Class
Common
```kotlin
class LazyLayoutPrefetchState()
```
State for lazy items prefetching, used by lazy layouts to instruct the prefetcher.
## Secondary Constructors
```kotlin
@ExperimentalFoundationApi
constructor(
prefetchScheduler: PrefetchScheduler? = null,
onNestedPrefetch: (NestedPrefetchScope.() -> Unit)? = null,
) : this() {
this.prefetchScheduler = prefetchScheduler
this.onNestedPrefetch = onNestedPrefetch
}
```
State for lazy items prefetching, used by lazy layouts to instruct the prefetcher.
#### Parameters
| | |
| --- | --- |
| prefetchScheduler | the `PrefetchScheduler` implementation to use to execute prefetch requests. If null is provided, the default `PrefetchScheduler` for the platform will be used. |
| onNestedPrefetch | a callback which will be invoked when this LazyLayout is prefetched in context of a parent LazyLayout, giving a chance to recursively prefetch its own children. See `NestedPrefetchScope`. |
```kotlin
@ExperimentalFoundationApi
constructor(onNestedPrefetch: (NestedPrefetchScope.() -> Unit)? = null) : this() {
this.onNestedPrefetch = onNestedPrefetch
}
```
State for lazy items prefetching, used by lazy layouts to instruct the prefetcher.
#### Parameters
| | |
| --- | --- |
| onNestedPrefetch | a callback which will be invoked when this LazyLayout is prefetched in context of a parent LazyLayout, giving a chance to recursively prefetch its own children. See `NestedPrefetchScope`. |
## Functions
schedulePrecomposition
```kotlin
fun schedulePrecomposition(@IntRange(from = 0) index: Int): PrefetchHandle
```
Schedules precomposition for the new item. If you also want to premeasure the item please use
`schedulePrecompositionAndPremeasure` instead. This function should only be called once per
item. If the item has already been composed at the time this request executes, either from a
previous call to this function or because the item is already visible, this request should
have no meaningful effect.
#### Parameters
| | |
| --- | --- |
| index | item index to prefetch. |
#### Returns
| | |
| --- | --- |
| | A `PrefetchHandle` which can be used to control the lifecycle of the prefetch request. Use `PrefetchHandle.cancel` to cancel the request or `PrefetchHandle.markAsUrgent` to mark the request as urgent. |
schedulePrecompositionAndPremeasure
```kotlin
fun schedulePrecompositionAndPremeasure(
@IntRange(from = 0) index: Int,
constraints: Constraints,
onItemPremeasured: (PrefetchResultScope.() -> Unit)? = null,
): PrefetchHandle
```
Schedules precomposition and premeasure for the new item. This should be used instead of
`schedulePrecomposition` if you also want to premeasure the item. This function should only
be called once per item. If the item has already been composed / measured at the time this
request executes, either from a previous call to this function or because the item is already
visible, this request should have no meaningful effect.
#### Parameters
| | |
| --- | --- |
| index | item index to prefetch. |
| constraints | `Constraints` to use for premeasuring. |
| onItemPremeasured | This callback is called when the item premeasuring is finished. If the request is canceled or no measuring is performed this callback won't be called. Use `PrefetchResultScope.getSize` to get the item's size. |
#### Returns
| | |
| --- | --- |
| | A `PrefetchHandle` which can be used to control the lifecycle of the prefetch request. Use `PrefetchHandle.cancel` to cancel the request or `PrefetchHandle.markAsUrgent` to mark the request as urgent. |