Use account service for dark scheme and fix build

Author: leolost2605

background/Background.vala

@@ -134,7 +134,7 @@ public interface Gala.Background.Background : Object, Gdk.Paintable {
         }
 
         public void snapshot (Gdk.Snapshot gdk_snapshot, double width, double height) {
-            texture.snapshot (gdk_snapshot, render_width, render_height);
+            texture.snapshot (gdk_snapshot, width, height);
         }
     }
 }

background/BackgroundManager.vala

@@ -18,14 +18,18 @@ public class Gala.Background.BackgroundManager : Object {
     private uint idle_id = 0;
 
     construct {
+        /*
+         * We can't use Granite for the color scheme since it connects to the portal which only becomes available
+         * some time after we are already showing.
+         */
+        Utils.init_color_scheme_watcher (queue_set_background);
+
         setup_background ();
         Gdk.Display.get_default ().get_monitors ().items_changed.connect (setup_background);
 
         set_background ();
         gnome_settings.changed.connect (queue_set_background);
         elementary_settings.changed.connect (queue_set_background);
-
-        Granite.Settings.get_default ().notify["prefers-color-scheme"].connect (queue_set_background);
     }
 
     private void setup_background () {
@@ -71,7 +75,7 @@ public class Gala.Background.BackgroundManager : Object {
         }
 
         if (elementary_settings.get_boolean ("dim-wallpaper-in-dark-style")
-            //  && Granite.Settings.get_default ().prefers_color_scheme == DARK //todo: other thread?
+            && Utils.get_color_scheme () == DARK
         ) {
             current_background = Background.get_dimmed (current_background);
         }

background/Utils.vala

@@ -4,6 +4,58 @@
  */
 
 namespace Gala.Background.Utils {
+    public enum ColorScheme {
+        NO_PREFERENCE,
+        DARK,
+        LIGHT
+    }
+
+    public delegate void OnStyleChange (ColorScheme new_style);
+
+    [DBus (name = "org.freedesktop.Accounts")]
+    private interface Accounts : Object {
+        public abstract string find_user_by_name (string name) throws IOError, DBusError;
+    }
+
+    [DBus (name = "io.elementary.pantheon.AccountsService")]
+    private interface AccountsService : DBusProxy {
+        public abstract int prefers_color_scheme { get; set; }
+        public abstract int prefers_accent_color { get; set; }
+    }
+
+    private const string FDO_ACCOUNTS_NAME = "org.freedesktop.Accounts";
+    private const string FDO_ACCOUNTS_PATH = "/org/freedesktop/Accounts";
+
+    private static AccountsService? accounts_service_proxy;
+
+    public static void init_color_scheme_watcher (OnStyleChange style_change_callback) {
+        try {
+            var accounts = Bus.get_proxy_sync<Accounts> (SYSTEM, FDO_ACCOUNTS_NAME, FDO_ACCOUNTS_PATH);
+
+            var path = accounts.find_user_by_name (Environment.get_user_name ());
+
+            accounts_service_proxy = Bus.get_proxy_sync<AccountsService> (SYSTEM, FDO_ACCOUNTS_NAME, path, GET_INVALIDATED_PROPERTIES);
+        } catch {
+            warning ("Could not connect to AccountsService. Default style will be used");
+            return;
+        }
+
+        accounts_service_proxy.g_properties_changed.connect ((changed, invalid) => {
+            var value = changed.lookup_value ("PrefersColorScheme", new VariantType ("i"));
+            if (value != null) {
+                style_change_callback (value.get_int32 ());
+            }
+        });
+    }
+
+    public static ColorScheme get_color_scheme () {
+        if (accounts_service_proxy != null) {
+            return accounts_service_proxy.prefers_color_scheme;
+        }
+
+        return LIGHT;
+    }
+
     private const double SATURATION_WEIGHT = 1.5;
     private const double WEIGHT_THRESHOLD = 1.0;