stride3d/stride · error · InvalidOperationException

BringItemToView cannot be used when the tree view is…

Error message

BringItemToView cannot be used when the tree view is virtualizing.

What it means

BringItemToView scrolls a TreeView so a given item is visible by walking parent containers to realize them. This only works with container generation that is not virtualized; when VirtualizingPanel.IsVirtualizing is true, containers for off-screen items do not exist and cannot be generated by this method, so the control throws InvalidOperationException up front instead of failing silently.

Solutions

Set VirtualizingPanel.IsVirtualizing="False" on the TreeView (accepting the performance cost).
Remove/disable the BringItemToView call and instead use container-free navigation (e.g. expand path via the view-model then rely on selection scrolling).
Guard the call: check treeView.IsVirtualizing (or the attached property) before invoking and take an alternate path.

Example fix

// before
treeView.BringItemToView(node, n => vm.GetParent(n));
// after
if (!treeView.IsVirtualizing)
    treeView.BringItemToView(node, n => vm.GetParent(n));
else
    ExpandPathTo(node); // expand ancestors so the container is realized

Defensive patterns

Strategy: validation

Validate before calling

if (treeView.IsVirtualizing)
    throw new NotSupportedException("BringItemToView requires a non-virtualizing TreeView");
treeView.BringItemToView(item, parent => vm.GetParent(parent));

Type guard

bool CanBringToView(TreeView tv) => !tv.IsVirtualizing;

Try / catch

try { treeView.BringItemToView(item, getParent); }
catch (InvalidOperationException ex) when (ex.Message.Contains("virtualizing")) { ExpandPathTo(item); /* fallback */ }

Prevention

Check IsVirtualizing before any programmatic scroll-to-item logic.
If virtualization is on, expand ancestors via the view-model instead of container walking.
Document the virtualization constraint next to any shared BringItemToView helper.

When it happens

Trigger: Calling treeView.BringItemToView(item, getParent) on a TreeView whose virtualization is enabled (VirtualizingPanel.IsVirtualizing=true, e.g. inside a large list with VirtualizingStackPanel), passing non-null item and getParent.

Common situations: Programmatic navigation/selection restore in editor-like trees; code written for a non-virtualized tree later moved into a virtualized layout; enabling virtualization for performance on large trees and existing BringItemToView calls start throwing.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/d756fe58aa40b8d0. Report an issue: GitHub.

Appendix: source

Thrown at sources/presentation/Stride.Core.Presentation.Wpf/Controls/TreeView.cs:158

        {
            base.OnApplyTemplate();

            scroller = DependencyObjectExtensions.CheckTemplatePart<ScrollViewer>(GetTemplateChild(ScrollViewerPartName));
            if (scroller != null)
            {
                scroller.ScrollChanged += ScrollChanged;
            }
        }

        // TODO: This method has been implemented with a lot of fail and retry, and should be cleaned.
        // TODO: Also, it is probably close to work with virtualization, but it needs some testing
        public bool BringItemToView([NotNull] object item, [NotNull] Func<object, object> getParent)
        {
            // Useful link: https://msdn.microsoft.com/en-us/library/ff407130%28v=vs.110%29.aspx
            if (item == null) throw new ArgumentNullException(nameof(item));
            if (getParent == null) throw new ArgumentNullException(nameof(getParent));
            if (IsVirtualizing)
                throw new InvalidOperationException("BringItemToView cannot be used when the tree view is virtualizing.");

            TreeViewItem container = null;

            var path = new List<object> { item };
            var parent = getParent(item);
            while (parent != null)
            {
                path.Add(parent);
                parent = getParent(parent);
            }

            for (var i = path.Count - 1; i >= 0; --i)
            {
                if (container != null)
                    container = (TreeViewItem)container.ItemContainerGenerator.ContainerFromItem(path[i]);
                else
                    container = (TreeViewItem)ItemContainerGenerator.ContainerFromItem(path[i]);

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