How could I get the image buffer of QCamera?

[stereoMatching]

QByteArray device = QCamera::availableDevices()[0];
        QCamera camera(device);
        QVideoWidget surface;
        surface.resize(320, 240);
        camera.setViewfinder(&surface);

QByteArray device = QCamera::availableDevices()[0];
        QCamera camera(device);
        QVideoWidget surface;
        surface.resize(320, 240);
        camera.setViewfinder(&surface);

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How could I get the image capture by QCamera?
I want to do some post-processing on the camera video
QCameraImageCapture is too slow for real time

Anything similar to following codes?

QCamera camera(device);
        QImage img = camera.getQImage(); //take the image buffer of camera

QCamera camera(device);
        QImage img = camera.getQImage(); //take the image buffer of camera

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