NestedScrollingParent3

Kotlin |Java

interface NestedScrollingParent3 : NestedScrollingParent2

androidx.core.view.NestedScrollingParent3

Known Direct Subclasses

CoordinatorLayout, NestedScrollView, SwipeRefreshLayout

CoordinatorLayout	CoordinatorLayout is a super-powered `FrameLayout`.
NestedScrollView	NestedScrollView is just like `android.widget.ScrollView`, but it supports acting as both a nested scrolling parent and child on both new and old versions of Android.
SwipeRefreshLayout	The SwipeRefreshLayout should be used whenever the user can refresh the contents of a view via a vertical swipe gesture.

This interface should be implemented by ViewGroup subclasses that wish to support scrolling operations delegated by a nested child view.

Classes implementing this interface should create a final instance of a NestedScrollingParentHelper as a field and delegate any View or ViewGroup methods to the NestedScrollingParentHelper 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 Unit	`onNestedScroll(@NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int, @NonNull consumed: IntArray)` React to a nested scroll in progress.

Inherited functions

From class NestedScrollingParent

`Int`	`getNestedScrollAxes()` Return the current axes of nested scrolling for this NestedScrollingParent. A NestedScrollingParent returning something other than `ViewCompat#SCROLL_AXIS_NONE` is currently acting as a nested scrolling parent for one or more descendant views in the hierarchy.
`Boolean`	`onNestedFling(@NonNull target: View, velocityX: Float, velocityY: Float, consumed: Boolean)` Request a fling from a nested scroll. This method signifies that a nested scrolling child has detected suitable conditions for a fling. Generally this means that a touch scroll has ended with a `velocity` in the direction of scrolling that meets or exceeds the `minimum fling velocity` along a scrollable axis. If a nested scrolling child view would normally fling but it is at the edge of its own content, it can use this method to delegate the fling to its nested scrolling parent instead. The parent may optionally consume the fling or observe a child fling.
`Boolean`	`onNestedPreFling(@NonNull target: View, velocityX: Float, velocityY: Float)` React to a nested fling before the target view consumes it. This method siginfies that a nested scrolling child has detected a fling with the given velocity along each axis. Generally this means that a touch scroll has ended with a `velocity` in the direction of scrolling that meets or exceeds the `minimum fling velocity` along a scrollable axis. If a nested scrolling parent is consuming motion as part of a `pre-scroll`, it may be appropriate for it to also consume the pre-fling to complete that same motion. By returning `true` from this method, the parent indicates that the child should not fling its own internal content as well.
`Unit`	`onNestedPreScroll(@NonNull target: View, dx: Int, dy: Int, @NonNull consumed: IntArray)` React to a nested scroll in progress before the target view consumes a portion of the scroll. When working with nested scrolling often the parent view may want an opportunity to consume the scroll before the nested scrolling child does. An example of this is a drawer that contains a scrollable list. The user will want to be able to scroll the list fully into view before the list itself begins scrolling. `onNestedPreScroll` is called when a nested scrolling child invokes `View#dispatchNestedPreScroll(int, int, int[], int[])`. The implementation should report how any pixels of the scroll reported by dx, dy were consumed in the `consumed` array. Index 0 corresponds to dx and index 1 corresponds to dy. This parameter will never be null. Initial values for consumed[0] and consumed[1] will always be 0.
`Unit`	`onNestedScroll(@NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int)` React to a nested scroll in progress. This method will be called when the ViewParent's current nested scrolling child view dispatches a nested scroll event. To receive calls to this method the ViewParent must have previously returned `true` for a call to `onStartNestedScroll(View, View, int)`. Both the consumed and unconsumed portions of the scroll distance are reported to the ViewParent. An implementation may choose to use the consumed portion to match or chase scroll position of multiple child elements, for example. The unconsumed portion may be used to allow continuous dragging of multiple scrolling or draggable elements, such as scrolling a list within a vertical drawer where the drawer begins dragging once the edge of inner scrolling content is reached.
`Unit`	`onNestedScrollAccepted(@NonNull child: View, @NonNull target: View, axes: Int)` React to the successful claiming of a nested scroll operation. This method will be called after `onStartNestedScroll` returns true. It offers an opportunity for the view and its superclasses to perform initial configuration for the nested scroll. Implementations of this method should always call their superclass's implementation of this method if one is present.
`Boolean`	`onStartNestedScroll(@NonNull child: View, @NonNull target: View, axes: Int)` React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate. This method will be called in response to a descendant view invoking `ViewCompat#startNestedScroll(View, int)`. Each parent up the view hierarchy will be given an opportunity to respond and claim the nested scrolling operation by returning `true`. This method may be overridden by ViewParent implementations to indicate when the view is willing to support a nested scrolling operation that is about to begin. If it returns true, this ViewParent will become the target view's nested scrolling parent for the duration of the scroll operation in progress. When the nested scroll is finished this ViewParent will receive a call to `onStopNestedScroll(View)`.
`Unit`	`onStopNestedScroll(@NonNull target: View)` React to a nested scroll operation ending. Perform cleanup after a nested scrolling operation. This method will be called when a nested scroll stops, for example when a nested touch scroll ends with a `MotionEvent#ACTION_UP` or `MotionEvent#ACTION_CANCEL` event. Implementations of this method should always call their superclass's implementation of this method if one is present.

From class NestedScrollingParent2

`Unit`	`onNestedPreScroll(@NonNull target: View, dx: Int, dy: Int, @NonNull consumed: IntArray, type: Int)` React to a nested scroll in progress before the target view consumes a portion of the scroll. When working with nested scrolling often the parent view may want an opportunity to consume the scroll before the nested scrolling child does. An example of this is a drawer that contains a scrollable list. The user will want to be able to scroll the list fully into view before the list itself begins scrolling. `onNestedPreScroll` is called when a nested scrolling child invokes `View#dispatchNestedPreScroll(int, int, int[], int[])`. The implementation should report how any pixels of the scroll reported by dx, dy were consumed in the `consumed` array. Index 0 corresponds to dx and index 1 corresponds to dy. This parameter will never be null. Initial values for consumed[0] and consumed[1] will always be 0.
`Unit`	`onNestedScroll(@NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int)` React to a nested scroll in progress. This method will be called when the ViewParent's current nested scrolling child view dispatches a nested scroll event. To receive calls to this method the ViewParent must have previously returned `true` for a call to `onStartNestedScroll(View, View, int, int)`. Both the consumed and unconsumed portions of the scroll distance are reported to the ViewParent. An implementation may choose to use the consumed portion to match or chase scroll position of multiple child elements, for example. The unconsumed portion may be used to allow continuous dragging of multiple scrolling or draggable elements, such as scrolling a list within a vertical drawer where the drawer begins dragging once the edge of inner scrolling content is reached.
`Unit`	`onNestedScrollAccepted(@NonNull child: View, @NonNull target: View, axes: Int, type: Int)` React to the successful claiming of a nested scroll operation. This method will be called after `onStartNestedScroll` returns true. It offers an opportunity for the view and its superclasses to perform initial configuration for the nested scroll. Implementations of this method should always call their superclass's implementation of this method if one is present.
`Boolean`	`onStartNestedScroll(@NonNull child: View, @NonNull target: View, axes: Int, type: Int)` React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate. This method will be called in response to a descendant view invoking `ViewCompat#startNestedScroll(View, int)`. Each parent up the view hierarchy will be given an opportunity to respond and claim the nested scrolling operation by returning `true`. This method may be overridden by ViewParent implementations to indicate when the view is willing to support a nested scrolling operation that is about to begin. If it returns true, this ViewParent will become the target view's nested scrolling parent for the duration of the scroll operation in progress. When the nested scroll is finished this ViewParent will receive a call to `onStopNestedScroll(View, int)`.
`Unit`	`onStopNestedScroll(@NonNull target: View, type: Int)` React to a nested scroll operation ending. Perform cleanup after a nested scrolling operation. This method will be called when a nested scroll stops, for example when a nested touch scroll ends with a `MotionEvent#ACTION_UP` or `MotionEvent#ACTION_CANCEL` event. Implementations of this method should always call their superclass's implementation of this method if one is present.

Public methods

onNestedScroll

abstract fun onNestedScroll(
    @NonNull target: View, 
    dxConsumed: Int, 
    dyConsumed: Int, 
    dxUnconsumed: Int, 
    dyUnconsumed: Int, 
    type: Int, 
    @NonNull consumed: IntArray
): Unit

React to a nested scroll in progress.

This method will be called when the ViewParent's current nested scrolling child view dispatches a nested scroll event. To receive calls to this method the ViewParent must have previously returned true for a call to onStartNestedScroll(View, View, int, int).

Both the consumed and unconsumed portions of the scroll distance are reported to the ViewParent. An implementation may choose to use the consumed portion to match or chase scroll position of multiple child elements, for example. The unconsumed portion may be used to allow continuous dragging of multiple scrolling or draggable elements, such as scrolling a list within a vertical drawer where the drawer begins dragging once the edge of inner scrolling content is reached.

This method is called when a nested scrolling child invokes NestedScrollingChild3#dispatchNestedScroll(int, int, int, int, int[], int, int[])} or one of methods it overloads.

An implementation must report how many pixels of the the x and y scroll distances were consumed by this nested scrolling parent by adding the consumed distances to the consumed parameter. If this View also implements NestedScrollingChild3, consumed should also be passed up to it's nested scrolling parent so that the parent may also add any scroll distance it consumes. Index 0 corresponds to dx and index 1 corresponds to dy.

Parameters
`target`	View: The descendant view controlling the nested scroll
`dxConsumed`	Int: Horizontal scroll distance in pixels already consumed by target
`dyConsumed`	Int: Vertical scroll distance in pixels already consumed by target
`dxUnconsumed`	Int: Horizontal scroll distance in pixels not consumed by target
`dyUnconsumed`	Int: Vertical scroll distance in pixels not consumed by target
`type`	Int: the type of input which cause this scroll event
`consumed`	IntArray: Output. Upon this method returning, will contain the scroll distances consumed by this nested scrolling parent and the scroll distances consumed by any other parent up the view hierarchy

See Also

NestedScrollingChild3#dispatchNestedScroll(int, int, int, int, int[], int, int[])