pyqt5 无边框窗口拖动

#隐藏边框
MainWindow.setWindowFlags(QtCore.Qt.FramelessWindowHint)
MainWindow.setAttribute(QtCore.Qt.WA_TranslucentBackground)

from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *
import sys
class Example(QWidget):
    _startPos = None
    _endPos = None
    _isTracking = False
    def __init__(self):
        super().__init__()
        self._initUI()
    def _initUI(self):
        self.setFixedSize(QSize(400, 400))
        self.setWindowFlags(Qt.FramelessWindowHint)  # 无边框
        self.setAttribute(QtCore.Qt.WA_TranslucentBackground)
        self.show()
    def mouseMoveEvent(self, e: QMouseEvent):  # 重写移动事件
        self._endPos = e.pos() - self._startPos
        self.move(self.pos() + self._endPos)
    def mousePressEvent(self, e: QMouseEvent):
        if e.button() == Qt.LeftButton:
            self._isTracking = True
            self._startPos = QPoint(e.x(), e.y())
    def mouseReleaseEvent(self, e: QMouseEvent):
        if e.button() == Qt.LeftButton:
            self._isTracking = False
            self._startPos = None
            self._endPos = None
if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())