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added in version 1.0.0
belongs to Maven artifact androidx.recyclerview:recyclerview:1.0.0-rc01

PagerSnapHelper

public class PagerSnapHelper
extends SnapHelper

java.lang.Object
   ↳ androidx.recyclerview.widget.RecyclerView.OnFlingListener
     ↳ androidx.recyclerview.widget.SnapHelper
       ↳ androidx.recyclerview.widget.PagerSnapHelper


Implementation of the SnapHelper supporting pager style snapping in either vertical or horizontal orientation.

PagerSnapHelper can help achieve a similar behavior to ViewPager. Set both RecyclerView and the items of the RecyclerView.Adapter to have ViewGroup.LayoutParams.MATCH_PARENT height and width and then attach PagerSnapHelper to the RecyclerView using SnapHelper.attachToRecyclerView(RecyclerView).

Summary

Public constructors

PagerSnapHelper()

Public methods

int[] calculateDistanceToFinalSnap(RecyclerView.LayoutManager layoutManager, View targetView)

Override this method to snap to a particular point within the target view or the container view on any axis.

View findSnapView(RecyclerView.LayoutManager layoutManager)

Override this method to provide a particular target view for snapping.

int findTargetSnapPosition(RecyclerView.LayoutManager layoutManager, int velocityX, int velocityY)

Override to provide a particular adapter target position for snapping.

Protected methods

LinearSmoothScroller createSnapScroller(RecyclerView.LayoutManager layoutManager)

This method is deprecated. use createScroller(RecyclerView.LayoutManager) instead.

Inherited methods

Public constructors

PagerSnapHelper

added in version 1.0.0
public PagerSnapHelper ()

Public methods

calculateDistanceToFinalSnap

added in version 1.0.0
public int[] calculateDistanceToFinalSnap (RecyclerView.LayoutManager layoutManager, 
                View targetView)

Override this method to snap to a particular point within the target view or the container view on any axis.

This method is called when the SnapHelper has intercepted a fling and it needs to know the exact distance required to scroll by in order to snap to the target view.

Parameters
layoutManager RecyclerView.LayoutManager: the RecyclerView.LayoutManager associated with the attached RecyclerView

targetView View: the target view that is chosen as the view to snap

Returns
int[] the output coordinates the put the result into. out[0] is the distance on horizontal axis and out[1] is the distance on vertical axis.

findSnapView

added in version 1.0.0
public View findSnapView (RecyclerView.LayoutManager layoutManager)

Override this method to provide a particular target view for snapping.

This method is called when the SnapHelper is ready to start snapping and requires a target view to snap to. It will be explicitly called when the scroll state becomes idle after a scroll. It will also be called when the SnapHelper is preparing to snap after a fling and requires a reference view from the current set of child views.

If this method returns null, SnapHelper will not snap to any view.

Parameters
layoutManager RecyclerView.LayoutManager: the RecyclerView.LayoutManager associated with the attached RecyclerView

Returns
View the target view to which to snap on fling or end of scroll

findTargetSnapPosition

added in version 1.0.0
public int findTargetSnapPosition (RecyclerView.LayoutManager layoutManager, 
                int velocityX, 
                int velocityY)

Override to provide a particular adapter target position for snapping.

Parameters
layoutManager RecyclerView.LayoutManager: the RecyclerView.LayoutManager associated with the attached RecyclerView

velocityX int: fling velocity on the horizontal axis

velocityY int: fling velocity on the vertical axis

Returns
int the target adapter position to you want to snap or RecyclerView.NO_POSITION if no snapping should happen

Protected methods

createSnapScroller

added in version 1.0.0
protected LinearSmoothScroller createSnapScroller (RecyclerView.LayoutManager layoutManager)

This method is deprecated.
use createScroller(RecyclerView.LayoutManager) instead.

Creates a scroller to be used in the snapping implementation.

Parameters
layoutManager RecyclerView.LayoutManager: The RecyclerView.LayoutManager associated with the attached RecyclerView.

Returns
LinearSmoothScroller a LinearSmoothScroller which will handle the scrolling.