QML Enum Example

example.py

from sys import exit, argv

from PyQt5.QtCore import pyqtSignal, pyqtProperty, Q_ENUMS, QObject
from PyQt5.QtQml import QQmlApplicationEngine, qmlRegisterType
from PyQt5.QtGui import QGuiApplication


app = None


class Switch(QObject):

    class State:
        On = 0
        Off = 1

    Q_ENUMS(State)

    stateChanged = pyqtSignal(State, arguments=['state'])

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._state = Switch.State.Off

    @pyqtProperty(State, notify=stateChanged)
    def state(self):
        return self._state

    @state.setter
    def state(self, state):
        if state != self._state:
            self._state = state
            self.stateChanged.emit(self._state)
    

def main():
    global app

    app = QGuiApplication(argv)

    qmlRegisterType(Switch, 'Switch', 1, 0, 'Switch')

    engine = QQmlApplicationEngine()
    engine.load('example.qml')

    exit(app.exec_())


if __name__ == '__main__':
    main()

example.qml

import QtQuick 2.0
import QtQuick.Window 2.0

import Switch 1.0

Window {
    title: 'QML Enum Example'
    visible: true
    width: 400
    height: 400

    color: colorSwitch.state === Switch.On ? "green" : "red"

    Switch {
        id: colorSwitch
        state: Switch.Off

        onStateChanged: console.log('state: ' + state)
    }

    Text {
        text: "Press window to switch state"
    }

    MouseArea {
        anchors.fill: parent

        onClicked: {
            if (colorSwitch.state === Switch.Off)
                colorSwitch.state = Switch.On
            else
                colorSwitch.state = Switch.Off
        }
    }
}