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
- Identify the visual job: show/hide, one value, coordinated values, content swap, size change, or gesture-driven motion.
- Choose the smallest API from the table below.
- Check lifecycle semantics: should hidden content leave composition, keep focus/state, or only become transparent?
- Check identity: for state-holder wrappers, choose
AnimatedContent.contentKey by visual shape rather than payload churn.
- Check performance: keep frame-rate animation values as
State and read them in layout/draw block modifiers when possible.
- Escalate to
Animatable or lower-level APIs only when target-state animation cannot express the motion.
Pick the smallest animation API
| Need | API |
|---|
| Show or hide a subtree with enter/exit semantics; content is removed after exit completes | AnimatedVisibility |
| Animate one property toward a target derived from state | animateFloatAsState / animateDpAsState / animateColorAsState / animateOffsetAsState / … |
| Several animated values keyed off one boolean, enum, or sealed state | rememberTransition + transition child animations (animateFloat, animateDp, animateColor, animateValue, …) |
| Smooth size when child layout height/width changes (e.g. text wraps) | Modifier.animateContentSize() |
| Swap between different composable trees for the same slot | AnimatedContent or Crossfade |
| User-driven motion (drag, fling, interruptible springs) | Animatable and related coroutine APIs (see Advanced pointers) |
Appear and disappear
Prefer AnimatedVisibility when the UI should leave or join the tree with enter/exit transitions.
AnimatedVisibility(visible = expanded) {
Text("Details…")
}
animateFloatAsState on alpha only fades; the composable
stays in composition and continues to participate in layout unless you gate it yourself. Use that tradeoff when you intentionally keep children mounted (state, focus) but visually hidden. For true remove-from-tree behavior, use
AnimatedVisibility (or conditional composition with
AnimatedVisibility /
AnimatedContent patterns from the
quick guide).
Background color
Use animateColorAsState for smooth color targets.
For animated fills behind children, the
quick guide recommends drawing with
Modifier.drawBehind rather than
Modifier.background() so the animated color is applied in the draw phase appropriately for performance.
val background = animateColorAsState(
targetValue = if (selected) selectedColor else idleColor,
label = "background",
)
Box(
Modifier.drawBehind { drawRect(background.value) },
) { /* content */ }
Size changes
Modifier.animateContentSize() animates layout size changes—common for expanding/collapsing text or dynamic chips—without hand-rolling width/height animations.
Value-based animations (animate*AsState)
Compose provides animate*AsState for Float, Dp, Color, Size, Offset, Rect, Int, IntOffset, IntSize, and more. You supply the target; the API owns the animation state.
- Pass an
AnimationSpec via animationSpec (e.g. spring, tween) when defaults are wrong for the UI.
- Set a distinct
label for debugging and tooling when multiple animations exist in one composable.
- For completion or sequencing details, see Value-based animations.
val width by animateDpAsState(
targetValue = if (expanded) 200.dp else 56.dp,
animationSpec = spring(dampingRatio = 0.7f, stiffness = Spring.StiffnessMedium),
label = "fabWidth",
)
Multiple properties: rememberTransition
When one piece of state (e.g. enum class Phase { A, B, C }) should drive several animated values in lockstep, use rememberTransition and define child animations on that transition:
val transition = rememberTransition(targetState = phase, label = "phase")
val alpha by transition.animateFloat(label = "alpha") { target ->
if (target == Phase.Visible) 1f else 0f
}
val offset by transition.animateDp(label = "offset") { target ->
if (target == Phase.Visible) 0.dp else 24.dp
}
Avoid multiple independent animate*AsState calls that should stay visually synchronized but can drift if specs or targets diverge. Older code may use updateTransition; prefer rememberTransition for new code.
Choosing between content-level APIs
Use the official
Choose an animation API tree when the table is not enough. Compressed rules:
| Situation | Prefer |
|---|
| Same composable, different target values for layout properties | animate*AsState or rememberTransition |
| Different composable content for the same region (tabs, steps) | AnimatedContent (custom transitionSpec, contentKey) or simpler Crossfade |
| Pager-like swipe between pages | Horizontal pager APIs from the animation docs / Material—follow the choose-api guidance |
| Transitions owned by Navigation Compose | Use navigation’s built-in transitions rather than bolting AnimatedContent on top of the same destination swap |
Art-based motion (illustrations, Lottie, complex vector timelines) is outside this skill; use dedicated libraries.
Decision flow (high level)
AnimatedContent keys for state holders
When AnimatedContent receives a state-holder wrapper such as AsyncResult<T>, Result<T>, or a sealed UiState, decide what should actually trigger the transition. Usually the animation should run when the content shape changes (loading → content → error), not when the payload inside the same shape changes.
Use contentKey to map rich state to the animation identity:
AnimatedContent(
targetState = result,
contentKey = { state ->
when (state) {
AsyncResult.Loading -> "loading"
is AsyncResult.Success -> "content"
is AsyncResult.Error -> "error"
}
},
label = "profile-content",
) { state ->
when (state) {
AsyncResult.Loading -> Loading()
is AsyncResult.Success -> Profile(state.value)
is AsyncResult.Error -> ErrorMessage(state.throwable)
}
}
Without contentKey, every unequal Success(value) can be treated as new content. That is useful if a payload change should animate, but noisy when fresh data updates the same screen shape.
Choose keys by visual shape:
| State change | Typical contentKey |
|---|
| Loading → Success → Error | Branch key: "loading", "content", "error" |
| Success item A → Success item B should crossfade | Stable item id |
| Success data refresh should update in place | Constant content key for Success |
| Error message text changes but error UI shape stays | Constant content key for Error |
Animated values and composition performance
animate*AsState returns
State that updates frequently. If that value feeds
Modifier.offset,
Modifier.graphicsLayer, scroll-adjacent layout, or other
frame-rate paths, avoid reading it in the composable body with
by and then passing it into value-form modifiers—use
deferred reads (block modifiers, draw/ layout lambdas) instead. See
compose-state-deferred-reads.
If recomposition counters spike during motion unrelated to bad stability, see
compose-recomposition-performance.
Escalation points
Load the official docs when one of these applies:
Common mistakes
| Mistake | Fix |
|---|
Fade with animateFloatAsState(alpha) but expect children to unmount | Use AnimatedVisibility or remove the subtree from composition when hidden |
Three animateDpAsState calls that must stay in sync with one enum | One rememberTransition + child animations |
Animated color on Modifier.background causing extra work | Prefer drawBehind { drawRect(animatedColor) } per quick guide |
Chaining LaunchedEffect + manual Animatable for simple target animation | Prefer animate*AsState or rememberTransition unless gestures require Animatable |
| Ignoring Navigation’s own transitions | Use Nav APIs for destination transitions; do not duplicate with AnimatedContent for the same swap |
AnimatedContent(targetState = asyncResult) animates on every data refresh | Add contentKey based on the visual shape or stable item identity |
When not to use this skill
- Side-effect timing (
LaunchedEffect, clicks launching work): use compose-side-effects.
- Deep performance tuning of where snapshot state is read: use
compose-state-deferred-reads as the primary reference.