Core systems & architecture

This section describes the organization of OpenGamepadUI's source code, and provides an overview of the architecture and systems that it uses.

Project Layout

OpenGamepadUI
├── addons                  # 3rd party libraries & Compiled rust extensions
├── assets                  # Images, sound, state, themes, shaders, etc.
├── core
│   ├── global              # (Deprecated) Global systems
│   ├── main.{gd,tscn}      # Loads the appropriate UI (e.g. Card UI)
│   ├── platform            # Platform-specific logic
│   ├── systems             # Core application logic and systems
│   └── ui                  # Menus and menu components
├── CREDITS.md              # Attributions for contributors
├── docs
├── entrypoint.{gd,tscn}    # Application entrypoint script/scene
├── extensions              # Rust GDExtension source code
├── export_presets.cfg
├── icon.svg
├── LICENSE                 # License file
├── Makefile                # Makefile
├── plugins                 # Used for plugin development
├── project.godot
├── README.md               # Project README
└── rootfs                  # Filesystem and scripts for final package

Addons

The addons directory contains 3rd party libraries used by OpenGamepadUI as well as compiled GDExtension code from the extensions folder. Some 3rd party libraries include the GUT testing framework and more.

Extensions

Godot Engine provides a lot of functionality, but not everything that OpenGamepadUI needs.

The extensions directory contains the Rust source code used to extend the functionality of the engine using GDExtension. This is typically done to add performance-sensitive code as well as add support for interacting with systems like Gamescope and DBus. When OpenGamepadUI is built, these extensions are compiled to the addons directory.

Assets

The assets directory contains all of the images, icons, sounds, shaders, themes, state, etc.

assets/
├── animations
├── audio
├── crypto
├── editor-icons
├── gamepad
├── icons
├── images
├── keyboard
├── label
├── shaders
├── state
├── styles
├── themes
├── ui
└── videos

Global Systems

The core/global directory contains "global" systems that can be used from any script in the project. This directory has been deprecated in favor of just putting these systems in the systems directory instead.

OpenGamepadUI has several global systems that are typically implemented as a custom resource. Resources in Godot are unique in that they are only ever loaded once by the engine. This allows nodes to access their functionality regardless of where they are in the scene tree.

Platform

The core/platform directory contains platform-specific logic, such as modifying the behavior, look, or feel of OpenGamepadUI when running on different hardware or OS platforms.

Examples of this might be using custom gamepad icons for a handheld, or running specific logic to start a driver.

Systems

The core/systems directory contains all the core application logic of OpenGamepadUI. These systems should not contain any UI-specific logic. An example of a core system is BluetoothManager, which provides methods for interacting with bluetooth.

Systems are usually implemented as a Node that can be added to the scene tree or implemented as a custom resource that can be loaded and referenced regardless of where it is called from the scene tree.

UI

The core/ui directory contains all of the user interface scenes and scripts of OpenGamepadUI. That includes things like menus as well as UI components like buttons and text boxes. Each menu scene provides the glue between the various UI components and backend systems.

Root Filesystem

The rootfs directory contains additional system configuration and supplemental scripts that should be part of the OpenGamepadUI package when installed. It includes things like polkit policies for executing certain commands with elevated privileges and helper scripts to interact with the system.

rootfs
├── Makefile
└── usr
    ├── bin
    │   └── opengamepadui
    ├── lib
    │   └── systemd
    │       └── user
    │           ├── ogui-overlay-mode.service
    │           └── systemd-sysext-updater.service
    └── share
        ├── applications
        │   └── opengamepadui.desktop
        ├── icons
        │   └── hicolor
        │       └── scalable
        │           └── apps
        │               └── opengamepadui.svg
        ├── opengamepadui
        │   └── scripts
        │       ├── make_nice
        │       ├── manage_input
        │       └── update_systemd_ext.sh
        └── polkit-1
            └── actions
                ├── org.shadowblip.manage_input.policy
                ├── org.shadowblip.nixos_updater.policy
                └── org.shadowblip.setcap.policy