StartStopEventWrapper

src/Uno.UI.RuntimeTests/Tests/Uno_Helpers/Given_StartStopEventWrapper.cs

@@ -13,14 +13,14 @@ public class Given_StartStopEventWrapper
 		[TestMethod]
 		public void When_Default_Event_Null()
 		{
-			var wrapper = new StartStopEventWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
 			Assert.IsNull(wrapper.Event);
 		}
 
 		[TestMethod]
 		public void When_Add_Handler_Event_Not_Null()
 		{
-			var wrapper = new StartStopEventWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
 			wrapper.AddHandler((s, e) => { });
 			Assert.IsNotNull(wrapper.Event);
 		}
@@ -31,7 +31,7 @@ public void When_Add_Remove_Event_Null()
 			void Handler(Accelerometer a, AccelerometerReadingChangedEventArgs e)
 			{
 			}
-			var wrapper = new StartStopEventWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
 			wrapper.AddHandler(Handler);
 			wrapper.RemoveHandler(Handler);
 			Assert.IsNull(wrapper.Event);
@@ -40,7 +40,7 @@ void Handler(Accelerometer a, AccelerometerReadingChangedEventArgs e)
 		[TestMethod]
 		public void When_Remove_On_Empty()
 		{
-			var wrapper = new StartStopEventWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
 			wrapper.RemoveHandler((s, e) => { });
 			Assert.IsNull(wrapper.Event);
 		}
@@ -49,7 +49,7 @@ public void When_Remove_On_Empty()
 		[TestMethod]
 		public void When_Remove_Nonexistent()
 		{
-			var wrapper = new StartStopEventWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>>(() => { }, () => { });
 			wrapper.AddHandler((s, e) => { });
 			wrapper.RemoveHandler((s, e) => { });
 			Assert.IsNotNull(wrapper.Event);
@@ -59,7 +59,7 @@ public void When_Remove_Nonexistent()
 		public void When_Single_Invoked()
 		{
 			var invoked = false;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => { });
 			wrapper.AddHandler((s, e) => invoked = true);
 			Assert.IsFalse(invoked);
 			wrapper.Event?.Invoke(null, EventArgs.Empty);
@@ -71,7 +71,7 @@ public void When_Multiple_Invoked()
 		{
 			var firstInvoked = false;
 			var secondInvoked = false;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => { });
 			wrapper.AddHandler((s, e) => firstInvoked = true);
 			wrapper.AddHandler((s, e) => secondInvoked = true);
 			Assert.IsFalse(firstInvoked);
@@ -90,7 +90,7 @@ void FirstHandler(object sender, EventArgs args)
 				firstInvoked = true;
 			}
 			var secondInvoked = false;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => { });
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => { });
 			wrapper.AddHandler(FirstHandler);
 			wrapper.AddHandler((s, e) => secondInvoked = true);
 			Assert.IsFalse(firstInvoked);
@@ -105,7 +105,7 @@ void FirstHandler(object sender, EventArgs args)
 		public void When_First_Subscriber_OnFirst_Invoked()
 		{
 			var onFirst = false;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => onFirst = true, () => { });
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => onFirst = true, () => { });
 			Assert.IsFalse(onFirst);
 			wrapper.AddHandler((s, e) => { });
 			Assert.IsTrue(onFirst);
@@ -115,7 +115,7 @@ public void When_First_Subscriber_OnFirst_Invoked()
 		public void When_Multiple_Subscribers_OnFirst_Once()
 		{
 			var onFirstCounter = 0;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => onFirstCounter++, () => { });
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => onFirstCounter++, () => { });
 			Assert.AreEqual(0, onFirstCounter);
 			wrapper.AddHandler((s, e) => { });
 			wrapper.AddHandler((s, e) => { });
@@ -134,7 +134,7 @@ void SecondSubscriber(object sender, EventArgs e)
 			}
 
 			var onFirstCounter = 0;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => onFirstCounter++, () => { });
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => onFirstCounter++, () => { });
 			Assert.AreEqual(0, onFirstCounter);
 			wrapper.AddHandler(FirstSubscriber);
 			wrapper.AddHandler(SecondSubscriber);
@@ -153,7 +153,7 @@ void FirstSubscriber(object sender, EventArgs e)
 			{
 			}
 			var onLast = false;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => onLast = true);
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => onLast = true);
 			wrapper.AddHandler(FirstSubscriber);
 			Assert.IsFalse(onLast);
 			wrapper.RemoveHandler(FirstSubscriber);
@@ -171,7 +171,7 @@ void SecondSubscriber(object sender, EventArgs e)
 			{
 			}
 			var onLastCounter = 0;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => onLastCounter++);
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => onLastCounter++);
 			wrapper.AddHandler(FirstSubscriber);
 			wrapper.AddHandler(SecondSubscriber);
 			Assert.AreEqual(0, onLastCounter);
@@ -188,7 +188,7 @@ void FirstSubscriber(object sender, EventArgs e)
 			}
 
 			var onLastCounter = 0;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => onLastCounter++);
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => onLastCounter++);
 			wrapper.AddHandler(FirstSubscriber);
 			Assert.AreEqual(0, onLastCounter);
 			wrapper.RemoveHandler(FirstSubscriber);
@@ -208,7 +208,7 @@ void SecondSubscriber(object sender, EventArgs e)
 			}
 
 			var onLastCounter = 0;
-			var wrapper = new StartStopEventWrapper<EventHandler<EventArgs>>(() => { }, () => onLastCounter++);
+			var wrapper = new StartStopDelegateWrapper<EventHandler<EventArgs>>(() => { }, () => onLastCounter++);
 			wrapper.AddHandler(FirstSubscriber);
 			wrapper.AddHandler(SecondSubscriber);
 			Assert.AreEqual(0, onLastCounter);

src/Uno.UWP/Helpers/StartStopDelegateWrapper.cs

@@ -0,0 +1,74 @@
+#nullable enable
+
+using System;
+
+namespace Uno.Helpers
+{
+	/// <summary>
+	/// Creates a wrapper around a generic event, which needs to be synchronized
+	/// and needs to run an action when first subscriber is added and when
+	/// last subscriber is removed. The operations executed when first subscriber
+	/// is added and last subscriber is removed will execute within
+	/// a synchronization lock, so please avoid blocking within the actions.
+	/// </summary>
+	internal class StartStopDelegateWrapper<TDelegate>
+		where TDelegate : Delegate
+	{
+		private readonly object _syncLock;
+		private readonly Action _onFirst;
+		private readonly Action _onLast;
+
+		/// <summary>
+		/// Creates a new instance of start-stop delegate wrapper.
+		/// </summary>
+		/// <param name="onFirst">Action to run when first subscriber is added.
+		/// This will run within a synchronization lock so it should not involve blocking operations.</param>
+		/// <param name="onLast">Action to run when last subscriber is removed.
+		/// This will run within a synchronization lock so it should not involve blocking operations.</param>
+		/// <param name="sharedLock">Optional shared object to lock on (when multiple events
+		/// rely on the same native platform operation.</param>
+		public StartStopDelegateWrapper(
+			Action onFirst,
+			Action onLast,
+			object? sharedLock = null)
+		{
+			_onFirst = onFirst;
+			_onLast = onLast;
+			_syncLock = sharedLock ?? new object();
+		}
+
+		public TDelegate? Event { get; private set; } = null;
+
+		public object SyncLock => _syncLock;
+
+		public void AddHandler(TDelegate handler)
+		{
+			lock (_syncLock)
+			{
+				var firstSubscriber = Event == null;
+				Event = (TDelegate)Delegate.Combine(Event, handler);
+				if (firstSubscriber)
+				{
+					_onFirst();
+				}
+			}
+		}
+
+		public void RemoveHandler(TDelegate handler)
+		{
+			lock (_syncLock)
+			{
+				if (Event != null)
+				{
+					Event = (TDelegate?)Delegate.Remove(Event, handler);
+					if (Event == null)
+					{
+						_onLast();
+					}
+				}
+			}
+		}
+
+		public bool IsActive => Event != null;
+	}
+}

src/Uno.UWP/Helpers/StartStopEventWrapper.cs

@@ -5,19 +5,11 @@
 namespace Uno.Helpers
 {
 	/// <summary>
-	/// Creates a wrapper around an event, which needs to be synchronized
-	/// and needs to run an action when first subscriber is added and when
-	/// last subscriber is removed. The operations executed when first subscriber
-	/// is added and last subscriber is removed will execute within
-	/// a synchronization lock, so please avoid blocking within the actions.
+	/// Start stop wrapper for EventHandler<T> events.
 	/// </summary>
-	internal class StartStopEventWrapper<TDelegate>
-		where TDelegate : Delegate
+	/// <typeparam name="TEventArgs">Event args type.</typeparam>
+	internal class StartStopEventWrapper<TEventArgs> : StartStopDelegateWrapper<EventHandler<TEventArgs>>
 	{
-		private readonly object _syncLock;
-		private readonly Action _onFirst;
-		private readonly Action _onLast;
-
 		/// <summary>
 		/// Creates a new instance of start-stop event wrapper.
 		/// </summary>
@@ -27,48 +19,16 @@ internal class StartStopEventWrapper<TDelegate>
 		/// This will run within a synchronization lock so it should not involve blocking operations.</param>
 		/// <param name="sharedLock">Optional shared object to lock on (when multiple events
 		/// rely on the same native platform operation.</param>
-		public StartStopEventWrapper(
-			Action onFirst,
-			Action onLast,
-			object? sharedLock = null)
+		public StartStopEventWrapper(Action onFirst, Action onLast, object? sharedLock = null) :
+			base(onFirst, onLast, sharedLock)
 		{
-			_onFirst = onFirst;
-			_onLast = onLast;
-			_syncLock = sharedLock ?? new object();
 		}
 
-		public TDelegate? Event { get; private set; }
-
-		public bool IsActive => Event != null;
-
-		public object SyncLock => _syncLock;
-
-		public void AddHandler(TDelegate handler)
-		{
-			lock (_syncLock)
-			{
-				var firstSubscriber = Event == null;
-				Event = (TDelegate)Delegate.Combine(Event, handler);
-				if (firstSubscriber)
-				{
-					_onFirst();
-				}
-			}
-		}
-
-		public void RemoveHandler(TDelegate handler)
-		{
-			lock (_syncLock)
-			{
-				if (Event != null)
-				{
-					Event = (TDelegate?)Delegate.Remove(Event, handler);
-					if (Event == null)
-					{
-						_onLast();
-					}
-				}
-			}
-		}
+		/// <summary>
+		/// Invokes the event.
+		/// </summary>
+		/// <param name="sender">Sender.</param>
+		/// <param name="args">Args.</param>
+		public void Invoke(object sender, TEventArgs args) => Event?.Invoke(sender, args);
 	}
 }

src/Uno.UWP/Helpers/StartStopTypedEventWrapper.cs

@@ -0,0 +1,35 @@
+#nullable enable
+
+using System;
+using Windows.Foundation;
+
+namespace Uno.Helpers
+{
+	/// <summary>
+	/// Start stop wrapper for TypedEventHandler<T> events.
+	/// </summary>
+	/// <typeparam name="TEventArgs">Event args type.</typeparam>
+	internal class StartStopTypedEventWrapper<TSender, TResult> : StartStopDelegateWrapper<TypedEventHandler<TSender, TResult>>
+	{
+		/// <summary>
+		/// Creates a new instance of start-stop event wrapper.
+		/// </summary>
+		/// <param name="onFirst">Action to run when first subscriber is added.
+		/// This will run within a synchronization lock so it should not involve blocking operations.</param>
+		/// <param name="onLast">Action to run when last subscriber is removed.
+		/// This will run within a synchronization lock so it should not involve blocking operations.</param>
+		/// <param name="sharedLock">Optional shared object to lock on (when multiple events
+		/// rely on the same native platform operation.</param>
+		public StartStopTypedEventWrapper(Action onFirst, Action onLast, object? sharedLock = null) :
+			base(onFirst, onLast, sharedLock)
+		{
+		}
+
+		/// <summary>
+		/// Invokes the event.
+		/// </summary>
+		/// <param name="sender">Sender.</param>
+		/// <param name="args">Args.</param>
+		public void Invoke(TSender sender, TResult args) => Event?.Invoke(sender, args);
+	}
+}