Convert PyQt5 QPixmap to numpy ndarray

Question

I have pixmap:

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

I want to convert it to OpenCV format. I tried to convert it to numpy.ndarray as described here but I got error sip.voidptr object has an unknown size

Is there any way to get numpy array (same format as cv2.VideoCapture read method returns)?

Answer 1

I got numpy array using this code:

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)) 

Answer 2

The copy can be avoided by doing:

channels_count = 4
pixmap = self._screen.grabWindow(0, self._x, self._y, self._width, self._height)
image = pixmap.toImage()
b = image.bits()
# sip.voidptr must know size to support python buffer interface
b.setsize(self._height * self._width * channels_count)
arr = np.frombuffer(b, np.uint8).reshape((self._height, self._width, channels_count))