Use uri instead of path for the background settings

Author: leolost2605

src/Cards/UserCard.vala

@@ -9,7 +9,7 @@ public class Greeter.UserCard : Greeter.BaseCard {
     public LightDM.User lightdm_user { get; construct; }
     public bool show_input { get; set; default = false; }
     public bool is_24h { get; set; default = true; }
-    // TODO: In Gtk4 remove this gesture and move it to MainWindow 
+    // TODO: In Gtk4 remove this gesture and move it to MainWindow
     public Gtk.GestureMultiPress click_gesture { get; private set; }
 
     private Pantheon.AccountsService greeter_act;
@@ -182,6 +182,7 @@ public class Greeter.UserCard : Greeter.BaseCard {
         Greeter.BackgroundImage background_image;
 
         var background_path = lightdm_user.background;
+        warning ("Set background path to %s", background_path);
         var background_exists = (
             background_path != null &&
             FileUtils.test (background_path, EXISTS) &&
@@ -323,7 +324,7 @@ public class Greeter.UserCard : Greeter.BaseCard {
         settings.set_value ("xkb-options", options);
     }
 
-    /* 
+    /*
      * When we get string typed settings from our settings daemon account service we might get a null value.
      * In this case we reset the value to avoid criticals and unwanted behaviour.
      */
@@ -382,7 +383,14 @@ public class Greeter.UserCard : Greeter.BaseCard {
 
         var background_settings = new GLib.Settings ("org.gnome.desktop.background");
         background_settings.set_enum ("picture-options", settings_act.picture_options);
-        set_or_reset_settings_key (background_settings, "picture-uri", lightdm_user.background);
+
+        try {
+            var uri = Filename.to_uri (lightdm_user.background, null);
+            set_or_reset_settings_key (background_settings, "picture-uri", uri);
+        } catch (Error e) {
+            critical ("Failed to set background URI: %s", e.message);
+        }
+
         set_or_reset_settings_key (background_settings, "primary-color", settings_act.primary_color);
     }