androidx.compose.runtime.snapshots

Interfaces

`ObserverHandle`	The type returned by observer registration methods that unregisters the observer when it is disposed.	Cmn
`SnapshotContextElement`	A `CoroutineContext` element that `enters` an associated snapshot whenever a coroutine associated with this context is resumed.	Cmn
`SnapshotMutableState`	A mutable value holder where reads to the `value` property during the execution of a `Composable` function, the current `RecomposeScope` will be subscribed to changes of that value.	Cmn
`StateObject`	Interface implemented by all snapshot aware state objects.	Cmn

Classes

`MutableSnapshot`	A snapshot of the values return by mutable states and other state objects.	Cmn
`Snapshot`	A snapshot of the values return by mutable states and other state objects.	Cmn
`SnapshotApplyResult`	The result of a applying a mutable snapshot.	Cmn
`SnapshotApplyResult.Failure`		Cmn
`SnapshotId`	The type of `Snapshot.snapshotId`.	Cmn android N JS
`SnapshotIdArray`	An array of `SnapshotId`.	Cmn android N JS
`SnapshotStateList`	An implementation of `MutableList` that can be observed and snapshot.	Cmn android
`SnapshotStateMap`	An implementation of `MutableMap` that can be observed and snapshot.	Cmn
`SnapshotStateObserver`	Helper class to efficiently observe snapshot state reads.	Cmn
`SnapshotStateSet`	An implementation of `MutableSet` that can be observed and snapshot.	Cmn android
`StateRecord`	Snapshot local value of a state object.	Cmn

Exceptions

SnapshotApplyConflictException

An exception that is thrown when SnapshotApplyResult.check is called on a result of a MutableSnapshot.apply that fails to apply.

Cmn

Objects

`Snapshot.Companion`		Cmn
`SnapshotApplyResult.Success`		Cmn
`SnapshotContextElement.Key`		Cmn

Annotations

`AutoboxingStateValueProperty`	This annotation designates that a property on a State class will autobox when it is read from or assigned to.	Cmn
`StateFactoryMarker`	Designates a function as a factory function that produces a State object.	Cmn

Type aliases

`SnapshotId`		android N JS
`SnapshotIdArray`		android N JS

Top-level functions summary

SnapshotStateList<T>

<T : Any?> SnapshotStateList(size: Int, init: (index: Int) -> T)

Creates a new snapshot state list with the specified size, where each element is calculated by calling the specified init function.

Cmn

Extension functions summary

`SnapshotContextElement`	`Snapshot.asContextElement()` Return a `SnapshotContextElement` that will `enter` this `Snapshot` whenever the associated coroutine is resumed and leave this snapshot when it suspends.	Cmn
`T`	`<T : StateRecord> T.readable(state: StateObject)` Return the current readable state record for the current snapshot.	Cmn
`T`	`<T : StateRecord> T.readable(state: StateObject, snapshot: Snapshot)` Return the current readable state record for the `snapshot`.	Cmn
`Int`	`SnapshotId.toInt()`	Cmn
`inline Int`	`Double.toInt()`	JS
`inline Int`	`Long.toInt()`	android N JS
`Long`	`SnapshotId.toLong()`	Cmn
`inline Long`	`Double.toLong()`	JS
`inline Long`	`Long.toLong()`	android N JS
`inline R`	`<T : StateRecord, R : Any?> T.withCurrent(block: (r) -> R)` Provides a `block` with the current record, without notifying any read observers.	Cmn
`inline R`	`<T : StateRecord, R : Any?> T.writable(state: StateObject, block: T.() -> R)` Call `block` with a writable state record for the given record.	Cmn
`inline R`	`<T : StateRecord, R : Any?> T.writable( state: StateObject, snapshot: Snapshot, block: T.() -> R )` Call `block` with a writable state record for `snapshot` of the given record.	Cmn

Top-level functions

SnapshotStateList

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.8.0

fun <T : Any?> SnapshotStateList(size: Int, init: (index: Int) -> T): SnapshotStateList<T>

Creates a new snapshot state list with the specified size, where each element is calculated by calling the specified init function.

The function init is called for each list element sequentially starting from the first one. It should return the value for a list element given its index.

Extension functions

asContextElement

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.2.0

fun Snapshot.asContextElement(): SnapshotContextElement

Return a SnapshotContextElement that will enter this Snapshot whenever the associated coroutine is resumed and leave this snapshot when it suspends. The snapshot still must be disposed separately when it will no longer be used.

import androidx.compose.runtime.snapshots.Snapshot
import androidx.compose.runtime.snapshots.asContextElement

runBlocking {
    val snapshot = Snapshot.takeSnapshot()
    try {
        withContext(snapshot.asContextElement()) {
            // Data observed by separately reading stateA and stateB are consistent with
            // the snapshot context element across suspensions
            doSomethingSuspending(someObject.stateA)
            doSomethingSuspending(someObject.stateB)
        }
    } finally {
        // Snapshot must be disposed after it will not be used again
        snapshot.dispose()
    }
}

readable

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.0.0

fun <T : StateRecord> T.readable(state: StateObject): T

Return the current readable state record for the current snapshot. It is assumed that this is the first record of state

readable

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.0.0

fun <T : StateRecord> T.readable(state: StateObject, snapshot: Snapshot): T

Return the current readable state record for the snapshot. It is assumed that this is the first record of state

toInt

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

fun SnapshotId.toInt(): Int

toInt

Artifact: androidx.compose.runtime:runtime

View Source

inline fun Double.toInt(): Int

toInt

android N JS

View Source

inline fun Long.toInt(): Int

toLong

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

fun SnapshotId.toLong(): Long

toLong

Artifact: androidx.compose.runtime:runtime

View Source

inline fun Double.toLong(): Long

toLong

android N JS

View Source

inline fun Long.toLong(): Long

withCurrent

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.0.0

inline fun <T : StateRecord, R : Any?> T.withCurrent(block: (r) -> R): R

Provides a block with the current record, without notifying any read observers.

See also
`readable`

writable

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.0.0

inline fun <T : StateRecord, R : Any?> T.writable(state: StateObject, block: T.() -> R): R

Call block with a writable state record for the given record. It is assumed that this is called for the first state record in a state object. A record is writable if it was created in the current mutable snapshot.

writable

Cmn

Artifact: androidx.compose.runtime:runtime

View Source

Added in 1.0.0

inline fun <T : StateRecord, R : Any?> T.writable(
    state: StateObject,
    snapshot: Snapshot,
    block: T.() -> R
): R

Call block with a writable state record for snapshot of the given record. It is assumed that this is called for the first state record in a state object. If the snapshot is read-only calling this will throw.