PyQt5 登录窗口

import sys

from PyQt5.QtWidgets import QWidget,QApplication,QLineEdit,QLabel,QPushButton,QDesktopWidget
from PyQt5.QtGui import QIcon,QPixmap
from PyQt5.QtCore import Qt


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

        self.initUI()

    def initUI(self):

        self.setGeometry(300, 300, 300, 160)
        self.setWindowIcon(QIcon("web.png"))
        self.setWindowFlags(Qt.FramelessWindowHint) #隐藏标题栏
        self.setFixedSize(self.width(),self.height()) #禁止调整大小

        #MainWindow.setWindowOpacity(0.85)  # 设置窗口透明度
        #MainWindow.setAttribute(QtCore.Qt.WA_TranslucentBackground)  # 设置窗口背景透明
        self.setAttribute(Qt.WA_TranslucentBackground) #窗体背景透明
        #设置背景图片

        pixmap = QPixmap("bg.png")
        lbl = QLabel(self)
        lbl.setPixmap(pixmap)
        lbl.setWindowOpacity(0.1)

        lbl_username = QLabel("用户名：",self)
        lbl_username.move(50,30)
        input_username = QLineEdit("",self)
        input_username.move(120, 30)

        lbl_passwd = QLabel("密码：",self)
        lbl_passwd.move(50, 60)
        input_passwd = QLineEdit("",self)
        input_passwd.move(120, 60)

        loginbtn = QPushButton("登录",self)
        loginbtn.move(70, 120)

        exitbtn = QPushButton("关闭", self)
        exitbtn.move(170, 120)
        exitbtn.clicked.connect(QApplication.instance().exit)


        self.center()
        self.setWindowTitle("用户登录")



    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())



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