title: Show timer progress on a CircularProgressIndicator in flutter
body: <p>I'm using a <code>RestartableTimer</code> (subclass of <code>Timer</code>) as a countdown timer, to "kick people out" of a form after a certain duration.</p>
  
  <p>I would like to display the progress of that timer, and I like the idea of a circular progress slowly filling up.</p>
  
  <p>I'm not showing my code because I don't really have anything to show. I have a completely static progress indicator and a working timer, in a widget (stateful or stateless, whichever works best).</p>
  
  <p>I face two issues and this is where I need help for :</p>
  
  <ul>
  <li><p>I don't know how to check every x milliseconds for the timer progress. How can I do that? I don't need copy-pasta code, but more of "what object / which direction" should I go for?</p></li>
  <li><p>The timer progress in ticks is not implemented (NotImplementedException) ; is there any way to have an equivalent somewhere else? That object works really well for me, except for that part.</p></li>
  </ul>
  
  <p>Am I SOL or is there a way to make it?</p>