Various updates.

Harmonia.WinUI/ViewModels/PlayerViewModel.cs

@@ -12,6 +12,8 @@ using System.ComponentModel;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Input;
+using Windows.System;
+using DispatcherQueue = Microsoft.UI.Dispatching.DispatcherQueue;
 
 namespace Harmonia.WinUI.ViewModels;
 
@@ -20,6 +22,7 @@ public partial class PlayerViewModel : ViewModelBase
     private readonly IAudioPlayer _audioPlayer;
     private readonly IAudioBitmapImageCache _audioBitmapImageCache;
     private readonly DispatcherTimer _timer;
+    private readonly DispatcherQueue _dispatcherQueue;
 
     private CancellationTokenSource? _songImageCancellationTokenSource;
 
@@ -185,6 +188,18 @@ public partial class PlayerViewModel : ViewModelBase
         }
     }
 
+    public bool CanUpdatePosition
+    {
+        get
+        {
+            return _audioPlayer.State != AudioPlaybackState.Stopped;
+        }
+        private set
+        {
+            OnPropertyChanged();
+        }
+    }
+
     public ICommand PlaySongCommand => new RelayCommand(Play);
     public ICommand PauseSongCommand => new RelayCommand(Pause);
     public ICommand StopSongCommand => new RelayCommand(Stop);
@@ -208,6 +223,8 @@ public partial class PlayerViewModel : ViewModelBase
         };
 
         _timer.Tick += TickTock;
+
+        _dispatcherQueue = DispatcherQueue.GetForCurrentThread();
     }
 
     #region Event Handlers
@@ -230,9 +247,13 @@ public partial class PlayerViewModel : ViewModelBase
         _songImageCancellationTokenSource = new();
         CancellationToken cancellationToken = _songImageCancellationTokenSource.Token;
 
-        BitmapImage? bitmapImage = await _audioBitmapImageCache.GetAsync(Song, cancellationToken);
+        //BitmapImage? bitmapImage = await _audioBitmapImageCache.GetAsync(Song, cancellationToken);
 
-        DispatcherQueue.GetForCurrentThread().TryEnqueue(() => SongImageSource = bitmapImage);
+        _dispatcherQueue.TryEnqueue(async () =>
+        {
+            BitmapImage? bitmapImage = await _audioBitmapImageCache.GetAsync(Song, cancellationToken);
+            SongImageSource = bitmapImage;
+        });
     }
 
     private void OnAudioPlayerPropertyChanged(object? sender, PropertyChangedEventArgs e)
@@ -241,6 +262,7 @@ public partial class PlayerViewModel : ViewModelBase
         {
             case nameof(_audioPlayer.State):
                 UpdateTimer();
+                OnPropertyChanged(nameof(CanUpdatePosition));
                 break;
         }
     }

Harmonia.WinUI/ViewModels/PlaylistViewModel.cs

@@ -9,6 +9,7 @@ using Harmonia.WinUI.Storage;
 using Microsoft.UI.Dispatching;
 using Microsoft.UI.Xaml.Media.Imaging;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
@@ -34,6 +35,7 @@ public partial class PlaylistViewModel : ViewModelBase
     private readonly IAudioEngine _audioEngine;
     private readonly IStorageProvider _storageProvider;
     private readonly DispatcherQueue _dispatcherQueue;
+    private readonly ConcurrentDictionary<int, CancellationTokenSource> _imageCancellationTokens = [];
 
     private Timer? _filterTimer;
 
@@ -118,6 +120,9 @@ public partial class PlaylistViewModel : ViewModelBase
     public ICommand RemoveDuplicateSongsCommand => new RelayCommand(RemoveDuplicateSongs);
 
     public bool IsUserUpdating { get; set; }
+    private bool _isUserInitiatingSongChange;
+
+    public event EventHandler? PlayingSongChangedAutomatically;
 
     public PlaylistViewModel(
         IAudioPlayer audioPlayer,
@@ -216,13 +221,34 @@ public partial class PlaylistViewModel : ViewModelBase
     private void OnPlayingSongChanged(object? sender, EventArgs e)
     {
         PlayingSong = _audioPlayer.PlayingSong;
+
+        if (_isUserInitiatingSongChange)
+        {
+            _isUserInitiatingSongChange = false;
+        }
+        else
+        {
+            PlayingSongChangedAutomatically?.Invoke(this, EventArgs.Empty);
+        }
     }
 
     public async Task PlaySongAsync(PlaylistSong playlistSong)
     {
+        _isUserInitiatingSongChange = true;
         await _audioPlayer.LoadAsync(playlistSong, PlaybackMode.LoadAndPlay);
     }
 
+    public async Task<BitmapImage?> GetBitmapImageAsync(int hashCode, PlaylistSong playlistSong)
+    {
+        _imageCancellationTokens.TryGetValue(hashCode, out CancellationTokenSource? cancellationTokenSource);
+        cancellationTokenSource?.Cancel();
+
+        cancellationTokenSource = new();
+        _imageCancellationTokens.AddOrUpdate(hashCode, cancellationTokenSource, (_,_) => cancellationTokenSource);
+
+        return await _audioBitmapImageCache.GetAsync(playlistSong.Song, cancellationTokenSource.Token);
+    }
+
     public async Task<BitmapImage?> GetBitmapAsync(PlaylistSong playlistSong, CancellationToken cancellationToken)
     {
         return await _audioBitmapImageCache.GetAsync(playlistSong.Song, cancellationToken);
@@ -412,6 +438,9 @@ public partial class PlaylistViewModel : ViewModelBase
 
     private bool CanPasteSongs()
     {
+        if (Playlist == null || SelectedPlaylistSongs.Count == 0)
+            return false;
+
         DataPackageView dataPackageView = Clipboard.GetContent();
 
         if (dataPackageView == null)