Fix missing Orientation check in VirtualizingStackPanel

[dbriard]

What does the pull request do?

The PR is a fix for a missing orientation check in VirtualizingStackPanel's CalculateMeasureViewport method.
It should solve the following bug: #17125

What is the current behavior?

ListBoxBug.mp4

What is the updated/expected behavior with this PR?

ListBoxOk.mp4

How was the solution implemented (if it's not obvious)?

anchorU = orientation == Orientation.Horizontal ? _scrollToElement.Bounds.Left : _scrollToElement.Bounds.Top;
instead of
anchorU = _scrollToElement.Bounds.Top;

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Breaking changes

None

Obsoletions / Deprecations

Fixed issues

Fixes #17125

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0052154-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[MrJul]

Thanks! Could you please add unit tests?

We already got ScrollIntoView_Correctly_Scrolls_Down_To_A_Page_Of_[Smaller/Larger]_Items for the vertical orientation, that can be used as a base for the horizontal ones.

[dbriard]

Thanks! Could you please add unit tests?

We already got ScrollIntoView_Correctly_Scrolls_Down_To_A_Page_Of_[Smaller/Larger]_Items for the vertical orientation, that can be used as a base for the horizontal ones.

Ok, I'll have a look tomorrow.

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0052188-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[MrJul]

Thank you for adding the tests!
The failures seem to be caused by target.Orientation not being set in CreateUnrootedTarget().

[dbriard]

Thank you for adding the tests! The failures seem to be caused by target.Orientation not being set in CreateUnrootedTarget().

Thank you for the clue. I tried to set the SV Template after changing the scroll Orientation, but that do not work better.

Unfortunatly, I have errors building the Avalonia project, so I cannot debug the Tests.

[MrJul]

Thank you for the clue. I tried to set the SV Template after changing the scroll Orientation, but that do not work better.

Oh, it seems to only miss a target.Orientation = orientation (target being the VirtualizingStackPanel), sorry if that wasn't clear.

Unfortunatly, I have errors building the Avalonia project, so I cannot debug the Tests.

Ensure that the submodules are up-to-date with git submodule update --init --recursive

[dbriard]

git submodule update --init --recursive

Thanks a lot @MrJul
The git command fixed the compilation issue :) and all the tests were green after setting the missing orientation on target!

[avaloniaui-bot]

You can test this PR using the following package version. 11.3.999-cibuild0052443-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[MrJul]

I think you've committed this file by mistake?

[dbriard]

Argh, sorry about that, I fixed it.

[avaloniaui-bot]

You can test this PR using the following package version. 11.3.999-cibuild0052445-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[MrJul]

LGTM, thanks!