mrview: deactivate pan gesture to avoid #761

[maxpietsch]

Deactivating the pan gesture to avoid spurious start and finish and sticky pan (remains in GestureUpdated state) reproducible by rendering things with latency, for instance via increased ODF render detail in ortho view mode:

Prior to this change with Qt 5.15.2:

QGestureEvent((QPanGesture(state=GestureStarted,lastOffset=0,0QPointF(0,0),offset=0,0,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureFinished,lastOffset=0,0QPointF(0,0),offset=0,0,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureStarted,lastOffset=0,0QPointF(0,0),offset=0,0,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureFinished,lastOffset=0,0QPointF(0,0),offset=0,0,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureStarted,lastOffset=0,0QPointF(0,0),offset=0,0,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureFinished,lastOffset=0,0QPointF(0,0),offset=0,0,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureStarted,hotSpot=961,577,lastOffset=0,0QPointF(0,0),offset=-150,-143,acceleration=1,delta=-150,-143)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-150,-143QPointF(-150,-143),offset=-243,-210,acceleration=1,delta=-93,-67)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-210QPointF(-243,-210),offset=-243,-210,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-210QPointF(-243,-210),offset=-243,-210,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-210QPointF(-243,-210),offset=-243,-210,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-210QPointF(-243,-210),offset=-246,-209,acceleration=1,delta=-3,1)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-246,-209QPointF(-246,-209),offset=-246,-209,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-246,-209QPointF(-246,-209),offset=-244,-91,acceleration=1,delta=2,118)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-244,-91QPointF(-244,-91),offset=-243,-81,acceleration=1,delta=1,10)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-81QPointF(-243,-81),offset=-243,-82,acceleration=1,delta=0,-1)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureUpdated,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
QGestureEvent((QPanGesture(state=GestureFinished,hotSpot=961,577,lastOffset=-243,-82QPointF(-243,-82),offset=-243,-82,acceleration=1,delta=0,0)))
...

fixes #761
related: 5687708

[jdtournier]

OK, so removing the pan gesture fixes the problem? I'm not sure what I'm looking at with all this output...

[maxpietsch]

Yes, not "grabbing" pan gestures solves the issue.

The output above is Qt debug output I added when mrview is started in debug mode. It shows the type and state of the gesture whenever the GUI parses a gesture. I did not voluntarily use pan gestures. When the sticky pan happens, PanGestures with GestureUpdated state are reported repeatedly even without touching the touchpad (delta=0,0).

BTW, explicitly unregistering QTapAndHoldGesture did not solve the issue. Unregistering the pan gesture or not grabbing it did solve it.

[jdtournier]

OK, good to hear. I guess there's still quite a bit of cleaning up to be done before we can merge this...?

[maxpietsch]

I was thinking of leaving the Qt debug output there in debug mode but happy to remove it.

[jdtournier]

No issues with leaving the debug output in debug mode if you feel like it.

I was looking more at the pan gesture handler - these lines. Is that still required?