Added playing song view. Adding styling to playing song. Fixed caching cancellation issue.

Harmonia.WinUI/ViewModels/PlayingSongViewModel.cs

@@ -0,0 +1,79 @@
+using Harmonia.Core.Models;
+using Harmonia.Core.Player;
+using Harmonia.WinUI.Caching;
+using Microsoft.UI.Dispatching;
+using Microsoft.UI.Xaml.Media.Imaging;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Harmonia.WinUI.ViewModels;
+
+public class PlayingSongViewModel : ViewModelBase
+{
+    private readonly IAudioPlayer _audioPlayer;
+    private readonly IAudioBitmapImageCache _audioBitmapImageCache;
+    private readonly DispatcherQueue _dispatcherQueue;
+
+    private CancellationTokenSource? _songImageCancellationTokenSource;
+
+    private Song? _song;
+    public Song? Song
+    {
+        get
+        {
+            return _song;
+        }
+        private set
+        {
+            SetProperty(ref _song, value);
+        }
+    }
+
+    private BitmapImage? _songImageSource;
+    public BitmapImage? SongImageSource
+    {
+        get
+        {
+            return _songImageSource;
+        }
+        private set
+        {
+            SetProperty(ref _songImageSource, value);
+        }
+    }
+
+    public PlayingSongViewModel(IAudioPlayer audioPlayer, IAudioBitmapImageCache audioBitmapImageCache)
+    {
+        _audioPlayer = audioPlayer;
+        _audioPlayer.PlayingSongChanged += OnAudioPlayerPlayingSongChanged;
+
+        _audioBitmapImageCache = audioBitmapImageCache;
+        _dispatcherQueue = DispatcherQueue.GetForCurrentThread();
+    }
+
+    private void OnAudioPlayerPlayingSongChanged(object? sender, EventArgs e)
+    {
+        Song = _audioPlayer.PlayingSong?.Song;
+        Task.Run(UpdateImage);
+    }
+
+    private async Task UpdateImage()
+    {
+        // TODO: Show default picture
+        if (Song == null)
+            return;
+
+        if (_songImageCancellationTokenSource != null)
+            await _songImageCancellationTokenSource.CancelAsync();
+
+        _songImageCancellationTokenSource = new();
+        CancellationToken cancellationToken = _songImageCancellationTokenSource.Token;
+
+        _dispatcherQueue.TryEnqueue(async () =>
+        {
+            BitmapImage? bitmapImage = await _audioBitmapImageCache.GetAsync(Song, cancellationToken);
+            SongImageSource = bitmapImage;
+        });
+    }
+}