I find most of the material is about discussing adding "pull to refresh" in the area below AppBarLayout, such as SwipeRefreshLayout, I wonder how to do this in the AppBarLayout, which means:
When pull down, the pull-to-refresh indicator appeaars in the AppBarLayout.
how to implement this? Thanks
=================UPDATE===================
I finally worked it out on my own way. Here is the video link recording the simple UI.
The key point is I rewrite the appbarlayout-spring-behavior from github. It's really helpeful. Simply put, I rewrited the AppBarLayoutSpringBehavior, adding a Pull-To-Refresh-Callback when draging, and add some logic to displaying the pull-to-refresh animation prevent simplely animating back to original state. After sometime, then I tell the behavior to animate back.
Though the rewriten code seems ugly, but it seems feasible. I will refactor my code to make it clean and modular
