Inspired by the great Android app "Pocket Casts" +Alex Lockwood
took it on him to recreate the pause/resume media playback button . While his approach is based on a canvas, i was curious how such an effect could be achieved with pure Android drawables.
A few hours later i had the effect implemented with animated VectorDrawables and state transitions. The outcome is very nice and contains some interesting insides for other people trying to work with animated vector drawables. The code can be found at this  gist.
Some technical remarks... While the effect looks straight forward, it takes a ton of xml files to implement (15!). The entry point to the code is the file ic_pause_resume.xml  which branches out into the concrete animated-vector files.
One thing that is not shown in the gist is how the "selection" property of the ImageView is toggled in normal java code once the user taps on the drawable. Based on this selection property the transition to another drawable is triggered.
I hope you get something out of it. :)