magladko/Qt5-to-ROS2

Qt5-to-ROS2

Step by step solution to port Qt5 application project into compilabe ROS2 package.

1. Create a cmake Qt project.
   • All qmake projects should be be ported to cmake first (CMake Port/Porting Guide).
2. Create a ROS2 workspace (e.g. ros_qt_ws) folder with ros_qt_ws/src/ subdirectory
3. Move the Qt project to ros_qt_ws/src/.

ros_qt_ws/
└── src
    └── qt_demo
        ├── CMakeLists.txt
        ├── main.cpp
        ├── mainwindow.cpp
        ├── mainwindow.h
        └── mainwindow.ui

4. Establish ROS2 package hierarchy:
   • Move all the source files to a new directory: ros_qt_ws/src/<Qt project>/src
   • Move the header files to the ros_qt_ws/src/<Qt project>/include/<Qt project>
   • Currently the ROS2 workspace with the Qt project file tree should look similarly to this:

ros_qt_ws/
└── src
    └── qt_demo
        ├── CMakeLists.txt
        ├── include
        │   └── qt_demo
        │       └── mainwindow.h
        └── src
            ├── main.cpp
            ├── mainwindow.cpp
            └── mainwindow.ui

5. Modify CMakeLists.txt file to comply with the ament_cmake guidelines. Example of such adjustment can be found in ros_qt_ws/src/qt_demo/CMakeLists.txt

   • A generic ROS2 package can be found under test_pkg_ws/src/my_package. It has been generated as a quick reference using command: ros2 pkg create --build-type ament_cmake --node-name my_node my_package.
   • NOTE: it is important to pay attention to the difference between ament_target_dependencies() and target_link_libraries() as some libraries might need adjustments in calls (reference)

6. Create package.xml in ros_qt_ws/src/<Qt project>/

ros_qt_ws/
└── src
    └── qt_demo
        ├── CMakeLists.txt
        ├── include
        │   └── qt_demo
        │       └── mainwindow.h
        ├── package.xml
        └── src
            ├── main.cpp
            ├── mainwindow.cpp
            └── mainwindow.ui

Working with Qt Creator and ROS2 package

To work with Qt creator it is best to:

1. compile the package with colcon build from the terminal.
2. launch the Qt Creator application from within the terminal that has already sourced ROS2 environment.
3. Ensure to delete any Qt Creator leftovers in the project, as they might make it impossible to load the package into Qt Creator (especially *.user files).
4. Open project by selecting package's CMakeLists.txt file.
5. Select Import Existing Build... option in Qt Creator and select the <workspace>/build/<package_name> directory.
6. It should now possible to compile and run ROS2 package from within the Qt Creator IDE.
7. NOTE: Sometimes it might be necessary to restart the setup running colcon build from CLI again.