compositor: Add an API to query if the stage is focused

gnome-shell needs to know whether the stage window is focused so
it can synchronize between stage window focus and Clutter key actor
focus. Track all X windows, even those without MetaWindows, when
tracking the focus window, and add a compositor-level API to determine
when the stage is focused.

https://bugzilla.gnome.org/show_bug.cgi?id=700735

src/compositor/compositor.c

@@ -391,6 +391,24 @@ meta_focus_stage_window (MetaScreen *screen,
                                         timestamp);
 }
 
+gboolean
+meta_stage_is_focused (MetaScreen *screen)
+{
+  ClutterStage *stage;
+  Window window;
+
+  stage = CLUTTER_STAGE (meta_get_stage_for_screen (screen));
+  if (!stage)
+    return FALSE;
+
+  window = clutter_x11_get_stage_window (stage);
+
+  if (window == None)
+    return FALSE;
+
+  return (screen->display->focus_xwindow == window);
+}
+
 gboolean
 meta_begin_modal_for_plugin (MetaScreen       *screen,
                              MetaPlugin       *plugin,

src/core/display-private.h

@@ -113,6 +113,9 @@ struct _MetaDisplay
    * or event that caused this.
    */
   MetaWindow *focus_window;
+  /* For windows we've focused that don't necessarily have an X window,
+   * like the no_focus_window or the stage X window. */
+  Window focus_xwindow;
   gulong focus_serial;
 
   /* last timestamp passed to XSetInputFocus */

src/core/display.c

@@ -1468,11 +1468,11 @@ meta_display_get_current_time (MetaDisplay *display)
 }
 
 static Bool
-find_timestamp_predicate (Display  *display,
+find_timestamp_predicate (Display  *xdisplay,
                           XEvent   *ev,
                           XPointer  arg)
 {
-  MetaDisplay *display = arg;
+  MetaDisplay *display = (MetaDisplay *) arg;
 
   return (ev->type == PropertyNotify &&
           ev->xproperty.atom == display->atom__MUTTER_TIMESTAMP_PING);
@@ -1495,7 +1495,7 @@ meta_display_get_current_time_roundtrip (MetaDisplay *display)
       XIfEvent (display->xdisplay,
                 &property_event,
                 find_timestamp_predicate,
-                display);
+                (XPointer) display);
       timestamp = property_event.xproperty.time;
     }
 
@@ -1883,11 +1883,12 @@ get_input_event (MetaDisplay *display,
 static void
 update_focus_window (MetaDisplay *display,
                      MetaWindow  *window,
+                     Window       xwindow,
                      gulong       serial)
 {
   display->focus_serial = serial;
 
-  if (window == display->focus_window)
+  if (display->focus_xwindow == xwindow)
     return;
 
   if (display->focus_window)
@@ -1904,11 +1905,13 @@ update_focus_window (MetaDisplay *display,
        */
       previous = display->focus_window;
       display->focus_window = NULL;
+      display->focus_xwindow = None;
 
       meta_window_set_focused_internal (previous, FALSE);
     }
 
   display->focus_window = window;
+  display->focus_xwindow = xwindow;
 
   if (display->focus_window)
     {
@@ -1993,6 +1996,7 @@ request_xserver_input_focus_change (MetaDisplay *display,
 
   update_focus_window (display,
                        meta_window,
+                       xwindow,
                        serial);
 
   meta_error_trap_pop (display);
@@ -2109,7 +2113,9 @@ handle_window_focus_event (MetaDisplay  *display,
 
   if (display->server_focus_serial > display->focus_serial)
     {
-      update_focus_window (display, focus_window,
+      update_focus_window (display,
+                           focus_window,
+                           focus_window ? focus_window->xwindow : None,
                            display->server_focus_serial);
     }
 }
@@ -2165,6 +2171,7 @@ event_callback (XEvent   *event,
                   display->focus_window->desc);
       update_focus_window (display,
                            meta_display_lookup_x_window (display, display->server_focus_window),
+                           display->server_focus_window,
                            display->server_focus_serial);
     }
 

src/meta/compositor-mutter.h

@@ -48,5 +48,6 @@ void meta_set_stage_input_region     (MetaScreen    *screen,
 void meta_empty_stage_input_region   (MetaScreen    *screen);
 void meta_focus_stage_window         (MetaScreen    *screen,
                                       guint32        timestamp);
+gboolean meta_stage_is_focused       (MetaScreen    *screen);
 
 #endif