Added tracking/capturing/restoration of audio playback state and position.

Harmonia.WinUI/ViewModels/PlayerViewModel.cs

@@ -225,6 +225,20 @@ public partial class PlayerViewModel : ViewModelBase
         _timer.Tick += TickTock;
 
         _dispatcherQueue = DispatcherQueue.GetForCurrentThread();
+
+        TryRestore();
+    }
+
+    private void TryRestore()
+    {
+        if (_audioPlayer.PlayingSong is null)
+            return;
+
+        Song = _audioPlayer.PlayingSong.Song;
+        Position = _audioPlayer.Position;
+        CurrentPosition = _audioPlayer.Position;
+
+        Task.Run(UpdateImage);
     }
 
     #region Event Handlers

Harmonia.WinUI/ViewModels/PlayingSongViewModel.cs

@@ -50,6 +50,17 @@ public partial class PlayingSongViewModel : ViewModelBase
 
         _audioBitmapImageCache = audioBitmapImageCache;
         _dispatcherQueue = DispatcherQueue.GetForCurrentThread();
+
+        TryRestore();
+    }
+
+    private void TryRestore()
+    {
+        if (_audioPlayer.PlayingSong is null)
+            return;
+
+        Song = _audioPlayer.PlayingSong.Song;
+        Task.Run(UpdateImage);
     }
 
     private void OnAudioPlayerPlayingSongChanged(object? sender, PlayingSongChangedEventArgs e)

Harmonia.WinUI/ViewModels/PlaylistDetailViewModel.cs

@@ -220,6 +220,8 @@ public partial class PlaylistDetailViewModel : ViewModelBase
         FilteredPlaylistSongs.CollectionChanged += OnFilteredPlaylistSongsCollectionChanged;
 
         Playlist = _playlistManager.CurrentPlaylist; // Testing
+        PlayingSong = _audioPlayer.PlayingSong; // Testing
+
         UpdateFilteredSongs();
     }