Better display manager background

custom/sddm-theme-clairvoyance/default.nix

@@ -1,5 +1,5 @@
-{ lib, stdenv, fetchFromGitHub, fira-mono }:
-
+{ lib, stdenv, fetchFromGitHub, fira-mono, wallpaper ? null }:
+with lib;
 stdenv.mkDerivation rec {
   pname = "materia-kde-theme";
   version = "20190530";
@@ -16,6 +16,8 @@ stdenv.mkDerivation rec {
   installPhase = ''
     mkdir -p $out/usr/share/sddm/themes/
     cp -a . $out/usr/share/sddm/themes/clairvoyance
+  '' + optionalString (wallpaper != null) ''
+    cp ${wallpaper} $out/usr/share/sddm/themes/clairvoyance/Assets/Background.jpg
   '';
 
   meta = with lib; {

flake.nix

@@ -37,7 +37,7 @@
         (final: _: {
           update-background = final.callPackage ./custom/update-background { backgrounds_directory = "$HOME/Immagini/Sfondi/1080+/1440+"; };
           lockscreen = final.callPackage ./custom/lockscreen { palette = final.rice.colorPalette; font = final.rice.font.normal; };
-          sddm-theme-clairvoyance = final.callPackage ./custom/sddm-theme-clairvoyance { };
+          sddm-theme-clairvoyance = final.callPackage ./custom/sddm-theme-clairvoyance { wallpaper = ./wallpapers/comfy_waves.jpg; };
         })
         (_: _: { stable = pkgs; })
         (_: _: { unstable = unstablePkgs; })