title: Android VideoView setAlpha() method like ImageView setAlpha()
body: <p>Android <code>ImageView</code> have <code>setAlpha(float)</code> method but I know android <code>videoView</code> have no <code>setAlpha()</code> method because android <code>videoview</code> is <code>surfaecview</code> .</p>
  
  <p>How can implement <code>setAlpha()</code> function in android <code>VideoView</code> like <code>imageview</code>. </p>