color-manager: Set up a D-Bus proxy to org.gnome.SettingsDaemon.Color

gsd-color provides this API, which exposes details about the night light
state. Currently, gsd-color also turns this state into CRTC gamma
changes, but this will eventually change, and this is a preparation for
this.

The proxy isn't yet used for anything.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2164>

data/dbus-interfaces/org.gnome.SettingsDaemon.Color.xml

@@ -0,0 +1,7 @@
+<node>
+  <interface name="org.gnome.SettingsDaemon.Color">
+    <property name="DisabledUntilTomorrow" type="b" access="readwrite"/>
+    <property name="NightLightActive" type="b" access="read"/>
+    <property name="Temperature" type="u" access="readwrite"/>
+  </interface>
+</node>

src/backends/meta-color-manager.c

@@ -51,6 +51,8 @@
 #include "backends/meta-color-device.h"
 #include "backends/meta-monitor.h"
 
+#include "meta-dbus-gsd-color.h"
+
 enum
 {
   PROP_0,
@@ -70,6 +72,8 @@ typedef struct _MetaColorManagerPrivate
   GCancellable *cancellable;
 
   GHashTable *devices;
+
+  MetaDbusSettingsDaemonColor *gsd_color;
 } MetaColorManagerPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (MetaColorManager, meta_color_manager, G_TYPE_OBJECT)
@@ -201,6 +205,33 @@ cd_client_connect_cb (GObject      *source_object,
                     color_manager);
 }
 
+static void
+on_gsd_color_ready (GObject      *source_object,
+                    GAsyncResult *res,
+                    gpointer      user_data)
+{
+  MetaColorManager *color_manager = META_COLOR_MANAGER (user_data);
+  MetaColorManagerPrivate *priv =
+    meta_color_manager_get_instance_private (color_manager);
+  MetaDbusSettingsDaemonColor *gsd_color;
+  g_autoptr (GError) error = NULL;
+
+  gsd_color =
+    meta_dbus_settings_daemon_color_proxy_new_for_bus_finish (res, &error);
+  if (!gsd_color)
+    {
+      if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        return;
+
+      g_warning ("Failed to create gsd-color D-Bus proxy: %s", error->message);
+      return;
+    }
+
+  meta_topic (META_DEBUG_COLOR,
+              "Connection to org.gnome.SettingsDaemon.Color established");
+  priv->gsd_color = gsd_color;
+}
+
 static void
 meta_color_manager_constructed (GObject *object)
 {
@@ -213,6 +244,15 @@ meta_color_manager_constructed (GObject *object)
   priv->cd_client = cd_client_new ();
   cd_client_connect (priv->cd_client, priv->cancellable, cd_client_connect_cb,
                      color_manager);
+
+  meta_dbus_settings_daemon_color_proxy_new_for_bus (
+    G_BUS_TYPE_SESSION,
+    G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START,
+    "org.gnome.SettingsDaemon.Color",
+    "/org/gnome/SettingsDaemon/Color",
+    priv->cancellable,
+    on_gsd_color_ready,
+    color_manager);
 }
 
 static void
@@ -225,6 +265,7 @@ meta_color_manager_finalize (GObject *object)
   g_cancellable_cancel (priv->cancellable);
   g_clear_object (&priv->cancellable);
   g_clear_pointer (&priv->devices, g_hash_table_unref);
+  g_clear_object (&priv->gsd_color);
 
   G_OBJECT_CLASS (meta_color_manager_parent_class)->finalize (object);
 }

src/meson.build

@@ -918,6 +918,13 @@ dbus_rtkit_built_sources = gnome.gdbus_codegen('meta-dbus-rtkit1',
 )
 mutter_built_sources += dbus_rtkit_built_sources
 
+dbus_gsd_color_built_sources = gnome.gdbus_codegen('meta-dbus-gsd-color',
+    join_paths(dbus_interfaces_dir, 'org.gnome.SettingsDaemon.Color.xml'),
+    interface_prefix: 'org.gnome.',
+    namespace: 'MetaDbus',
+)
+mutter_built_sources += dbus_gsd_color_built_sources
+
 wayland_protocol_server_headers = []
 wayland_protocol_client_headers = []
 wayland_protocol_sources = []

src/tests/dbusmock-templates/gsd-color.py

@@ -0,0 +1,31 @@
+'''gsd-color proxy mock template
+'''
+
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 3 of the License, or (at your option) any
+# later version.  See http://www.gnu.org/copyleft/lgpl.html for the full text
+# of the license.
+
+__author__ = 'Jonas Ådahl'
+__copyright__ = '(c) 2021 Red Hat Inc.'
+
+import dbus
+import os
+from dbusmock import MOCK_IFACE
+
+
+BUS_NAME = 'org.gnome.SettingsDaemon.Color'
+MAIN_OBJ = '/org/gnome/SettingsDaemon/Color'
+MAIN_IFACE = BUS_NAME
+SYSTEM_BUS = False
+
+
+def load(mock, parameters=None):
+    mock.night_light_active = False
+    mock.temperature = 6500
+
+    mock.AddProperty(MAIN_IFACE, 'NightLightActive', dbus.Boolean())
+    mock.AddProperty(MAIN_IFACE, 'Temperature', dbus.UInt32())
+    mock.Set(MAIN_IFACE, 'NightLightActive', mock.night_light_active)
+    mock.Set(MAIN_IFACE, 'Temperature', dbus.UInt32(mock.temperature))

src/tests/meta-dbus-runner.py

@@ -43,6 +43,7 @@ class MutterDBusTestCase(DBusTestCase):
 
         klass.start_from_local_template('localed')
         klass.start_from_local_template('colord')
+        klass.start_from_local_template('gsd-color')
 
         klass.system_bus_con = klass.get_dbus(system_bus=True)
         klass.session_bus_con = klass.get_dbus(system_bus=False)