Center image on remaining space when scroll on ViewPager android -

i saw beatport's app intro viewpager, , want create effect on scroll, example, when changing next fragment, background image of fragment before adjust in center of remaining space. maybe wasn't specific, i'll glad if take @ beatport's app intro more understanding. effect called parallax , found pieces of code, can´t implement fragments, images.

here code:

https://github.com/je4a/parallaxviewpager/tree/master/sample/src/main/java/com/parallaxviewpager/sample