Maximum Touch Points When Using Multi-Touch

Question

This is probably a very simple question (but I'm asking it & don't know the answer, so I guess I shouldn't say that), but I want to know what the maximum number of touch points the user's device can handle. For most scenarios, this will probably never be reached (most of us only have 10 fingers, and can we even fit them all on the screen at the same time anyway?), but it never hurts to be safe and it probably won't give the app a good name if it crashes when 3 little kids touch your screen! Is there some kind of system variable that has this information? Thanks.

Answer 1

You can use the Android PacakgeManager to ask Android if it supports touch and if so what kinds:
PackageManager.GetSystemAvailableFeatures
PackageManager.HasSystemFeature

Relevant Features:

PackageManager.FeatureTouchScreen - Touch is available
PackageManager.FeatureTouchScreenMultiTouch - Two finger gestures
PackageManager.FeatureTouchScreenMultiTouchDistinct - Two or more fingers independently
PackageManager.FeatureTouchScreenJazzHand - 5 or more fingers independently

Android doesn't provide a property for a more specific maximum, and I don't think it defines an overall max that devices can provide. I think most current Android phones support 10. Assume infinite are possible even if the app only tracks fewer - bounds check and discard values out of range rather than crashing.

I used to have a 30 touch-point screen, and my colleagues and I surpassed that number with multiple people finger-painting at the same time. My painting app lost track of the extra touches, but it failed gracefully and didn't crash!