common: Add API to get the refresh rate.

Bug 15391

Return the primary monitor refresh rate in Hertz if available from GDK,
or 60 as the default value.

Signed-off-by: Olivier Fourdan <fourdan@xfce.org>

common/xfwm-common.c

@@ -125,6 +125,24 @@ xfwm_get_primary_monitor_geometry (GdkScreen    *screen,
 
 
 
+gint
+xfwm_get_primary_refresh_rate (GdkScreen *screen)
+{
+#if GTK_CHECK_VERSION(3, 22, 0)
+  GdkDisplay *display;
+  GdkMonitor *monitor;
+
+  display = gdk_screen_get_display (screen);
+  monitor = gdk_display_get_primary_monitor (display);
+
+  return gdk_monitor_get_refresh_rate (monitor) / 1000;
+#else
+  return 60;
+#endif
+}
+
+
+
 gint
 xfwm_get_n_monitors (GdkScreen *screen)
 {

common/xfwm-common.h

@@ -37,6 +37,8 @@ void              xfwm_get_monitor_geometry             (GdkScreen    *screen,
 void              xfwm_get_primary_monitor_geometry     (GdkScreen    *screen,
                                                          GdkRectangle *geometry);
 
+gint              xfwm_get_primary_refresh_rate         (GdkScreen    *screen);
+
 gint              xfwm_get_n_monitors                   (GdkScreen    *screen);
 
 gchar            *xfwm_make_display_name                (GdkScreen    *screen);