feat(skia): Gif support

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

@@ -0,0 +1,145 @@
+#nullable enable
+
+using System;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using SkiaSharp;
+
+namespace Microsoft.UI.Composition;
+
+internal sealed class ImageFrameProvider : IDisposable
+{
+	private readonly SKImage[] _images;
+	private readonly SKCodecFrameInfo[]? _frameInfos;
+	private readonly Timer? _timer;
+	private readonly Stopwatch? _stopwatch;
+	private readonly long _totalDuration;
+	private readonly Action? _onFrameChanged;
+
+	private int _currentFrame;
+	private bool _disposed;
+
+	private ImageFrameProvider(SKImage[] images, SKCodecFrameInfo[]? frameInfos, long totalDuration, Action? onFrameChanged)
+	{
+		_images = images;
+		_frameInfos = frameInfos;
+		_totalDuration = totalDuration;
+		_onFrameChanged = onFrameChanged;
+		Debug.Assert(frameInfos is not null || images.Length == 1);
+		Debug.Assert(totalDuration != 0 || images.Length == 1);
+		Debug.Assert(onFrameChanged is not null || images.Length == 1);
+
+		if (_images.Length == 0)
+		{
+			throw new ArgumentException("Images array shouldn't be empty");
+		}
+
+		if (_images.Length > 1)
+		{
+			_stopwatch = Stopwatch.StartNew();
+			_timer = new Timer(OnTimerCallback, null, dueTime: _frameInfos![0].Duration, period: Timeout.Infinite);
+		}
+	}
+
+	public SKImage? CurrentImage => _images[_currentFrame];
+
+	private int GetCurrentFrameIndex()
+	{
+		var currentTimestampInMilliseconds = _stopwatch!.ElapsedMilliseconds % _totalDuration;
+		for (int i = 0; i < _frameInfos!.Length; i++)
+		{
+			if (currentTimestampInMilliseconds < _frameInfos[i].Duration)
+			{
+				return i;
+			}
+
+			currentTimestampInMilliseconds -= _frameInfos[i].Duration;
+		}
+
+		throw new InvalidOperationException("This shouldn't be reachable. A timestamp in total duration range should map to a frame");
+	}
+
+	private void SetCurrentFrame()
+	{
+		var frameIndex = GetCurrentFrameIndex();
+		if (_currentFrame != frameIndex)
+		{
+			_currentFrame = frameIndex;
+			Debug.Assert(_onFrameChanged is not null);
+			_onFrameChanged();
+		}
+	}
+
+	private void OnTimerCallback(object? state)
+	{
+		SetCurrentFrame();
+
+		var timestamp = _stopwatch!.ElapsedMilliseconds % _totalDuration;
+		var nextFrameTimeStamp = 0;
+		for (int i = 0; i <= _currentFrame; i++)
+		{
+			nextFrameTimeStamp += _frameInfos![i].Duration;
+		}
+
+		var dueTime = nextFrameTimeStamp - timestamp;
+		if (dueTime < 0)
+		{
+			// Defensive check. When pausing the program for debugging, the calculations can go wrong.
+			dueTime = 16;
+		}
+
+		try
+		{
+			_timer!.Change(dueTime, period: Timeout.Infinite);
+		}
+		catch (ObjectDisposedException)
+		{
+		}
+	}
+
+	public static bool TryCreate(SKCodec codec, Action onFrameChanged, [NotNullWhen(true)] out ImageFrameProvider? provider)
+	{
+		var imageInfo = codec.Info;
+		var frameInfos = codec.FrameInfo;
+		imageInfo = new SKImageInfo(imageInfo.Width, imageInfo.Height, SKColorType.Bgra8888, SKAlphaType.Premul);
+		var bitmap = new SKBitmap(imageInfo);
+		var images = GC.AllocateUninitializedArray<SKImage>(frameInfos.Length);
+		var totalDuration = 0;
+		for (int i = 0; i < frameInfos.Length; i++)
+		{
+			var options = new SKCodecOptions(i);
+			codec.GetPixels(imageInfo, bitmap.GetPixels(), options);
+			var currentBitmap = SKImage.FromBitmap(bitmap);
+			if (currentBitmap is null)
+			{
+				provider = null;
+				return false;
+			}
+
+			images[i] = currentBitmap;
+			totalDuration += frameInfos[i].Duration;
+		}
+
+		provider = new ImageFrameProvider(images, frameInfos, totalDuration, onFrameChanged);
+		return true;
+	}
+
+	public static ImageFrameProvider Create(SKImage image)
+		=> new([image], null, 0, null);
+
+	public void Dispose()
+	{
+		if (!_disposed)
+		{
+			_timer?.Dispose();
+			_disposed = true;
+			GC.SuppressFinalize(this);
+		}
+	}
+
+	~ImageFrameProvider()
+	{
+		Dispose();
+	}
+}

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

@@ -1,36 +1,40 @@
 #nullable enable
 
-
 using SkiaSharp;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Runtime.CompilerServices;
 using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
 using Uno.Extensions;
 using Uno.Foundation.Logging;
+using Uno.UI.Dispatching;
 using Windows.Graphics;
 
 namespace Microsoft.UI.Composition
 {
 	internal partial class SkiaCompositionSurface : CompositionObject, ICompositionSurface
 	{
-		// Don't use field directly. Instead, use Image property.
-		private SKImage? _image;
+		private ImageFrameProvider? _frameProvider;
 
-		public SKImage? Image
+		private ImageFrameProvider? FrameProvider
 		{
-			get => _image;
-			private set
+			get => _frameProvider;
+			set
 			{
-				_image = value;
-				OnPropertyChanged(nameof(Image), isSubPropertyChange: false);
+				_frameProvider?.Dispose();
+				_frameProvider = value;
 			}
 		}
 
+		public SKImage? Image => FrameProvider?.CurrentImage;
+
 		internal SkiaCompositionSurface(SKImage image)
 		{
-			Image = image;
+			_frameProvider = ImageFrameProvider.Create(image);
 		}
 
 		internal (bool success, object nativeResult) LoadFromStream(Stream imageStream) => LoadFromStream(null, null, imageStream);
@@ -54,7 +58,7 @@ internal SkiaCompositionSurface(SKImage image)
 
 				if (result == SKCodecResult.Success)
 				{
-					Image = SKImage.FromBitmap(bitmap);
+					FrameProvider = ImageFrameProvider.Create(SKImage.FromBitmap(bitmap));
 				}
 
 				return (result == SKCodecResult.Success || result == SKCodecResult.IncompleteInput, result);
@@ -63,13 +67,20 @@ internal SkiaCompositionSurface(SKImage image)
 			{
 				try
 				{
-					Image = SKImage.FromEncodedData(stream);
-					return Image is null
-						? (false, "Failed to decode image")
-						: (true, "Success");
+					using var codec = SKCodec.Create(stream);
+					var onFrameChanged = () => NativeDispatcher.Main.Enqueue(() => OnPropertyChanged(nameof(Image), isSubPropertyChange: false), NativeDispatcherPriority.High);
+					if (!ImageFrameProvider.TryCreate(codec, onFrameChanged, out var provider))
+					{
+						FrameProvider = null;
+						return (false, "Failed to decode image");
+					}
+
+					FrameProvider = provider;
+					return (true, "Success");
 				}
 				catch (Exception e)
 				{
+					FrameProvider = null;
 					return (false, e.Message);
 				}
 			}
@@ -84,8 +95,14 @@ internal unsafe void CopyPixels(int pixelWidth, int pixelHeight, ReadOnlyMemory<
 
 			using (var pData = data.Pin())
 			{
-				Image = SKImage.FromPixelCopy(info, (IntPtr)pData.Pointer, pixelWidth * 4);
+				FrameProvider = ImageFrameProvider.Create(SKImage.FromPixelCopy(info, (IntPtr)pData.Pointer, pixelWidth * 4));
 			}
 		}
+
+		private protected override void DisposeInternal()
+		{
+			base.DisposeInternal();
+			FrameProvider = null;
+		}
 	}
 }

src/Uno.UI/UI/Xaml/Controls/Image/Image.skia.cs

@@ -34,6 +34,7 @@ partial void OnSourceChanged(ImageSource newValue, bool forceReload)
 			_sourceDisposable.Disposable = null;
 			_lastMeasuredSize = default;
 			_imageSprite.Brush = null;
+			_currentSurface?.Dispose();
 			_currentSurface = null;
 			_pendingImageData = new();
 			InvalidateMeasure();
@@ -138,6 +139,7 @@ private void TryProcessPendingSource()
 			_pendingImageData = new();
 			if (currentData.HasData)
 			{
+				_currentSurface?.Dispose();
 				_currentSurface = currentData.CompositionSurface;
 				_surfaceBrush = Visual.Compositor.CreateSurfaceBrush(_currentSurface);
 				_surfaceBrush.UsePaintColorToColorSurface = MonochromeColor is not null;