Optimize large-manifest browsing and archive startup

FModel/Framework/RangeObservableCollection.cs

@@ -2,11 +2,14 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
+using System.ComponentModel;
 
 namespace FModel.Framework;
 
 public sealed class RangeObservableCollection<T> : ObservableCollection<T>
 {
+    private static readonly PropertyChangedEventArgs CountChanged = new(nameof(Count));
+    private static readonly PropertyChangedEventArgs IndexerChanged = new("Item[]");
     private bool _suppressNotification;
 
     protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
@@ -20,15 +23,26 @@ public void AddRange(IEnumerable<T> list)
         if (list == null)
             throw new ArgumentNullException(nameof(list));
 
-        _suppressNotification = true;
-
+        var changed = false;
         foreach (var item in list)
-            Add(item);
+        {
+            Items.Add(item);
+            changed = true;
+        }
+
+        if (!changed || _suppressNotification)
+            return;
 
-        _suppressNotification = false;
+        OnPropertyChanged(CountChanged);
+        OnPropertyChanged(IndexerChanged);
         OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
     }
 
+    /// <summary>
+    /// Adds an item while constructing a collection that has not been published to a binding yet.
+    /// </summary>
+    public void AddWithoutNotification(T item) => Items.Add(item);
+
     public void SetSuppressionState(bool state)
     {
         _suppressNotification = state;
@@ -38,4 +52,4 @@ public void InvokeOnCollectionChanged(NotifyCollectionChangedAction changedActio
     {
         OnCollectionChanged(new NotifyCollectionChangedEventArgs(changedAction));
     }
-}
+}

FModel/MainWindow.xaml

@@ -316,7 +316,7 @@
                                             <MultiBinding StringFormat="{}'{0}' has {1} folders and {2} packages">
                                                 <Binding Path="SelectedItem.Header" ElementName="AssetsFolderName" FallbackValue="None" />
                                                 <Binding Path="SelectedItem.FoldersView.Count" ElementName="AssetsFolderName" FallbackValue="0" />
-                                                <Binding Path="SelectedItem.AssetsList.Assets.Count" ElementName="AssetsFolderName" FallbackValue="0" />
+                                                <Binding Path="SelectedItem.AssetsList.Count" ElementName="AssetsFolderName" FallbackValue="0" />
                                             </MultiBinding>
                                         </TextBlock.Text>
                                     </TextBlock>
@@ -371,7 +371,7 @@
                                         <ColumnDefinition Width="*" />
                                     </Grid.ColumnDefinitions>
 
-                                    <TextBlock Grid.Row="0" Grid.Column="0" Text="{Binding SelectedItem.AssetsList.Assets.Count, ElementName=AssetsFolderName, FallbackValue=0}" VerticalAlignment="Center" HorizontalAlignment="Left" />
+                                    <TextBlock Grid.Row="0" Grid.Column="0" Text="{Binding SelectedItem.AssetsList.Count, ElementName=AssetsFolderName, FallbackValue=0}" VerticalAlignment="Center" HorizontalAlignment="Left" />
                                     <TextBlock Grid.Row="0" Grid.Column="1" Text="Packages Count" VerticalAlignment="Center" HorizontalAlignment="Right" />
                                     <TextBlock Grid.Row="1" Grid.Column="0" Text="{Binding SelectedItem.FoldersView.Count, ElementName=AssetsFolderName, FallbackValue=0}" VerticalAlignment="Center" HorizontalAlignment="Left" />
                                     <TextBlock Grid.Row="1" Grid.Column="1" Text="Folders Count" VerticalAlignment="Center" HorizontalAlignment="Right" />
@@ -386,7 +386,7 @@
                         </Grid>
                     </TabItem>
                     <TabItem Style="{StaticResource TabItemFillSpace}"
-                             Header="{Binding SelectedItem.AssetsList.Assets.Count, FallbackValue=0, ElementName=AssetsFolderName}"
+                             Header="{Binding SelectedItem.AssetsList.Count, FallbackValue=0, ElementName=AssetsFolderName}"
                              HeaderStringFormat="{}{0} Packages">
                         <DockPanel>
 

FModel/MainWindow.xaml.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.IO;
 using System.Linq;
@@ -7,6 +8,8 @@
 using System.Windows.Controls;
 using System.Windows.Controls.Primitives;
 using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Threading;
 using FModel.Services;
 using FModel.Settings;
 using FModel.ViewModels;
@@ -106,6 +109,14 @@ await Task.WhenAll(
             ApplicationViewModel.InitZlib()
         );
 
+        var auxiliaryInitialization = Task.WhenAll(
+            _applicationView.CUE4Parse.InitMappings(),
+            ApplicationViewModel.InitDetex(),
+            ApplicationViewModel.InitVgmStream(),
+            ApplicationViewModel.InitImGuiSettings(newOrUpdated),
+            UserSettings.Default.DecompileLua ? ApplicationViewModel.InitUnluac() : Task.CompletedTask
+        );
+
         await _applicationView.CUE4Parse.Initialize();
         await _applicationView.AesManager.InitAes();
         await _applicationView.UpdateProvider(true);
@@ -116,16 +127,12 @@ await Task.WhenAll(
         await Task.WhenAll(
             _applicationView.CUE4Parse.VerifyConsoleVariables(),
             _applicationView.CUE4Parse.VerifyOnDemandArchives(),
-            _applicationView.CUE4Parse.InitMappings(),
-            ApplicationViewModel.InitDetex(),
-            ApplicationViewModel.InitVgmStream(),
-            ApplicationViewModel.InitImGuiSettings(newOrUpdated),
+            auxiliaryInitialization,
             Task.Run(() =>
             {
                 if (UserSettings.Default.DiscordRpc == EDiscordRpc.Always)
                     _discordHandler.Initialize(_applicationView.GameDisplayName);
-            }),
-            UserSettings.Default.DecompileLua ? ApplicationViewModel.InitUnluac() : Task.CompletedTask
+            })
         ).ConfigureAwait(false);
 
 #if DEBUG
@@ -254,6 +261,9 @@ private void OnAssetsTreeMouseDoubleClick(object sender, MouseButtonEventArgs e)
     private void OnPreviewTexturesToggled(object sender, RoutedEventArgs e) => ItemContainerGenerator_StatusChanged(AssetsExplorer.ItemContainerGenerator, EventArgs.Empty);
     private void ItemContainerGenerator_StatusChanged(object sender, EventArgs e)
     {
+        if (_applicationView.IsAssetPreviewLoadingSuspended)
+            return;
+
         if (sender is not ItemContainerGenerator { Status: GeneratorStatus.ContainersGenerated } generator)
             return;
 
@@ -277,6 +287,94 @@ private void ItemContainerGenerator_StatusChanged(object sender, EventArgs e)
         }
     }
 
+    public void RefreshVisibleAssetPreviews()
+        => ItemContainerGenerator_StatusChanged(AssetsExplorer.ItemContainerGenerator, EventArgs.Empty);
+
+    public async Task<bool> SelectFolderAsync(IReadOnlyList<TreeItem> path)
+    {
+        if (path.Count == 0)
+            return false;
+
+        // Set the complete model path first. A virtualized container will pick up the
+        // expansion state whenever WPF realizes it, independently of UI timing.
+        for (var i = 0; i < path.Count - 1; i++)
+            path[i].IsExpanded = true;
+
+        ItemsControl parent = AssetsFolderName;
+        TreeViewItem container = null;
+
+        for (var i = 0; i < path.Count; i++)
+        {
+            container = await GetTreeViewItemAsync(parent, path[i]);
+            if (container == null)
+                return false;
+
+            // Only ancestors must be expanded. Expanding the target itself can realize a
+            // large child subtree even though Go To never needs to display those children.
+            if (i < path.Count - 1)
+            {
+                container.IsExpanded = true;
+            }
+
+            parent = container;
+        }
+
+        container.IsSelected = false;
+        container.IsSelected = true;
+        await Dispatcher.InvokeAsync(static () => { }, DispatcherPriority.Background);
+        return ReferenceEquals(AssetsFolderName.SelectedItem, path[^1]);
+    }
+
+    private async Task<TreeViewItem> GetTreeViewItemAsync(ItemsControl parent, TreeItem item)
+    {
+        // FoldersView is bound with IsAsync=True. For large sibling collections its sorted
+        // view can take substantially longer than a fixed number of dispatcher turns.
+        var timeoutAt = DateTime.UtcNow + TimeSpan.FromSeconds(15);
+        while (DateTime.UtcNow < timeoutAt)
+        {
+            parent.ApplyTemplate();
+            var presenter = parent.Template.FindName("ItemsHost", parent) as ItemsPresenter ??
+                            FindVisualChild<ItemsPresenter>(parent);
+            if (presenter == null)
+            {
+                parent.UpdateLayout();
+                presenter = FindVisualChild<ItemsPresenter>(parent);
+            }
+
+            presenter?.ApplyTemplate();
+            var index = parent.Items.IndexOf(item);
+            if (index >= 0 && presenter != null && VisualTreeHelper.GetChildrenCount(presenter) > 0 &&
+                VisualTreeHelper.GetChild(presenter, 0) is NavigableVirtualizingStackPanel panel)
+            {
+                _ = panel.Children; // Ensure that the item generator is connected.
+                panel.BringItemIntoView(index);
+                parent.UpdateLayout();
+
+                if (parent.ItemContainerGenerator.ContainerFromIndex(index) is TreeViewItem container)
+                    return container;
+            }
+
+            await Task.Delay(1);
+        }
+
+        return null;
+    }
+
+    private static T FindVisualChild<T>(DependencyObject parent) where T : DependencyObject
+    {
+        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
+        {
+            var child = VisualTreeHelper.GetChild(parent, i);
+            if (child is T match)
+                return match;
+
+            if (FindVisualChild<T>(child) is { } descendant)
+                return descendant;
+        }
+
+        return null;
+    }
+
     private void OnAssetsTreeSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
     {
         if (sender is not TreeView { SelectedItem: TreeItem }) return;
@@ -338,7 +436,7 @@ private async void OnPreviewKeyDown(object sender, KeyEventArgs e)
                 }
 
                 var childFolder = folder;
-                while (childFolder.Folders.Count == 1 && childFolder.AssetsList.Assets.Count == 0)
+                while (childFolder.Folders.Count == 1 && childFolder.AssetsList.Count == 0)
                 {
                     childFolder.IsExpanded = true;
                     childFolder = childFolder.Folders[0];
@@ -360,14 +458,14 @@ private async void OnFoldersPreviewKeyDown(object sender, KeyEventArgs e)
         if (e.Key != Key.Enter || sender is not TreeView treeView || treeView.SelectedItem is not TreeItem folder)
             return;
 
-        if ((folder.IsExpanded || folder.Folders.Count == 0) && folder.AssetsList.Assets.Count > 0)
+        if ((folder.IsExpanded || folder.Folders.Count == 0) && folder.AssetsList.Count > 0)
         {
             _applicationView.SelectedLeftTabIndex++;
             return;
         }
 
         var childFolder = folder;
-        while (childFolder.Folders.Count == 1 && childFolder.AssetsList.Assets.Count == 0)
+        while (childFolder.Folders.Count == 1 && childFolder.AssetsList.Count == 0)
         {
             childFolder.IsExpanded = true;
             childFolder = childFolder.Folders[0];

FModel/ViewModels/ApplicationViewModel.cs

@@ -6,6 +6,7 @@
 using System.Linq;
 using System.Threading.Tasks;
 using System.Windows;
+using System.Windows.Threading;
 using CUE4Parse_Conversion.Textures.BC;
 using CUE4Parse.Compression;
 using CUE4Parse.Encryption.Aes;
@@ -27,6 +28,10 @@ namespace FModel.ViewModels;
 
 public class ApplicationViewModel : ViewModel
 {
+    private readonly object _providerStatusLock = new();
+    private (string Label, string Prefix)? _pendingProviderStatus;
+    private bool _providerStatusScheduled;
+
     private EBuildKind _build;
     public EBuildKind Build
     {
@@ -60,6 +65,8 @@ public bool IsAssetsExplorerVisible
         }
     }
 
+    public bool IsAssetPreviewLoadingSuspended { get; set; }
+
     private int _selectedLeftTabIndex;
     public int SelectedLeftTabIndex
     {
@@ -113,13 +120,13 @@ public ApplicationViewModel()
         CUE4Parse.Provider.VfsRegistered += (sender, count) =>
         {
             if (sender is not IAesVfsReader reader) return;
-            Status.UpdateStatusLabel($"{count} Archives ({reader.Name})", "Registered");
+            QueueProviderStatus($"{count} Archives ({reader.Name})", "Registered");
             CUE4Parse.GameDirectory.Add(reader);
         };
         CUE4Parse.Provider.VfsMounted += (sender, count) =>
         {
             if (sender is not IAesVfsReader reader) return;
-            Status.UpdateStatusLabel($"{count:N0} Packages ({reader.Name})", "Mounted");
+            QueueProviderStatus($"{count:N0} Packages ({reader.Name})", "Mounted");
             CUE4Parse.GameDirectory.Verify(reader);
         };
         CUE4Parse.Provider.VfsUnmounted += (sender, _) =>
@@ -135,6 +142,34 @@ public ApplicationViewModel()
         Status.SetStatus(EStatusKind.Ready);
     }
 
+    private void QueueProviderStatus(string label, string prefix)
+    {
+        lock (_providerStatusLock)
+        {
+            _pendingProviderStatus = (label, prefix);
+            if (_providerStatusScheduled)
+                return;
+
+            _providerStatusScheduled = true;
+        }
+
+        _ = Application.Current.Dispatcher.BeginInvoke(PublishProviderStatus, DispatcherPriority.Background);
+    }
+
+    private void PublishProviderStatus()
+    {
+        (string Label, string Prefix)? update;
+        lock (_providerStatusLock)
+        {
+            update = _pendingProviderStatus;
+            _pendingProviderStatus = null;
+            _providerStatusScheduled = false;
+        }
+
+        if (update is { } status)
+            Status.UpdateStatusLabel(status.Label, status.Prefix);
+    }
+
     public DirectorySettings AvoidEmptyGameDirectory(bool bAlreadyLaunched)
     {
         var gameDirectory = UserSettings.Default.GameDirectory;