DepthAI C++ Library

Core C++ library

Documentation

Documentation is available over at Luxonis DepthAI API

Disclaimer

DepthAI library doesn't yet provide API stability guarantees. While we take care to properly deprecate old functions, some changes might still be breaking. We expect to provide API stability from version 3.0.0 onwards.

Dependencies

• cmake >= 3.4
• libusb1 development package (MacOS & Linux only)
• C/C++11 compiler
• [optional] OpenCV 4

MacOS: brew install libusb

Linux: sudo apt install libusb-1.0-0-dev

Integration

CMake

Targets available to link to are:

• depthai::core - Core library, without using opencv internally
• depthai::opencv - Core + support for opencv related helper functions (requires OpenCV4)

Using find_package

Build static or dynamic version of library and install (See: Building and Installing)

Add find_package and target_link_libraries to your project

find_package(depthai CONFIG REQUIRED)
...
target_link_libraries([my-app] PRIVATE depthai::opencv)

And point CMake to either build directory or install directory:

-D depthai_DIR=depthai-core/build

or

-D depthai_DIR=depthai-core/build/install/lib/cmake/depthai

If library was installed to default search path like /usr/local on Linux, specifying depthai_DIR isn't necessary as CMake will find it automatically.

Using add_subdirectory

This method is more intrusive but simpler as it doesn't require building the library separately.

Add add_subdirectory which points to depthai-core folder before project command. Then link to any required targets.

add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/depthai-core EXCLUDE_FROM_ALL)
...
project(my-app)
...
target_link_libraries([my-app] PRIVATE depthai::opencv)

Non-CMake integration (Visual Studio, Xcode, CodeBlocks, ...)

To integrate into a different build system than CMake, prefered way is compiling as dynamic library and pointing to correct include directories.

1. First build as dynamic library: Building Dynamic library
2. Then install: Installing
3. Set needed library directories:
   • build/install/lib (for linking to either depthai-core or depthai-opencv)
   • build/install/bin (for .dll's)
4. And include directories
   • build/install/include (library headers)
   • build/install/include/depthai-shared/3rdparty (shared 3rdparty headers)
   • build/install/lib/cmake/depthai/dependencies/include (dependencies headers)

ℹ️ Threading library might need to be linked to explicitly.

Building

Make sure submodules are updated

git submodule update --init --recursive

ℹ️ To speed up build times, use cmake --build build --parallel [num CPU cores] (CMake >= 3.12). For older versions use: Linux/macOS: cmake --build build -- -j[num CPU cores], MSVC: cmake --build build -- /MP[num CPU cores]

Static library

cmake -H. -Bbuild
cmake --build build

Dynamic library

cmake -H. -Bbuild -D BUILD_SHARED_LIBS=ON
cmake --build build

Installing

To install specify optional prefix and build target install

cmake -H. -Bbuild -D CMAKE_INSTALL_PREFIX=[path/to/install/dir]
cmake --build build
cmake --build build --target install

If CMAKE_INSTALL_PREFIX isn't specified, the library is installed under build folder install.

Running tests

To run the tests build the library with the following options

cmake -H. -Bbuild -D DEPTHAI_TEST_EXAMPLES=ON -D DEPTHAI_BUILD_TESTS=ON -D DEPTHAI_BUILD_EXAMPLES=ON
cmake --build build

Then navigate to build folder and run ctest

cd build
ctest

Style check

The library uses clang format to enforce a certain coding style. If a style check is failing, run the clangformat target, check the output and push changes.

To use this target clang format must be installed, preferably clang-format-10

sudo apt install clang-format-10

And to apply formatting

cmake --build build --target clangformat

Documentation generation

Doxygen is used to generate documentation. Follow doxygen download and install the required binaries for your platform.

After that specify CMake define -D DEPTHAI_BUILD_DOCS=ON and build the target doxygen

Debugging tips

Debugging can be done using Visual Studio Code and either GDB or LLDB (extension 'CodeLLDB'). LLDB in some cases was much faster to step with and resolved more incomplete_type variables than GDB. Your mileage may vary though.

If there is a need to step into Hunter libraries, that can be achieved by removing previous built artifacts

rm -r ~/.hunter

And configuring the project with the following CMake option set to ON

cmake . -D HUNTER_KEEP_PACKAGE_SOURCES=ON

This retains the libraries source code, so that debugger can step through it (the paths are already set up correctly)

Troubleshooting

Hunter

Hunter is a CMake-only dependency manager for C/C++ projects.

If you are stuck with error message which mentions external libraries (subdirectory of .hunter) like the following:

/usr/bin/ld: /home/[user]/.hunter/_Base/062a19a/ccfed35/a84a713/Install/lib/liblzma.a(stream_flags_decoder.c.o): warning: relocation against `lzma_footer_magic' in read-only section `.text'

Try erasing the Hunter cache folder.

Linux/MacOS:

rm -r ~/.hunter

Windows:

del C:/.hunter

or

del C:/[user]/.hunter