In this lesson, we will talk about how to align a view's vertical center to another view's edge, which is a difficult layout challenge without
ConstraintLayout. Using a center constraint made relative to another view's edge, we can keep a view centered on that edge regardless of change's to that edge's position. One example of this kind of layout occurs when a Floating Action Button (FAB) is aligned at the bottom of an app bar or hero image.
We will look at how to quickly create a vertical center constraint for a FAB relative to a hero image. We will also look at the behavior and position of the FAB as the hero image's size changes.