ItemAnimators VS flexbox-layout

Next, we looked at overriding SimpleItemAnimator but noticed that this class is missing a lot of logic required for orchestrating the animations. We realized that the Android SDK does not really allow us to easily customize RecyclerView item animations - what a shame! Doing some research on this we found two open-source libraries (here and here - note: this is no endorsement) that provide a variety of custom ItemAnimators by using a base ItemAnimator implementation that is very similar to the DefaultItemAnimator class but allows for proper customization. We ended up creating our own BaseItemAnimator by looking at DefaultItemAnimator and adapting it to our needs and then creating the actual implementation for the reaction feature. This allowed us to customize the “Add” animation like so:

In order to properly encapsulate the reaction view logic, we created a class that extends RecyclerView and has a bind method that takes in the list of reactions and updates the RecyclerView’s adapter with that list. Given that we had to support a multi-line layout, we initially looked into using GridLayoutManager to achieve this but ended up finding an open-source library by Google named flexbox-layout that provides a LayoutManager that supports laying out items in multiple flex-rows, which is exactly what we needed. Using these ingredients, we were able to get a simple version of our layout up and running. What’s next was adding custom animations and improving performance.

You could use FlexBoxLayout, though that's for the old system.

I would highly recommend using sp for text sizes as users can change the font size in their settings. So if someone has bad vision and large text, your app would be disregarding scaling the text up. This does make it more difficult to create layouts that work for all text sizes, but there are patterns such as a constraint layout flow or flex box which will make everything in one row if the content fits our stack on top of each other if it doesn't fit in a single row.

This blog doesn't really mention the actual case Flow tries to solve. It is more akin to FlexBoxLayout where it can wrap the row/column if the child widget's size exceeds the size of the container.