python - flux caméra écran dans un QLabel - Stack Overflow

I want to use python OpenCV bindings to display webcam stream in a QLabel. I found some previous posts here:

• updating QLabel in non-GUI thread continuously


• Displaying a video stream in QLabel with PySide

In the beginning I tried a simple "while" loop:

def onRun(self):
    self.playing = True
    capture = cv2.VideoCapture(0)
    while self.playing:
        _, data = capture.read()
        data = cv2.cvtColor(data, cv2.cv.CV_BGR2RGB)
        qImage = QtGui.QImage(data, data.shape[1], data.shape[0], 
            QtGui.QImage.Format_RGB888)
        self.lblImage.setPixmap(QtGui.QPixmap.fromImage(qImage))
        self.lblImage.adjustSize()
        time.sleep(0.02)

But I met with a "white-window" problem. I found that proper way to solve this is to create a new thread. My question is: what is it all about new thread? should I create QThread or something? And what is it signal/slot emitting in a thread?

I've never used threads so it's totally new thing to me.

I can't test this myself, but would it not be enough to simply process the pending events within the loop?

That is:

def onRun(self):
    self.playing = True
    capture = cv2.VideoCapture(0)
    while self.playing:
        ...
        QtGui.qApp.processEvents()
        time.sleep(0.02)

I want to use python OpenCV bindings to display webcam stream in a QLabel. I found some previous posts here:

• updating QLabel in non-GUI thread continuously


• Displaying a video stream in QLabel with PySide

In the beginning I tried a simple "while" loop:

def onRun(self):
    self.playing = True
    capture = cv2.VideoCapture(0)
    while self.playing:
        _, data = capture.read()
        data = cv2.cvtColor(data, cv2.cv.CV_BGR2RGB)
        qImage = QtGui.QImage(data, data.shape[1], data.shape[0], 
            QtGui.QImage.Format_RGB888)
        self.lblImage.setPixmap(QtGui.QPixmap.fromImage(qImage))
        self.lblImage.adjustSize()
        time.sleep(0.02)

But I met with a "white-window" problem. I found that proper way to solve this is to create a new thread. My question is: what is it all about new thread? should I create QThread or something? And what is it signal/slot emitting in a thread?

I've never used threads so it's totally new thing to me.

I can't test this myself, but would it not be enough to simply process the pending events within the loop?

That is:

def onRun(self):
    self.playing = True
    capture = cv2.VideoCapture(0)
    while self.playing:
        ...
        QtGui.qApp.processEvents()
        time.sleep(0.02)

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