title: Android transition animation linear cross fade effect
body: <p>I need to make cross fade effect on two bitmaps in a way that first bitmap is being replaced by the second one linearly from top to bottom. In other words first bitmap should
  dissapear from top to bottom and in it's place second bitmap should appear.
  There are many examples with cross fade with animations (changing alpha), or using TransitionDrawable, but i was not able to find the one i am looking for.
  Anyone knows how to do that?</p>
  
  <p>Thanks</p>