Adds a --nested option

This adds a --nested option to request that mutter no longer run as a
classic X compositor with an output window mapped on the X Composite
Overlay Window and also not assume it is running directly under X.

The intention is that in this mode Mutter will itself launch a headless
X server and display output will be handled by Clutter and Cogl. This
will enable running Mutter nested as an application within an X session.

This patch introduces an internal meta_is_wayland_compositor() function
as a means to condition the way mutter operates when running as a
traditional X compositor vs running as a wayland compositor where the
compositor and display server are combined into a single process.

Later we also expect to add a --kms option as another way of enabling
this wayland compositor mode that will assume full control of the
display hardware instead of running as a nested application.

src/core/mutter.c

@@ -46,8 +46,15 @@ print_version (const gchar    *option_name,
 }
 
 static gchar *plugin = "default";
+static gboolean opt_nested = FALSE;
 
 GOptionEntry mutter_options[] = {
+  {
+    "nested", 0, 0, G_OPTION_ARG_NONE,
+    &opt_nested,
+    N_("Run nested as an application for testing"),
+    NULL,
+  },
   {
     "version", 0, G_OPTION_FLAG_NO_ARG, G_OPTION_ARG_CALLBACK,
     print_version,
@@ -77,6 +84,8 @@ main (int argc, char **argv)
       exit (1);
     }
 
+  meta_set_is_wayland_compositor (opt_nested);
+
   if (plugin)
     meta_plugin_manager_load (plugin);
 

src/core/util.c

@@ -55,6 +55,7 @@ static gint verbose_topics = 0;
 static gboolean is_debugging = FALSE;
 static gboolean replace_current = FALSE;
 static int no_prefix = 0;
+static gboolean is_wayland_compositor = FALSE;
 
 #ifdef WITH_VERBOSE_MODE
 static FILE* logfile = NULL;
@@ -194,6 +195,18 @@ meta_set_replace_current_wm (gboolean setting)
   replace_current = setting;
 }
 
+gboolean
+meta_is_wayland_compositor (void)
+{
+  return is_wayland_compositor;
+}
+
+void
+meta_set_is_wayland_compositor (gboolean value)
+{
+  is_wayland_compositor = value;
+}
+
 char *
 meta_g_utf8_strndup (const gchar *src,
                      gsize        n)

src/meta/util.h

@@ -37,6 +37,8 @@ void     meta_set_debugging (gboolean setting);
 gboolean meta_is_syncing (void);
 void     meta_set_syncing (gboolean setting);
 void     meta_set_replace_current_wm (gboolean setting);
+gboolean meta_is_wayland_compositor (void);
+void     meta_set_is_wayland_compositor (gboolean setting);
 
 void meta_debug_spew_real (const char *format,
                            ...) G_GNUC_PRINTF (1, 2);