[net11.0][XSG] Trimmable EventTrigger

src/Controls/src/Core/Interactivity/EventTrigger.cs

@@ -1,7 +1,7 @@
 #nullable disable
 using System;
 using System.Collections.Generic;
-using System.Linq;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Maui.Controls.Internals;
@@ -14,26 +14,90 @@ namespace Microsoft.Maui.Controls
 	[ContentProperty("Actions")]
 	public sealed class EventTrigger : TriggerBase
 	{
-		static readonly MethodInfo s_handlerinfo = typeof(EventTrigger).GetRuntimeMethods().Single(mi => mi.Name == "OnEventTriggered" && mi.IsPublic == false);
 		readonly List<WeakReference<BindableObject>> _associatedObjects = new List<WeakReference<BindableObject>>();
-
-		EventInfo _eventinfo;
-
+		readonly IEventSubscriptionStrategy _strategy;
 		string _eventname;
-		Delegate _handlerdelegate;
 
 		/// <summary>
 		/// Initializes a new <see cref="EventTrigger" /> instance.
 		/// </summary>
-		public EventTrigger() : base(typeof(BindableObject))
+		[RequiresUnreferencedCode("EventTrigger uses reflection to subscribe to events. Use EventTrigger.Create<T>() factory methods for trimming-safe alternatives.")]
+#if !NETSTANDARD
+		[RequiresDynamicCode("EventTrigger uses reflection to subscribe to events. Use EventTrigger.Create<T>() factory methods for trimming-safe alternatives.")]
+#endif
+		public EventTrigger()
+			: base(typeof(BindableObject))
+		{
+			_strategy = new ReflectionStrategy(this);
+		}
+
+		private EventTrigger(Func<EventTrigger, IEventSubscriptionStrategy> strategyFactory)
+			: base(typeof(BindableObject))
+		{
+			_strategy = strategyFactory(this);
+		}
+
+#nullable enable
+		/// <summary>
+		/// Creates an AOT-safe EventTrigger for events using <see cref="EventHandler"/>.
+		/// </summary>
+		/// <typeparam name="TBindable">The type of the bindable object that owns the event.</typeparam>
+		/// <param name="eventName">The name of the event to respond to.</param>
+		/// <param name="addHandler">A static lambda to subscribe to the event.</param>
+		/// <param name="removeHandler">A static lambda to unsubscribe from the event.</param>
+		/// <returns>A new EventTrigger instance.</returns>
+		/// <example>
+		/// <code>
+		/// EventTrigger.Create&lt;Button&gt;("Clicked",
+		///     static (b, h) =&gt; b.Clicked += h,
+		///     static (b, h) =&gt; b.Clicked -= h);
+		/// </code>
+		/// </example>
+		public static EventTrigger Create<TBindable>(
+			string eventName,
+			Action<TBindable, EventHandler> addHandler,
+			Action<TBindable, EventHandler> removeHandler) where TBindable : BindableObject
+		{
+			return new EventTrigger(trigger => new StaticStrategy<TBindable>(addHandler, removeHandler, trigger))
+			{
+				Event = eventName
+			};
+		}
+
+		/// <summary>
+		/// Creates an AOT-safe EventTrigger for events using <see cref="EventHandler{TEventArgs}"/>.
+		/// </summary>
+		/// <typeparam name="TBindable">The type of the bindable object that owns the event.</typeparam>
+		/// <typeparam name="TEventArgs">The type of the event arguments.</typeparam>
+		/// <param name="eventName">The name of the event to respond to.</param>
+		/// <param name="addHandler">A static lambda to subscribe to the event.</param>
+		/// <param name="removeHandler">A static lambda to unsubscribe from the event.</param>
+		/// <returns>A new EventTrigger instance.</returns>
+		/// <example>
+		/// <code>
+		/// EventTrigger.Create&lt;Entry, TextChangedEventArgs&gt;("TextChanged",
+		///     static (e, h) =&gt; e.TextChanged += h,
+		///     static (e, h) =&gt; e.TextChanged -= h);
+		/// </code>
+		/// </example>
+		public static EventTrigger Create<TBindable, TEventArgs>(
+			string eventName,
+			Action<TBindable, EventHandler<TEventArgs>> addHandler,
+			Action<TBindable, EventHandler<TEventArgs>> removeHandler)
+			where TBindable : BindableObject
+			where TEventArgs : EventArgs
 		{
-			Actions = new SealedList<TriggerAction>();
+			return new EventTrigger(trigger => new StaticStrategy<TBindable, TEventArgs>(addHandler, removeHandler, trigger))
+			{
+				Event = eventName
+			};
 		}
+#nullable disable
 
 		/// <summary>
 		/// Gets the collection of <see cref="TriggerAction" /> objects to invoke when the event fires.
 		/// </summary>
-		public IList<TriggerAction> Actions { get; }
+		public IList<TriggerAction> Actions { get; } = new SealedList<TriggerAction>();
 
 		/// <summary>
 		/// Gets or sets the name of the event that triggers the actions.
@@ -56,8 +120,7 @@ public string Event
 		internal override void OnAttachedTo(BindableObject bindable)
 		{
 			base.OnAttachedTo(bindable);
-			if (!string.IsNullOrEmpty(Event))
-				AttachHandlerTo(bindable);
+			_strategy.AttachHandlerTo(bindable);
 			_associatedObjects.Add(new WeakReference<BindableObject>(bindable));
 		}
 
@@ -67,7 +130,7 @@ internal override void OnDetachingFrom(BindableObject bindable)
 			{
 				if (wr.TryGetTarget(out var target) && target == bindable)
 				{
-					DetachHandlerFrom(bindable);
+					_strategy.DetachHandlerFrom(bindable);
 					return true;
 				}
 				return false;
@@ -81,32 +144,118 @@ internal override void OnSeal()
 			((SealedList<TriggerAction>)Actions).IsReadOnly = true;
 		}
 
-		void AttachHandlerTo(BindableObject bindable)
+		private void InvokeActions(object sender)
+		{
+			if (sender is not BindableObject bindable)
+				return;
+
+			foreach (TriggerAction action in Actions)
+				action.DoInvoke(bindable);
+		}
+
+#nullable enable
+		private interface IEventSubscriptionStrategy
 		{
-			try
+			void AttachHandlerTo(BindableObject target);
+			void DetachHandlerFrom(BindableObject target);
+		}
+
+		[RequiresUnreferencedCode("Uses reflection to subscribe to events.")]
+#if !NETSTANDARD
+		[RequiresDynamicCode("Uses reflection to subscribe to events.")]
+#endif
+		private sealed class ReflectionStrategy(EventTrigger trigger) : IEventSubscriptionStrategy
+		{
+			private EventInfo? _eventInfo;
+			private Delegate? _handler;
+
+			public void AttachHandlerTo(BindableObject target)
 			{
-				_eventinfo = bindable.GetType().GetRuntimeEvent(Event);
-				_handlerdelegate = ((EventHandler)OnEventTriggered).Method.CreateDelegate(_eventinfo.EventHandlerType, this);
+				if (string.IsNullOrEmpty(trigger.Event))
+					return;
+
+				try
+				{
+					_eventInfo = target.GetType().GetRuntimeEvent(trigger.Event);
+					if (_eventInfo == null)
+					{
+						LogWarning(target);
+						return;
+					}
+
+					// Create a delegate that matches the event's signature
+					var handlerMethod = typeof(ReflectionStrategy).GetMethod(nameof(OnEventTriggered), BindingFlags.NonPublic | BindingFlags.Instance);
+					_handler = handlerMethod!.CreateDelegate(_eventInfo.EventHandlerType!, this);
+					_eventInfo.AddEventHandler(target, _handler);
+				}
+				catch (Exception)
+				{
+					LogWarning(target);
+				}
 			}
-			catch (Exception)
+
+			public void DetachHandlerFrom(BindableObject target)
+			{
+				if (_eventInfo != null && _handler != null)
+					_eventInfo.RemoveEventHandler(target, _handler);
+			}
+
+			private void OnEventTriggered(object? sender, EventArgs e)
+			{
+				trigger.InvokeActions(sender);
+			}
+
+			private void LogWarning(BindableObject target)
 			{
-				MauiLogger<EventTrigger>.Log(LogLevel.Warning, $"Cannot attach EventTrigger to {bindable.GetType()}.{Event}. Check if the handler exists and if the signature is right.");
+				Application.Current?.FindMauiContext()?.CreateLogger<EventTrigger>()?
+					.LogWarning("Cannot attach EventTrigger to {Type}.{Event}. Check if the event exists and the signature is correct.", 
+						target.GetType(), trigger.Event);
 			}
-			if (_eventinfo != null && _handlerdelegate != null)
-				_eventinfo.AddEventHandler(bindable, _handlerdelegate);
 		}
 
-		void DetachHandlerFrom(BindableObject bindable)
+		private sealed class StaticStrategy<TBindable>(
+			Action<TBindable, EventHandler> addHandler,
+			Action<TBindable, EventHandler> removeHandler,
+			EventTrigger trigger)
+				: IEventSubscriptionStrategy
+				where TBindable : BindableObject
 		{
-			if (_eventinfo != null && _handlerdelegate != null)
-				_eventinfo.RemoveEventHandler(bindable, _handlerdelegate);
+			public void AttachHandlerTo(BindableObject target)
+			{
+				if (target is TBindable typedTarget)
+					addHandler(typedTarget, InvokeActions);
+			}
+
+			public void DetachHandlerFrom(BindableObject target)
+			{
+				if (target is TBindable typedTarget)
+					removeHandler(typedTarget, InvokeActions);
+			}
+
+			private void InvokeActions(object? sender, EventArgs e) => trigger.InvokeActions(sender);
 		}
 
-		void OnEventTriggered(object sender, EventArgs e)
+		private sealed class StaticStrategy<TBindable, TEventArgs>(
+			Action<TBindable, EventHandler<TEventArgs>> addHandler,
+			Action<TBindable, EventHandler<TEventArgs>> removeHandler,
+			EventTrigger trigger)
+				: IEventSubscriptionStrategy
+				where TBindable : BindableObject
+				where TEventArgs : EventArgs
 		{
-			var bindable = (BindableObject)sender;
-			foreach (TriggerAction action in Actions)
-				action.DoInvoke(bindable);
+			public void AttachHandlerTo(BindableObject target)
+			{
+				if (target is TBindable typedTarget)
+					addHandler(typedTarget, InvokeActions);
+			}
+
+			public void DetachHandlerFrom(BindableObject target)
+			{
+				if (target is TBindable typedTarget)
+					removeHandler(typedTarget, InvokeActions);
+			}
+
+			private void InvokeActions(object? sender, TEventArgs e) => trigger.InvokeActions(sender);
 		}
 	}
 }

src/Controls/src/Core/PublicAPI/net-android/PublicAPI.Unshipped.txt

@@ -47,3 +47,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~override Microsoft.Maui.Controls.Handlers.Items.MauiRecyclerView<TItemsView, TAdapter, TItemsViewSource>.OnInterceptTouchEvent(Android.Views.MotionEvent e) -> bool
 ~override Microsoft.Maui.Controls.Handlers.Items.MauiRecyclerView<TItemsView, TAdapter, TItemsViewSource>.OnTouchEvent(Android.Views.MotionEvent e) -> bool
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/Core/PublicAPI/net-ios/PublicAPI.Unshipped.txt

@@ -48,3 +48,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~const Microsoft.Maui.Controls.AppThemeBinding.AppThemeResource = "__MAUI_ApplicationTheme__" -> string
 ~override Microsoft.Maui.Controls.Platform.Compatibility.ShellFlyoutRenderer.ViewWillTransitionToSize(CoreGraphics.CGSize toSize, UIKit.IUIViewControllerTransitionCoordinator coordinator) -> void
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/Core/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt

@@ -48,3 +48,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~const Microsoft.Maui.Controls.AppThemeBinding.AppThemeResource = "__MAUI_ApplicationTheme__" -> string
 ~override Microsoft.Maui.Controls.Platform.Compatibility.ShellFlyoutRenderer.ViewWillTransitionToSize(CoreGraphics.CGSize toSize, UIKit.IUIViewControllerTransitionCoordinator coordinator) -> void
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/Core/PublicAPI/net-tizen/PublicAPI.Unshipped.txt

@@ -45,3 +45,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~Microsoft.Maui.Controls.ResourceDictionary.AddFactory(string key, System.Func<object> factory, bool shared = true) -> void
 ~const Microsoft.Maui.Controls.AppThemeBinding.AppThemeResource = "__MAUI_ApplicationTheme__" -> string
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/Core/PublicAPI/net-windows/PublicAPI.Unshipped.txt

@@ -45,3 +45,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~Microsoft.Maui.Controls.ResourceDictionary.AddFactory(string key, System.Func<object> factory, bool shared = true) -> void
 ~const Microsoft.Maui.Controls.AppThemeBinding.AppThemeResource = "__MAUI_ApplicationTheme__" -> string
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/Core/PublicAPI/net/PublicAPI.Unshipped.txt

@@ -45,3 +45,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~Microsoft.Maui.Controls.ResourceDictionary.AddFactory(string key, System.Func<object> factory, bool shared = true) -> void
 ~const Microsoft.Maui.Controls.AppThemeBinding.AppThemeResource = "__MAUI_ApplicationTheme__" -> string
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/Core/PublicAPI/netstandard/PublicAPI.Unshipped.txt

@@ -36,3 +36,5 @@ virtual Microsoft.Maui.Controls.LongPressingEventArgs.GetPosition(Microsoft.Maui
 ~Microsoft.Maui.Controls.ResourceDictionary.AddFactory(System.Type targetType, System.Func<Microsoft.Maui.Controls.Style> factory, bool shared = true) -> void
 ~Microsoft.Maui.Controls.ResourceDictionary.AddFactory(string key, System.Func<object> factory, bool shared = true) -> void
 ~static Microsoft.Maui.Controls.VisualStateManager.GetVisualStateGroups(Microsoft.Maui.Controls.VisualElement visualElement) -> Microsoft.Maui.Controls.VisualStateGroupList
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable>(string! eventName, System.Action<TBindable!, System.EventHandler!>! addHandler, System.Action<TBindable!, System.EventHandler!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!
+static Microsoft.Maui.Controls.EventTrigger.Create<TBindable, TEventArgs>(string! eventName, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! addHandler, System.Action<TBindable!, System.EventHandler<TEventArgs!>!>! removeHandler) -> Microsoft.Maui.Controls.EventTrigger!

src/Controls/src/SourceGen/AnalyzerReleases.Unshipped.md

@@ -31,3 +31,5 @@ MAUIX2011 | XamlParsing | Warning | AmbiguousMemberWithStaticType
 MAUIX2012 | XamlParsing | Error | CSharpExpressionsRequirePreviewFeatures
 MAUIX2013 | XamlParsing | Error | AsyncLambdaNotSupported
 MAUIX2015 | XamlInflation | Warning | DuplicatePropertyAssignment
+MAUIX2016 | XamlInflation | Error | EventTriggerEventNotFound
+MAUIX2017 | XamlInflation | Warning | EventTriggerTargetTypeNotResolved

src/Controls/src/SourceGen/Descriptors.cs

@@ -333,6 +333,22 @@ public static class Descriptors
 			defaultSeverity: DiagnosticSeverity.Warning,
 			isEnabledByDefault: true);
 
+		public static DiagnosticDescriptor EventTriggerEventNotFound = new DiagnosticDescriptor(
+			id: "MAUIX2016",
+			title: new LocalizableResourceString(nameof(MauiGResources.EventTriggerEventNotFoundTitle), MauiGResources.ResourceManager, typeof(MauiGResources)),
+			messageFormat: new LocalizableResourceString(nameof(MauiGResources.EventTriggerEventNotFoundMessage), MauiGResources.ResourceManager, typeof(MauiGResources)),
+			category: "XamlInflation",
+			defaultSeverity: DiagnosticSeverity.Error,
+			isEnabledByDefault: true);
+
+		public static DiagnosticDescriptor EventTriggerTargetTypeNotResolved = new DiagnosticDescriptor(
+			id: "MAUIX2017",
+			title: new LocalizableResourceString(nameof(MauiGResources.EventTriggerTargetTypeNotResolvedTitle), MauiGResources.ResourceManager, typeof(MauiGResources)),
+			messageFormat: new LocalizableResourceString(nameof(MauiGResources.EventTriggerTargetTypeNotResolvedMessage), MauiGResources.ResourceManager, typeof(MauiGResources)),
+			category: "XamlInflation",
+			defaultSeverity: DiagnosticSeverity.Warning,
+			isEnabledByDefault: true);
+
 		// public static BuildExceptionCode TypeResolution = new BuildExceptionCode("XC", 0000, nameof(TypeResolution), "");
 		// public static BuildExceptionCode PropertyResolution = new BuildExceptionCode("XC", 0001, nameof(PropertyResolution), "");
 		// public static BuildExceptionCode MissingEventHandler = new BuildExceptionCode("XC", 0002, nameof(MissingEventHandler), "");