A Qt6/Qt5 platform theme using the KDE Color Scheme format, meant to be easily configurable.

• An easy config in JSON
• Works with Qt5 & Qt6 on the same config
• Works with KDE apps
• Doesn't freeze the Plasma XDG Desktop Portal

First add the input to your flake.

qtengine = {
  url = "github:kossLAN/qtengine";
  inputs.nixpkgs.follows = "nixpkgs";
};

Then use the provided NixOS module.

imports = [inputs.qtengine.nixosModules.default];

# Add your desired theme to your system packages
environment.systemPackages = with pkgs.kdePackages; [
  breeze
  breeze.qt5 # Needed if you want Qt5 support.
  breeze-icons
];

programs.qtengine = {
  enable = true;
  
  config = {
    theme = {
      colorScheme = "${pkgs.kdePackages.breeze}/share/color-schemes/BreezeDark.colors";
      iconTheme = "breeze-dark";
      style = "breeze";

      font = {
        family = "<font name>";
        size = 11;
        weight = -1;
      };

      fontFixed = {
        family = "<font name>";
        size = 11;
        weight = -1;
      };
    };

    misc = {
      singleClickActivate = false;
      menusHaveIcons = true;
      shortcutsForContextMenus = true;
    };
  };
};

First install the AUR package.

yay -S qtengine
# yay -S qtengine-git

Then copy the example config from /etc/qtengine/config.example.json to ~/.config/qtengine/config.json. Additionally, it can be sourced from a folder in your XDG_CONFIG_DIRS, or by using the QTENGINE_CONFIG environment variable.

Finally set the environment variable QT_QPA_PLATFORMTHEME to qtengine.

First you'll need the following Qt6 dependencies

required: extra-cmake-modules qtbase kconfig kcolorscheme kiconthemes
optional: qtdeclarative

If you want Qt5 support you'll also need

required: qtbase kconfig kconfigwidgets kiconthemes
optional: qtdeclarative qtquickcontrols2

Then build the project

cmake -DCMAKE_BUILD_TYPE:STRING=Release -B build

# OPTIONAL: if you don't want to build with Qt5 support
cmake -DCMAKE_BUILD_TYPE:STRING=Release -DBUILD_QT5=OFF -B build

cmake --build build
cmake --install build

# OPTIONAL: or you can just use the Justfile if you have just
just build
just install

Then write a config at ~/.config/qtengine/config.json, additionally it can be sourced from a folder in your XDG_CONFIG_DIRS, or by using the QTENGINE_CONFIG environment variable.

{
  "theme": {
    "colorScheme": "<path to KColorScheme file>",
    "iconTheme": "breeze-dark",
    "style": "breeze",
    "font": {
      "family": "<font name>",
      "size": 11,
      "weight": -1
    },
    "fontFixed": {
      "family": "<font name>",
      "size": 11,
      "weight": -1
    }
  },
  "misc": {
    "menusHaveIcons": true,
    "singleClickActivate": false,
    "shortcutsForContextMenus": true
  }
}

Finally set the environment variable QT_QPA_PLATFORMTHEME to qtengine.

Thank you hyprqt6engine & qt6ct for being the foundation of this project. Also a thanks to outfoxxed because I "borrowed" a lot of his C++ build tools that made working in C++ a lot less painful, especially on NixOS.