gnome_desktop

Ruby bindings for libgnome-desktop-4, the GNOME Utility Library — the locale and language name database behind GNOME's language chooser, the XKB layout registry behind its input-source list, the monitor-vendor table, the thumbnail factory, the wall clock and the idle monitor.

require "gnome_desktop"

ok, language, country = GnomeDesktop.parse_locale("en_GB.UTF-8@euro")
GnomeDesktop.get_language_from_code("en", nil)   # => "English"

xkb = GnomeDesktop::XkbInfo.new
xkb.all_layouts                                  # => ["us", "gb", "de", ...]
xkb.get_layout_info("us")                        # => [true, "English (US)", "en", "us", ""]

GnomeDesktop::PnpIds.new.get_pnp_id("DEL")       # => "Dell Inc."
GnomeDesktop::WallClock.new.clock                # => "3 Nov 00:42"

This is GnomeDesktop-4.0. Three other namespaces ship from the same C package and are not defined here: GnomeDesktop-3.0 is the GTK3 generation of the same library, and GnomeBG-4.0 and GnomeRR-4.0 both depend on Gdk-4.0, so each belongs in a gem of its own rather than dragging GTK4 into this one.

libgnome-desktop ships a GObject Introspection typelib that describes every class, method, property and signal it has. GnomeDesktop::Loader — twenty lines — hands that typelib to ruby-gnome's GObjectIntrospection::Loader, which defines the Ruby classes from it at require time.

So this gem is pure Ruby: no extension of its own, no Cargo workspace, no per-platform binary. You get the whole namespace rather than the subset somebody got round to wrapping by hand, and it does not drift when the library gains API.

It is worth being precise about what that does and does not buy you at install time. gem install gnome_desktop still compiles C, because gobject-introspection and glib2 are themselves native extensions built against glib — so a compiler and glib's development headers are needed. What this gem adds on top of that is nothing: those two are what every ruby-gnome application already has, since gtk4 depends on them. If you are writing a Ruby GTK app, gnome_desktop costs you no build step you were not already paying.

This is how ruby-gnome itself ships gtksourceview5, libsecret and the rest.

The typelib is a C-library artefact, so it belongs to your distribution and this gem cannot install it. Two things are needed: the introspection data for libgnome-desktop-4, and gsettings-desktop-schemas, because GnomeDesktop::XkbInfo's constructor opens a GSettings for org.gnome.desktop.input-sources and a missing schema is a g_error, which aborts the process rather than raising.

If your distribution has renamed one of these, the file to search for is GnomeDesktop-4.0.typelib. Two more typelibs come along as dependencies — GDesktopEnums-3.0 (from gsettings-desktop-schemas, which is not an obvious place to look for it) and GdkPixbuf-2.0 — plus Gio-2.0 from glib, which the glib2 gem already requires.

Several of these lookups read data files rather than compute: xkeyboard-config supplies the keyboard layout registry, hwdata the monitor-vendor table, iso-codes and the system locale archive the country and language names. A machine without them returns empty lists and nils, which is not a fault in this binding.

If the typelibs are not in the default search path, point GI_TYPELIB_PATH at the directory holding GnomeDesktop-4.0.typelib and GSETTINGS_SCHEMA_DIR at the one holding gschemas.compiled. The dev shell in flake.nix does both.

One trap worth knowing. The typelib must come from the same glib build as the gobject-introspection gem. Mixing two registers GIO twice in one process and fails with cannot register existing type 'GTlsCertificate'. Under nix, take both from one nixpkgs — and note that glib's typelibs are in its out output, not the default bin one.

GnomeDesktop::DesktopThumbnailFactory.new cannot be called through the typelib. Its one argument is GnomeDesktopThumbnailSize, a plain C enum with no GType, so GI has nothing to marshal it from and reports the signature as interface(NilClass(void)). The GnomeDesktop::DesktopThumbnailSize constants are defined and the class exists; constructing it needs a fix upstream in libgnome-desktop's annotations, not here.

The gem needs GnomeDesktop-4.0.typelib and everything that typelib declares, resolved transitively by the loader at require time. A missing one surfaces as Typelib file for namespace 'X' not found, one at a time, so the whole chain is listed here rather than discovered by repeated failure:

• pkgs.gnome-desktop — its typelib, which is where GnomeDesktop-4.0.typelib lives
• pkgs.gsettings-desktop-schemas — its typelib
• pkgs.gdk-pixbuf — GdkPixbuf-2.0
• pkgs.glib — GLib-2.0, GObject-2.0 and Gio-2.0, which nearly every GNOME typelib declares

Note the .out: a package's default output is often bin, which carries no typelibs. makeSearchPath takes the first output, so it has to be asked for out explicitly — this is the single most common way to get a search path that looks right and finds nothing.

{
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

  outputs = { nixpkgs, ... }:
    let
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};

      typelibPath = pkgs.lib.makeSearchPath "lib/girepository-1.0"
        (map (drv: drv.out or drv) [ pkgs.gnome-desktop pkgs.gsettings-desktop-schemas pkgs.gdk-pixbuf pkgs.glib ]);
    in
    {
      devShells.${system}.default = pkgs.mkShell {
        packages = [ pkgs.ruby_3_4 pkgs.bundler ] ++ [ pkgs.gnome-desktop pkgs.gsettings-desktop-schemas pkgs.gdk-pixbuf pkgs.glib ];

        shellHook = ''
          export GI_TYPELIB_PATH="${typelibPath}''${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}"
        '';
      };
    };
}

Everything must come from one nixpkgs. A typelib built against a different glib than the gobject-introspection gem registers GIO twice in the process and fails with cannot register existing type 'GTlsCertificate'.

If you are packaging an application rather than entering a shell, the same typelibPath goes on the wrapper:

makeWrapper ${ruby}/bin/ruby $out/bin/my-app \
  --set GI_TYPELIB_PATH "${typelibPath}"

nix develop
bin/test

gem kit release

That is the whole thing. It gates on the changelog having an entry for this version, on no deprecation deadline coming due, and on a clean working tree; then builds, pushes and tags.

There is nothing to wait for in CI. This gem is pure Ruby, so gem build produces one gnome_desktop-X.Y.Z.gem that is the same artefact wherever it is built — no extension, no per-platform gems, nothing for a workflow to hand back.

Apache-2.0. libgnome-desktop itself is LGPL-2.0-or-later; this gem links nothing and copies no libgnome-desktop code — it reads a description of it at runtime.