# Compilation

For more details and other workflows see the "Advanced guide" below.

## Checking out the code

```bash
git clone https://github.com/libjxl/libjxl.git --recursive --shallow-submodules
```

This repository uses git submodules to handle some third party dependencies
under `third_party`, that's why it is important to pass `--recursive`. If you
didn't check out with `--recursive`, or any submodule has changed, run:

```bash
git submodule update --init --recursive --depth 1 --recommend-shallow
```

The `--shallow-submodules` and `--depth 1 --recommend-shallow` options create
shallow clones which only downloads the commits requested, and is all that is
needed to build `libjxl`. Should full clones be necessary, you could always run:

```bash
git submodule foreach git fetch --unshallow
git submodule update --init --recursive
```

which pulls the rest of the commits in the submodules.

Important: If you downloaded a zip file or tarball from the web interface you
won't get the needed submodules and the code will not compile. You can download
these external dependencies from source running `./deps.sh`. The git workflow
described above is recommended instead.

## Installing dependencies

Required dependencies for compiling the code, in a Debian/Ubuntu based
distribution run:

```bash
sudo apt install cmake pkg-config libbrotli-dev
```

Optional dependencies for supporting other formats in the `cjxl`/`djxl` tools,
in a Debian/Ubuntu based distribution run:

```bash
sudo apt install libgif-dev libjpeg-dev libopenexr-dev libpng-dev libwebp-dev
```

We recommend using a recent Clang compiler (version 7 or newer), for that
install clang and set `CC` and `CXX` variables.

```bash
sudo apt install clang
export CC=clang CXX=clang++
```

## Building

```bash
cd libjxl
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTING=OFF ..
cmake --build . -- -j$(nproc)
```

The encoder/decoder tools will be available in the `build/tools` directory.

## <a name="installing"></a> Installing

```bash
sudo cmake --install .
```



## Advanced guide

### Building with Docker

We build a common environment based on Debian/Ubuntu using Docker. Other
systems may have different combinations of versions and dependencies that
have not been tested and may not work. For those cases we recommend using the
Docker container as explained in the
[step by step guide](doc/developing_in_docker.md).

### Building JPEG XL for developers

For experienced developers, we provide build instructions for several other environments:

*   [Building on Debian](doc/developing_in_debian.md)
*   Building on Windows with [vcpkg](doc/developing_in_windows_vcpkg.md) (Visual Studio 2019)
*   Building on Windows with [MSYS2](doc/developing_in_windows_msys.md)
*   [Cross Compiling for Windows with Crossroad](doc/developing_with_crossroad.md)

If you encounter any difficulties, please use Docker instead.