The pan gesture as defined by Qt is two fingers. Despite what the documentation pictures suggest (they show one finger being used.) You can confirm this yourself by looking at the Qt source code standardgestures.cpp, where QPanGestureRecognizer is defined.

On most desktops, a single finger touch just moves the cursor, in other words, acts like a mouse device. The user expects that. I think it is unstated by the platform interface designers that few gestures should be made with a single touch, since then it interferes with acting like a mouse (excepting a flick or swipe, where the speed of it differentiates it from a mouse movement.) I could be wrong, I don't know the Android platform.

I am not sure why Qt defines the QPanGesture. The QPinchGesture has a panning component, that is it tells you when the center between the two fingers moves. If all you want to do is 'let the user move the document or view with two fingers' then you don't need the QPanGesture, just the QPinchGesture. Just because the pan gesture exists, you don't need to use it.

But if you subscribe to both, your app should expect to receive them both at the same time for certain user inputs. That is, since they are both two finger gestures, it seems likely that a given user multitouch could be interpreted as either a pan gesture or a pinch gesture, at least for a short period until the user moves the two fingers to distinguish the gesture.