pyqt5 draw on mouse press

__main__.py

#!/usr/bin/env python3
import sys
from PyQt5 import Qt, QtCore


class Canvas(Qt.QWidget):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.point = Qt.QPoint()  # the current point to draw

    def mousePressEvent(self, event):
        self.point = event.pos()  # set point to the current mouse coordinates
        self.update()

    def paintEvent(self, _):
        qp = Qt.QPainter(self)
        qp.setPen(Qt.QPen(QtCore.Qt.black, 10))
        qp.drawPoint(self.point)


def main():
    app = Qt.QApplication(sys.argv)
    w = Canvas()
    w.setWindowTitle('Draw point on mouse press')
    w.resize(400, 300)

    # center
    w.adjustSize()  # update w.rect() now
    w.move(app.desktop().screen().rect().center() - w.rect().center())
    w.show()
    return app.exec_()


if __name__ == '__main__':
    sys.exit(main())