title: how to detect bluetooth mouse wheel being up or down on android app
body: <p>I want to detect bluetooth mouse wheel changes,and I know what's the actionCode for mouse wheel changes,but don't know it's being up or down.</p>
  
  <pre><code>    public boolean onGenericMotion(View v, MotionEvent event) {
          if (event.getActionMasked() == MotionEvent.ACTION_SCROLL) {
          //how to detect mouse wheel being up or down?
          }
          return false;
      }
  </code></pre>
  
  <p>Thanks very much!</p>