animateLayoutChanges=“true” in BottomSheetView showing unexpected behaviour

Question

I have a BottomSheetView which has animateLayoutChanges=\"true\". Initially it shows up fine. But if change the visibility of a view (insi

Answer 1

I was running into the same issue and determined to find a fix. I was able to find the underlying cause but unfortunately I do not see a great fix at the moment.

The Cause: The problem occurs between the bottomsheet behavior and the LayoutTransition. When the LayoutTransition is created, it creates a OnLayoutChangeListener on the view so that it can capture its endValues and setup an animator with the proper values. This OnLayoutChangeListener is triggered in the bottomSheetBehavior's onLayout() call when it first calls parent.onLayout(child). The parent will layout the child as it normally would, ignoring any offsets that the behavior would change later. The problem lies here. The values of the view at this point are captured by the OnLayoutChangeListener and stored in the animator. When the animation runs, it will animate to these values, not to where your behavior defines. Unfortunately, the LayoutTransition class does not give us access to the animators to allow updating of the end values.

The Fix: Currently, I don't see an elegant fix that involves LayoutTransitions. I am going to submit a bug for a way to access and update LayoutTransition animators. For now you can disable any layoutTransition on the parent container using layoutTransition.setAnimateParentHierachy(false). Then you can animate the change yourself. I'll update my answer with a working example as soon as I can.