How to create a smooth transition with a view moving to overlay above an activity?

Question

I'm investigating how the author of "inflickr"

https://play.google.com/store/apps/details?id=kr.infli

created the smooth transitions to bring his 'picture info' views above the picture itself. What method did the author use to create this effect?

Answer 1

Regarding Inflikr, there is only one activity involved.

The custom view (in black here) have a gesture detector and on a scroll up it will pull a details's view placed at the bottom (red frame).

The detail's view is transparent, when sliding up it increase alpha on a black shader on the custom view so the white text become readable even on a bright photo.

ps: rendered on device using scalpel

Thanks