Fix UI freeze while loading clip

SentryReplay.Tests/VideoPlayerControllerTests.cs

@@ -236,6 +236,31 @@ public async Task PlaybackSpeed_AppliesToExistingAndFuturePlayers()
         back.Speed.ShouldBe(1.0);
     }
 
+    [Fact]
+    public async Task GoToClipAsync_ShowsLoadingWhileCurrentClipStops()
+    {
+        using var firstClipFiles = TestClipFiles.Create(chunkCount: 1);
+        using var secondClipFiles = TestClipFiles.Create(chunkCount: 1);
+        var front = new FakeCameraPlayer();
+        using var controller = CreateController(front);
+
+        controller.LoadClips([firstClipFiles.Clip, secondClipFiles.Clip]);
+        controller.Playlist.MoveTo(0);
+        await WaitUntilAsync(() => front.PlayCount > 0);
+
+        front.StopGate = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        var changeClipTask = controller.GoToClipAsync(secondClipFiles.Clip);
+
+        await WaitUntilAsync(() => front.StopCount > 0);
+
+        controller.IsLoading.ShouldBeTrue();
+
+        front.StopGate.SetResult(null);
+        await changeClipTask;
+        await WaitUntilAsync(() => controller.CurrentClip == secondClipFiles.Clip);
+    }
+
     [Fact]
     public async Task LoadClipsAsync_StopsCurrentPlaybackAndResetsSelection()
     {
@@ -292,6 +317,7 @@ private sealed class FakeCameraPlayer : ICameraPlayer
         public List<TimeSpan> SeekPositions { get; } = [];
         public bool OpenResult { get; init; } = true;
         public bool ThrowOnStop { get; init; }
+        public TaskCompletionSource<object> StopGate { get; set; }
         public bool IsOpen { get; private set; }
         public double Speed { get; set; } = 1.0;
         public int PlayCount { get; private set; }
@@ -328,6 +354,11 @@ public Task PauseAsync()
         public Task StopAsync()
         {
             StopCount++;
+            if (StopGate is not null)
+            {
+                return StopGate.Task;
+            }
+
             return ThrowOnStop
                 ? Task.FromException(new InvalidOperationException("stop failed"))
                 : Task.CompletedTask;

SentryReplay/MainWindow.xaml.cs

@@ -7,6 +7,7 @@
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Navigation;
+using System.Windows.Threading;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using FlyleafLib.Controls.WPF;
@@ -535,13 +536,16 @@ private async Task PlaySelectedClipAsync()
             return;
 
         ClearError();
+        IsLoading = true;
+        await Dispatcher.Yield(DispatcherPriority.Background);
 
         try
         {
             await _playerController.GoToClipAsync(SelectedClip);
         }
         catch (Exception ex)
         {
+            IsLoading = false;
             Log.Error(
                 ex,
                 "Failed to play selected clip. ClipName={ClipName}; ClipPath={ClipPath}",

SentryReplay/Playback/FlyleafCameraPlayer.cs

@@ -99,14 +99,12 @@ public Task PauseAsync()
 
     public Task StopAsync()
     {
-        StopAndClose();
-        return Task.CompletedTask;
+        return Task.Run(StopAndClose);
     }
 
     public Task CloseAsync()
     {
-        StopAndClose();
-        return Task.CompletedTask;
+        return Task.Run(StopAndClose);
     }
 
     public Task SeekAsync(TimeSpan position)

SentryReplay/Playback/VideoPlayerController.cs

@@ -214,7 +214,7 @@ public async Task NextAsync()
         if (!Playlist.HasNext)
             return;
 
-        await StopAsync();
+        await PrepareForClipChangeAsync();
         Playlist.MoveNext();
     }
 
@@ -223,27 +223,25 @@ public async Task PreviousAsync()
         if (!Playlist.HasPrevious)
             return;
 
-        await StopAsync();
+        await PrepareForClipChangeAsync();
         Playlist.MovePrevious();
     }
 
     public async Task GoToClipAsync(CamClip clip)
     {
-        if (clip is null || clip == Playlist.CurrentClip)
+        if (clip is null || clip == Playlist.CurrentClip || !Playlist.Clips.Contains(clip))
             return;
 
-        BeginNewRequest();
-        await StopAsync();
+        await PrepareForClipChangeAsync();
         Playlist.MoveTo(clip);
     }
 
     public async Task GoToClipAsync(int index)
     {
-        if (index == Playlist.CurrentIndex)
+        if (index == Playlist.CurrentIndex || index < 0 || index >= Playlist.Clips.Count)
             return;
 
-        BeginNewRequest();
-        await StopAsync();
+        await PrepareForClipChangeAsync();
         Playlist.MoveTo(index);
     }
 
@@ -334,6 +332,21 @@ private void CancelAndDisposePlaybackCts()
         cts.Dispose();
     }
 
+    private async Task PrepareForClipChangeAsync()
+    {
+        BeginNewRequest();
+        CancelAndDisposePlaybackCts();
+        ErrorMessage = null;
+        IsLoading = true;
+
+        await Task.Yield();
+
+        await RunSerializedPlaybackOperationAsync(async _ =>
+        {
+            await StopPlaybackInternalAsync(resetTimeline: true, clearLoading: false);
+        });
+    }
+
     private async Task PlayInternalAsync(long requestId, CamClip clip)
     {
         if (clip is null)
@@ -399,7 +412,7 @@ await RunSerializedPlaybackOperationAsync(async ct =>
         }
     }
 
-    private async Task StopPlaybackInternalAsync(bool resetTimeline)
+    private async Task StopPlaybackInternalAsync(bool resetTimeline, bool clearLoading = true)
     {
         Volatile.Write(ref _currentMediaRequestId, 0);
         await StopAndClosePlayersAsync();
@@ -410,7 +423,11 @@ private async Task StopPlaybackInternalAsync(bool resetTimeline)
 
         if (resetTimeline)
         {
-            IsLoading = false;
+            if (clearLoading)
+            {
+                IsLoading = false;
+            }
+
             IsPlaying = false;
             Position = TimeSpan.Zero;
             Duration = TimeSpan.Zero;