如何在PyQt中嵌入模式绘图

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget
from PyQt5.QtGui import QPainter, QPen, QColor
from PyQt5.QtCore import Qt


class DrawingWidget(QWidget):
    def paintEvent(self, event):
        painter = QPainter(self)
        pen = QPen(Qt.red, 5, Qt.SolidLine)
        painter.setPen(pen)
        painter.drawRect(10, 10, 100, 100)  # 绘制一个红色的矩形


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        
        self.setWindowTitle("PyQt Embedding Mode Drawing Example")
        self.setGeometry(100, 100, 500, 400)
        
        drawing_widget = DrawingWidget(self)
        self.setCentralWidget(drawing_widget)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    
    main_window = MainWindow()
    main_window.show()
    
    sys.exit(app.exec_())