C++ Conan CMake Qt6 Breakout game

This project uses C++20 and Qt 6.1.2.

• [x] Using Qt6 with CMake and Conan
• [x] Using a custom static library
• [x] Github actions to build on Ubuntu
• [x] A unit test environment

Building

First, we clone the GitHub repository:

git clone https://github.com/shekeraoleksandr/breakoutGame.git

Then create a build folder inside of the repository's folder and navigate into it:

cd breakoutGame && mkdir build && cd build

Once we've created the build directory, we can run Conan and CMake in one step:

cmake .. -DCMAKE_BUILD_TYPE=Debug

In this case, we have configured our build system to compile debug versions of the binaries. Now we can build with the following command:

cmake --build .

To execute the program:

./bin/breakoutSrc 

Details

Warning: Qt6 works only with the Conan version < 2.0.

To reinstall Conan:

pip install --force-reinstall -v "conan==1.60.0"

Using Qt6 with CMake and Conan

The only way I could get Qt6 to work with Conan and CMake was by including the conan.cmake file from: https://github.com/conan-io/cmake-conan

The main problems that I ran into were:

Wayland conflict:

ERROR: Conflict in wayland/1.21.0:
'wayland/1.21.0' requires 'libffi/3.4.4' while 'glib/2.73.0' requires 'libffi/3.4.3'.

To fix it I had to specify the version of libffi I wanted to use in the root CMakeLists.txt:

conan_cmake_run(REQUIRES
        qt/6.1.2
        libffi/3.4.2
    ...

Package manager mode install:

xorg/system: ERROR: while executing system_requirements(): 
System requirements: 'libx11-xcb-dev, ...' are missing but can't install because tools.system.package_manager:mode is 'check'.
Please update packages manually or set 'tools.system.package_manager:mode' to 'install' in the [conf] section of the profile, 
or in the command line using '-c tools.system.package_manager:mode=install'

To fix it I had to add tools.system.package_manager:mode=install in the conf section of my profile, in my case profiles are located in /home/user/.conan/profiles/ but your path can be different. Also I created my profile using conan_cmake_profile in the root CMakeLists.txt:

conan_cmake_profile(FILEPATH    "${CMAKE_BINARY_DIR}/profile"
                    SETTINGS    os=Linux
                                os_build=Linux
                                arch=x86_64
                                arch_build=x86_64
                                compiler=gcc
                                compiler.version=9
                                compiler.libcxx=libstdc++11
                                build_type=Release
                    OPTIONS     qt:shared=True
                    CONF        "tools.system.package_manager:mode=install"
                                "tools.system.package_manager:sudo=True")    

To use this profile over default I added PROFILE profile to the root CMakeLists.txt:

conan_cmake_run(REQUIRES
        ...
        PROFILE profile)

Xcb plugin not found:

qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

There may be several solutions to this problem, discussed here.

I personally added qt:shared=True to the OPTIONS section of the profile that creates in the root CMakeLists.txt:

conan_cmake_profile(FILEPATH    "${CMAKE_BINARY_DIR}/profile"
                    ...
                    OPTIONS     qt:shared=True
                    ...

It can also be added to the conan_cmake_run:

conan_cmake_run(REQUIRES
        ...
        OPTIONS qt:shared=True
        ...

Using a custom library

The library is called BreakoutLib it exist include/.

Even though no linking is actually done when building the library by itself, this line must still be included in the library's CMake file:

target_link_libraries(MyLib PRIVATE
    Qt6::Core
)

Unit Tests and GitHub Actions

I could only get Qt6 to build on Github Actions if I used ubuntu-latest.

I faced the xcb error and to solve it I specified a virtual display for the CTest execution.

- name: Install xvfb
  run: sudo apt install xvfb

- name: Run Tests with xvfb
  run: xvfb-run ctest --rerun-failed --output-on-failure