在PyQt5中使用双缓冲技术绘制rect时出现重影图像

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

class MyWidget(QWidget):
    def __init__(self):
        super().__init__()

    def paintEvent(self, event):
        # 创建后台缓冲区
        pixmap = QPixmap(self.size())
        pixmap.fill(Qt.transparent)
        
        # 在后台缓冲区上进行绘制
        painter = QPainter(pixmap)
        painter.drawRect(10, 10, 100, 100)
        painter.end()
        
        # 将后台缓冲区的内容复制到前台缓冲区
        painter = QPainter(self)
        painter.drawPixmap(0, 0, pixmap)
        painter.end()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    widget = MyWidget()
    widget.show()
    sys.exit(app.exec_())