Create wallpaper portal

data/pantheon.portal

@@ -1,4 +1,4 @@
 [portal]
 DBusName=org.freedesktop.impl.portal.desktop.pantheon
-Interfaces=org.freedesktop.impl.portal.Access;org.freedesktop.impl.portal.AppChooser;org.freedesktop.impl.portal.Background;
+Interfaces=org.freedesktop.impl.portal.Access;org.freedesktop.impl.portal.AppChooser;org.freedesktop.impl.portal.Background;org.freedesktop.impl.portal.Wallpaper
 UseIn=pantheon

src/Wallpaper/Portal.vala

@@ -0,0 +1,126 @@
+/*
+ * SPDX-FileCopyrigthText: 2024 elementary, Inc. (https://elementary.io)
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+[DBus (name = "org.freedesktop.impl.portal.Wallpaper")]
+public class Wallpaper.Portal : Object {
+    private DBusConnection connection;
+
+    public Portal (DBusConnection connection) {
+        this.connection = connection;
+    }
+
+    [DBus (name = "SetWallpaperURI")]
+    public async uint set_wallpaper_uri (
+        ObjectPath handle,
+        string app_id,
+        string parent_window,
+        string uri,
+        HashTable<string, Variant> options
+    ) throws DBusError, IOError {
+        unowned string set_on = "both"; // Possible values are background, lockscreen or both.
+        unowned bool show_preview = false; // FIXME: implement preview dialog
+
+        unowned var _set_on = options.get ("set-on");
+        if (_set_on.is_of_type (GLib.VariantType.STRING)) {
+            set_on = _set_on.get_string ();
+        }
+
+        unowned var _show_preview = options.get ("show-preview");
+        if (_show_preview.is_of_type (GLib.VariantType.BOOLEAN)) {
+            show_preview = _show_preview.get_boolean ();
+        }
+
+        // Currently only support Both
+        if (set_on == "background" || set_on == "lockscreen") {
+            return 1;
+        }
+
+        var file = File.new_for_uri (uri);
+        if (!get_is_file_in_bg_dir (file)) {
+            file = copy_for_library (file);
+        }
+
+        if (file != null) {
+            var settings = new Settings ("org.gnome.desktop.background");
+            settings.set_string ("picture-uri", file.get_uri ());
+        }
+
+        return 0;
+    }
+
+    private static bool get_is_file_in_bg_dir (File file) {
+        string path = file.get_path ();
+
+        foreach (unowned string directory in get_bg_directories ()) {
+            if (path.has_prefix (directory)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private static File? copy_for_library (File source) {
+        File? dest = null;
+
+        try {
+            var timestamp = new DateTime.now_local ().format ("%Y-%m-%d-%H-%M-%S");
+            var filename = "%s-%s".printf (timestamp, source.get_basename ());
+            dest = ensure_local_bg_exists ().get_child (filename);
+            source.copy (dest, FileCopyFlags.OVERWRITE | FileCopyFlags.ALL_METADATA);
+        } catch (Error e) {
+            warning (e.message);
+        }
+
+        return dest;
+    }
+
+    private static string[] get_bg_directories () {
+        string[] background_directories = {};
+
+        // Add user background directory first
+        background_directories += get_local_bg_directory ();
+
+        foreach (var bg_dir in get_system_bg_directories ()) {
+            background_directories += bg_dir;
+        }
+
+        if (background_directories.length == 0) {
+            warning ("No background directories found");
+        }
+
+        return background_directories;
+    }
+
+    private static File ensure_local_bg_exists () {
+        var folder = File.new_for_path (get_local_bg_directory ());
+        if (!folder.query_exists ()) {
+            try {
+                folder.make_directory_with_parents ();
+            } catch (Error e) {
+                warning (e.message);
+            }
+        }
+
+        return folder;
+    }
+
+    private static string get_local_bg_directory () {
+        return Path.build_filename (Environment.get_user_data_dir (), "backgrounds") + "/";
+    }
+
+    private static string[] get_system_bg_directories () {
+        string[] directories = {};
+        foreach (unowned string data_dir in Environment.get_system_data_dirs ()) {
+            var system_background_dir = Path.build_filename (data_dir, "backgrounds") + "/";
+            if (FileUtils.test (system_background_dir, FileTest.EXISTS)) {
+                debug ("Found system background directory: %s", system_background_dir);
+                directories += system_background_dir;
+            }
+        }
+
+        return directories;
+    }
+}

src/XdgDesktopPortalPantheon.vala

@@ -40,6 +40,9 @@ private void on_bus_acquired (DBusConnection connection, string name) {
 
         connection.register_object ("/org/freedesktop/portal/desktop", new Background.Portal (connection));
         debug ("Background Portal registered!");
+
+        connection.register_object ("/org/freedesktop/portal/desktop", new Wallpaper.Portal (connection));
+        debug ("Wallpaper Portal registered!");
     } catch (Error e) {
         critical ("Unable to register the object: %s", e.message);
     }

src/meson.build

@@ -8,6 +8,7 @@ executable(
     'AppChooser/Portal.vala',
     'Background/NotificationRequest.vala',
     'Background/Portal.vala',
+    'Wallpaper/Portal.vala',
     configure_file(input: 'Config.vala.in', output: '@BASENAME@', configuration: conf_data),
     'ExternalWindow.vala',
     'XdgDesktopPortalPantheon.vala',