[mutter] DisplayConfig: Add 'legacy-ui-scaling-factor' property

[Jonas Ådahl <jadahl src gnome org>]

commit fad5657edaa4734bff2b8e5d5cd4da1bec89e167
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Oct 11 17:59:04 2017 +0800

    DisplayConfig: Add 'legacy-ui-scaling-factor' property
    
    We have this value in mutter; lets share it so that for example
    gnome-settings-daemon doesn't have to calculate it itself.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788820

 src/backends/meta-monitor-manager.c    |    7 +++++++
 src/org.gnome.Mutter.DisplayConfig.xml |    4 ++++
 2 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-monitor-manager.c b/src/backends/meta-monitor-manager.c
index 1ba007c..441a9a0 100644
--- a/src/backends/meta-monitor-manager.c
+++ b/src/backends/meta-monitor-manager.c
@@ -1261,12 +1261,14 @@ meta_monitor_manager_handle_get_current_state (MetaDBusDisplayConfig *skeleton,
                                                GDBusMethodInvocation *invocation)
 {
   MetaMonitorManager *manager = META_MONITOR_MANAGER (skeleton);
+  MetaSettings *settings = meta_backend_get_settings (manager->backend);
   GVariantBuilder monitors_builder;
   GVariantBuilder logical_monitors_builder;
   GVariantBuilder properties_builder;
   GList *l;
   int i;
   MetaMonitorManagerCapability capabilities;
+  int ui_scaling_factor;
   int max_screen_width, max_screen_height;
 
   g_variant_builder_init (&monitors_builder,
@@ -1444,6 +1446,11 @@ meta_monitor_manager_handle_get_current_state (MetaDBusDisplayConfig *skeleton,
                              g_variant_new_boolean (TRUE));
     }
 
+  ui_scaling_factor = meta_settings_get_ui_scaling_factor (settings);
+  g_variant_builder_add (&properties_builder, "{sv}",
+                         "legacy-ui-scaling-factor",
+                         g_variant_new_int32 (ui_scaling_factor));
+
   if (meta_monitor_manager_get_max_screen_size (manager,
                                                 &max_screen_width,
                                                 &max_screen_height))
diff --git a/src/org.gnome.Mutter.DisplayConfig.xml b/src/org.gnome.Mutter.DisplayConfig.xml
index aab2e0f..fe8e022 100644
--- a/src/org.gnome.Mutter.DisplayConfig.xml
+++ b/src/org.gnome.Mutter.DisplayConfig.xml
@@ -394,6 +394,10 @@
                                       always use the same scale. Absence of
                                       this means logical monitor scales can
                                       differ.
+       * "legacy-ui-scaling-factor" (i): The legacy scaling factor traditionally
+                                         used to scale X11 clients (commonly
+                                         communicated via the
+                                         Gdk/WindowScalingFactor XSetting entry).
     -->
     <method name="GetCurrentState">
       <arg name="serial" direction="out" type="u" />