如何在PyQt5中用画笔在图像上画线

from PyQt5.QtWidgets import QApplication, QMainWindow, QLabel
from PyQt5.QtGui import QImage, QPainter, QPen
from PyQt5.QtCore import Qt

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        
        self.setWindowTitle("Drawing Lines")
        self.setGeometry(100, 100, 500, 500)
        
        self.image = QImage(self.size(), QImage.Format_RGB32)
        self.image.fill(Qt.white)

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawImage(self.rect(), self.image, self.image.rect())
        
        pen = QPen()
        pen.setWidth(2)
        pen.setColor(Qt.red)
        
        painter.setPen(pen)
        painter.drawLine(50, 50, 200, 200)

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