Highlight active playlist. Various optimizations and fixes.

Harmonia.WinUI/Views/PlaylistsView.xaml.cs

@@ -1,12 +1,99 @@
+using CommunityToolkit.WinUI;
+using Harmonia.WinUI.ViewModels;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
+using System.ComponentModel;
 
 namespace Harmonia.WinUI.Views;
 
 public sealed partial class PlaylistsView : UserControl
 {
+    private readonly PlaylistsViewModel _viewModel;
+
     public PlaylistsView()
     {
         InitializeComponent();
+
+        _viewModel = (PlaylistsViewModel)DataContext;
+        _viewModel.PropertyChanging += OnViewModelPropertyChanging;
+        _viewModel.PropertyChanged += OnViewModelPropertyChanged;
     }
+
+    private void OnViewModelPropertyChanging(object? sender, PropertyChangingEventArgs e)
+    {
+        switch (e.PropertyName)
+        {
+            case nameof(_viewModel.ActivePlaylist):
+                UpdateListViewItemStyle(PlaylistItemStyle.Normal);
+                break;
+        }
+    }
+
+    private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        switch (e.PropertyName)
+        {
+            case nameof(_viewModel.ActivePlaylist):
+                UpdateListViewItemStyle(PlaylistItemStyle.Selected);
+                break;
+        }
+    }
+
+    private void UpdateListViewItemStyle(PlaylistItemStyle style)
+    {
+        ListViewItem listViewItem = (ListViewItem)PlaylistsListView.ContainerFromItem(_viewModel.ActivePlaylist);
+
+        if (listViewItem is null)
+            return;
+
+        FrameworkElement? frameworkElement = TryGetFrameworkElement(listViewItem, "PlaylistListViewItem");
+
+        if (frameworkElement == null)
+            return;
+
+        string playlistItemIconBrushName = style == PlaylistItemStyle.Selected ? "SelectedPlaylistIconPath" : "PlaylistIconPath";
+        string playlistItemTitleBrushName = style == PlaylistItemStyle.Selected ? "SelectedPlaylistTitleTextBlock" : "PlaylistTitleTextBlock";
+        string playlistItemSubtitleBrushName = style == PlaylistItemStyle.Selected ? "SelectedPlaylistSubtitleTextBlock" : "PlaylistSubtitleTextBlock";
+
+        UpdateElementStyle(frameworkElement, "MusicNoteListPathIcon", playlistItemIconBrushName);
+        UpdateElementStyle(frameworkElement, "PlaylistTitleTextBlock", playlistItemTitleBrushName);
+        UpdateElementStyle(frameworkElement, "PlaylistSubtitleTextBlock", playlistItemSubtitleBrushName);
+    }
+
+    private static FrameworkElement? TryGetFrameworkElement(ListViewItem listViewItem, string elementName)
+    {
+        if (listViewItem.Name == elementName)
+        {
+            return listViewItem;
+        }
+        else
+        {
+            if (listViewItem.FindDescendant(elementName) is not FrameworkElement frameworkElement)
+                return null;
+
+            return frameworkElement;
+        }
+    }
+
+    private void UpdateElementStyle(FrameworkElement dependencyObject, string elementName, string resourceName)
+    {
+        if (dependencyObject.FindDescendant(elementName) is not FrameworkElement frameworkElement)
+            return;
+
+        Resources.TryGetValue(resourceName, out object? resource);
+
+        if (resource == null)
+            Application.Current.Resources.TryGetValue(resourceName, out resource);
+
+        if (resource is not Style style)
+            return;
+
+        frameworkElement.Style = style;
+    }
+}
+
+public enum PlaylistItemStyle
+{
+    Normal,
+    Selected
 }