Add prefers_accent_color (#483)

lib/Widgets/Settings.vala

@@ -2,6 +2,7 @@
 namespace Granite {
     [DBus (name = "io.elementary.pantheon.AccountsService")]
     private interface Pantheon.AccountsService : Object {
+        public abstract int prefers_accent_color { owned get; set; }
         public abstract int prefers_color_scheme { owned get; set; }
     }
 
@@ -14,6 +15,56 @@ namespace Granite {
      * Granite.Settings provides a way to share Pantheon desktop settings with applications.
      */
     public class Settings : Object {
+        /**
+         * Possible accent color preferences expressed by the user
+         */
+         public enum AccentColor {
+            /**
+             * The user has not expressed a accent color preference.
+             */
+            NO_PREFERENCE,
+            /**
+             * The user prefers red as accent color.
+             */
+            RED,
+            /**
+             * The user prefers orange as accent color.
+             */
+            ORANGE,
+            /**
+             * The user prefers yellow as accent color.
+             */
+            YELLOW,
+            /**
+             * The user prefers green as accent color.
+             */
+            GREEN,
+            /**
+             * The user prefers mint as accent color.
+             */
+            MINT,
+            /**
+             * The user prefers blue as accent color.
+             */
+            BLUE,
+            /**
+             * The user prefers purple as accent color.
+             */
+            PURPLE,
+            /**
+             * The user prefers pink as accent color.
+             */
+            PINK,
+            /**
+             * The user prefers brown as accent color.
+             */
+            BROWN,
+            /**
+             * The user prefers gray as accent color.
+             */
+            GRAY
+        }
+
         /**
          * Possible color scheme preferences expressed by the user
          */
@@ -32,8 +83,24 @@ namespace Granite {
             LIGHT
         }
 
+        private AccentColor? _prefers_accent_color = null;
         private ColorScheme? _prefers_color_scheme = null;
 
+        /**
+         * Accent color the user would prefer or if the user has expressed no preference.
+         */
+         public AccentColor prefers_accent_color {
+            get {
+                if (_prefers_accent_color == null) {
+                    setup_prefers_accent_color ();
+                }
+                return _prefers_accent_color;
+            }
+            private set {
+                _prefers_accent_color = value;
+            }
+        }
+
         /**
          * Whether the user would prefer if apps use a dark or light color scheme or if the user has expressed no preference.
          */
@@ -88,6 +155,28 @@ namespace Granite {
             }
         }
 
+        private void setup_prefers_accent_color () {
+            try {
+                pantheon_act = GLib.Bus.get_proxy_sync (
+                    GLib.BusType.SYSTEM,
+                    "org.freedesktop.Accounts",
+                    user_path,
+                    GLib.DBusProxyFlags.GET_INVALIDATED_PROPERTIES
+                );
+
+                prefers_accent_color = (AccentColor) pantheon_act.prefers_accent_color;
+
+                ((GLib.DBusProxy) pantheon_act).g_properties_changed.connect ((changed, invalid) => {
+                    var accent_color = changed.lookup_value ("PrefersAccentColor", new VariantType ("i"));
+                    if (accent_color != null) {
+                        prefers_accent_color = (AccentColor) accent_color.get_int32 ();
+                    }
+                });
+            } catch (Error e) {
+                critical (e.message);
+            }
+        }
+
         private void setup_prefers_color_scheme () {
             try {
                 pantheon_act = GLib.Bus.get_proxy_sync (