wallpaper-engine-kde-plugin on NixOS

wallpaper-engine-kde-plugin.nix

{ config, lib, pkgs, ...}:

let 
  # References: https://github.com/xerhaxs/nixos/blob/main/nixosModules/pkgs/wallpaper-engine-kde-plugin.nix and https://discourse.nixos.org/t/wallpaper-engine-on-nixos-wallpaper-engine-kde-plugin/19744/25
  glslang-submodule = with pkgs; stdenv.mkDerivation {
    name = "glslang";
    installPhase = ''
      mkdir -p $out
    '';
    src = fetchFromGitHub {
      owner = "KhronosGroup";
      repo = "glslang";
      rev = "c34bb3b6c55f6ab084124ad964be95a699700d34";
      sha256 = "IMROcny+b5CpmzEfvKBYDB0QYYvqC5bq3n1S4EQ6sXc=";
    };
  };

  wallpaper-engine-kde-plugin = with pkgs; stdenv.mkDerivation rec {
    pname = "wallpaperEngineKde";
    version = "96230de92f1715d3ccc5b9d50906e6a73812a00a";
    src = fetchFromGitHub {
      owner = "Jelgnum";
      repo = "wallpaper-engine-kde-plugin";
      rev = version;
      hash = "sha256-vkWEGlDQpfJ3fAimJHZs+aX6dh/fLHSRy2tLEsgu/JU=";
      fetchSubmodules = true;
        };

    nativeBuildInputs = [
      cmake
      kdePackages.extra-cmake-modules
      glslang-submodule
      pkg-config
      gst_all_1.gst-libav
      shaderc
      ninja
    ];

    buildInputs = [
      mpv
      lz4
      vulkan-headers
      vulkan-tools
      vulkan-loader
    ] 
    ++ (with kdePackages; with qt6Packages; [
      qtbase
      qt6.full
      kpackage
      kdeclarative
      libplasma
      qtwebsockets
      qtwebengine
      qtwebchannel
      qtmultimedia
      qtdeclarative
    ])
    ++ [(python3.withPackages (python-pkgs: [ python-pkgs.websockets ]))];

    cmakeFlags = [ "-DUSE_PLASMAPKG=OFF" ];
    dontWrapQtApps = true;

    postPatch = ''
      rm -rf src/backend_scene/third_party/glslang
      ln -s ${glslang-submodule.src} src/backend_scene/third_party/glslang
    '';
    #Optional informations
    meta = with lib; {
      description = "Wallpaper Engine KDE plasma plugin";
      homepage = "https://github.com/Jelgnum/wallpaper-engine-kde-plugin";
      license = licenses.gpl2Plus;
      platforms = platforms.linux;
    };
  };
in 

{
  options.nixos = {
    pkgs.wallpaper-engine-kde-plugin = {
      enable = lib.mkOption {
        type = lib.types.bool;
        default = false;
        example = true;
        description = "Enable wallpaper-engine-kde-plugin.";
      };
    };
  };

  config = lib.mkIf (config.nixos.pkgs.wallpaper-engine-kde-plugin.enable) {
    environment.systemPackages = with pkgs; [
      wallpaper-engine-kde-plugin
      kdePackages.qtwebsockets
      kdePackages.qtwebchannel
      (python3.withPackages (python-pkgs: [ python-pkgs.websockets ]))
    ];

    system.activationScripts = {
      wallpaper-engine-kde-plugin.text = ''
        wallpaperenginetarget=/share/plasma/wallpapers/com.github.catsout.wallpaperEngineKde
        mkdir -p /home/${builtins.head (builtins.attrNames config.users.users)}/.local/share/plasma/wallpapers
        chown -R ${builtins.head (builtins.attrNames config.users.users)}:users /home/${builtins.head (builtins.attrNames config.users.users)}/.local/share/plasma
        if [ ! -e /home/${builtins.head (builtins.attrNames config.users.users)}/.local$wallpaperenginetarget ]; then
          ln -sf ${wallpaper-engine-kde-plugin}$wallpaperenginetarget /home/${builtins.head (builtins.attrNames config.users.users)}/.local$wallpaperenginetarget
        fi;
      '';
    };
  };
}

So I solved the issue, though honestly I'm not sure why it works. I searched up my issue online, and found this post. But since I'm still a completely beginner to nix and nixos, I didn't know how to run the script it gives.

So I decided to follow the script manually. I found out the exact nix store path, and manually created a symlink between the two:
ln -sf /nix/store/g55hivkdl0vr5w7mw7d5cq41cl5nkm3r-wallpaperEngineKde-96230de92f1715d3ccc5b9d50906e6a73812a00a/share/plasma/wallpapers/com.github.catsout.wallpaperEngineKde/ ~/.local/share/plasma/wallpapers/com.github.catsout.wallpaperEngineKde

Restarted my system, and lo and behold, somehow now it works perfectly. I don't know if the store path would be the same for all systems, but for anyone with the same problem, the solution seems to be just manually create a symlink from ~/.local/share/plasma/wallpapers/, pointing to the com.github.catsout.wallpaperEngineKde folder in the nix store path.

Probably not the best or most "Nix" solution, but it works.

@BBArikL, if I'm not mistaken, the very last line of your script should be doing the same thing, but somehow it doesn't seem to be working? Maybe the file path is wrong, or the if statement is messing something up?

Hey! Yes the store path is different between each system and each nix generation (its basically a hash that is derived from your system configuration). Before, I was not using a leading / for the wallpaper engine target, but I was corrected by people in that discourse thread to add that leading forward slash. I think I have an inconsistent usage of the $wallpaperenginetarget. I'll make a new revision but I cannot test it right now. For people on nixos unstable, I'd recommend to go for the one in the official (nix) repo. If it ever comes on nixos stable, I will stop maintaining this gist and use the one which is in the nix repo.

Thanks for making this package!

OK, this error disappeared after use this config: https://github.com/xerhaxs/nixos/blob/main/nixosModules/pkgs/wallpaper-engine-kde-plugin.nix

I indeed needed this as well to make python run properly. Seems like video wallpapers run (after installing qtmultimediate) while all scene wallpapers have a black screen. Is that an issue with the packaging or the plugin itself? wallpaper-engine-kde-plugin seems to support scene wallpapers so I'm not sure if I'm just doing something wrong