Added playlist view and initial playlist view logic.

Harmonia.UI/Converters/RepeatStateToIconConverter.cs

@@ -0,0 +1,28 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Data.Converters;
+using Harmonia.Core.Player;
+using System;
+using System.Globalization;
+
+namespace Harmonia.UI.Converters;
+
+public class RepeatStateToIconConverter : IValueConverter
+{
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value is not RepeatState repeatMode)
+            return null;
+
+        string resourceName = repeatMode == RepeatState.RepeatOne
+            ? "RepeatOneIcon"
+            : "RepeatIcon";
+
+        return Application.Current?.FindResource(resourceName);
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        throw new NotImplementedException();
+    }
+}

Harmonia.UI/Converters/VolumeStateToIconConverter.cs

@@ -0,0 +1,37 @@
+using Avalonia.Controls;
+using Avalonia.Data.Converters;
+using Avalonia;
+using Harmonia.UI.Models;
+using System;
+using System.Globalization;
+using Harmonia.Core.Playlists;
+
+namespace Harmonia.UI.Converters;
+
+public class VolumeStateToIconConverter : IValueConverter
+{
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value is not VolumeState volumeState)
+            return AvaloniaProperty.UnsetValue;
+
+        return Application.Current?.FindResource($"Volume{volumeState}Icon") ?? AvaloniaProperty.UnsetValue;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture) => throw new NotImplementedException();
+}
+
+public class PlaylistSongEqualityConverter : IValueConverter
+{
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value is PlaylistSong playingSong && parameter is PlaylistSong currentSong)
+        {
+            return playingSong == currentSong;
+        }
+
+        return false;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture) => throw new NotImplementedException();
+}