Detecting Wayland versus X11 with PyGObject

[rmartin16 (Russell Martin)]

Hello, I am looking for a way to detect whether the display is using Wayland or X11 via PyGObject.

It seems GDK is providing macros to manage this in C…but this project is pure Python. I have a few different ideas but they seem a bit fragile since they involve environment variables or inspecting class names. Thank you.

[jfrancis (Jason Francis)]

Hello, here is a simple Gtk4 example.

from gi.repository import Gdk, GdkWayland
gi.require_versions({'Gdk': '4.0', 'GdkWayland': '4.0'})

is_wayland = isinstance(Gdk.Display.get_default(), GdkWayland.WaylandDisplay)

[rmartin16 (Russell Martin)]

Thank you, @jfrancis Alas, this project is limited to Gtk3 currently.

[ebassi (Emmanuele Bassi)]

It is the same in GTK3.

[rmartin16 (Russell Martin)]

That’s promising, @ebassi, thank you.

When I try this with Gtk3, though, I get an error:

>>> import gi
>>> gi.require_version("Gdk", "3.0")
>>> gi.require_version("GdkWayland", "3.0")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/russell/.pyenv/versions/briefcase-3.10/lib/python3.10/site-packages/gi/__init__.py", line 125, in require_version
    raise ValueError('Namespace %s not available for version %s' %
ValueError: Namespace GdkWayland not available for version 3.0

Maybe the inverse is a safe alternative:

>>> from gi.repository import Gdk, GdkX11
>>> 
>>> is_wayland = not isinstance(Gdk.Display.get_default(), GdkX11.X11Display)
>>> is_wayland
False

Clarifications about my understanding are definitely welcome.

[ebassi (Emmanuele Bassi)]

Ah, right: there’s no introspection data for GDK’s Wayland backend in GTK3. You’ll have to check the type name, for instance:

import gi
gi.require_versions({'Gdk': '3.0'})
from gi.repository import GObject, Gdk

Gdk.init([])
d = Gdk.Display.get_default()
print(GObject.type_name(d.__gtype__))

will print out GdkWaylandDisplay if the display connection is using Wayland, and GdkX11Display if the display connection is using X11.

@rmartin16

Maybe the inverse is a safe alternative:

It is; on Linux/Unix, GTK can only either use X11 or Wayland, so if the display instance is not GdkX11Display then GTK is using Wayland.