Does Avalonia not support Wayland

[PulpFiction98]

I found that Avalonia is still using X11 on a Linux system using Wayland

[DoubleDBE]

Which is a good thing. Wayland has its annoying limitations.

[DoubleDBE]

Well for example absolute window positioning programmatically (and other stuff).

If I remember correctly it's up to the implementer to allow this or provide an API for it.

I'm not sure how "low level" Avalonia goes, hence the scepticism about wayland.

If Avalonia goes wayland but still has a way to position / have full control over a window, fine by me!

[thevortexcloud]

Well for example absolute window positioning programmatically (and other stuff).

This always comes up but it's far more complicated than it sounds due to Wayland trying to support everything. EG a simple desktop might only have X and Y coordinates. But a VR display might have X, Y and Z and no practical "display bounds". Similarly, on non rectangular displays you need a completely different coordinate system than you do on a rectangular one (and any program that assumes a square display also wont work properly). A less niche case is things like tiling window managers which will never properly support placing things in exact positions.

The current approach which is still being discussed is to instead allow for placing windows into "zones". Which are somewhat vaguely defined and is up to the compositor to decide what each zone is.

https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/264

Wayland itself however does not prohibit something adding absolute positioning support, it's just up to the compositor to implement it. EG The IVI shell does add support for some more advanced window layouts.

https://wayland.pages.freedesktop.org/weston/toc/ivi-shell.html

There are also things like Kiosk compositors which make zero sense to have any concept of a window. EG

https://github.com/cage-kiosk/cage?tab=readme-ov-file

The problem most people have with Wayland is that they are thinking backwards and like X11.

[DoubleDBE]

Well for example absolute window positioning programmatically (and other stuff).

This always comes up but it's far more complicated than it sounds due to Wayland trying to support everything. EG a simple desktop might only have X and Y coordinates. But a VR display might have X, Y and Z and no practical "display bounds". Similarly, on non rectangular displays you need a completely different coordinate system than you do on a rectangular one (and any program that assumes a square display also wont work properly). A less niche case is things like tiling window managers which will never properly support placing things in exact positions.

Wayland itself however does not prohibit something adding absolute positioning support, it's just up to the compositor to implement it.

Okay but how does Avalonia fit in here? Is Avalonia a "compositor"?

[thevortexcloud]

No. Avalonia is not a compositor (although I guess it would be possible to implement one using Avalonia? Not sure why you would though). Compositor is just the Wayland term for a server that implements Wayland (and generally handles window management). Avalonia would be a Wayland client. The server can expose what ever extensions it wants clients to use. Obviously, if it's not part of the core protocol it's not particularly portable though. But there are already a lot of desktop and non desktop specific Wayland extensions programs are already making extensive use of. EG KDE has server side decorations.

https://wayland.app/protocols/kde-server-decoration

[DoubleDBE]

Seems like a fun thing to maintain 😅 Seems like it's all very "if this && if that && if so, we're good!"

But it might be due to my lack of knowledge about this stuff, so please forgive me if i'm a bit short sighted about this.

Thanks for the information though 👌

[thevortexcloud]

There was a port in progress. But it's not clear when/if it will release. It has been in development for awhile and the PR for it was closed.

#11546.

[PulpFiction98]

I saw this issue when embedding an SDL3 window with Avalonia. Although I was using Wayland, Avalonia created an X11 handle for me

[thevortexcloud]

Avalonia is currently X11 only (or XWayland). Native Wayland may happen one day though.

[PulpFiction98]

You seem to have a lot of research on X11 and Wayland. Would you be interested in helping me take a look at the problems I encountered?
libsdl-org/SDL#12221
If you have any ideas, thank you very much

[thevortexcloud]

Unfortunately I am not a Wayland expert (in fact I have never made a program to use it directly). I just tend to pay attention to these sorts of things. XWayland is supposed to work more or less the same as regular X11 does from an application perspective (after all, it's a compatibility layer to make X programs work on Wayland).

That said, from memory SDL has many different backends. Perhaps you specifically need to specifically enable the X11 one? I seem to recall that SDL3 switched to using Wayland by default (after trying several times to do the same for SDL2 but failing). I have not touched SDL3 before so I am not sure how to do that, but in SDL2 you can either do it via an environment variable or code.

https://wiki.libsdl.org/SDL2/FAQUsingSDL
https://wiki.libsdl.org/SDL2/SDL_VideoInit

[PulpFiction98]

Thanks