title: Android tablet touch event rate not constant?
body: <p>I'm making a touch trajectory recording activity for an Android app, and testing it on a Samsung T580 tablet. The accuracy of timing of touch events is crucial. I have a canvas with a static image displayed on the screen, and the user is continuously tracing a figure with his finger. Each time a touch event happens, in the view's onTouchEvent I record the position and the event time using event.x, event.y and event.eventTime.</p>
  
  <p>I was expecting a constant 60Hz event rate with 16.66 ms period between events. However, what I get is a period of ~3 seconds of constant rate of 16/17ms, and then a highly variable series where the period oscillates from 5 to 35ms, for about ~1 second, and then settles back to constant rate, as on the plot.</p>
  
  <p>Touch event period plot</p>
  
  <p><img src="https://i.stack.imgur.com/Xt7Iy.png" alt="Touch event period plot"></p>
  
  <p>What is going on? Can I still be confident that the event.eventTime is giving me an accurate timestamp? Or is there a way to make the period constant?</p>