display: Add new virtual gdk_display_get_startup_notification_id() method.

Includes implementation for Wayland and X11, which are the only backends
implementing the Startup Notification Protocol, returns NULL otherwise.

#1084

gdk/gdkdisplay.c

@@ -1283,6 +1283,28 @@ gdk_display_notify_startup_complete (GdkDisplay  *display,
   GDK_DISPLAY_GET_CLASS (display)->notify_startup_complete (display, startup_id);
 }
 
+/**
+ * gdk_display_get_startup_notification_id:
+ * @display: (type GdkX11Display): a #GdkDisplay
+ *
+ * Gets the startup notification ID for a Wayland display, or %NULL
+ * if no ID has been defined.
+ *
+ * Returns: the startup notification ID for @display, or %NULL
+ *
+ * Since: 4.0
+ */
+const gchar *
+gdk_display_get_startup_notification_id (GdkDisplay *display)
+{
+  g_return_val_if_fail (GDK_IS_DISPLAY (display), NULL);
+
+  if (GDK_DISPLAY_GET_CLASS (display)->get_startup_notification_id == NULL)
+    return NULL;
+
+  return GDK_DISPLAY_GET_CLASS (display)->get_startup_notification_id (display);
+}
+
 void
 _gdk_display_pause_events (GdkDisplay *display)
 {

gdk/gdkdisplay.h

@@ -94,6 +94,8 @@ gboolean gdk_display_supports_input_shapes     (GdkDisplay    *display);
 GDK_AVAILABLE_IN_ALL
 void     gdk_display_notify_startup_complete   (GdkDisplay    *display,
                                                 const gchar   *startup_id);
+GDK_AVAILABLE_IN_ALL
+const gchar * gdk_display_get_startup_notification_id (GdkDisplay *display);
 
 GDK_AVAILABLE_IN_ALL
 GdkAppLaunchContext *gdk_display_get_app_launch_context (GdkDisplay *display);

gdk/gdkdisplayprivate.h

@@ -136,6 +136,8 @@ struct _GdkDisplayClass
 
   void                       (*notify_startup_complete) (GdkDisplay  *display,
                                                          const gchar *startup_id);
+  const gchar *              (*get_startup_notification_id) (GdkDisplay  *display);
+
   void                       (*event_data_copy) (GdkDisplay     *display,
                                                  const GdkEvent *event,
                                                  GdkEvent       *new_event);

gdk/wayland/gdkdisplay-wayland.c

@@ -857,6 +857,23 @@ gdk_wayland_display_get_next_serial (GdkDisplay *display)
   return ++serial;
 }
 
+/**
+ * gdk_wayland_display_get_startup_notification_id:
+ * @display: (type GdkX11Display): a #GdkDisplay
+ *
+ * Gets the startup notification ID for a Wayland display, or %NULL
+ * if no ID has been defined.
+ *
+ * Returns: the startup notification ID for @display, or %NULL
+ *
+ * Since: 4.0
+ */
+const gchar *
+gdk_wayland_display_get_startup_notification_id (GdkDisplay  *display)
+{
+  return GDK_WAYLAND_DISPLAY (display)->startup_notification_id;
+}
+
 /**
  * gdk_wayland_display_set_startup_notification_id:
  * @display: (type GdkWaylandDisplay): a #GdkDisplay
@@ -1005,6 +1022,7 @@ gdk_wayland_display_class_init (GdkWaylandDisplayClass *class)
   display_class->supports_input_shapes = gdk_wayland_display_supports_input_shapes;
   display_class->get_app_launch_context = _gdk_wayland_display_get_app_launch_context;
   display_class->get_next_serial = gdk_wayland_display_get_next_serial;
+  display_class->get_startup_notification_id = gdk_wayland_display_get_startup_notification_id;
   display_class->notify_startup_complete = gdk_wayland_display_notify_startup_complete;
   display_class->create_surface_impl = _gdk_wayland_display_create_surface_impl;
   display_class->get_keymap = _gdk_wayland_display_get_keymap;

gdk/wayland/gdkwaylanddisplay.h

@@ -54,6 +54,8 @@ void                    gdk_wayland_display_set_cursor_theme    (GdkDisplay  *di
                                                                  const gchar *theme,
                                                                  gint         size);
 GDK_AVAILABLE_IN_ALL
+const gchar *           gdk_wayland_display_get_startup_notification_id (GdkDisplay *display);
+GDK_AVAILABLE_IN_ALL
 void                    gdk_wayland_display_set_startup_notification_id (GdkDisplay *display,
                                                                          const char *startup_id);
 

gdk/x11/gdkdisplay-x11.c

@@ -3042,6 +3042,7 @@ gdk_x11_display_class_init (GdkX11DisplayClass * class)
   display_class->get_app_launch_context = _gdk_x11_display_get_app_launch_context;
 
   display_class->get_next_serial = gdk_x11_display_get_next_serial;
+  display_class->get_startup_notification_id = gdk_x11_display_get_startup_notification_id;
   display_class->notify_startup_complete = gdk_x11_display_notify_startup_complete;
   display_class->create_surface_impl = _gdk_x11_display_create_surface_impl;
   display_class->get_keymap = gdk_x11_display_get_keymap;