NestedScrollingParentHelper

public class NestedScrollingParentHelper


Helper class for implementing nested scrolling parent views compatible with Android platform versions earlier than Android 5.0 Lollipop (API 21).

ViewGroup subclasses should instantiate a final instance of this class as a field at construction. For each ViewGroup method that has a matching method signature in this class, delegate the operation to the helper instance in an overridden method implementation. This implements the standard framework policy for nested scrolling.

Views invoking nested scrolling functionality should always do so from the relevant androidx.core.view.ViewCompat, androidx.core.view.ViewGroupCompat or androidx.core.view.ViewParentCompat compatibility shim static methods. This ensures interoperability with nested scrolling views on Android 5.0 Lollipop and newer.

Summary

Public constructors

Construct a new helper for a given ViewGroup

Public methods

@ViewCompat.ScrollAxis int

Return the current axes of nested scrolling for this ViewGroup.

void
onNestedScrollAccepted(
    @NonNull View child,
    @NonNull View target,
    @ViewCompat.ScrollAxis int axes
)

Called when a nested scrolling operation initiated by a descendant view is accepted by this ViewGroup.

void
onNestedScrollAccepted(
    @NonNull View child,
    @NonNull View target,
    @ViewCompat.ScrollAxis int axes,
    @ViewCompat.NestedScrollType int type
)

Called when a nested scrolling operation initiated by a descendant view is accepted by this ViewGroup.

void

React to a nested scroll operation ending.

void
onStopNestedScroll(
    @NonNull View target,
    @ViewCompat.NestedScrollType int type
)

React to a nested scroll operation ending.

Public constructors

NestedScrollingParentHelper

public NestedScrollingParentHelper(@NonNull ViewGroup viewGroup)

Construct a new helper for a given ViewGroup

Public methods

getNestedScrollAxes

@ViewCompat.ScrollAxis
public int getNestedScrollAxes()

Return the current axes of nested scrolling for this ViewGroup.

This is a delegate method. Call it from your ViewGroup subclass method/androidx.core.view.NestedScrollingParent interface method with the same signature to implement the standard policy.

onNestedScrollAccepted

public void onNestedScrollAccepted(
    @NonNull View child,
    @