Transparent background in ImageButton with ripple effect?

If android:background="?attr/selectableItemBackground" this works than I believe this answer should solve your problem:

https://stackoverflow.com/a/28087443/2534007

Create your own RippleDrawable and you need to use mask for the Ripple if you're going to use transparent background.

 <!-- A red ripple masked against an opaque rectangle. -->
 <ripple android:color="#ffff0000">
   <item android:id="@android:id/mask"
         android:drawable="@android:color/white" />
 </ripple>