Tweak Wayland detection for robustness

changes/2777.misc.rst

@@ -0,0 +1 @@
+Toga's determination for whether a Linux host is running X11 or Wayland is now more robust.

gtk/src/toga_gtk/app.py

@@ -1,5 +1,4 @@
 import asyncio
-import os
 import signal
 import sys
 from pathlib import Path
@@ -12,7 +11,7 @@
 from toga.handlers import simple_handler
 
 from .keys import gtk_accel
-from .libs import TOGA_DEFAULT_STYLES, Gdk, Gio, GLib, Gtk
+from .libs import IS_WAYLAND, TOGA_DEFAULT_STYLES, Gdk, Gio, GLib, Gtk
 from .screens import Screen as ScreenImpl
 
 
@@ -206,7 +205,7 @@ def set_main_window(self, window):
 
     def get_screens(self):
         display = Gdk.Display.get_default()
-        if "WAYLAND_DISPLAY" in os.environ:  # pragma: no-cover-if-linux-x
+        if IS_WAYLAND:  # pragma: no-cover-if-linux-x
             # `get_primary_monitor()` doesn't work on wayland, so return as it is.
             return [
                 ScreenImpl(native=display.get_monitor(i))

gtk/src/toga_gtk/libs/gtk.py

@@ -3,13 +3,23 @@
 gi.require_version("Gdk", "3.0")
 gi.require_version("Gtk", "3.0")
 
-from gi.repository import Gdk, GdkPixbuf, Gio, GLib, GObject, Gtk  # noqa: E402, F401
+from gi.repository import (  # noqa: E402, F401
+    Gdk,
+    GdkPixbuf,
+    GdkX11,
+    Gio,
+    GLib,
+    GObject,
+    Gtk,
+)
 
 if Gdk.Screen.get_default() is None:  # pragma: no cover
     raise RuntimeError(
         "Cannot identify an active display. Is the `DISPLAY` environment variable set correctly?"
     )
 
+IS_WAYLAND = not isinstance(Gdk.Display.get_default(), GdkX11.X11Display)
+
 # The following imports will fail if the underlying libraries or their API
 # wrappers aren't installed; handle failure gracefully (see
 # https://github.com/beeware/toga/issues/26)

gtk/src/toga_gtk/screens.py

@@ -1,9 +1,7 @@
-import os
-
 from toga.screens import Screen as ScreenInterface
 from toga.types import Position, Size
 
-from .libs import Gdk
+from .libs import IS_WAYLAND, Gdk
 
 
 class Screen:
@@ -31,7 +29,7 @@ def get_size(self) -> Size:
         return Size(geometry.width, geometry.height)
 
     def get_image_data(self):
-        if "WAYLAND_DISPLAY" in os.environ:  # pragma: no cover
+        if IS_WAYLAND:  # pragma: no cover
             # Not implemented on wayland due to wayland security policies.
             self.interface.factory.not_implemented("Screen.get_image_data() on Wayland")
         else:  # pragma: no-cover-if-linux-wayland

gtk/tests_backend/app.py

@@ -1,11 +1,12 @@
+import os
 from pathlib import Path
 
 import PIL.Image
 import pytest
 
 import toga
 from toga_gtk.keys import gtk_accel, toga_key
-from toga_gtk.libs import Gdk, Gtk
+from toga_gtk.libs import IS_WAYLAND, Gdk, Gtk
 
 from .dialogs import DialogsMixin
 from .probe import BaseProbe
@@ -16,13 +17,14 @@ class AppProbe(BaseProbe, DialogsMixin):
     supports_key_mod3 = True
     # Gtk 3.24.41 ships with Ubuntu 24.04 where present() works on Wayland
     supports_current_window_assignment = not (
-        BaseProbe.IS_WAYLAND and BaseProbe.GTK_VERSION < (3, 24, 41)
+        IS_WAYLAND and BaseProbe.GTK_VERSION < (3, 24, 41)
     )
 
     def __init__(self, app):
         super().__init__()
         self.app = app
         assert isinstance(self.app._impl.native, Gtk.Application)
+        assert IS_WAYLAND is (os.environ.get("WAYLAND_DISPLAY", "") != "")
 
     @property
     def config_path(self):

gtk/tests_backend/probe.py

@@ -1,13 +1,11 @@
 import asyncio
-import os
 
 import toga
 from toga_gtk.libs import Gtk
 
 
 class BaseProbe:
     GTK_VERSION = Gtk.MAJOR_VERSION, Gtk.MINOR_VERSION, Gtk.MICRO_VERSION
-    IS_WAYLAND = os.environ.get("WAYLAND_DISPLAY", "") != ""
 
     def repaint_needed(self):
         return Gtk.events_pending()

gtk/tests_backend/screens.py

@@ -1,7 +1,7 @@
 import pytest
-from gi.repository import GdkX11
 
 from toga.images import Image as TogaImage
+from toga_gtk.libs import IS_WAYLAND, GdkX11
 
 from .probe import BaseProbe
 
@@ -12,15 +12,15 @@ def __init__(self, screen):
         self.screen = screen
         self._impl = screen._impl
         self.native = screen._impl.native
-        if self.IS_WAYLAND:
+        if IS_WAYLAND:
             # The native display type on Wayland is `__gi__.GdkWaylandMonitor`
             # However, that class can't be imported directly.
             pass
         else:
             assert isinstance(self.native, GdkX11.X11Monitor)
 
     def get_screenshot(self, format=TogaImage):
-        if self.IS_WAYLAND:
+        if IS_WAYLAND:
             pytest.skip("Screen.as_image() is not implemented on Wayland.")
         else:
             return self.screen.as_image(format=format)

gtk/tests_backend/widgets/canvas.py

@@ -2,7 +2,7 @@
 
 from PIL import Image
 
-from toga_gtk.libs import Gdk, Gtk
+from toga_gtk.libs import IS_WAYLAND, Gdk, Gtk
 
 from .base import SimpleProbe
 
@@ -12,7 +12,7 @@ class CanvasProbe(SimpleProbe):
 
     def reference_variant(self, reference):
         if reference == "multiline_text":
-            if self.IS_WAYLAND:
+            if IS_WAYLAND:
                 return f"{reference}-gtk-wayland"
             else:
                 return f"{reference}-gtk-x11"

gtk/tests_backend/window.py

@@ -1,4 +1,4 @@
-from toga_gtk.libs import Gdk, Gtk
+from toga_gtk.libs import IS_WAYLAND, Gdk, Gtk
 
 from .dialogs import DialogsMixin
 from .probe import BaseProbe
@@ -12,8 +12,8 @@ class WindowProbe(BaseProbe, DialogsMixin):
     supports_move_while_hidden = False
     supports_unminimize = False
     # Wayland mostly prohibits interaction with the larger windowing environment
-    supports_minimize = not BaseProbe.IS_WAYLAND
-    supports_placement = not BaseProbe.IS_WAYLAND
+    supports_minimize = not IS_WAYLAND
+    supports_placement = not IS_WAYLAND
 
     def __init__(self, app, window):
         super().__init__()