[qt5] center a window on screen

centering.py

__author__ = 'tom'

import sys
from PyQt5.QtWidgets import QWidget, QApplication


class Example(QWidget):
    def __init__(self, app: QApplication):
        super().__init__()
        self.app = app
        self.init_ui()

    def init_ui(self):
        self.setWindowTitle('Center')
        self.resize(250, 150)

    def center(self):
        # geometry of the main window
        qr = self.frameGeometry()

        # center point of screen
        cp = self.app.primaryScreen().availableGeometry().center()

        # move rectangle's center point to screen's center point
        qr.moveCenter(cp)

        # top left of rectangle becomes top left of window centering it
        self.move(qr.topLeft())


if __name__ == "__main__":
    app = QApplication(sys.argv)
    
    ex = Example(app)
    ex.center()
    ex.show()
    
    sys.exit(app.exec_())

updated to eliminate the use of QDesktopWidget