This is a simple library that merges the event loop of ROS2 and Qt. This is done by providing a custom executor.
In your main.cpp init the node in the following way :
#include <QCoreApplication>
#include <rclcpp/rclcpp.hpp>
#include <lib_ros2_qt/qt_executor.h>
using namespace rclcpp;
int main(int argc, char* argv[]) {
QCoreApplication a(argc, argv);
rclcpp::init(argc, argv);
auto server = std::make_shared<TestNode>();
QtExecutor executor;
executor.add_node(server);
executor.start();
auto res = a.exec();
rclcpp::shutdown();
return res;
}
The Qt library can be useful for ROS nodes when developping GUI applications, or even in headless nodes using network communications (tcp/ip, modbus, canbus, bluetooth ...).
Both Qt and ROS2 need to have their own event loop spinning : rclcpp::executors::SingleThreadedExecutor::spin() for ROS, QCoreApplication::exec() for Qt.