Fix "WPF- OxyPlot doesn't render inside a Popup" (#1796)

[Tetedeiench]

Fix "WPF- OxyPlot doesn't render inside a Popup" (#1796)

Fixes #1796 .

Checklist

• I have included examples or tests
• I have updated the change log
• I am listed in the CONTRIBUTORS file
• I have cleaned up the commit history (use rebase and squash)

Changes proposed in this pull request:

• Fix WPF- OxyPlot doesn't render inside a Popup (fix included) WPF- OxyPlot doesn't render inside a Popup (fix included) #1796

@oxyplot/admins

[VisualMelon]

I've tested and the fix looks good to me.

We probably need an example (so that it's easier to test in future); I put a simple example together in https://github.com/VisualMelon/oxyplot/tree/bugfix-wpf-popup which we could use, but if you have a better idea for a use-case that involves popups that would be welcome!

[VisualMelon]

Should ideally have the unrelease/added/changed/fixed/removed sections like in https://raw.githubusercontent.com/oxyplot/oxyplot/StemSeriesActualMarker/CHANGELOG.md , but we can do that separately

[VisualMelon]

(Note to self: need to check the Skia stuff as well)

[VisualMelon]

Fixed Skia stuff in my branch, and added a pointless/fun popup pre-view for the example browser (so we can accidently test popups and Skia scaling at the same time, all the time)

[VisualMelon]

I think I'm happy to merge this; need separate PRs for:

• Skia Fix
• Example of some sort...
• Re-start changelog

Will leave it a little longer for the other maintainers to take a look.

[Tetedeiench]

I'm happy my PR was useful :) Sorry for the changelog, did my best.

Adding a popup in the examples is a great idea 👍

[VisualMelon]

Just to keep you in the loop, I'm somewhat indisposed at the moment, and don't want to hit merge until I have the energy to follow up with the other bits properly. Hopefully I'll be back in action some time in the next few days.

[Jonarw]

Looks good to me, no objections to merging this.

Fixed Skia stuff in my branch, and added a pointless/fun popup pre-view for the example browser (so we can accidently test popups and Skia scaling at the same time, all the time)

Sounds great!

I am wondering: The code until now assumed that at the root of the visual tree is always a Window, which obviously isn't true, because it can also be a PopupRoot. Are there any other possibilities for the root of the visual tree besides these two that we'd want to support?

[AELIENUS]

I am currently testing a solution for ElementHosts with the code provided in this PR. The only addition to this would be to also match to AdornerDecorators in IsInVisualTree. Although i have to test this a little be more. Please check #1800 for reference.

[VisualMelon]

@AELIENUS thanks for following that up!