This repository demonstrate rqt plugin on ROS2.
The steps of creating ROS2 version of plugin is quite similar to ROS1, for steps please refer to ROS1 version here.
If you are not familiar with qt, you may check out how to manually connect the signals and slots for your ui in the manual_connect branch.
This example uses the auto-connect feature to connect the slot and signal.
However, the downside is that you will need to pass your node_ manually to your custom widget.
virtual void initPlugin(qt_gui_cpp::PluginContext& context) override; // run (1)
virtual void restoreSettings(const qt_gui_cpp::Settings& plugin_settings, const qt_gui_cpp::Settings& instance_settings) override; // run (2)
virtual void saveSettings(qt_gui_cpp::Settings& plugin_settings, qt_gui_cpp::Settings& instance_settings) const override; // run (3)
virtual void shutdownPlugin() override; // run (4)