title: How to call onDraw periodically?
body: <p>I use ScrollView class in my application. I draw some data on canvas from the compass, these data are periodically updated by user's interaction.</p>
  
  <p>How can I periodically call onDraw method without user's touch on the display? Can I periodically refresh content of the canvas without other thread and calling <code>view.postInvalidate()</code>?</p>