# NestedScrollingParent2

Artifact: [androidx.core:core](https://developer.android.com/jetpack/androidx/releases/core) [View Source](https://cs.android.com/search?q=file:androidx/core/view/NestedScrollingParent2.java+class:androidx.core.view.NestedScrollingParent2) Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/core#1.1.0)

*** ** * ** ***

<br />

```
interface NestedScrollingParent2 : NestedScrollingParent
```

<br />

Known direct subclasses [CoordinatorLayout](https://developer.android.com/reference/kotlin/androidx/coordinatorlayout/widget/CoordinatorLayout), [NestedScrollingParent3](https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent3), [SwipeRefreshLayout](https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/SwipeRefreshLayout)

|---|---|
| `https://developer.android.com/reference/kotlin/androidx/coordinatorlayout/widget/CoordinatorLayout` | CoordinatorLayout is a super-powered `https://developer.android.com/reference/android/widget/FrameLayout.html`. |
| `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent3` | This interface should be implemented by `https://developer.android.com/reference/android/view/ViewGroup.html` subclasses that wish to support scrolling operations delegated by a nested child view. |
| `https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/SwipeRefreshLayout` | The SwipeRefreshLayout should be used whenever the user can refresh the contents of a view via a vertical swipe gesture. |

Known indirect subclasses [CoordinatorLayout](https://developer.android.com/reference/kotlin/androidx/coordinatorlayout/widget/CoordinatorLayout), [MotionLayout](https://developer.android.com/reference/kotlin/androidx/constraintlayout/motion/widget/MotionLayout), [NestedScrollView](https://developer.android.com/reference/kotlin/androidx/core/widget/NestedScrollView), [SwipeRefreshLayout](https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/SwipeRefreshLayout)

|---|---|
| `https://developer.android.com/reference/kotlin/androidx/coordinatorlayout/widget/CoordinatorLayout` | CoordinatorLayout is a super-powered `https://developer.android.com/reference/android/widget/FrameLayout.html`. |
| `https://developer.android.com/reference/kotlin/androidx/constraintlayout/motion/widget/MotionLayout` | A subclass of ConstraintLayout that supports animating between various states **Added in 2.0** |
| `https://developer.android.com/reference/kotlin/androidx/core/widget/NestedScrollView` | NestedScrollView is just like `https://developer.android.com/reference/android/widget/ScrollView.html`, but it supports acting as both a nested scrolling parent and child on both new and old versions of Android. |
| `https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/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 `https://developer.android.com/reference/android/view/ViewGroup.html` subclasses that wish to support scrolling operations delegated by a nested child view.

Classes implementing this interface should create a final instance of a `https://developer.android.com/reference/kotlin/androidx/core/view/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 `https://developer.android.com/reference/kotlin/androidx/core/view/ViewCompat`, `https://developer.android.com/reference/kotlin/androidx/core/view/ViewGroupCompat` or `https://developer.android.com/reference/kotlin/androidx/core/view/ViewParentCompat` compatibility shim static methods. This ensures interoperability with nested scrolling views on all versions of Android.

## Summary

| ### Public functions |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onNestedPreScroll(android.view.View,int,int,int[],int)( target: https://developer.android.com/reference/android/view/View.html, dx: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, dy: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, consumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int-array/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html>, type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html )` React to a nested scroll in progress before the target view consumes a portion of the scroll. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onNestedScroll(android.view.View,int,int,int,int,int)( target: https://developer.android.com/reference/android/view/View.html, dxConsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, dyConsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, dxUnconsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, dyUnconsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html )` React to a nested scroll in progress. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onNestedScrollAccepted(android.view.View,android.view.View,int,int)(child: https://developer.android.com/reference/android/view/View.html, target: https://developer.android.com/reference/android/view/View.html, axes: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)` React to the successful claiming of a nested scroll operation. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html` | `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStartNestedScroll(android.view.View,android.view.View,int,int)(child: https://developer.android.com/reference/android/view/View.html, target: https://developer.android.com/reference/android/view/View.html, axes: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)` React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStopNestedScroll(android.view.View,int)(target: https://developer.android.com/reference/android/view/View.html, type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)` React to a nested scroll operation ending. |

### Inherited functions

From [androidx.core.view.NestedScrollingParent](https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent) `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#getNestedScrollAxes()()`

Return the current axes of nested scrolling for this NestedScrollingParent.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onNestedFling(android.view.View,float,float,boolean)(

target: https://developer.android.com/reference/android/view/View.html,

velocityX: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html,

velocityY: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html,

consumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html

)`

Request a fling from a nested scroll.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onNestedPreFling(android.view.View,float,float)(target: https://developer.android.com/reference/android/view/View.html, velocityX: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html, velocityY: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-float/index.html)`

React to a nested fling before the target view consumes it.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onNestedPreScroll(android.view.View,int,int,int[])(target: https://developer.android.com/reference/android/view/View.html, dx: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, dy: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, consumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int-array/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html>)`

React to a nested scroll in progress before the target view consumes a portion of the scroll.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onNestedScroll(android.view.View,int,int,int,int)(

target: https://developer.android.com/reference/android/view/View.html,

dxConsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html,

dyConsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html,

dxUnconsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html,

dyUnconsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html

)`

React to a nested scroll in progress.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onNestedScrollAccepted(android.view.View,android.view.View,int)(child: https://developer.android.com/reference/android/view/View.html, target: https://developer.android.com/reference/android/view/View.html, axes: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`

React to the successful claiming of a nested scroll operation.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onStartNestedScroll(android.view.View,android.view.View,int)(child: https://developer.android.com/reference/android/view/View.html, target: https://developer.android.com/reference/android/view/View.html, axes: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`

React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.
`https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent#onStopNestedScroll(android.view.View)(target: https://developer.android.com/reference/android/view/View.html)`

React to a nested scroll operation ending.

## Public functions

### onNestedPreScroll

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/core#1.1.0)

```
fun onNestedPreScroll(
    target: View,
    dx: Int,
    dy: Int,
    consumed: IntArray<Int>,
    type: Int
): Unit
```

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 `https://developer.android.com/reference/android/view/View.html#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.

| Parameters |
|---|---|
| `target: https://developer.android.com/reference/android/view/View.html` | View that initiated the nested scroll |
| `dx: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Horizontal scroll distance in pixels |
| `dy: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Vertical scroll distance in pixels |
| `consumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int-array/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html>` | Output. The horizontal and vertical scroll distance consumed by this parent |
| `type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | the type of input which cause this scroll event |

### onNestedScroll

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/core#1.1.0)

```
fun onNestedScroll(
    target: View,
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    type: Int
): 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 `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStartNestedScroll(android.view.View,android.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.

| Parameters |
|---|---|
| `target: https://developer.android.com/reference/android/view/View.html` | The descendent view controlling the nested scroll |
| `dxConsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Horizontal scroll distance in pixels already consumed by target |
| `dyConsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Vertical scroll distance in pixels already consumed by target |
| `dxUnconsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Horizontal scroll distance in pixels not consumed by target |
| `dyUnconsumed: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Vertical scroll distance in pixels not consumed by target |
| `type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | the type of input which cause this scroll event |

### onNestedScrollAccepted

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/core#1.1.0)

```
fun onNestedScrollAccepted(child: View, target: View, axes: Int, type: Int): Unit
```

React to the successful claiming of a nested scroll operation.

This method will be called after `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStartNestedScroll(android.view.View,android.view.View,int,int)` 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.

| Parameters |
|---|---|
| `child: https://developer.android.com/reference/android/view/View.html` | Direct child of this ViewParent containing target |
| `target: https://developer.android.com/reference/android/view/View.html` | View that initiated the nested scroll |
| `axes: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Flags consisting of `https://developer.android.com/reference/kotlin/androidx/core/view/ViewCompat#SCROLL_AXIS_HORIZONTAL()`, `https://developer.android.com/reference/kotlin/androidx/core/view/ViewCompat#SCROLL_AXIS_VERTICAL()` or both |
| `type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | the type of input which cause this scroll event |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStartNestedScroll(android.view.View,android.view.View,int,int)` |   |
| `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStopNestedScroll(android.view.View,int)` |   |

### onStartNestedScroll

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/core#1.1.0)

```
fun onStartNestedScroll(child: View, target: View, axes: Int, type: Int): Boolean
```

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 `https://developer.android.com/reference/kotlin/androidx/core/view/ViewCompat#startNestedScroll(android.view.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 `https://developer.android.com/reference/kotlin/androidx/core/view/NestedScrollingParent2#onStopNestedScroll(android.view.View,int)`.

| Parameters |
|---|---|
| `child: https://developer.android.com/reference/android/view/View.html` | Direct child of this ViewParent containing target |
| `target: https://developer.android.com/reference/android/view/View.html` | View that initiated the nested scroll |
| `axes: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Flags consisting of `https://developer.android.com/reference/kotlin/androidx/core/view/ViewCompat#SCROLL_AXIS_HORIZONTAL()`, `https://developer.android.com/reference/kotlin/androidx/core/view/ViewCompat#SCROLL_AXIS_VERTICAL()` or both |
| `type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | the type of input which cause this scroll event |

| Returns |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html` | true if this ViewParent accepts the nested scroll operation |

### onStopNestedScroll

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/core#1.1.0)

```
fun onStopNestedScroll(target: View, type: Int): Unit
```

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 `https://developer.android.com/reference/android/view/MotionEvent.html#ACTION_UP` or `https://developer.android.com/reference/android/view/MotionEvent.html#ACTION_CANCEL` event. Implementations of this method should always call their superclass's implementation of this method if one is present.

| Parameters |
|---|---|
| `target: https://developer.android.com/reference/android/view/View.html` | View that initiated the nested scroll |
| `type: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | the type of input which cause this scroll event |