[gnome-settings-daemon] power: add a method to retrieve the backlight output id

[Cosimo Cecchi <cosimoc src gnome org>]

commit a653c34b468f5f42f42832e887f10ba4dd4bae98
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Thu Nov 13 10:22:01 2014 -0800

    power: add a method to retrieve the backlight output id
    
    We're going to use this later.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=704086

 plugins/power/gpm-common.c |   22 ++++++++++++++++++++++
 plugins/power/gpm-common.h |    1 +
 2 files changed, 23 insertions(+), 0 deletions(-)
---
diff --git a/plugins/power/gpm-common.c b/plugins/power/gpm-common.c
index 1b97af1..b3eeeac 100644
--- a/plugins/power/gpm-common.c
+++ b/plugins/power/gpm-common.c
@@ -512,6 +512,28 @@ out:
 }
 
 int
+backlight_get_output_id (GnomeRRScreen *rr_screen)
+{
+        GnomeRROutput *output;
+        GnomeRRCrtc *crtc;
+        GdkScreen *gdk_screen;
+        gint x, y;
+
+        output = get_primary_output (rr_screen);
+        if (output == NULL)
+                return -1;
+
+        crtc = gnome_rr_output_get_crtc (output);
+        if (crtc == NULL)
+                return -1;
+
+        gdk_screen = gdk_screen_get_default ();
+        gnome_rr_crtc_get_position (crtc, &x, &y);
+
+        return gdk_screen_get_monitor_at_point (gdk_screen, x, y);
+}
+
+int
 backlight_get_abs (GnomeRRScreen *rr_screen, GError **error)
 {
         GnomeRROutput *output;
diff --git a/plugins/power/gpm-common.h b/plugins/power/gpm-common.h
index 675dfeb..481c358 100644
--- a/plugins/power/gpm-common.h
+++ b/plugins/power/gpm-common.h
@@ -45,6 +45,7 @@ void             reset_idletime                         (void);
 
 int              gsd_power_backlight_abs_to_percentage  (int min, int max, int value);
 gboolean         backlight_available                    (GnomeRRScreen *rr_screen);
+int              backlight_get_output_id                (GnomeRRScreen *rr_screen);
 int              backlight_get_abs                      (GnomeRRScreen *rr_screen, GError **error);
 int              backlight_get_percentage               (GnomeRRScreen *rr_screen, GError **error);
 int              backlight_get_min                      (GnomeRRScreen *rr_screen);