Compose: animations

Core principle

Pick the smallest API that matches the problem: built-in visibility and layout transitions first, then a single animated value, then a shared transition object when several values must move together, then gesture-level or imperative APIs when the framework cannot express the motion.

Review procedure

1. Identify the visual job: show/hide, one value, coordinated values, content swap, size change, or gesture-driven motion.
2. Choose the smallest API from the table below.
3. Check lifecycle semantics: should hidden content leave composition, keep focus/state, or only become transparent?
4. Check identity: for state-holder wrappers, choose AnimatedContent.contentKey by visual shape rather than payload churn.
5. Check performance: keep frame-rate animation values as State and read them in layout/draw block modifiers when possible.
6. Escalate to Animatable or lower-level APIs only when target-state animation cannot express the motion.

Pick the smallest animation API