QGraphicsView元素用鼠标移动不流畅

Question

我有一个QGraphicsView元素，它没有边框，标题等，我想在屏幕上四处移动。我已经实现了用鼠标移动它的功能，但是它并不平滑，它在跳跃并且没有正确跟随鼠标。

def mousePressEvent(self, event):
    self.mouseMovePos = None
    if event.button() == QtCore.Qt.LeftButton:
        self.mouseMovePos = event.globalPos()

def mouseMoveEvent(self, event):
    if event.buttons() == QtCore.Qt.LeftButton:
        currPos = self.mapToGlobal(self.pos())
        globalPos = event.globalPos()
        diff = globalPos - self.mouseMovePos
        newPos = self.mapFromGlobal(currPos + diff / 40)
        self.move(newPos)

也许是因为性能？有没有一种方法可以使窗口平滑地跟随我的鼠标？