title: How to animate android activity background
body: <p>In my android app I want to show a background animation. 
  I had done it using images by changing the images with time.
  But my problem by using images for each frame of animation the app size was becoming  huge
  I know it is not a good way.</p>
  
  <p>I want to do it in efficient and good way.</p>
  
  <p>If I am doing this by using images which is the best way. How can I do that?</p>