Littlefoot: Getting touchMove events for static contacts


I am a bit surprised that each time I touch the lightpad surface a touchMove event is fired even if my fingers do not move at all on the surface.

From touch related research I know that during the first few milliseconds while the finger is stabilizing against the surface, the shape of the contact deforms, normally growing in size (see below). Is that what triggers this event? If so, which are the displacement thresholds for a lightpad to trigger a touchMove events?



Hi. Any moderator or anyone has any update on this behavior?

Sorry, but I don’t understand what you’re trying to learn with this question?

It’s obviously expected behaviour that the device will emit a stream of move events, with some arbitrary threshold based on the mechanics of the surface and internal filtering that we’ve done based on testing. But there’s no way we could somehow give you numbers about what that is, and I fail to see how somehow knowing the “displacement threshold” (whatever that means) would be in any way useful.

This reminds me of the times when people have moaned about JUCE sending mouse-move events at times when they didn’t expect there to be one: If you’re writing code that’s too flaky to work when a single random mouse move event happens, then that code’s going to be hopeless in the real world, where your users will include many clumsy people with shaky hands!

Hi Jules

I’m trying to distinguish tap gestures from swipe gestures. They are clearly different for a physical point of view. However they are really hard to tell apart in the Blocks.

Ideally tap contacts should not produce move events, as they are essentially static. But this is not the case with Blocks.

Additionally, the values in the initial move event are very similar for both tap and swipe gestures. That’s why I asked for the threshold info. It might help discriminate them.

The situation starts to clarify with the second touch event, but I found that often there is no second event for some touches (even swipes) or it takes really long to fire, making gesture detection very inaccurate.

I agree that people with diminished dexterity might have problems with this approach. But I still think it is worth pursuing. So does your CEO by the way. He’s the one who invited me to try this technique on the Blocks.

Kind regards

OK, gotcha. But again, I’m not really sure what we information we could give you that’d help… there are no magic secret numbers hidden away that would be useful in figuring out what to do - I think even if we were doing this ourselves it’d be a case of tweaking values until it feels right.

I can’t really help any more myself but if you think there’d be anything to gain by talking directly to our hardware guys then I can put you in touch.

Thanks Jules. At this point what would help me is knowing more about the inner working of touch move events. That’s where my key logic runs.

I feel I may have detected some inconsistencies. However it’s hard to tell for sure without debugging or more advanced console logging.