title: What is the equivalent of Android's RecyclerView.SCROLL_STATE_IDLE in Flutter
body: <p>Android gives scroll states like <code>RecyclerView.SCROLL_STATE_IDLE</code> which tells when user stops the scroll. I'm not able to find any <strong>alternative</strong> in flutter for <code>Pageview</code> or <code>ListView</code> ScrollListener.</p>
  <h3>My Problem</h3>
  <p>I need to detect scroll up/down in PageView to perform some operation based on that. Flutter gives the direction (<code>_myPageViewController.position.userScrollDirection</code>) but it gives a continuous callback. I need to detect it only when the user stops scrolling.</p>
  <h3>Another scenario</h3>
  <p>I need to do auto-play videos in a listView. So I need to detect when the user stops scrolling and then get the position and play that.</p>
  <p>In android I would have done this with the help <code>RecyclerView.SCROLL_STATE_IDLE</code> state in <code>RecyclerView's</code> scrollListener. Need something similar in flutter.</p>