[Wayland-bugs] [Bug 104643] Implement fake mode-setting using wp_viewporter

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104643

Bug ID: 104643
Summary: Implement fake mode-setting using wp_viewporter
Product: Wayland
Version: unspecified
Hardware: Other
OS: All
Status: NEW
Severity: enhancement
Priority: medium
Component: XWayland
Assignee: wayland-***@lists.freedesktop.org
Reporter: ***@posteo.de
QA Contact: xorg-***@lists.x.org

Tracker bug for the experiment to implement fake mode-setting for xwayland. The
idea is to not really set the mode but to make clients believe they can and to
scale their output accordingly.

The main motivation is to work around the fact that a lot of legacy
applications, especially proprietary ones, don't support different screen
resolutions and therefore fail to start in xwayland. This is a regression for a
number of users, potentially preventing them to switch to wayland-based
compositors (e.g. using gnome-X11 instead of gnome-wayland).


Related:
https://bugzilla.gnome.org/show_bug.cgi?id=791405
https://bugzilla.redhat.com/show_bug.cgi?id=1289714

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104643

Robert Mader <***@posteo.de> changed:

What |Removed |Added
----------------------------------------------------------------------------
Depends on| |104644


Referenced Bugs:

https://bugs.freedesktop.org/show_bug.cgi?id=104644
[Bug 104644] Implement randr 1.2 hooks for xwayland

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104643

--- Comment #1 from Robert Mader <***@posteo.de> ---
Just for those interested: development can roughly be followed in the following
repo https://github.com/treba123/xserver/commits/xwayland-fake-mode-viewport

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104643

--- Comment #2 from Robert Mader <***@posteo.de> ---
Just a little update since it's been some time:

The current patch-set (1 and 2) for xwayland and gnome are already quite
promising. Quite a big number of games no get properly detected when they
change their resolution and the rendering is now mostly correct.

The code is still quite static, messy and incomplete though.
Also, while now rendering correctly, the mouse if often restricted to a area
corresponding to the mode which got set, making parts of the surface
inaccessible. But I think that won't be to hard to work around.
Further more I'll have to mess with the gnome fullscreen detection as it
currently doesn't work with this approach.

Anyway, I'm quite confident about the whole thing and although it won't make it
to xserver 1.20 and gnome 3.28, for the next versions it should be possible.

1)
https://github.com/treba123/xserver/commit/4341d12b21f871b41c86f45ddb033b6ba818edbb
2)
https://github.com/treba123/mutter/commit/189f2ae00253f7a099efb7597575438671f74c41

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104643

--- Comment #3 from raneon <***@rainer-finke.de> ---
I've had this issue too on Plasma Wayland with several games on Wine. The only
workaround that I was able to find is to use a virtual wine desktop to
predefine a resolution. But this would need a proper fix from my point of view.