将 PyQt5 QPixmap 转换为 numpy ndarray

我有像素图：

pixmap = self._screen.grabWindow(0,
                                 self._x, self._y,
                                 self._width, self._height)

我想将其转换为 OpenCV 格式。 我尝试将其转换为numpy.ndarray如上所述here https://stackoverflow.com/questions/37552924/convert-qpixmap-to-numpy但我得到了错误sip.voidptr object has an unknown size

有没有办法获得 numpy 数组（格式与cv2.VideoCapture read方法返回）？

我使用以下代码得到了 numpy 数组：

channels_count = 4
pixmap = self._screen.grabWindow(0, self._x, self._y, self._width, self._height)
image = pixmap.toImage()
s = image.bits().asstring(self._width * self._height * channels_count)
arr = np.fromstring(s, dtype=np.uint8).reshape((self._height, self._width, channels_count))