ScrollIntoView has one row offset, if scroll backwards

[VisualAlf]

Assume we have a collection with 50 items numbered 1..50. The Table can show 10 items at a time.

Now when we table.ScrollIntoView(<item19>), the item19 shows as the last row in the table.
OK.

But when we have the view start with item35 in the first row and then table.ScrollIntoView(<item19>), the first row shows item20, not item19. That is, scrolling backwards is always one row off.

I checked with the plain ListView so to exclude a (flaw) Winui 3 behavior. Works fine.

[w-ahmad]

this is because of the header row, the ScrollIntoView(object item) doesn't take care of this behavior. The method itself is not overridable. I use a ScrollRowIntoView(int index) method to overcome this issue but the method is private. I can make it visible if that works for you!

please let me know if there are any other possibilities to do that.

[VisualAlf]

Yes, please. I do need that.

How'd you like something like

    public void ShowRowInView(object? item)
    {
        if (item == null || _scrollViewer is null || Items.IndexOf(item) == -1) return;
        int index = Items.IndexOf(item);

        DispatcherQueue.TryEnqueue(async () =>
        {
            var row = await ScrollRowIntoView(index);
            row?.Focus(FocusState.Programmatic);
        });
    }

So the signature would be the same as for the original void ScrollIntoView(object item)

[w-ahmad]

If the intention is to align the method signature with the base class, it should be ScrollRowIntoView(object item) rather than ShowRowIntoView(object item). However, using an object to scroll a row into view would have drawbacks when there are duplicate items in ItemsSource. See the enhancement I proposed here microsoft/microsoft-ui-xaml#9890.

[VisualAlf]

OK with me.
I checked my recent projects and I found that I nearly all the times scroll to the SelectedItem.
So using the index instead of the object would require an additional lookup.