NestedScrollingChild2

public interface NestedScrollingChild2
implements NestedScrollingChild

androidx.core.view.NestedScrollingChild2


This interface should be implemented by View subclasses that wish to support dispatching nested scrolling operations to a cooperating parent ViewGroup.

Classes implementing this interface should create a final instance of a NestedScrollingChildHelper as a field and delegate any View methods to the NestedScrollingChildHelper methods of the same signature.

Views invoking nested scrolling functionality should always do so from the relevant ViewCompat, ViewGroupCompat or ViewParentCompat compatibility shim static methods. This ensures interoperability with nested scrolling views on all versions of Android.

Summary

Public methods

abstract boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow, int type)

Dispatch one step of a nested scroll in progress before this view consumes any portion of it.

abstract boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow, int type)

Dispatch one step of a nested scroll in progress.

abstract boolean hasNestedScrollingParent(int type)

Returns true if this view has a nested scrolling parent for the given input type.

abstract boolean startNestedScroll(int axes, int type)

Begin a nestable scroll operation along the given axes, for the given input type.

abstract void stopNestedScroll(int type)

Stop a nested scroll in progress for the given input type.

Inherited methods

Public methods

dispatchNestedPreScroll

public abstract boolean dispatchNestedPreScroll (int dx, 
                int dy, 
                int[] consumed, 
                int[] offsetInWindow, 
                int type)

Dispatch one step of a nested scroll in progress before this view consumes any portion of it.

Nested pre-scroll events are to nested scroll events what touch intercept is to touch. dispatchNestedPreScroll offers an opportunity for the parent view in a nested scrolling operation to consume some or all of the scroll operation before the child view consumes it.

Parameters
dx int: Horizontal scroll distance in pixels

dy int: Vertical scroll distance in pixels

consumed int: Output. If not null, consumed[0] will contain the consumed component of dx and consumed[1] the consumed dy.

offsetInWindow int: Optional. If not null, on return this will contain the offset in local view coordinates of this view from before this operation to after it completes. View implementations may use this to adjust expected input coordinate tracking.

type int: the type of input which cause this scroll event

Returns
boolean true if the parent consumed some or all of the scroll delta

dispatchNestedScroll

public abstract boolean dispatchNestedScroll (int dxConsumed, 
                int dyConsumed, 
                int dxUnconsumed, 
                int dyUnconsumed, 
                int[] offsetInWindow, 
                int type)

Dispatch one step of a nested scroll in progress.

Implementations of views that support nested scrolling should call this to report info about a scroll in progress to the current nested scrolling parent. If a nested scroll is not currently in progress or nested scrolling is not enabled for this view this method does nothing.

Compatible View implementations should also call dispatchNestedPreScroll</