Неопределенный индикатор выполнения в виде анимации в центре главного окна

from PyQt5.QtWidgets import QWidget, QApplication, QVBoxLayout, QLabel, QSizePolicy
from PyQt5.QtGui import QMovie
from PyQt5.QtCore import QByteArray, Qt
import sys
 
class ImagePlayer(QWidget):
    def __init__(self, filename, title, parent=None):
        QWidget.__init__(self, parent)
 
        self.movie = QMovie(filename, QByteArray(), self)
 
        size = self.movie.scaledSize()
        self.setGeometry(200, 200, size.width(), size.height())
        self.setWindowTitle(title)
 
        self.movie_screen = QLabel()
        self.movie_screen.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
        self.movie_screen.setAlignment(Qt.AlignCenter)
 
        main_layout = QVBoxLayout()
        main_layout.addWidget(self.movie_screen)
 
        self.setLayout(main_layout)
 
        self.movie.setCacheMode(QMovie.CacheAll)
        self.movie.setSpeed(100)
        self.movie_screen.setMovie(self.movie)
        self.movie.start()
 
if __name__ == "__main__":
    gif = "loading.gif"
    app = QApplication(sys.argv)
    player = ImagePlayer(gif, "was")
    player.show()
    sys.exit(app.exec_())