Recomposer

public class Recomposer(effectCoroutineContext: CoroutineContext) : CompositionContext()

The scheduler for performing recomposition and applying updates to one or more Compositions.

Functions

public fun asRecomposerInfo(): RecomposerInfo

Obtain a read-only RecomposerInfo for this Recomposer.

public suspend fun runRecomposeAndApplyChanges(): Unit

Await the invalidation of any associated Composers, recompose them, and apply their changes to their associated Compositions if recomposition is successful.

While runRecomposeAndApplyChanges is running, awaitIdle will suspend until there are no more invalid composers awaiting recomposition.

This method will not return unless the Recomposer is closed and all effects in managed compositions complete. Unhandled failure exceptions from child coroutines will be thrown by this method.

@ExperimentalComposeApi
    public suspend fun runRecomposeConcurrentlyAndApplyChanges(
        recomposeCoroutineContext: CoroutineContext
    ): Unit

Await the invalidation of any associated Composers, recompose them, and apply their changes to their associated Compositions if recomposition is successful.

While runRecomposeConcurrentlyAndApplyChanges is running, awaitIdle will suspend until there are no more invalid composers awaiting recomposition.

Recomposition of invalidated composers will occur in recomposeCoroutineContext. recomposeCoroutineContext must not contain a Job.

This method will not return unless the Recomposer is closed and all effects in managed compositions complete. Unhandled failure exceptions from child coroutines will be thrown by this method.

public fun cancel()

Permanently shut down this Recomposer for future use. currentState will immediately reflect State.ShuttingDown (or a lower state) before this call returns. All ongoing recompositions will stop, new composer invalidations with this Recomposer at the root will no longer occur, and any LaunchedEffects currently running in compositions managed by this Recomposer will be cancelled. Any rememberCoroutineScope scopes from compositions managed by this Recomposer will also be cancelled. See join to await the completion of all of these outstanding tasks.

public fun close()

Close this Recomposer. Once all effects launched by managed compositions complete, any active call to runRecomposeAndApplyChanges will return normally and this Recomposer will be State.ShutDown. See join to await the completion of all of these outstanding tasks.

public suspend fun join()

Await the completion of a cancel operation.

public suspend fun awaitIdle()

Suspends until the currently pending recomposition frame is complete. Any recomposition for this recomposer triggered by actions before this call begins will be complete and applied (if recomposition was successful) when this call returns.

If runRecomposeAndApplyChanges is not currently running the Recomposer is considered idle and this method will not suspend.

public fun pauseCompositionFrameClock()

Pause broadcasting the frame clock while recomposing. This effectively pauses animations, or any other use of the withFrameNanos, while the frame clock is paused.

pauseCompositionFrameClock should be called when the recomposer is not being displayed for some reason such as not being the current activity in Android, for example.

Calls to pauseCompositionFrameClock are thread-safe and idempotent (calling it when the frame clock is already paused is a no-op).

public fun resumeCompositionFrameClock()

Resume broadcasting the frame clock after is has been paused. Pending calls to withFrameNanos will start receiving frame clock broadcasts at the beginning of the frame and a frame will be requested if there are pending calls to withFrameNanos if a frame has not already been scheduled.

Calls to resumeCompositionFrameClock are thread-safe and idempotent (calling it when the frame clock is running is a no-op).

Companion Object

Properties

public val runningRecomposers: StateFlow<Set<RecomposerInfo>>

An observable Set of RecomposerInfos for currently running Recomposers. Emitted sets are immutable.