title: How do I get Bitmap from a TransitionDrawable
body: <p>I have a TransitionDrawable whose Bitmap I need. When I use <code>getCurrent()</code> to get its Drawable, apparently the result is still a <code>TransitionDrawable</code>. But the truth is the TransitionDrawable was created in another class using</p>
  
  <pre><code>final TransitionDrawable td = new TransitionDrawable(new Drawable[] {
    new ColorDrawable(android.R.color.transparent), drawable });
  </code></pre>
  
  <p>where <code>drawable</code> is a BitmapDrawable. But if I try to cast as</p>
  
  <pre><code>Bitmap bmp = (BitmapDrawable) transitionDrawable.getCurrent();
  </code></pre>
  
  <p>then I get a class cast exception.</p>
  
  <p>For context, this is the TransitionDrawable in line 378 of ImageWorker of BitmapFun.</p>