LimitOffsetRxPagingSource

Kotlin |Java

@RestrictTo([Scope.LIBRARY_GROUP]) abstract class LimitOffsetRxPagingSource<Value : Any> : RxPagingSource<Int, Value>

kotlin.Any
↳	androidx.paging.PagingSource<Key, Value>
	↳	androidx.paging.rxjava2.RxPagingSource<kotlin.Int, Value>
		↳	androidx.room.paging.rxjava2.LimitOffsetRxPagingSource

Summary

Public constructors
`LimitOffsetRxPagingSource(supportSQLiteQuery: SupportSQLiteQuery, db: RoomDatabase, vararg tables: String)`
`LimitOffsetRxPagingSource(sourceQuery: RoomSQLiteQuery, db: RoomDatabase, vararg tables: String)`

Public methods
open Int?	`getRefreshKey(state: PagingState<Int, Value>)` Provide a Key used for the initial load for the next PagingSource due to invalidation of this PagingSource.
open Single<PagingSource.LoadResult<Int, Value>>	`loadSingle(params: PagingSource.LoadParams<Int>)` Loading API for PagingSource.

Protected methods
abstract List<Value>	`convertRows(cursor: Cursor)`

Inherited functions

From class PagingSource

`Key?`	`getRefreshKey(state: PagingState<Key, Value>)` Provide a Key used for the initial load for the next PagingSource due to invalidation of this PagingSource. The Key is provided to load via LoadParams.key. The Key returned by this method should cause load to load enough items to fill the viewport around the last accessed position, allowing the next generation to transparently animate in. The last accessed position can be retrieved via state.anchorPosition, which is typically the top-most or bottom-most item in the viewport due to access being triggered by binding items as they scroll into view. For example, if items are loaded based on integer position keys, you can return `( (state.anchorPosition ?: 0) - state.config.initialLoadSize / 2).coerceAtLeast(0)`. Alternately, if items contain a key used to load, get the key from the item in the page at index state.anchorPosition then try to center it based on `state.config.initialLoadSize`.
`Unit`	`invalidate()` Signal the PagingSource to stop loading. This method is idempotent. i.e., If invalidate has already been called, subsequent calls to this method should have no effect.
`Unit`	`registerInvalidatedCallback(onInvalidatedCallback: () -> Unit)` Add a callback to invoke when the PagingSource is first invalidated. Once invalidated, a PagingSource will not become valid again. A PagingSource will only invoke its callbacks once - the first time invalidate is called, on that thread. If this PagingSource is already invalid, the provided onInvalidatedCallback will be triggered immediately.
`Unit`	`unregisterInvalidatedCallback(onInvalidatedCallback: () -> Unit)` Remove a previously added invalidate callback.

From class RxPagingSource

PagingSource.LoadResult<Key, Value>

load(params: PagingSource.LoadParams<Key>)

Loading API for PagingSource.

Implement this method to trigger your async load (e.g. from database or network).

Properties
open Boolean	`jumpingSupported` `true` if this PagingSource supports jumping, `false` otherwise.

Inherited properties

From class PagingSource

Boolean

invalid

Whether this PagingSource has been invalidated, which should happen when the data this PagingSource represents changes since it was first instantiated.

Boolean

jumpingSupported

true if this PagingSource supports jumping, false otherwise.

Override this to true if pseudo-fast scrolling via jumps is supported.

A jump occurs when a RecyclerView scrolls through a number of placeholders defined by PagingConfig.jumpThreshold and triggers a load with LoadType.

PagingSources that support jumps should override getRefreshKey to return a Key that would load data fulfilling the viewport given a user's current PagingState.anchorPosition.

Boolean

keyReuseSupported

true if this PagingSource expects to re-use keys to load distinct pages without a call to invalidate, false otherwise.

Public constructors

LimitOffsetRxPagingSource

LimitOffsetRxPagingSource(
    supportSQLiteQuery: SupportSQLiteQuery, 
    db: RoomDatabase, 
    vararg tables: String)

LimitOffsetRxPagingSource

LimitOffsetRxPagingSource(
    sourceQuery: RoomSQLiteQuery, 
    db: RoomDatabase, 
    vararg tables: String)

Public methods

getRefreshKey

open fun getRefreshKey(state: PagingState<Int, Value>): Int?

Provide a Key used for the initial load for the next PagingSource due to invalidation of this PagingSource. The Key is provided to load via LoadParams.key.

The Key returned by this method should cause load to load enough items to fill the viewport around the last accessed position, allowing the next generation to transparently animate in. The last accessed position can be retrieved via state.anchorPosition, which is typically the top-most or bottom-most item in the viewport due to access being triggered by binding items as they scroll into view.

For example, if items are loaded based on integer position keys, you can return ( (state.anchorPosition ?: 0) - state.config.initialLoadSize / 2).coerceAtLeast(0).

Alternately, if items contain a key used to load, get the key from the item in the page at index state.anchorPosition then try to center it based on state.config.initialLoadSize.

Parameters
state: PagingState<Int, Value>	PagingState of the currently fetched data, which includes the most recently accessed position in the list via PagingState.anchorPosition.

Return
Key	passed to load after invalidation used for initial load of the next generation. The Key returned by getRefreshKey should load pages centered around user's current viewport. If the correct Key cannot be determined, `null` can be returned to allow load decide what default key to use.

loadSingle

open fun loadSingle(params: PagingSource.LoadParams<Int>): Single<PagingSource.LoadResult<Int, Value>>

Loading API for PagingSource.

Implement this method to trigger your async load (e.g. from database or network).

Protected methods

convertRows

@NonNull protected abstract fun convertRows(cursor: Cursor): List<Value>

Properties

jumpingSupported

open val jumpingSupported: Boolean

true if this PagingSource supports jumping, false otherwise.

Override this to true if pseudo-fast scrolling via jumps is supported.

A jump occurs when a RecyclerView scrolls through a number of placeholders defined by PagingConfig.jumpThreshold and triggers a load with LoadType.

PagingSources that support jumps should override getRefreshKey to return a Key that would load data fulfilling the viewport given a user's current PagingState.anchorPosition.

See Also

PagingConfig.jumpThreshold