTracker, ShellAppearance appearance)
 		{
+			if (appearance is null)
+			{
+				return;
+			}
+
 			var foreground = appearance.ForegroundColor;
 			var background = appearance.BackgroundColor;
 			var titleColor = appearance.TitleColor;

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellToolbarTracker.cs

@@ -31,6 +31,7 @@
 using Paint = Android.Graphics.Paint;
 using R = Android.Resource;
 
+#pragma warning disable IDE0031 // Use null propagation
 namespace Microsoft.Maui.Controls.Platform.Compatibility
 {
 	public class ShellToolbarTracker : Java.Lang.Object, AView.IOnClickListener, IShellToolbarTracker, IFlyoutBehaviorObserver
@@ -102,7 +103,10 @@ public bool CanNavigateBack
 		{
 			get
 			{
-				if (_page?.Navigation?.NavigationStack?.Count > 1)
+				var navStackCount = _page?.Navigation?.NavigationStack?.Count ?? 0;
+				var canNavFromStack = navStackCount > 1;
+
+				if (canNavFromStack)
 					return true;
 
 				return _canNavigateBack;
@@ -478,7 +482,9 @@ protected virtual async void UpdateLeftBarButtonItem(Context context, AToolbar t
 				defaultDrawerArrowDrawable = true;
 			}
 
-			icon?.Progress = (CanNavigateBack) ? 1 : 0;
+			var canNav = CanNavigateBack;
+			var progress = canNav ? 1 : 0;
+			icon?.Progress = progress;
 
 			if (command != null || CanNavigateBack)
 			{
@@ -507,6 +513,11 @@ protected virtual async void UpdateLeftBarButtonItem(Context context, AToolbar t
 
 			_drawerToggle.SyncState();
 
+			// Re-apply icon Progress AFTER SyncState since SyncState resets it to 0
+			if (icon is not null)
+			{
+				icon.Progress = progress;
+			}
 
 			//this needs to be set after SyncState
 			UpdateToolbarIconAccessibilityText(toolbar, _shell);
@@ -651,6 +662,18 @@ protected virtual void UpdateToolbarItems(AToolbar toolbar, Page page)
 			if (SearchHandler != null && SearchHandler.SearchBoxVisibility != SearchBoxVisibility.Hidden)
 			{
 				var context = ShellContext.AndroidContext;
+
+				// If the SearchHandler changed (e.g., navigating between pages with different SearchHandlers),
+				// dispose the old search view so it gets recreated with the new handler's icons/settings.
+				if (_searchView != null && _searchView.SearchHandler != SearchHandler)
+				{
+					_searchView.View.RemoveFromParent();
+					_searchView.View.ViewAttachedToWindow -= OnSearchViewAttachedToWindow;
+					_searchView.SearchConfirmed -= OnSearchConfirmed;
+					_searchView.Dispose();
+					_searchView = null;
+				}
+
 				if (_searchView == null)
 				{
 					_searchView = GetSearchView(context);
@@ -691,6 +714,13 @@ protected virtual void UpdateToolbarItems(AToolbar toolbar, Page page)
 			}
 			else
 			{
+				// BUG FIX: Remove the collapsible search menu item when navigating to a page without SearchHandler
+				// Previously, only _searchView was cleaned up, but the menu item remained visible
+				if (menu.FindItem(_placeholderMenuItemId) is not null)
+				{
+					menu.RemoveItem(_placeholderMenuItemId);
+				}
+
 				if (_searchView != null)
 				{
 					_searchView.View.RemoveFromParent();