Added playlist view and initial playlist view logic.

Harmonia.UI/ViewModels/PlaylistViewModel.cs

@@ -0,0 +1,65 @@
+using Harmonia.Core.Player;
+using Harmonia.Core.Playlists;
+using System;
+using System.Collections.ObjectModel;
+using System.Threading.Tasks;
+using System.Threading;
+using Avalonia.Media.Imaging;
+using System.Collections.Concurrent;
+using Harmonia.UI.Caching;
+
+namespace Harmonia.UI.ViewModels;
+
+public class PlaylistViewModel : ViewModelBase
+{
+    private readonly IAudioPlayer _audioPlayer;
+    private readonly IAudioBitmapCache _audioBitmapImageCache;
+    private readonly ConcurrentDictionary<string, Bitmap> _bitmapDictionary = [];
+
+    public PlaylistSong? PlayingSong => _audioPlayer.PlayingSong;
+
+    private ObservableCollection<PlaylistSong> _playlistSongs = [];
+    public ObservableCollection<PlaylistSong> PlaylistSongs
+    {
+        get
+        {
+            return _playlistSongs;
+        }
+        set
+        {
+            _playlistSongs = value;
+            OnPropertyChanged();
+        }
+    }
+
+    public PlaylistViewModel(IAudioPlayer audioPlayer, IAudioBitmapCache audioBitmapImageCache)
+    {
+        _audioPlayer = audioPlayer;
+        _audioPlayer.PlaylistChanged += OnAudioPlayerPlaylistChanged;
+        _audioPlayer.PlayingSongChanged += OnAudioPlayerPlayingSongChanged;
+
+        _audioBitmapImageCache = audioBitmapImageCache;
+    }
+
+    private void OnAudioPlayerPlaylistChanged(object? sender, EventArgs e)
+    {
+        PlaylistSong[] playlistSongs = _audioPlayer.Playlist?.Songs.ToArray() ?? [];
+
+        PlaylistSongs = [.. playlistSongs];
+    }
+
+    private void OnAudioPlayerPlayingSongChanged(object? sender, EventArgs e)
+    {
+        OnPropertyChanged(nameof(PlayingSong));
+    }
+
+    public void PlaySong(PlaylistSong playlistSong)
+    {
+        _audioPlayer.LoadAsync(playlistSong, PlaybackMode.LoadAndPlay);
+    }
+
+    public async Task<Bitmap?> GetBitmapAsync(PlaylistSong playlistSong, CancellationToken cancellationToken)
+    {
+        return await _audioBitmapImageCache.GetAsync(playlistSong.Song, cancellationToken);
+    }
+}