RubyQt6

require 'qt6/qtwidgets'

# Create a widget inherit from RubyQt6::Bando::<...>, so that we
# can use `q_object` macro to define signals and slots.
class MyWidget < RubyQt6::Bando::QWidget
  q_object do
    signal "quit_clicked()"             # signals are automatically generated by RubyQt6, must not be implemented
    slot "on_slider_value_changed(int)" # slots must be implemented later
  end

  def initialize
    super                               # NOTE: You must call `super` first

    quit = QPushButton.new('Quit')
    quit.set_font(QFont.new('Times', 18, QFont::Bold))

    @lcd = QLCDNumber.new(2)
    slider = QSlider.new(Qt::Horizontal)
    slider.set_range(0, 99)
    slider.set_value(0)

    layout = QVBoxLayout.new
    layout.add_widget(quit)
    layout.add_widget(@lcd)
    layout.add_widget(slider)
    set_layout(layout)

    quit.clicked.connect(self, :quit_clicked)
    slider.value_changed.connect(self, :on_slider_value_changed)
  end

  def on_slider_value_changed(value)
    @lcd.display(value)
  end
end

if __FILE__ == $PROGRAM_NAME
  app = QApplication.new
  widget = MyWidget.new
  widget.quit_clicked.connect(app, :quit)
  widget.show
  app.exec
end