MainWindow.py

# -*- coding: utf-8 -*-

import os

from PyQt5 import QtGui
from PyQt5.QtWidgets import (
    QMainWindow, QApplication,
)
from PyQt5.uic import loadUi

class ApplicationWindow(QMainWindow):
    def __init__(self):
        super(ApplicationWindow, self).__init__()
        self.ui = loadUi(
            os.path.join(os.path.dirname(__file__), "ui", "MainWindow.ui"),
            self
        )
        self.set_icon()
        self.showMaximized()

    def set_icon(self):
        """
        Add icon to application window
        """
        icon = QtGui.QIcon()
        _path= os.path.join(os.path.dirname(__file__), "ui", "resources", "M_icon.png")
        icon.addPixmap(QtGui.QPixmap(f"{_path}"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.setWindowIcon(icon)