Android L: transition - create dialog from FAB

I would like to create a transtion in a sdk 21 android app with a transition from FAB to dialog in one action. Where to start, I just found tutorials on how to make a transition between two actions or scene transitions between two layouts. As far as I understand, I will only have one layout in one activity and transition from FAB view to dialog view.

Can someone give me some advice on how to implement this?