Lottie playback controls

src/Avalonia.Labs.Lottie/Lottie.cs

@@ -53,6 +53,12 @@ public class Lottie : Control
     public static readonly StyledProperty<int> RepeatCountProperty =
         AvaloniaProperty.Register<Lottie, int>(nameof(RepeatCount), Infinity);
 
+    /// <summary>
+    /// Defines the <see cref="AutoPlay"/> property.
+    /// </summary>
+    public static readonly StyledProperty<bool> AutoPlayProperty =
+        AvaloniaProperty.Register<Lottie, bool>(nameof(AutoPlay), true);
+
     /// <summary>
     /// Gets or sets the Lottie animation path.
     /// </summary>
@@ -90,6 +96,25 @@ public int RepeatCount
         set => SetValue(RepeatCountProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets whether the animation should automatically play when loaded.
+    /// </summary>
+    public bool AutoPlay
+    {
+        get => GetValue(AutoPlayProperty);
+        set => SetValue(AutoPlayProperty, value);
+    }
+
+    /// <summary>
+    /// Event triggered when the animation completes.
+    /// </summary>
+    public event EventHandler? AnimationCompleted;
+
+    /// <summary>
+    /// Event triggered when the animation completes a repetition. The event argument is the repetition number.
+    /// </summary>
+    public event EventHandler<int>? AnimationCompletedRepetition;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="Lottie"/> class.
     /// </summary>
@@ -119,7 +144,7 @@ protected override void OnLoaded(RoutedEventArgs e)
         {
             return;
         }
-        
+
         _customVisual = compositor.CreateCustomVisual(new LottieCompositionCustomVisualHandler());
         ElementComposition.SetElementChildVisual(this, _customVisual);
 
@@ -138,11 +163,14 @@ protected override void OnLoaded(RoutedEventArgs e)
         _customVisual.SendHandlerMessage(
             new LottiePayload(
                 LottieCommand.Update,
-                _animation, 
-                Stretch, 
+                _animation,
+                Stretch,
                 StretchDirection));
-
-        Start();
+
+        if (AutoPlay)
+        {
+            Start();
+        }
     }
 
     protected override void OnUnloaded(RoutedEventArgs e)
@@ -167,9 +195,9 @@ private void OnLayoutUpdated(object? sender, EventArgs e)
         _customVisual.Size = new Vector2((float)Bounds.Size.Width, (float)Bounds.Size.Height);
         _customVisual.SendHandlerMessage(
             new LottiePayload(
-                LottieCommand.Update, 
-                _animation, 
-                Stretch, 
+                LottieCommand.Update,
+                _animation,
+                Stretch,
                 StretchDirection));
     }
 
@@ -224,7 +252,11 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
             {
                 _repeatCount = change.GetNewValue<int>();
                 Stop();
-                Start();
+
+                if (AutoPlay)
+                {
+                    Start();
+                }
                 break;
             }
         }
@@ -253,8 +285,8 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
 
     private SkiaSharp.Skottie.Animation? Load(string path, Uri? baseUri)
     {
-        var uri = path.StartsWith("/") 
-            ? new Uri(path, UriKind.Relative) 
+        var uri = path.StartsWith("/")
+            ? new Uri(path, UriKind.Relative)
             : new Uri(path, UriKind.RelativeOrAbsolute);
         if (uri.IsAbsoluteUri && uri.IsFile)
         {
@@ -297,7 +329,10 @@ private void Load(string? path)
             InvalidateArrange();
             InvalidateMeasure();
 
-            Start();
+            if (AutoPlay)
+            {
+                Start();
+            }
         }
         catch (Exception e)
         {
@@ -308,22 +343,72 @@ private void Load(string? path)
         }
     }
 
-    private void Start()
+    /// <summary>
+    /// Starts or resumes the animation.
+    /// </summary>
+    public void Start()
     {
         _customVisual?.SendHandlerMessage(
             new LottiePayload(
                 LottieCommand.Start,
                 _animation,
-                Stretch, 
-                StretchDirection, 
-                _repeatCount));
+                Stretch,
+                StretchDirection,
+                _repeatCount,
+                OnAnimationCompleted: OnAnimationCompleted,
+                OnAnimationCompletedRepetition: OnAnimationCompletedRepetition));
     }
 
-    private void Stop()
+    /// <summary>
+    /// Stops the animation.
+    /// </summary>
+    public void Stop()
     {
         _customVisual?.SendHandlerMessage(new LottiePayload(LottieCommand.Stop));
     }
 
+    /// <summary>
+    /// Pauses the animation.
+    /// </summary>
+    public void Pause()
+    {
+        _customVisual?.SendHandlerMessage(new LottiePayload(LottieCommand.Pause));
+    }
+
+    /// <summary>
+    /// Resumes the animation if paused.
+    /// </summary>
+    public void Resume()
+    {
+        _customVisual?.SendHandlerMessage(new LottiePayload(LottieCommand.Resume));
+    }
+
+    /// <summary>
+    /// Seeks to a given frame in the animation.
+    /// </summary>
+    public void SeekToFrame(float frame)
+    {
+        _customVisual?.SendHandlerMessage(new LottiePayload(LottieCommand.Seek, SeekFrame: frame));
+    }
+
+    /// <summary>
+    /// Seeks to a given progress value between 0 and 1.
+    /// </summary>
+    public void SeekToProgress(float progress)
+    {
+        _customVisual?.SendHandlerMessage(new LottiePayload(LottieCommand.Seek, SeekProgress: progress));
+    }
+
+    private void OnAnimationCompleted()
+    {
+        AnimationCompleted?.Invoke(this, EventArgs.Empty);
+    }
+
+    private void OnAnimationCompletedRepetition(int repetition)
+    {
+        AnimationCompletedRepetition?.Invoke(this, repetition);
+    }
+
     private void DisposeImpl()
     {
         _customVisual?.SendHandlerMessage(new LottiePayload(LottieCommand.Dispose));

src/Avalonia.Labs.Lottie/LottieCommand.cs

@@ -5,5 +5,8 @@ internal enum LottieCommand
     Start,
     Stop,
     Update,
-    Dispose
+    Dispose,
+    Pause,
+    Resume,
+    Seek
 }

src/Avalonia.Labs.Lottie/LottieCompositionCustomVisualHandler.cs

@@ -12,13 +12,16 @@ internal class LottieCompositionCustomVisualHandler : CompositionCustomVisualHan
     private TimeSpan _primaryTimeElapsed, _animationElapsed;
     private TimeSpan? _lastServerTime;
     private bool _running;
+    private bool _paused;
     private SkiaSharp.Skottie.Animation? _animation;
     private Stretch? _stretch;
     private StretchDirection? _stretchDirection;
     private SkiaSharp.SceneGraph.InvalidationController? _ic;
     private readonly object _sync = new();
     private int _repeatCount;
     private int _count;
+    private Action? _onAnimationCompleted;
+    private Action<int>? _onAnimationCompletedRepetition;
 
     public override void OnMessage(object message)
     {
@@ -39,17 +42,52 @@ public override void OnMessage(object message)
             }:
             {
                 _running = true;
+                _paused = false;
                 _lastServerTime = null;
                 _stretch = st;
                 _stretchDirection = sd;
                 _animation = an;
                 _repeatCount = rp;
                 _count = 0;
                 _animationElapsed = TimeSpan.Zero;
+                _onAnimationCompleted = msg.OnAnimationCompleted;
+                _onAnimationCompletedRepetition = msg.OnAnimationCompletedRepetition;
                 RegisterForNextAnimationFrameUpdate();
                 break;
             }
             case
+            {
+                LottieCommand: LottieCommand.Pause
+            }:
+            {
+                _paused = true;
+                break;
+            }
+            case
+            {
+                LottieCommand: LottieCommand.Resume
+            }:
+            {
+                _paused = false;
+                RegisterForNextAnimationFrameUpdate();
+                break;
+            }
+            case
+            {
+                LottieCommand: LottieCommand.Seek
+            }:
+            {
+                if (msg.SeekFrame.HasValue)
+                {
+                    SeekToFrame(msg.SeekFrame.Value);
+                }
+                else if (msg.SeekProgress.HasValue)
+                {
+                    SeekToProgress(msg.SeekProgress.Value);
+                }
+                break;
+            }
+            case
             {
                 LottieCommand: LottieCommand.Update,
                 Stretch: { } st,
@@ -84,16 +122,48 @@ public override void OnMessage(object message)
 
     public override void OnAnimationFrameUpdate()
     {
+        if (!_running || _paused)
+            return;
+
+        if (_lastServerTime.HasValue)
+        {
+            var delta = CompositionNow - _lastServerTime.Value;
+            _primaryTimeElapsed += delta;
+            _animationElapsed += delta;
+        }
+
+        _lastServerTime = CompositionNow;
+
+        GetFrameTime(); // This will handle cycle completion and repetitions
+
         if (!_running)
+            return; // Animation has completed all repetitions
+
+        Invalidate();
+        RegisterForNextAnimationFrameUpdate();
+    }
+
+    private void SeekToFrame(float frame)
+    {
+        if (_animation == null)
+        {
             return;
+        }
 
+        _animationElapsed = TimeSpan.FromSeconds(frame / _animation.Fps);
+        Invalidate();
+        RegisterForNextAnimationFrameUpdate();
+    }
 
-        if (_repeatCount == 0 || (_repeatCount > 0 && _count >= _repeatCount))
+    private void SeekToProgress(float progress)
+    {
+        if (_animation == null)
         {
-            _running = false;
-            _animationElapsed = TimeSpan.Zero;
+            return;
         }
 
+        progress = Math.Min(Math.Max(progress, 0), 1);
+        _animationElapsed = TimeSpan.FromSeconds(_animation.Duration.TotalSeconds * progress);
         Invalidate();
         RegisterForNextAnimationFrameUpdate();
     }
@@ -125,6 +195,19 @@ private double GetFrameTime()
             _ic?.End();
             _ic?.Begin();
             _count++;
+
+            if (_repeatCount != Lottie.Infinity && _count >= _repeatCount)
+            {
+                // Animation has finished all repetitions
+                _running = false;
+                _onAnimationCompleted?.Invoke();
+                return _animation.Duration.TotalSeconds; // Return the last frame
+            }
+
+            // Animation cycle completed, but not finished all repetitions
+            _onAnimationCompletedRepetition?.Invoke(_count);
+
+            frameTime = 0; // Reset frame time for the next cycle
         }
 
         return frameTime;
@@ -183,8 +266,8 @@ public override void OnRender(ImmediateDrawingContext context)
                 _lastServerTime = CompositionNow;
             }
 
-            if (_animation is not { } an 
-                || _stretch is not { } st 
+            if (_animation is not { } an
+                || _stretch is not { } st
                 || _stretchDirection is not { } sd)
             {
                 return;

src/Avalonia.Labs.Lottie/LottiePayload.cs

@@ -1,3 +1,4 @@
+using System;
 using Avalonia.Media;
 
 namespace Avalonia.Labs.Lottie;
@@ -7,4 +8,8 @@ internal record struct LottiePayload(
     SkiaSharp.Skottie.Animation? Animation = null,
     Stretch? Stretch = null,
     StretchDirection? StretchDirection = null,
-    int? RepeatCount = null);
+    int? RepeatCount = null,
+    float? SeekFrame = null,
+    float? SeekProgress = null,
+    Action? OnAnimationCompleted = null,
+    Action<int>? OnAnimationCompletedRepetition = null);