Just

just is the project's task runner. It provides a consistent interface for building, running and cleaning the project.

tip

To see every available command at any time, run:

Show available Just commands

just help

Initialise the project

info

If you have already run just init before (like when following the Project Setup Guide), you don't need to run it again.

There is no harm in re-running it, though.

Run this once after cloning the repository.

Paste this in the Docker shell

just init

This:

• Pulls the required Git submodules.
• Installs project dependencies.
• Builds the entire project.

Build the project

Everything

Build Everything (C++, C, JS, WASM, Python, React App, ...).

Paste this inside the Docker shell

just build all

C++ and C

Build C++ Core and C Bindings.

This is CMake-based with GCC / MSVC.

build-c-cpp/ CMake build folder.

Paste this inside the Docker shell

just build cpp

Key files:

• CMakeLists.txt
• core/CMakeLists.txt.
• bindings/c/CMakeLists.txt.

JS / WASM

Build JavaScript / WASM Bindings.

This is CMake-based with Emscripten (to compile to WebAssembly).

• build-wasm/ CMake build folder.
• packages/js/build-wasm/ copied folder (from build-wasm/).

Paste this inside the Docker shell

just build js

Key Files:

• CMakeLists.txt
• bindings/js/CMakeLists.txt.

Build Browser & Node.js npm packages.

This is pnpm-based, yet it requires the outputs from the just build js command.

packages/js/dist folder.

Paste this inside the Docker shell

just build packages-js

Key files:

• package.json
• pnpm-workspace.yaml
• packages/js/package.json
• packages/js/vite.config.js

Common Confusion

just build js only produces the raw WASM/JS bindings. To build the publishable img2num npm package — which targets both the browser and Node.js — run just build packages-js. It compiles the WASM bindings first (so it works from a clean checkout) and then bundles the browser and Node builds into packages/js/dist/.

Python

Build Python Bindings + Wheel

This uses uv and scikit-build-core to build the Pybind11 Python bindings in bindings/py alongside the Python wrapper in packages/py.

dist folder.

Paste this inside the Docker shell

just build py

Key files:

• pyproject.toml
• packages/py/pyproject.toml
• CMakeLists.txt
• bindings/py/CMakeLists.txt.

Documentation

Build

Build the documentation:

Paste this in the Docker shell

just docs build

Server

Start the documentation server:

Paste this in the Docker shell

just docs start

Example applications

Build first

Excluding the React.js example application, the respective projects must be built first before you can run them or see the latest changes you made.

C++ console app

Run it

just console-cpp <path-to-image>

C console app

Run it

just console-c <path-to-image>

React.js web app

Run it

just react-js start

Next open http://localhost:5173/example-apps/react-js/ in your browser.

Python console app

Run it

just console-py <path-to-image>

Node.js console app

Run it

just console-js <path-to-image>

Cleaning

Remove generated build files:

C++

Paste this inside the Docker shell

just clean cpp

JS / WASM

Paste this inside the Docker shell

just clean js

JS Packages

Paste this inside the Docker shell

just clean packages-js

Python Packages

Paste this inside the Docker shell

just clean packages-py