如何在自定义窗口小部件具有焦点时指定不同的图像

from PyQt5.QtWidgets import QWidget, QApplication
from PyQt5.QtGui import QPainter, QPixmap
from PyQt5.QtCore import Qt, QRect

class CustomWidget(QWidget):
    def __init__(self):
        super().__init__()
        self.setFixedSize(200, 200)
        self.setFocusPolicy(Qt.StrongFocus)
        self.setWindowTitle('Custom Widget')
        self.normal_image = QPixmap('normal_image.png')
        self.focused_image = QPixmap('focused_image.png')

    def paintEvent(self, event):
        painter = QPainter(self)
        if self.hasFocus():
            painter.drawPixmap(QRect(0, 0, 200, 200), self.focused_image)
        else:
            painter.drawPixmap(QRect(0, 0, 200, 200), self.normal_image)

    def focusInEvent(self, event):
        self.update()

    def focusOutEvent(self, event):
        self.update()

if __name__ == '__main__':
    app = QApplication([])
    widget = CustomWidget()
    widget.show()
    app.exec_()