core: Add private API to override compositor configuration

Add private API for overriding the compositor configuration, i.e. the
compositor type (X11 WM or Wayland compositor) and backend type. This
will make it possible to add a special test backend used by src/tests/.

https://bugzilla.gnome.org/show_bug.cgi?id=777732

src/backends/meta-backend-private.h

@@ -97,7 +97,7 @@ struct _MetaBackendClass
 
 };
 
-void meta_init_backend (MetaBackendType backend_type);
+void meta_init_backend (GType backend_gtype);
 
 ClutterBackend * meta_backend_get_clutter_backend (MetaBackend *backend);
 

src/backends/meta-backend.c

@@ -796,31 +796,14 @@ meta_get_clutter_backend (void)
 }
 
 void
-meta_init_backend (MetaBackendType backend_type)
+meta_init_backend (GType backend_gtype)
 {
-  GType type;
   MetaBackend *backend;
   GError *error = NULL;
 
-  switch (backend_type)
-    {
-    case META_BACKEND_TYPE_X11:
-      type = META_TYPE_BACKEND_X11;
-      break;
-
-#ifdef HAVE_NATIVE_BACKEND
-    case META_BACKEND_TYPE_NATIVE:
-      type = META_TYPE_BACKEND_NATIVE;
-      break;
-#endif
-
-    default:
-      g_assert_not_reached ();
-    }
-
   /* meta_backend_init() above install the backend globally so
    * so meta_get_backend() works even during initialization. */
-  backend = g_object_new (type, NULL);
+  backend = g_object_new (backend_gtype, NULL);
   if (!g_initable_init (G_INITABLE (backend), NULL, &error))
     {
       g_warning ("Failed to create backend: %s", error->message);

src/core/main-private.h

@@ -0,0 +1,34 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * 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/>.
+ */
+
+#ifndef META_MAIN_PRIVATE_H
+#define META_MAIN_PRIVATE_H
+
+typedef enum _MetaCompositorType
+{
+#ifdef HAVE_WAYLAND
+  META_COMPOSITOR_TYPE_WAYLAND,
+#endif
+  META_COMPOSITOR_TYPE_X11,
+} MetaCompositorType;
+
+void meta_override_compositor_configuration (MetaCompositorType compositor_type,
+                                             GType              backend_gtype);
+
+#endif /* META_MAIN_PRIVATE_H */

src/core/main.c

@@ -52,6 +52,7 @@
 #include <meta/prefs.h>
 #include <meta/compositor.h>
 #include <meta/meta-backend.h>
+#include "core/main-private.h"
 
 #include <glib-object.h>
 #include <glib-unix.h>
@@ -82,10 +83,14 @@
 # endif
 
 #include "backends/meta-backend-private.h"
+#include "backends/x11/meta-backend-x11.h"
 
-#if defined(HAVE_NATIVE_BACKEND) && defined(HAVE_WAYLAND)
+#ifdef HAVE_NATIVE_BACKEND
+#include "backends/native/meta-backend-native.h"
+#ifdef HAVE_WAYLAND
 #include <systemd/sd-login.h>
-#endif
+#endif /* HAVE_WAYLAND */
+#endif /* HAVE_NATIVE_BACKEND */
 
 /*
  * The exit code we'll return to our parent process when we eventually die.
@@ -394,7 +399,7 @@ check_for_wayland_session_type (void)
 
 static void
 calculate_compositor_configuration (MetaCompositorType *compositor_type,
-                                    MetaBackendType    *backend_type)
+                                    GType              *backend_gtype)
 {
 #ifdef HAVE_WAYLAND
   gboolean run_as_wayland_compositor = opt_wayland;
@@ -411,12 +416,12 @@ calculate_compositor_configuration (MetaCompositorType *compositor_type,
 
 #ifdef CLUTTER_WINDOWING_EGL
   if (opt_display_server || (run_as_wayland_compositor && !opt_nested))
-    *backend_type = META_BACKEND_TYPE_NATIVE;
+    *backend_gtype = META_TYPE_BACKEND_NATIVE;
   else
 #endif
 #endif
 #endif
-    *backend_type = META_BACKEND_TYPE_X11;
+    *backend_gtype = META_TYPE_BACKEND_X11;
 
 #ifdef HAVE_WAYLAND
   if (run_as_wayland_compositor)
@@ -426,6 +431,19 @@ calculate_compositor_configuration (MetaCompositorType *compositor_type,
     *compositor_type = META_COMPOSITOR_TYPE_X11;
 }
 
+static gboolean _compositor_configuration_overridden = FALSE;
+static MetaCompositorType _compositor_type_override;
+static GType _backend_gtype_override;
+
+void
+meta_override_compositor_configuration (MetaCompositorType compositor_type,
+                                        GType              backend_gtype)
+{
+  _compositor_configuration_overridden = TRUE;
+  _compositor_type_override = compositor_type;
+  _backend_gtype_override = backend_gtype;
+}
+
 /**
  * meta_init: (skip)
  *
@@ -438,7 +456,7 @@ meta_init (void)
   struct sigaction act;
   sigset_t empty_mask;
   MetaCompositorType compositor_type;
-  MetaBackendType backend_type;
+  GType backend_gtype;
 
   sigemptyset (&empty_mask);
   act.sa_handler = SIG_IGN;
@@ -460,7 +478,15 @@ meta_init (void)
   if (g_getenv ("MUTTER_DEBUG"))
     meta_set_debugging (TRUE);
 
-  calculate_compositor_configuration (&compositor_type, &backend_type);
+  if (_compositor_configuration_overridden)
+    {
+      compositor_type = _compositor_type_override;
+      backend_gtype = _backend_gtype_override;
+    }
+  else
+    {
+      calculate_compositor_configuration (&compositor_type, &backend_gtype);
+    }
 
 #ifdef HAVE_WAYLAND
   if (compositor_type == META_COMPOSITOR_TYPE_WAYLAND)
@@ -488,7 +514,7 @@ meta_init (void)
   if (!meta_is_wayland_compositor ())
     meta_select_display (opt_display_name);
 
-  meta_init_backend (backend_type);
+  meta_init_backend (backend_gtype);
 
   meta_clutter_init ();
 

src/core/util-private.h

@@ -28,22 +28,6 @@
 #include <meta/util.h>
 #include <glib/gi18n-lib.h>
 
-typedef enum _MetaCompositorType
-{
-#ifdef HAVE_WAYLAND
-  META_COMPOSITOR_TYPE_WAYLAND,
-#endif
-  META_COMPOSITOR_TYPE_X11,
-} MetaCompositorType;
-
-typedef enum _MetaBackendType
-{
-#ifdef HAVE_NATIVE_BACKEND
-  META_BACKEND_TYPE_NATIVE,
-#endif
-  META_BACKEND_TYPE_X11,
-} MetaBackendType;
-
 void     meta_set_verbose (gboolean setting);
 void     meta_set_debugging (gboolean setting);
 void     meta_set_syncing (gboolean setting);