[mutter/wip/halfline/black-stage-before-dpms-off: 2/2] xrandr: set stage to black before dpms off

[Ray Strode <halfline src gnome org>]

commit a001e4d5d5ecd5395dbcf31b521f95e2a268776a
Author: Ray Strode <rstrode redhat com>
Date:   Sat Oct 17 15:01:17 2015 -0400

    xrandr: set stage to black before dpms off
    
    redraws aren't processed when dpms has been turned
    off, so we need to set the stage to black before
    the screen goes dark, so that when it comes back
    it's not showing stale contents.

 src/backends/x11/meta-monitor-manager-xrandr.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/x11/meta-monitor-manager-xrandr.c b/src/backends/x11/meta-monitor-manager-xrandr.c
index 9008841..3c114cf 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -43,6 +43,8 @@
 #include <meta/errors.h>
 #include "meta-monitor-config.h"
 
+#include "meta-stage.h"
+
 #define ALL_TRANSFORMS ((1 << (META_MONITOR_TRANSFORM_FLIPPED_270 + 1)) - 1)
 
 /* Look for DPI_FALLBACK in:
@@ -647,6 +649,23 @@ get_xmode_name (XRRModeInfo *xmode)
 }
 
 static void
+update_stage_visibility_for_power_save_mode (MetaMonitorManager *manager)
+{
+  MetaBackend *backend = meta_get_backend ();
+  ClutterActor *stage = meta_backend_get_stage (backend);
+
+  if ((manager->power_save_mode != META_POWER_SAVE_ON) &&
+      (manager->power_save_mode != META_POWER_SAVE_UNSUPPORTED))
+    {
+      meta_stage_set_black (META_STAGE (stage), TRUE);
+    }
+  else
+    {
+      meta_stage_set_black (META_STAGE (stage), FALSE);
+    }
+}
+
+static void
 meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
 {
   MetaMonitorManagerXrandr *manager_xrandr = META_MONITOR_MANAGER_XRANDR (manager);
@@ -693,6 +712,8 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
       manager->power_save_mode = META_POWER_SAVE_UNSUPPORTED;
     }
 
+  update_stage_visibility_for_power_save_mode (manager);
+
   XRRGetScreenSizeRange (manager_xrandr->xdisplay, DefaultRootWindow (manager_xrandr->xdisplay),
                         &min_width,
                         &min_height,