SmoothScroller

Kotlin |Java

abstract class SmoothScroller

kotlin.Any
↳	androidx.recyclerview.widget.RecyclerView.SmoothScroller

Known Direct Subclasses

RecyclerView.SmoothScroller implementation which uses a LinearInterpolator until the target position becomes a child of the RecyclerView and then uses a DecelerateInterpolator to slowly approach to target position.

Base class for smooth scrolling. Handles basic tracking of the target view position and provides methods to trigger a programmatic scroll.

An instance of SmoothScroller is only intended to be used once. You should create a new instance for each call to LayoutManager#startSmoothScroll(SmoothScroller).

Summary

Nested classes
open	`Action` Holds information about a smooth scroll request by a `SmoothScroller`.
abstract	`ScrollVectorProvider` An interface which is optionally implemented by custom `RecyclerView.LayoutManager` to provide a hint to a `SmoothScroller` about the location of the target position.

Public constructors
`<init>()`

Public methods
open PointF?	`computeScrollVectorForPosition(targetPosition: Int)` Compute the scroll vector for a given target position.
open View!	`findViewByPosition(position: Int)`
open Int	`getChildCount()`
open Int	`getChildPosition(view: View!)`
open RecyclerView.LayoutManager?	`getLayoutManager()`
open Int	`getTargetPosition()` Returns the adapter position of the target item
open Unit	`instantScrollToPosition(position: Int)`
open Boolean	`isPendingInitialRun()` Returns true if SmoothScroller has been started but has not received the first animation callback yet.
open Boolean	`isRunning()`
open Unit	`setTargetPosition(targetPosition: Int)`

Protected methods
open Unit	`normalize(@NonNull scrollVector: PointF)` Normalizes the vector.
open Unit	`onChildAttachedToWindow(child: View!)`
abstract Unit	`onSeekTargetStep(@Px dx: Int, @Px dy: Int, @NonNull state: RecyclerView.State, @NonNull action: RecyclerView.SmoothScroller.Action)` RecyclerView will call this method each time it scrolls until it can find the target position in the layout.
abstract Unit	`onStart()` Called when smooth scroll is started.
abstract Unit	`onStop()` Called when smooth scroller is stopped.
abstract Unit	`onTargetFound(@NonNull targetView: View, @NonNull state: RecyclerView.State, @NonNull action: RecyclerView.SmoothScroller.Action)` Called when the target position is laid out.
Unit	`stop()` Stops running the SmoothScroller in each animation callback.

SmoothScroller()

@Nullable open fun computeScrollVectorForPosition(targetPosition: Int): PointF?

Compute the scroll vector for a given target position.

This method can return null if the layout manager cannot calculate a scroll vector for the given position (e.g. it has no current scroll position).

Parameters
`targetPosition`	Int: the position to which the scroller is scrolling

Return
`PointF?`	the scroll vector for a given target position

open fun findViewByPosition(position: Int): View!

See Also

open fun getChildCount(): Int

See Also

open fun getChildPosition(view: View!):