Add gdk_screen_get_monitor_workarea

The function returns the part of a monitors area that should be
used for positioning popups, menus, etc. The only non-trivial
implementation atm is in the X backend, all the other backends
just return the full monitor area. The X implementation is
currently suboptimal, since it requires roundtrips to collect
the necessary information. It should be changed to monitor
the properties for changes, when XFixes allows to monitor
individual properties.
https://bugzilla.gnome.org/show_bug.cgi?id=641999

docs/reference/gdk/gdk3-sections.txt

@@ -199,6 +199,7 @@ gdk_screen_make_display_name
 gdk_screen_get_n_monitors
 gdk_screen_get_primary_monitor
 gdk_screen_get_monitor_geometry
+gdk_screen_get_monitor_workarea
 gdk_screen_get_monitor_at_point
 gdk_screen_get_monitor_at_window
 gdk_screen_get_monitor_height_mm

gdk/broadway/gdkscreen-broadway.c

@@ -321,6 +321,7 @@ gdk_broadway_screen_class_init (GdkBroadwayScreenClass *klass)
   screen_class->get_monitor_height_mm = gdk_broadway_screen_get_monitor_height_mm;
   screen_class->get_monitor_plug_name = gdk_broadway_screen_get_monitor_plug_name;
   screen_class->get_monitor_geometry = gdk_broadway_screen_get_monitor_geometry;
+  screen_class->get_monitor_workarea = gdk_broadway_screen_get_monitor_geometry;
   screen_class->is_composited = gdk_broadway_screen_is_composited;
   screen_class->make_display_name = gdk_broadway_screen_make_display_name;
   screen_class->get_active_window = gdk_broadway_screen_get_active_window;

gdk/gdk.symbols

@@ -271,6 +271,7 @@ gdk_screen_get_height_mm
 gdk_screen_get_monitor_at_point
 gdk_screen_get_monitor_at_window
 gdk_screen_get_monitor_geometry
+gdk_screen_get_monitor_workarea
 gdk_screen_get_monitor_height_mm
 gdk_screen_get_monitor_plug_name
 gdk_screen_get_monitor_width_mm

gdk/gdkscreen.c

@@ -750,12 +750,16 @@ gdk_screen_get_monitor_plug_name (GdkScreen *screen,
 /**
  * gdk_screen_get_monitor_geometry:
  * @screen: a #GdkScreen
- * @monitor_num: the monitor number, between 0 and gdk_screen_get_n_monitors (screen)
+ * @monitor_num: the monitor number
- * @dest: (out) (allow-none): a #GdkRectangle to be filled with the monitor geometry
+ * @dest: (out) (allow-none): a #GdkRectangle to be filled with
+ *     the monitor geometry
  *
  * Retrieves the #GdkRectangle representing the size and position of
  * the individual monitor within the entire screen area.
  *
+ * Monitor numbers start at 0. To obtain the number of monitors of
+ * @screen, use gdk_screen_get_n_monitors().
+ *
  * Note that the size of the entire screen area can be retrieved via
  * gdk_screen_get_width() and gdk_screen_get_height().
  *
@@ -769,6 +773,33 @@ gdk_screen_get_monitor_geometry (GdkScreen    *screen,
   GDK_SCREEN_GET_CLASS(screen)->get_monitor_geometry (screen, monitor_num, dest);
 }
 
+/**
+ * gdk_screen_get_monitor_workarea:
+ * @screen: a #GdkScreen
+ * @monitor_num: the monitor number
+ * @dest: (out) (allow-none): a #GdkRectangle to be filled with
+ *     the monitor workarea
+ *
+ * Retrieves the #GdkRectangle representing the size and position of
+ * the "work area" on a monitor within the entire screen area.
+ *
+ * The work area should be considered when positioning menus and
+ * similar popups, to avoid placing them below panels, docks or other
+ * desktop components.
+ *
+ * Monitor numbers start at 0. To obtain the number of monitors of
+ * @screen, use gdk_screen_get_n_monitors().
+ *
+ * Since: 3.4
+ */
+void
+gdk_screen_get_monitor_workarea (GdkScreen    *screen,
+                                 gint          monitor_num,
+                                 GdkRectangle *dest)
+{
+  GDK_SCREEN_GET_CLASS(screen)->get_monitor_workarea (screen, monitor_num, dest);
+}
+
 /**
  * gdk_screen_list_visuals:
  * @screen: the relevant #GdkScreen.

gdk/gdkscreen.h

@@ -57,11 +57,15 @@ GList *      gdk_screen_list_visuals          (GdkScreen   *screen);
 GList *      gdk_screen_get_toplevel_windows  (GdkScreen   *screen);
 gchar *      gdk_screen_make_display_name     (GdkScreen   *screen);
 
-gint          gdk_screen_get_n_monitors        (GdkScreen *screen);
+gint         gdk_screen_get_n_monitors        (GdkScreen    *screen);
-gint          gdk_screen_get_primary_monitor   (GdkScreen *screen);
+gint         gdk_screen_get_primary_monitor   (GdkScreen    *screen);
-void          gdk_screen_get_monitor_geometry  (GdkScreen *screen,
+void         gdk_screen_get_monitor_geometry  (GdkScreen    *screen,
-                                                gint       monitor_num,
+                                               gint          monitor_num,
-                                                GdkRectangle *dest);
+                                               GdkRectangle *dest);
+void         gdk_screen_get_monitor_workarea  (GdkScreen    *screen,
+                                               gint          monitor_num,
+                                               GdkRectangle *area);
+
 gint          gdk_screen_get_monitor_at_point  (GdkScreen *screen,
                                                 gint       x,
                                                 gint       y);

gdk/gdkscreenprivate.h

@@ -62,6 +62,9 @@ struct _GdkScreenClass
   void         (* get_monitor_geometry)  (GdkScreen    *screen,
                                           gint          monitor_num,
                                           GdkRectangle *dest);
+  void         (* get_monitor_workarea)  (GdkScreen    *screen,
+                                          gint          monitor_num,
+                                          GdkRectangle *dest);
   GList *      (* list_visuals)          (GdkScreen *screen);
   GdkVisual *  (* get_system_visual)     (GdkScreen *screen);
   GdkVisual *  (* get_rgba_visual)       (GdkScreen *screen);

gdk/quartz/gdkscreen-quartz.c

@@ -462,6 +462,7 @@ gdk_quartz_screen_class_init (GdkQuartzScreenClass *klass)
   screen_class->get_monitor_height_mm = gdk_quartz_screen_get_monitor_height_mm;
   screen_class->get_monitor_plug_name = gdk_quartz_screen_get_monitor_plug_name;
   screen_class->get_monitor_geometry = gdk_quartz_screen_get_monitor_geometry;
+  screen_class->get_monitor_workarea = gdk_quartz_screen_get_monitor_geometry;
   screen_class->is_composited = gdk_quartz_screen_is_composited;
   screen_class->make_display_name = gdk_quartz_screen_make_display_name;
   screen_class->get_active_window = gdk_quartz_screen_get_active_window;

gdk/wayland/gdkscreen-wayland.c

@@ -502,6 +502,7 @@ _gdk_screen_wayland_class_init (GdkScreenWaylandClass *klass)
   screen_class->get_monitor_height_mm = gdk_wayland_screen_get_monitor_height_mm;
   screen_class->get_monitor_plug_name = gdk_wayland_screen_get_monitor_plug_name;
   screen_class->get_monitor_geometry = gdk_wayland_screen_get_monitor_geometry;
+  screen_class->get_monitor_workarea = gdk_wayland_screen_get_monitor_geometry;
   screen_class->get_system_visual = gdk_wayland_screen_get_system_visual;
   screen_class->get_rgba_visual = gdk_wayland_screen_get_rgba_visual;
   screen_class->is_composited = gdk_wayland_screen_is_composited;

gdk/win32/gdkscreen-win32.c

@@ -222,6 +222,7 @@ gdk_win32_screen_class_init (GdkWin32ScreenClass *klass)
   screen_class->get_monitor_height_mm = gdk_win32_screen_get_monitor_height_mm;
   screen_class->get_monitor_plug_name = gdk_win32_screen_get_monitor_plug_name;
   screen_class->get_monitor_geometry = gdk_win32_screen_get_monitor_geometry;
+  screen_class->get_monitor_workarea = gdk_win32_screen_get_monitor_geometry;
   screen_class->get_system_visual = _gdk_win32_screen_get_system_visual;
   screen_class->get_rgba_visual = gdk_win32_screen_get_rgba_visual;
   screen_class->is_composited = gdk_win32_screen_is_composited;
@@ -238,4 +239,4 @@ gdk_win32_screen_class_init (GdkWin32ScreenClass *klass)
   screen_class->query_depths = _gdk_win32_screen_query_depths;
   screen_class->query_visual_types = _gdk_win32_screen_query_visual_types;
   screen_class->list_visuals = _gdk_win32_screen_list_visuals;
-}
+}

gdk/x11/gdkscreen-x11.c

@@ -305,6 +305,113 @@ gdk_x11_screen_get_monitor_geometry (GdkScreen    *screen,
     *dest = x11_screen->monitors[monitor_num].geometry;
 }
 
+static int
+get_current_desktop (GdkScreen *screen)
+{
+  Display *display;
+  Window win;
+  Atom current_desktop, type;
+  int format;
+  unsigned long n_items, bytes_after;
+  unsigned char *data_return = NULL;
+  int workspace = 0;
+
+  display = GDK_DISPLAY_XDISPLAY (gdk_screen_get_display (screen));
+  win = XRootWindow (display, GDK_SCREEN_XNUMBER (screen));
+
+  current_desktop = XInternAtom (display, "_NET_CURRENT_DESKTOP", True);
+
+  XGetWindowProperty (display,
+                      win,
+                      current_desktop,
+                      0, G_MAXLONG,
+                      False, XA_CARDINAL,
+                      &type, &format, &n_items, &bytes_after,
+                      &data_return);
+
+  if (type == XA_CARDINAL && format == 32 && n_items > 0)
+    workspace = (int) data_return[0];
+
+  if (data_return)
+    XFree (data_return);
+
+  return workspace;
+}
+
+static void
+get_work_area (GdkScreen    *screen,
+               GdkRectangle *area)
+{
+  Atom            workarea;
+  Atom            type;
+  Window          win;
+  int             format;
+  gulong          num;
+  gulong          leftovers;
+  gulong          max_len = 4 * 32;
+  guchar         *ret_workarea;
+  long           *workareas;
+  int             result;
+  int             disp_screen;
+  int             desktop;
+  Display        *display;
+
+  display = GDK_DISPLAY_XDISPLAY (gdk_screen_get_display (screen));
+  disp_screen = GDK_SCREEN_XNUMBER (screen);
+  workarea = XInternAtom (display, "_NET_WORKAREA", True);
+
+  /* Defaults in case of error */
+  area->x = 0;
+  area->y = 0;
+  area->width = gdk_screen_get_width (screen);
+  area->height = gdk_screen_get_height (screen);
+
+  if (workarea == None)
+    return;
+
+  win = XRootWindow (display, disp_screen);
+  result = XGetWindowProperty (display,
+                               win,
+                               workarea,
+                               0,
+                               max_len,
+                               False,
+                               AnyPropertyType,
+                               &type,
+                               &format,
+                               &num,
+                               &leftovers,
+                               &ret_workarea);
+  if (result != Success ||
+      type == None ||
+      format == 0 ||
+      leftovers ||
+      num % 4 != 0)
+    return;
+
+  desktop = get_current_desktop (screen);
+
+  workareas = (long *) ret_workarea;
+  area->x = workareas[desktop * 4];
+  area->y = workareas[desktop * 4 + 1];
+  area->width = workareas[desktop * 4 + 2];
+  area->height = workareas[desktop * 4 + 3];
+
+  XFree (ret_workarea);
+}
+
+static void
+gdk_x11_screen_get_monitor_workarea (GdkScreen    *screen,
+                                     gint          monitor_num,
+                                     GdkRectangle *dest)
+{
+  GdkRectangle workarea;
+
+  gdk_x11_screen_get_monitor_geometry (screen, monitor_num, dest);
+  get_work_area (screen, &workarea);
+  gdk_rectangle_intersect (&workarea, dest, dest);
+}
+
 static GdkVisual *
 gdk_x11_screen_get_rgba_visual (GdkScreen *screen)
 {
@@ -1603,6 +1710,7 @@ gdk_x11_screen_class_init (GdkX11ScreenClass *klass)
   screen_class->get_monitor_height_mm = gdk_x11_screen_get_monitor_height_mm;
   screen_class->get_monitor_plug_name = gdk_x11_screen_get_monitor_plug_name;
   screen_class->get_monitor_geometry = gdk_x11_screen_get_monitor_geometry;
+  screen_class->get_monitor_workarea = gdk_x11_screen_get_monitor_workarea;
   screen_class->get_system_visual = _gdk_x11_screen_get_system_visual;
   screen_class->get_rgba_visual = gdk_x11_screen_get_rgba_visual;
   screen_class->is_composited = gdk_x11_screen_is_composited;