chore: Address comments

Author: MartinZikmund

src/Uno.UI.Composition/Composition/AnimatedImageFrameProvider.skia.cs

@@ -19,7 +19,7 @@ internal sealed class AnimatedImageFrameProvider : IFrameProvider
 	private readonly WeakReference<Action> _onFrameChanged;
 
 	private int _currentFrame;
-	private bool _disposed;
+	private int _disposed;
 
 	// Note: The Timer will keep holding onto the AnimatedImageFrameProvider until stopped (it's a static root).
 	// But we only stop the timer when we dispose AnimatedImageFrameProvider from SkiaCompositionSurface finalizer.
@@ -118,9 +118,8 @@ private void OnTimerCallback(object? state)
 
 	public void Dispose()
 	{
-		if (!_disposed)
+		if (Interlocked.Exchange(ref _disposed, 1) == 0)
 		{
-			_disposed = true;
 			_timer?.Dispose();
 
 			for (int i = 0; i < _images.Length; i++)

src/Uno.UI.Composition/Composition/FrameProviderFactory.skia.cs

@@ -37,7 +37,7 @@ public static bool TryCreate(SKManagedStream stream, Action onFrameChanged, [Not
 
 		var images = GC.AllocateUninitializedArray<SKImage>(frameInfos.Length);
 		var durations = new int[frameInfos.Length];
-		var totalDuration = 0;
+		long totalDuration = 0;
 
 		for (int i = 0; i < frameInfos.Length; i++)
 		{

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_Image.cs

@@ -862,16 +862,23 @@ public async Task When_AnimatedWebP_Changes_Frames()
 			var screenshot1 = await UITestHelper.ScreenShot(image);
 			var pixel1 = screenshot1.GetPixel(screenshot1.Width / 2, screenshot1.Height / 2);
 
-			// Wait long enough for animation to advance (frames are 200ms each).
-			await Task.Delay(400);
-
-			// Take second screenshot - at least one should differ because the animation cycles.
-			var screenshot2 = await UITestHelper.ScreenShot(image);
-			var pixel2 = screenshot2.GetPixel(screenshot2.Width / 2, screenshot2.Height / 2);
+			// Poll until the center pixel changes (animation has frames every 200ms).
+			// Use a polling loop instead of a fixed delay to avoid flakiness on slow CI.
+			var changed = false;
+			var sw = Stopwatch.StartNew();
+			while (sw.Elapsed < TimeSpan.FromSeconds(5))
+			{
+				await Task.Delay(100);
+				var screenshot2 = await UITestHelper.ScreenShot(image);
+				var pixel2 = screenshot2.GetPixel(screenshot2.Width / 2, screenshot2.Height / 2);
+				if (pixel2 != pixel1)
+				{
+					changed = true;
+					break;
+				}
+			}
 
-			// The animated WebP has red, green, blue, yellow, cyan, magenta frames.
-			// After enough delay, the center pixel should have changed color at least once.
-			Assert.AreNotEqual(pixel1, pixel2, "Animated WebP should show different frames over time");
+			Assert.IsTrue(changed, "Animated WebP should show different frames over time");
 		}
 #endif
 	}