Add clutter_backend_get_n_screens()

Add clutter_backend_get_n_screens(), which returns the number of screens
manager by the ClutterBackend, and change clutter_backend_get_screen_number()
to return the screen number of the currently used screen; this is semantically
equivalent to clutter_glx_get_default_screen(), but leaves the door open for
a "screen" abstraction in Clutter, handled by the backend. Update the GLX
and EGL backends to retrieve and set the screen_num and n_screens members of
ClutterBackend using Xlib calls.

clutter/clutter-backend.c

@@ -312,7 +312,25 @@ clutter_backend_get_screen_number (ClutterBackend *backend)
 {
   g_return_val_if_fail (CLUTTER_IS_BACKEND (backend), -1);
 
-  return backend->screen_n;
+  return backend->screen_num;
+}
+
+/**
+ * clutter_backend_get_n_screens:
+ * @backend: a #ClutterBackend
+ *
+ * Gets the number of screens managed by @backend.
+ *
+ * Return value: the number of screens
+ *
+ * Since: 0.4
+ */
+gint
+clutter_backend_get_n_screens (ClutterBackend *backend)
+{
+  g_return_val_if_fail (CLUTTER_IS_BACKEND (backend), 0);
+
+  return backend->n_screens;
 }
 
 /**

clutter/clutter-backend.h

@@ -52,7 +52,8 @@ struct _ClutterBackend
   gint res_width;
   gint res_height;
 
-  gint screen_n;
+  gint screen_num;
+  gint n_screens;
 
   /* events queue: every backend must implement one */
   GQueue *events_queue;
@@ -101,6 +102,7 @@ gint clutter_backend_get_height        (ClutterBackend *backend);
 gint clutter_backend_get_width_mm      (ClutterBackend *backend);
 gint clutter_backend_get_height_mm     (ClutterBackend *backend);
 gint clutter_backend_get_screen_number (ClutterBackend *backend);
+gint clutter_backend_get_n_screens     (ClutterBackend *backend);
 
 void  clutter_backend_set_double_click_time     (ClutterBackend *backend,
                                                  guint           msec);

clutter/egl/clutter-backend-egl.c

@@ -62,19 +62,24 @@ clutter_backend_egl_post_parse (ClutterBackend  *backend,
       CLUTTER_NOTE (MISC, "Getting the X screen");
 
       if (clutter_screen == 0)
-        backend_egl->xscreen = DefaultScreen (backend_egl->xdpy);
+        backend_egl->xscreen = DefaultScreenOfDisplay (backend_egl->xdpy);
       else
-        {
-          Screen *xscreen;
-
-          xscreen = ScreenOfDisplay (backend_egl->xdpy, clutter_screen);
-          backend_egl->xscreen = XScreenNumberOfScreen (xscreen);
-        }
+        backend_egl->xscreen = ScreenOfDisplay (backend_egl->xdpy,
+                                                clutter_screen);
 
+      backend_egl->xscreen_num = XScreenNumberOfScreen (backend_egl->xscreen);
       backend_egl->xwin_root = RootWindow (backend_egl->xdpy,
-                                           backend_egl->xscreen);
+                                           backend_egl->xscreen_num);
       
       backend_egl->display_name = g_strdup (clutter_display_name);
+
+      /* generic backend properties */
+      backend->res_width = WidthOfScreen (backend_egl->xscreen);
+      backend->res_height = HeightOfScreen (backend_egl->xscreen);
+      backend->mm_width = WidthMMOfScreen (backend_egl->xscreen);
+      backend->mm_height = HeightMMOfScreen (backend_egl->xscreen);
+      backend->screen_num = backend_egl->xscreen_num;
+      backend->n_screens = ScreenCount (backend_egl->xdpy)
     }
 
   g_free (clutter_display_name);
@@ -82,7 +87,7 @@ clutter_backend_egl_post_parse (ClutterBackend  *backend,
   CLUTTER_NOTE (MISC, "X Display `%s' [%p] opened (screen:%d, root:%u)",
                 backend_egl->display_name,
                 backend_egl->xdpy,
-                backend_egl->xscreen,
+                backend_egl->xscreen_num,
                 (unsigned int) backend_egl->xwin_root);
 
   return TRUE;
@@ -105,7 +110,7 @@ clutter_backend_egl_init_stage (ClutterBackend  *backend,
       stage_egl = CLUTTER_STAGE_EGL (stage);
       stage_egl->xdpy = backend_egl->xdpy;
       stage_egl->xwin_root = backend_egl->xwin_root;
-      stage_egl->xscreen = backend_egl->xscreen;
+      stage_egl->xscreen = backend_egl->xscreen_num;
 
       g_object_set_data (G_OBJECT (stage), "clutter-backend", backend);
 
@@ -249,7 +254,8 @@ clutter_backend_egl_init (ClutterBackendEgl *backend_egl)
 
   backend->res_width = backend->res_height = -1;
   backend->mm_width = backend->mm_height = -1;
-  backend->screen_n = 0;
+  backend->screen_num = 0;
+  backend->n_screens = 0;
 
   backend->double_click_time = 250;
   backend->double_click_distance = 5
@@ -339,7 +345,7 @@ clutter_egl_get_default_screen (void)
       return -1;
     }
 
-  return backend_singleton->xscreen;
+  return backend_singleton->xscreen_num;
 }
 
 /**

clutter/egl/clutter-backend-egl.h

@@ -46,7 +46,8 @@ struct _ClutterBackendEgl
   Display *xdpy;
   gchar   *display_name;
   Window   xwin_root;
-  int      xscreen;
+  int      xscreen_num;
+  Screen  *xscreen;
 
   /* main stage singleton */
   ClutterActor *stage;

clutter/glx/clutter-backend-glx.c

@@ -112,7 +112,8 @@ clutter_backend_glx_post_parse (ClutterBackend  *backend,
       backend->res_height = HeightOfScreen (backend_glx->xscreen);
       backend->mm_width = WidthMMOfScreen (backend_glx->xscreen);
       backend->mm_height = HeightMMOfScreen (backend_glx->xscreen);
-      backend->screen_n = ScreenCount (backend_glx->xdpy);
+      backend->screen_num = backend_glx->xscreen_num;
+      backend->n_screens = ScreenCount (backend_glx->xdpy);
     }
 
   g_free (clutter_display_name);
@@ -309,7 +310,8 @@ clutter_backend_glx_init (ClutterBackendGlx *backend_glx)
 
   backend->res_width = backend->res_height = -1;
   backend->mm_width = backend->mm_height = -1;
-  backend->screen_n = 0;
+  backend->screen_num = 0;
+  backend->n_screens = 0;
 
   /* FIXME - find a way to set this stuff from XSettings */
   backend->double_click_time = 250;

doc/reference/clutter-sections.txt

@@ -509,6 +509,7 @@ clutter_backend_get_height
 clutter_backend_get_width_mm
 clutter_backend_get_height_mm
 clutter_backend_get_screen_number
+clutter_backend_get_n_screens
 clutter_backend_get_double_click_time
 clutter_backend_set_double_click_time
 clutter_backend_get_double_click_distance

doc/reference/tmpl/clutter-backend.sgml

@@ -103,6 +103,15 @@ ClutterBackend
 @Returns: 
 
 
+<!-- ##### FUNCTION clutter_backend_get_n_screens ##### -->
+<para>
+
+</para>
+
+@backend: 
+@Returns: 
+
+
 <!-- ##### FUNCTION clutter_backend_get_double_click_time ##### -->
 <para>