GUI Interaction with Xbox Controller

Question

I'd like to be able to show Xbox controller events on a very simple GUI using PyQt5 which was created using the QT Designer. I'm using xbox360controller Python package to communicate the controller with my Python interface. The following example code works as it should, and instead of printing the values I'd like to set the text on the only label on the GUI:

import signal
from xbox360controller import Xbox360Controller


def on_button_pressed(button):
    print('Button {0} was pressed'.format(button.name))


def on_button_released(button):
    print('Button {0} was released'.format(button.name))


def on_axis_moved(axis):
    print('Axis {0} moved to {1} {2}'.format(axis.name, axis.x, axis.y))

try:
    with Xbox360Controller(0, axis_threshold=0.2) as controller:
        # Button A events
        controller.button_a.when_pressed = on_button_pressed
        controller.button_a.when_released = on_button_released

        # Left and right axis move event
        controller.axis_l.when_moved = on_axis_moved
        controller.axis_r.when_moved = on_axis_moved

        signal.pause()
except KeyboardInterrupt:
    pass

This is the simple GUI:

My idea was something like this, but I'm very lost:

class MainWindow(Ui_MainWindow, Ui_MainClass):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)
        self.controller = Xbox360Controller(0, axis_threshold=0.2)
        self.controller.button_a.when_pressed = on_button_pressed()
        self.controller.button_a.when_released = on_button_released()

        # Left and right axis move event
        self.controller.axis_l.when_moved = on_axis_moved
        self.controller.axis_r.when_moved = on_axis_moved

    def on_button_pressed(self, button):
        print('Button {0} was pressed'.format(button.name))
        self.label_joy.setText(f'Button {0} was pressed'.format(button.name))

    def on_button_released(self, button):
        print('Button {0} was released'.format(button.name))
        self.label_joy.setText(f'Button {0} was released'.format(button.name))

    def on_axis_moved(self, axis):
        print('Axis {0} moved to {1} {2}'.format(axis.name, axis.x, axis.y)) 
        self.label_joy.setText('Axis {0} moved to {1} {2}'.format(axis.name, axis.x, axis.y))    
    

if __name__ == "__main__":
    app = QApplication([])
    form = MainWindow()
    form.show()
    sys.exit(app.exec_())

(I'm using Ubuntu 18.04)

user_6622587 · Answer

You have 2 errors:

The first is that self.controller.button_a.when_pressed = on_button_pressed() is equivalent to value = on_button_pressed() self.controller.button_a.when_pressed = value, so you have not assigned the callback but you have assigned None since that is what the function returns.
Even if you correct the above, there is also another error: callbacks are invoked in a secondary thread, so in conclusion you would be modifying the GUI from another thread, which Qt prohibits. In this case the solution is to use the Qt signals to transmit the information since they are thread-safe.

import sys
from functools import cached_property

from PyQt5 import QtCore, QtWidgets

from xbox360controller import Xbox360Controller
from xbox360controller.controller import Button, Axis, RawAxis


class Controller(QtCore.QObject):
    button_pressed = QtCore.pyqtSignal(Button)
    button_released = QtCore.pyqtSignal(Button)

    axis_moved = QtCore.pyqtSignal(object)

    def __init__(self, parent=None):
        super().__init__(parent)

        try:
            self.Xbox360_controller
        except Exception as e:
            print(e)
            sys.exit(-1)

        for button in self.Xbox360_controller.buttons:
            button.when_pressed = self._on_button_pressed
            button.when_released = self._on_button_released

        for axis in self.Xbox360_controller.axes:
            axis.when_moved = self._on_axis_moved

    @cached_property
    def Xbox360_controller(self):
        return Xbox360Controller(0, axis_threshold=0.2)

    def _on_button_pressed(self, button):
        self.button_pressed.emit(button)

    def _on_button_released(self, button):
        self.button_released.emit(button)

    def _on_axis_moved(self, axis):
        self.axis_moved.emit(axis)

    def close(self):
        self.Xbox360Controller.close()


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.label = QtWidgets.QLabel(alignment=QtCore.Qt.AlignCenter)
        self.setCentralWidget(self.label)

    def handle_button_pressed(self, button):
        self.label.setText(f"Button {button.name} was pressed")

    def handle_button_released(self, button):
        self.label.setText(f"Button {button.name} was released")

    def handle_axis_moved(self, axis):
        if isinstance(axis, Axis):
            self.label.setText(f"Axis {axis.name} moved to {axis.x} {axis.y}")
        elif isinstance(axis, RawAxis):
            self.label.setText(f"Axis {axis.name} moved to {axis.value}")


def main():
    app = QtWidgets.QApplication(sys.argv)

    w = MainWindow()
    w.show()

    controller = Controller()
    controller.button_pressed.connect(w.handle_button_pressed)
    controller.button_released.connect(w.handle_button_released)
    controller.axis_moved.connect(w.handle_axis_moved)

    ret = app.exec_()

    controller.close()

    sys.exit(ret)


if __name__ == "__main__":
    main()

GUI Interaction with Xbox Controller

1 Answers