[gnome-power-manager/gnome-2-26] Check whether xrandr-1.3 features are really supported by xorg-server.

[Priit Laes <plaes src gnome org>]

commit 383f735200a5f838ee93eb137df65df7e266fc4c
Author: Priit Laes <plaes plaes org>
Date:   Mon May 11 16:11:45 2009 +0300

    Check whether xrandr-1.3 features are really supported by xorg-server.
    Fixes #582142.
---
 src/gpm-brightness-xrandr.c |   49 +++++++++++++++++++++++++++++++++++++++---
 1 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/src/gpm-brightness-xrandr.c b/src/gpm-brightness-xrandr.c
index d6fb595..b7a5515 100644
--- a/src/gpm-brightness-xrandr.c
+++ b/src/gpm-brightness-xrandr.c
@@ -60,8 +60,11 @@ struct GpmBrightnessXRandRPrivate
 	Display			*dpy;
 	guint			 shared_value;
 	gboolean		 has_extension;
+#if (RANDR_MAJOR == 1 && RANDR_MINOR >= 3)
+	gboolean		 has_randr13;
+#endif
 	gboolean		 hw_changed;
-	/* An cache of XRRScreenResources is used as XRRGetScreenResources is expensive */
+	/* A cache of XRRScreenResources is used as XRRGetScreenResources is expensive */
 	GPtrArray		*resources;
 };
 
@@ -170,6 +173,34 @@ gpm_brightness_xrandr_setup_display (GpmBrightnessXRandR *brightness)
 	return TRUE;
 }
 
+#if (RANDR_MAJOR == 1 && RANDR_MINOR >= 3)
+/**
+ * gpm_brightness_xrandr_setup_version: Check whether xserver really supports xrandr-1.3 features.
+ **/
+static gboolean
+gpm_brightness_xrandr_setup_version (GpmBrightnessXRandR *brightness)
+{
+	gint major, minor;
+
+	g_return_val_if_fail (GPM_IS_BRIGHTNESS_XRANDR (brightness), FALSE);
+
+	/* get the display */
+	brightness->priv->dpy = GDK_DISPLAY();
+	if (!brightness->priv->dpy) {
+		egg_error ("Cannot open display");
+		return FALSE;
+	}
+	if (!XRRQueryVersion (brightness->priv->dpy, &major, &minor)) {
+		return FALSE;
+	}
+	if (major == 1 && minor < 3) {
+		egg_debug ("RandR version %d.%d does not support XRRGetScreenResourcesCurrent", major, minor);
+		return FALSE;
+	}
+	return TRUE;
+}
+#endif
+
 /**
  * gpm_brightness_xrandr_output_get_limits:
  **/
@@ -616,9 +647,14 @@ gpm_brightness_xrandr_update_cache (GpmBrightnessXRandR *brightness)
 		root = RootWindow (brightness->priv->dpy, screen);
 		/* XRRGetScreenResourcesCurrent is less expensive than
 		   XRRGetScreenResources, however it is available only
-		   in RandR 1.3 or higher */
+		   in RandR 1.3 or higher and of course xserver needs
+		   to support it.
+		*/
 #if (RANDR_MAJOR == 1 && RANDR_MINOR >= 3)
-		resource = XRRGetScreenResourcesCurrent (brightness->priv->dpy, root);
+		if (brightness->priv->has_randr13)
+			resource = XRRGetScreenResourcesCurrent (brightness->priv->dpy, root);
+		else
+			resource = XRRGetScreenResources (brightness->priv->dpy, root);
 #else
 		resource = XRRGetScreenResources (brightness->priv->dpy, root);
 #endif
@@ -684,8 +720,13 @@ gpm_brightness_xrandr_init (GpmBrightnessXRandR *brightness)
 
 	/* can we do this */
 	brightness->priv->has_extension = gpm_brightness_xrandr_setup_display (brightness);
-	if (brightness->priv->has_extension == FALSE)
+	if (brightness->priv->has_extension == FALSE) {
+		egg_debug ("no XRANDR extension, so aborting init");
 		return;
+	}
+#if (RANDR_MAJOR == 1 && RANDR_MINOR >= 3)
+	brightness->priv->has_randr13 = gpm_brightness_xrandr_setup_version (brightness);
+#endif
 
 	screen = gdk_screen_get_default ();
 	window = gdk_screen_get_root_window (screen);