title: background fade in & out on touch
body: <p>I'm trying to create a way of getting a views background to respond to show that it's registered the users touch, but I'd like it to look good so would like the background colour to change to a highlight colour on touch and then back out again.</p>
  
  <p>So far I've created a transition animation which animates on the touched view's background :</p>
  
  <pre><code>animatedBackgroundView.setBackgroundResource(R.anim.background_touch);
  animatedBackgroundView.setOnTouchListener(new View.OnTouchListener() {
      @Override
      public boolean onTouch(View view, MotionEvent motionEvent) {
          TransitionDrawable transition = (TransitionDrawable) view.getBackground();
          transition.startTransition(500);
      }
  });
  </code></pre>
  
  <p>with the background animation resource file :</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;transition xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item android:drawable="#22ffffff" /&gt;
      &lt;item android:drawable="#00ffffff" /&gt;
  &lt;/transition&gt;
  </code></pre>
  
  <p>And this works great, but if the view already has a background then that is destroyed.</p>
  
  <p>Is there a way to dynamically create a similar transition animation effect without destroying the existing background?</p>