Generate blur effect in QmainWindow python

Good evening I would like you to help me put a blur effect in a window in pyqt the result that I hope is something like this:

this is the code:

import sys
from PyQt5.QtWidgets import QMainWindow,QApplication, QGraphicsEffect,QGraphicsDropShadowEffect
from PyQt5 import QtCore
from PyQt5 import QtGui
from PyQt5 import uic

class Principal(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        uic.loadUi("window.ui",self)

        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)
        self.setAttribute(QtCore.Qt.WA_NoSystemBackground,True)
        self.setAttribute(QtCore.Qt.WA_TranslucentBackground,True)
        self.desenfoque = QGraphicsDropShadowEffect()
        self.desenfoque.setBlurRadius(0.4)
        self.setGraphicsEffect(self.desenfoque)
    def paintEvent(self,event=None):
        painter = QtGui.QPainter(self)
        painter.setOpacity(0.7)
        painter.setBrush(QtCore.Qt.white)
        painter.setPen(QtGui.QPen(QtCore.Qt.white))
        painter.drawRect(self.rect())

app = QApplication([])
p = Principal()
p.show()
app.exec_()