AppBarLayout scroll behavior with layout_scrollFlags

Since the introduction of AppBar in 2015, Android developers have spent lots of time styling and modifying it, making beautiful and unique apps. The ways of modifying Toolbar and flexible area beneath it are quite impressive. Yet, still the entry threshold is quite high for those who want to make their first steps in Material design world.

Partly, this is because of an incomplete documentation and the lack of diverse examples. I, myself struggled to make the layout I wanted and as easy as it sounds — to make it scroll the way I want to. This was the moment I decided to write this blog post, so it helps others :)

Maybe you want to scroll a Toolbar, so it hides completely and the only thing visible is the text? Or expand and collapse an image below the Toolbar? Or, doesn’t matter if the user is on the bottom of the layout, — you want to show him a Toolbar immediately on a scroll up action (there is a description of various scrolling techniques here). All of this is possible and easy to do with scroll flags!

Why do you need those flags in the first place? Well, when you want to have expandable Toolbar, Floating Action Button and a content to scroll over, the best option would be to put them into CoordinatorLayout and use its facilities in order to customize the behavior of each of those components. CoordinatorLayout bounds the behavior of a few views together. It makes them work as a whole — smooth and natural. You just need to put Toolbar into the AppBarLayout, which is a…