Astropad and Tablet events



  • Hi all, I'm trying to use Astropad (app provides OsX tablet interface with an iPad) and I'm getting odd results with tablet events in QT. First of all I've been in contact with the devs and they seem to think it's a QT bug rather than an Astropad bug and in any case Astropad works with other graphics programs that I've tried.

    I'm coding in python using pyqt and have Python 3.5.0 and QT 5.5.0 installed.

    At the level of QWidget you get an initial TabletPress event with no pressure followed immediately by a TabletRelease event with pressure at which point the rest of the stroke is only reported as mouse events, with are low frequency and don’t contain pressure info.

    Astropad:

    	TabletPress: pointer=1 pressure=0.0 tilt=(27,12)
    	TabletRelease: pointer=1 pressure=0.13333334028720856 tilt=(27,12)
    	MousePress
    	MouseMove
    	MouseMove
    	...[ many MouseMove ]...
    	MouseRelease
    

    Works as you'd expect with Wacom tablet though accepting the tablet events does't stop the mouse events being fired:

    	TabletPress: pointer=1 pressure=0.4313725531101227 tilt=(0,0)
    	MousePress
    	TabletMove: pointer=1 pressure=0.45098039507865906 tilt=(0,0)
    	MouseMove
    	TabletMove: pointer=1 pressure=0.45098039507865906 tilt=(0,0)
    	TabletMove: pointer=1 pressure=0.4470588266849518 tilt=(0,0)
    	...[ many MouseMove and many more TableMove ] ...
    	TabletRelease: pointer=1 pressure=0.0 tilt=(0,0)
    	MouseMove
    	MouseRelease
    

    At the level of QApplication I'm seeing TabletEnterProximity and TabletLeaveProximity events as you'd expect.

    Any ideas on how to fix or work around this? It looks like QT is getting confused and is interpreting the stroke on the tablet as having lifted and falling back to default mouse handling. I've tried re-emmiting a tablet press or move event from code with no joy.


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Since it touches the lower levels of Qt, I'd recommend bringing this question to the interest mailing list. You'll find there Qt's developers/maintainers (this forum is more user oriented)



  • Thanks for the welcome!

    I've posted the question to the interest list.

    Cheers.


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