Fix background updating when label hidden #12138

[Beilinson]

Description

There is a bug currently where updating certain label properties with labelPrimitive.showBackground=true and labelPrimitive.show=false will cause the background to disappear after setting labelPrimitive.show=true. The first sandcastle from the linked issue demonstrates this.

Cause

Label backgrounds are removed from the backgroundBillboardCollection when either showBackground=false, show=false, or label.text.length === 0. They are re-added properly, however their width and height is not updated because repositionAllGlyphs() is called ahead of that.

Solution

When hiding the label entirely, don't remove the backgroundBillboard, rather set backgroundBillboard.show = false. In order to prevent useless billboards, do remove if showBackground=false is set explicitly.

Issue number and link

#12138

Testing plan

Link to sandcastle 1

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @Beilinson!

✅ We can confirm we have a CLA on file for you.

[mzschwartz5]

Good start, thanks for identifying the issue and a fix for it!

I have a couple style comments and questions before we merge.

[mzschwartz5]

Oh, also - unit tests! We're definitely going to want some coverage of this edge case you're fixing.