initialize properties on a background thread to not block the UI thread

src/modules/cmdpal/Microsoft.CmdPal.Core.ViewModels/ListViewModel.cs

@@ -67,7 +67,6 @@ public partial class ListViewModel : PageViewModel, IDisposable
 
     private bool _isDynamic;
 
-    private Task? _initializeItemsTask;
     private CancellationTokenSource? _cancellationTokenSource;
     private CancellationTokenSource? _fetchItemsCancellationTokenSource;
 
@@ -200,13 +199,6 @@ public partial class ListViewModel : PageViewModel, IDisposable
             // Check for cancellation before initializing first twenty items
             cancellationToken.ThrowIfCancellationRequested();
 
-            var firstTwenty = newViewModels.Take(20);
-            foreach (var item in firstTwenty)
-            {
-                cancellationToken.ThrowIfCancellationRequested();
-                item?.SafeInitializeProperties();
-            }
-
             // Cancel any ongoing search
             _cancellationTokenSource?.Cancel();
 
@@ -262,18 +254,6 @@ public partial class ListViewModel : PageViewModel, IDisposable
 
         _cancellationTokenSource = new CancellationTokenSource();
 
-        _initializeItemsTask = new Task(() =>
-        {
-            try
-            {
-                InitializeItemsTask(_cancellationTokenSource.Token);
-            }
-            catch (OperationCanceledException)
-            {
-            }
-        });
-        _initializeItemsTask.Start();
-
         DoOnUiThread(
             () =>
             {
@@ -301,32 +281,6 @@ public partial class ListViewModel : PageViewModel, IDisposable
             });
     }
 
-    private void InitializeItemsTask(CancellationToken ct)
-    {
-        // Were we already canceled?
-        ct.ThrowIfCancellationRequested();
-
-        ListItemViewModel[] iterable;
-        lock (_listLock)
-        {
-            iterable = Items.ToArray();
-        }
-
-        foreach (var item in iterable)
-        {
-            ct.ThrowIfCancellationRequested();
-
-            // TODO: GH #502
-            // We should probably remove the item from the list if it
-            // entered the error state. I had issues doing that without having
-            // multiple threads muck with `Items` (and possibly FilteredItems!)
-            // at once.
-            item.SafeInitializeProperties();
-
-            ct.ThrowIfCancellationRequested();
-        }
-    }
-
     /// <summary>
     /// Apply our current filter text to the list of items, and update
     /// FilteredItems to match the results.

src/modules/cmdpal/Microsoft.CmdPal.UI/ExtViews/ListPage.xaml

@@ -276,6 +276,7 @@
                             IsDoubleTapEnabled="True"
                             IsItemClickEnabled="True"
                             ItemClick="Items_ItemClick"
+                            ContainerContentChanging="ItemsList_ContainerContentChanging"
                             ItemTemplate="{StaticResource ListItemViewModelTemplate}"
                             ItemsSource="{x:Bind ViewModel.FilteredItems, Mode=OneWay}"
                             RightTapped="Items_RightTapped"
@@ -295,6 +296,7 @@
                             IsDoubleTapEnabled="True"
                             IsItemClickEnabled="True"
                             ItemClick="Items_ItemClick"
+                            ContainerContentChanging="ItemsList_ContainerContentChanging"
                             ItemTemplateSelector="{StaticResource GridItemTemplateSelector}"
                             ItemsSource="{x:Bind ViewModel.FilteredItems, Mode=OneWay}"
                             RightTapped="Items_RightTapped"

src/modules/cmdpal/Microsoft.CmdPal.UI/ExtViews/ListPage.xaml.cs

@@ -427,4 +427,12 @@ public sealed partial class ListPage : Page,
         Keyboard,
         Pointer,
     }
+
+    private void ItemsList_ContainerContentChanging(ListViewBase sender, ContainerContentChangingEventArgs args)
+    {
+        if (args.Item is ListItemViewModel item)
+        {
+            _ = Task.Run(() => item.SafeInitializeProperties());
+        }
+    }
 }