1 files changed, 52 insertions, 0 deletions
diff --git a/src/tests/x11-compositor-checker.c b/src/tests/x11-compositor-checker.c
new file mode 100644
index 000000000..77e415909
--- /dev/null
+++ b/src/tests/x11-compositor-checker.c
@@ -0,0 +1,52 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+/*
+ * Copyright (C) 2022 Alan Jenkins.
+ * Copyright (C) 2023 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+static int
+has_compositor (Display *dpy,
+                int      screen)
+{
+  char prop_name[20];
+
+  snprintf (prop_name, 20, "_NET_WM_CM_S%d", screen);
+  return XGetSelectionOwner (dpy, XInternAtom (dpy, prop_name, False)) != None;
+}
+
+int
+main (void)
+{
+  Display *dpy = XOpenDisplay ("");
+
+  if (has_compositor (dpy, XDefaultScreen (dpy)))
+    {
+      printf ("X11 Compositor is available for display %s.%d\n",
+              DisplayString (dpy), XDefaultScreen (dpy));
+      return 0;
+    }
+
+  printf ("NO X11 Compositor is available for display %s:%d\n",
+          DisplayString (dpy), XDefaultScreen (dpy));
+
+  return 1;
+}