[mutter/wip/underscan: 1/2] monitor-manager: add a property to discover if underscan is supported

[Cosimo Cecchi <cosimoc src gnome org>]

commit 5459dd1e5974b31a2306826cb3e659f0a7a671b2
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Wed Jul 1 17:42:46 2015 -0700

    monitor-manager: add a property to discover if underscan is supported
    
    So that clients such as the control center can decide to hide an
    underscanning checkbutton when the output does not support it.

 src/backends/meta-monitor-manager-private.h    |    1 +
 src/backends/meta-monitor-manager.c            |    2 +
 src/backends/native/meta-monitor-manager-kms.c |   17 +++++++++
 src/backends/x11/meta-monitor-manager-xrandr.c |   46 ++++++++++++++++++++++++
 4 files changed, 66 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-monitor-manager-private.h b/src/backends/meta-monitor-manager-private.h
index d21888e..e73aec9 100644
--- a/src/backends/meta-monitor-manager-private.h
+++ b/src/backends/meta-monitor-manager-private.h
@@ -145,6 +145,7 @@ struct _MetaOutput
   gboolean is_primary;
   gboolean is_presentation;
   gboolean is_underscanning;
+  gboolean supports_underscanning;
 
   gpointer driver_private;
   GDestroyNotify driver_notify;
diff --git a/src/backends/meta-monitor-manager.c b/src/backends/meta-monitor-manager.c
index 21ab215..4fe9717 100644
--- a/src/backends/meta-monitor-manager.c
+++ b/src/backends/meta-monitor-manager.c
@@ -647,6 +647,8 @@ meta_monitor_manager_handle_get_resources (MetaDBusDisplayConfig *skeleton,
                              g_variant_new_string (get_connector_type_name (output->connector_type)));
       g_variant_builder_add (&properties, "{sv}", "underscanning",
                              g_variant_new_boolean (output->is_underscanning));
+      g_variant_builder_add (&properties, "{sv}", "supports-underscanning",
+                             g_variant_new_boolean (output->supports_underscanning));
 
       edid_file = manager_class->get_edid_file (manager, output);
       if (edid_file)
diff --git a/src/backends/native/meta-monitor-manager-kms.c b/src/backends/native/meta-monitor-manager-kms.c
index cc2b18e..b8f271d 100644
--- a/src/backends/native/meta-monitor-manager-kms.c
+++ b/src/backends/native/meta-monitor-manager-kms.c
@@ -863,6 +863,22 @@ crtc_free (CoglKmsCrtc *crtc)
   g_slice_free (CoglKmsCrtc, crtc);
 }
 
+static gboolean
+get_supports_underscan (MetaMonitorManagerKms *manager_kms,
+                        MetaOutput *output)
+{
+  MetaCRTC *crtc = output->crtc;
+
+  if (!crtc)
+    return FALSE;
+
+  MetaCRTCKms *crtc_kms = crtc->driver_private;
+  if (!crtc_kms->underscan_prop_id)
+    return FALSE;
+
+  return TRUE;
+}
+
 static void
 set_underscan (MetaMonitorManagerKms *manager_kms,
                MetaOutput *output)
@@ -1059,6 +1075,7 @@ meta_monitor_manager_kms_apply_configuration (MetaMonitorManager *manager,
       output->is_primary = output_info->is_primary;
       output->is_presentation = output_info->is_presentation;
       output->is_underscanning = output_info->is_underscanning;
+      output->supports_underscanning = get_supports_underscan (manager_kms, output);
 
       set_underscan (manager_kms, output);
     }
diff --git a/src/backends/x11/meta-monitor-manager-xrandr.c b/src/backends/x11/meta-monitor-manager-xrandr.c
index 13010b0..86d24b5 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -246,6 +246,51 @@ output_get_underscanning_xrandr (MetaMonitorManagerXrandr *manager_xrandr,
   return (strcmp (str, "on") == 0);
 }
 
+static gboolean
+output_get_supports_underscanning_xrandr (MetaMonitorManagerXrandr *manager_xrandr,
+                                          MetaOutput               *output)
+{
+  Atom atom, actual_type;
+  int actual_format, i;
+  unsigned long nitems, bytes_after;
+  g_autofree unsigned char *buffer = NULL;
+  XRRPropertyInfo *property_info;
+  Atom *values;
+  gboolean supports_underscanning = FALSE;
+
+  atom = XInternAtom (manager_xrandr->xdisplay, "underscan", False);
+  XRRGetOutputProperty (manager_xrandr->xdisplay,
+                        (XID)output->winsys_id,
+                        atom,
+                        0, G_MAXLONG, False, False, XA_ATOM,
+                        &actual_type, &actual_format,
+                        &nitems, &bytes_after, &buffer);
+
+  if (actual_type != XA_ATOM || actual_format != 32 || nitems < 1)
+    return FALSE;
+
+  property_info = XRRQueryOutputProperty (manager_xrandr->xdisplay,
+                                          (XID) output->winsys_id,
+                                          atom);
+  values = (Atom *) property_info->values;
+
+  for (i = 0; i < property_info->num_values; i++)
+    {
+      /* The output supports underscanning if "on" is a valid value
+       * for the underscan property.
+       */
+      char *name = XGetAtomName (manager_xrandr->xdisplay, values[i]);
+      if (strcmp (name, "on") == 0)
+        supports_underscanning = TRUE;
+
+      XFree (name);
+    }
+
+  XFree (property_info);
+
+  return supports_underscanning;
+}
+
 static int
 normalize_backlight (MetaOutput *output,
                      int         hw_value)
@@ -804,6 +849,7 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
          meta_output->is_primary = ((XID)meta_output->winsys_id == primary_output);
          meta_output->is_presentation = output_get_presentation_xrandr (manager_xrandr, meta_output);
          meta_output->is_underscanning = output_get_underscanning_xrandr (manager_xrandr, meta_output);
+          meta_output->supports_underscanning = output_get_supports_underscanning_xrandr (manager_xrandr, 
meta_output);
          output_get_backlight_limits_xrandr (manager_xrandr, meta_output);
 
          if (!(meta_output->backlight_min == 0 && meta_output->backlight_max == 0))