Add support for grim in wayland sessions

Tests/test_imagegrab.py

@@ -44,6 +44,7 @@ class TestImageGrab:
             sys.platform not in ("win32", "darwin")
             and not shutil.which("gnome-screenshot")
             and not shutil.which("spectacle")
+            and not shutil.which("grim")
         ):
             with pytest.raises(OSError) as e:
                 ImageGrab.grab()

docs/reference/ImageGrab.rst

@@ -16,7 +16,7 @@ or the clipboard to a PIL image memory.
     the entire screen is copied, and on macOS, it will be at 2x if on a Retina screen.
 
     On Linux, if ``xdisplay`` is ``None`` and the default X11 display does not return
-    a snapshot of the screen, ``gnome-screenshot`` or ``spectacle`` will be used as a
+    a snapshot of the screen, ``gnome-screenshot``, ``grim`` or ``spectacle`` will be used as a
     fallback if they are installed. To disable this behaviour, pass ``xdisplay=""``
     instead.
 

src/PIL/ImageGrab.py

@@ -91,6 +91,8 @@ def grab(
                 args = ["gnome-screenshot", "-f"]
             elif shutil.which("spectacle"):
                 args = ["spectacle", "-n", "-b", "-f", "-o"]
+            elif shutil.which("grim"):
+                args = ["grim"]
             else:
                 raise
             fh, filepath = tempfile.mkstemp(".png")