GeezerVison

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Also fixes #1992

Actually the same problem exists with TouchHandler. Should we clear the tap state there too? Or do we define calling its methods as UB when the touch panel is sleeping (as when it's sleeping, it's not possible to know whether the screen is touched or not)

TouchHandler doesn't cause any bugs, but it could certainly in the future. If we choose to define it as UB then we should guard

// DisplayApp.cpp
  if (touchHandler.IsTouching()) {
    currentScreen->OnTouchEvent(touchHandler.GetX(), touchHandler.GetY());
  }

with a state == Running check

I would avoid any UB.

I mean defining calling the methods as UB by documentation i.e the documentation for the function IsTouching() saying "if the device is sleeping, the value returned is undefined". There is no UB C++ spec wise

I think the perfect type of that function would not be bool but std::optional<bool>. The value std::nullopt would represent the case where no measurement can be made (screen asleep) and the bool would be the measurement, if possible (screen awake).

Otherwise return always false if the screen is asleep. Because no screen, no touch.

Excellent idea, optional makes perfect sense here semantically. I will try it out

Actually the same problem exists with TouchHandler. Should we clear the tap state there too? Or do we define calling its methods as UB when the touch panel is sleeping (as when it's sleeping, it's not possible to know whether the screen is touched or not)

I think we could just clear the tap in TouchHandler as soon as the touch panel is sleeping as well, since I don't think we want to handle touch while the device is sleeping.

So this has turned out to be a bit trickier than I thought. TLDR the touch panel still delivers events when sleeping, so trying to pretend it doesn't with TouchController having a null state is incompatible with double tap wake / tap wake. So instead I've opted to unify the touch processing into something a little more sensible, so the TouchController always has up to date touch state even when the device is sleeping.

So the original problem is addressed with DisplayApp not receiving or processing any touch events while sleeping, and clearing touch state on sleep entry

Cleaned up the OnTouchEvent method as it was just an alias for PushMessage after Unify touch handling, no other changes