title: Scrollview: check if a view is visible on screen or not
body: <p>I have a ScrollView defined like:</p>
  
  <pre><code>&lt;ScrollView
      ... 
      .../&gt;
      &lt;LinearLayout
          ...
          ...&gt;
  
          &lt;!-- content --&gt;
  
      &lt;/LinearLayout&gt;
  &lt;/ScrollView&gt;
  </code></pre>
  
  <p>And I fill the LinearLayout dynamically with some ImageViews. Now, is there a way to check when an ImageView gets visible or invisible (for example when i scroll down)?</p>