# Building

## Dependencies

Required:

- C++17 compiler
- zlib (`zlib1g-dev` / `zlib-devel` / Homebrew `zlib`)

libzip and Eigen 3.4+ are fetched automatically by CMake when not found
locally — no manual installation required.

## Installing dependencies

The examples below include GoogleTest, which is only required when building
the tests. Ninja is optional but recommended.

On Debian-based systems:

```bash
sudo apt-get install \
   zlib1g-dev \
   ninja-build \
   libgtest-dev
```

On Mac OS, you can install the dependencies with brew:

```bash
brew install googletest ninja zlib
```

On Windows, you can install the dependencies through vcpkg and chocolatey:

```powershell
choco install ninja -y
vcpkg install gtest zlib
```

## Building to use in other projects

The recommended way to consume trx-cpp is via `add_subdirectory` or
FetchContent — this always works regardless of how libzip is resolved.
When using either approach, **zlib is the only dependency you need
pre-installed**; libzip and Eigen 3.4+ are fetched automatically if not
already present. Because Eigen is a public dependency of trx-cpp, your
code can use `Eigen3::Eigen` (and include Eigen headers) without a
separate `find_package(Eigen3)` call.

```cmake
# CMakeLists.txt of your project
add_subdirectory(path/to/trx-cpp)           # vendored copy
target_link_libraries(your_target PRIVATE trx-cpp::trx)

# — or via FetchContent —
include(FetchContent)
FetchContent_Declare(trx-cpp
    GIT_REPOSITORY https://github.com/tee-ar-ex/trx-cpp.git
    GIT_TAG        main)
FetchContent_MakeAvailable(trx-cpp)
target_link_libraries(your_target PRIVATE trx-cpp::trx)
```

**Installing trx-cpp** (`cmake --install`) requires libzip to be available
as a system-installed package with CMake config support. When libzip is
auto-fetched by CMake (the default), the install step is automatically skipped
with a status message.

To enable installation, first install libzip through your package manager:

```bash
# Debian/Ubuntu
sudo apt-get install libzip-dev

# macOS
brew install libzip
```

```powershell
# Windows (vcpkg)
vcpkg install libzip
```

Then configure and install trx-cpp normally:

```bash
cmake -S . -B build \
  -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DTRX_BUILD_EXAMPLES=OFF \
  -DTRX_ENABLE_INSTALL=ON \
  -DCMAKE_INSTALL_PREFIX=/path/to/installation/directory
cmake --build build --config Release
cmake --install build
```

After installation, consume the package with:

```cmake
find_package(trx-cpp CONFIG REQUIRED)
target_link_libraries(your_target PRIVATE trx-cpp::trx)
```

Key CMake options:

- `TRX_ENABLE_INSTALL`: Install package config and targets (default ON for top-level builds)
- `TRX_BUILD_EXAMPLES`: Build example executables (default ON)
- `TRX_BUILD_TESTS`: Build tests (default OFF)
- `TRX_BUILD_DOCS`: Build docs with Doxygen/Sphinx (default OFF)
- `TRX_ENABLE_CLANG_TIDY`: Run clang-tidy during builds (default OFF)
- `TRX_USE_CONAN`: Use Conan setup in `cmake/ConanSetup.cmake` (default OFF)
- `TRX_FETCH_EIGEN`: Fetch Eigen3 with FetchContent when not found locally (default ON)

## Building for testing

```bash
cmake -S . -B build \
  -G Ninja \
  -DTRX_BUILD_TESTS=ON \
  -DTRX_ENABLE_NIFTI=ON \
  -DTRX_BUILD_EXAMPLES=OFF

cmake --build build
ctest --test-dir build --output-on-failure
```

Tests require GTest to be discoverable by CMake (e.g., via a system package or
`GTest_DIR`). If GTest is not found, tests will be skipped.
zlib must be discoverable by CMake (`ZLIB::ZLIB`), including for NIfTI I/O.

## Building documentation:

Building the docs requires both Doxygen and `sphinx-build` on your PATH.

```bash
cmake -S . -B build \
  -G Ninja \
  -DTRX_BUILD_DOCS=ON

cmake --build build --target docs
```