nixos-artwork: add file path attributes

This makes things so much easier, and we install to
the path that both gnome-backgrounds and
elementary-wallpapers install to.

(cherry picked from commit 62587f4)

nixos/modules/services/x11/desktop-managers/gnome3.nix

@@ -37,10 +37,10 @@ let
      chmod -R a+w $out/share/gsettings-schemas/nixos-gsettings-overrides
      cat - > $out/share/gsettings-schemas/nixos-gsettings-overrides/glib-2.0/schemas/nixos-defaults.gschema.override <<- EOF
        [org.gnome.desktop.background]
-       picture-uri='file://${pkgs.nixos-artwork.wallpapers.simple-dark-gray}/share/artwork/gnome/nix-wallpaper-simple-dark-gray.png'
+       picture-uri='file://${pkgs.nixos-artwork.wallpapers.simple-dark-gray.gnomeFilePath}'
 
        [org.gnome.desktop.screensaver]
-       picture-uri='file://${pkgs.nixos-artwork.wallpapers.simple-dark-gray-bottom}/share/artwork/gnome/nix-wallpaper-simple-dark-gray_bottom.png'
+       picture-uri='file://${pkgs.nixos-artwork.wallpapers.simple-dark-gray-bottom.gnomeFilePath}'
 
        [org.gnome.shell]
        favorite-apps=[ 'org.gnome.Epiphany.desktop', 'org.gnome.Geary.desktop', 'org.gnome.Music.desktop', 'org.gnome.Photos.desktop', 'org.gnome.Nautilus.desktop', 'org.gnome.Software.desktop' ]

nixos/modules/services/x11/display-managers/lightdm.nix

@@ -128,7 +128,8 @@ in
 
       background = mkOption {
         type = types.str;
-        default = "${pkgs.nixos-artwork.wallpapers.simple-dark-gray-bottom}/share/artwork/gnome/nix-wallpaper-simple-dark-gray_bottom.png";
+        # Manual cannot depend on packages, we are actually setting the default in config below.
+        defaultText = "pkgs.nixos-artwork.wallpapers.simple-dark-gray-bottom.gnomeFilePath";
         description = ''
           The background image or color to use.
         '';
@@ -207,6 +208,9 @@ in
       }
     ];
 
+    # Keep in sync with the defaultText value from the option definition.
+    services.xserver.displayManager.lightdm.background = mkDefault pkgs.nixos-artwork.wallpapers.simple-dark-gray-bottom.gnomeFilePath;
+
     # Set default session in session chooser to a specified values – basically ignore session history.
     # Auto-login is already covered by a config value.
     services.xserver.displayManager.job.preStart = optionalString (!cfg.autoLogin.enable && dmcfg.defaultSession != null) ''

nixos/modules/system/boot/loader/grub/grub.nix

@@ -83,7 +83,7 @@ let
              ] ++ (optional (cfg.fontSize!=null) "--size ${toString cfg.fontSize}")))
          );
 
-  defaultSplash = "${pkgs.nixos-artwork.wallpapers.simple-dark-gray-bootloader}/share/artwork/gnome/nix-wallpaper-simple-dark-gray_bootloader.png";
+  defaultSplash = pkgs.nixos-artwork.wallpapers.simple-dark-gray-bootloader.gnomeFilePath;
 in
 
 {

pkgs/data/misc/nixos-artwork/wallpapers.nix

@@ -3,12 +3,18 @@
 let
   mkNixBackground = { name, src, description }:
 
-    stdenv.mkDerivation {
+  let
+    pkg = stdenv.mkDerivation {
       inherit name src;
 
       dontUnpack = true;
 
       installPhase = ''
+        # GNOME
+        mkdir -p $out/share/backgrounds/nixos
+        ln -s $src $out/share/backgrounds/nixos/${src.name}
+
+        # TODO: is this path still needed?
         mkdir -p $out/share/artwork/gnome
         ln -s $src $out/share/artwork/gnome/${src.name}
 
@@ -22,13 +28,19 @@ X-KDE-PluginInfo-Name=${name}
 _EOF
       '';
 
+      passthru = {
+        gnomeFilePath = "${pkg}/share/backgrounds/nixos/${src.name}";
+        kdeFilePath = "${pkg}/share/wallpapers/${name}/contents/images/${src.name}";
+      };
+
       meta = with stdenv.lib; {
         inherit description;
         homepage = https://github.com/NixOS/nixos-artwork;
         license = licenses.free;
         platforms = platforms.all;
       };
     };
+in pkg;
 
 in
 

pkgs/desktops/pantheon/desktop/elementary-default-settings/default.nix

@@ -49,7 +49,7 @@ stdenv.mkDerivation rec {
 
   mesonFlags = [
     "--sysconfdir=${placeholder "out"}/etc"
-    "-Ddefault-wallpaper=${nixos-artwork.wallpapers.simple-dark-gray}/share/artwork/gnome/nix-wallpaper-simple-dark-gray.png"
+    "-Ddefault-wallpaper=${nixos-artwork.wallpapers.simple-dark-gray.gnomeFilePath}"
     "-Dplank-dockitems=false"
   ];
 

pkgs/desktops/pantheon/desktop/elementary-greeter/default.nix

@@ -89,7 +89,7 @@ stdenv.mkDerivation rec {
     # Needed until https://github.com/elementary/greeter/issues/360 is fixed
     (substituteAll {
       src = ./hardcode-fallback-background.patch;
-      default_wallpaper = "${nixos-artwork.wallpapers.simple-dark-gray}/share/artwork/gnome/nix-wallpaper-simple-dark-gray.png";
+      default_wallpaper = "${nixos-artwork.wallpapers.simple-dark-gray.gnomeFilePath}";
     })
   ];
 
@@ -113,7 +113,7 @@ stdenv.mkDerivation rec {
     # Use NixOS default wallpaper
     substituteInPlace $out/etc/lightdm/io.elementary.greeter.conf \
       --replace "#default-wallpaper=/usr/share/backgrounds/elementaryos-default" \
-      "default-wallpaper=${nixos-artwork.wallpapers.simple-dark-gray}/share/artwork/gnome/nix-wallpaper-simple-dark-gray.png"
+      "default-wallpaper=${nixos-artwork.wallpapers.simple-dark-gray.gnomeFilePath}"
 
     substituteInPlace $out/share/xgreeters/io.elementary.greeter.desktop \
       --replace "Exec=io.elementary.greeter" "Exec=$out/bin/io.elementary.greeter"