Summary: Ctors | Methods | Inherited Methods

NestedScrollingChildHelper

Kotlin |Java

public class NestedScrollingChildHelper
extends Object

java.lang.Object
↳	androidx.core.view.NestedScrollingChildHelper

---

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

View subclasses should instantiate a final instance of this class as a field at construction. For each View 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 ViewCompat, ViewGroupCompat or ViewParentCompat compatibility shim static methods. This ensures interoperability with nested scrolling views on Android 5.0 Lollipop and newer.

Summary

Public constructors
NestedScrollingChildHelper(View view) Construct a new helper for a given view.

Public methods
boolean	dispatchNestedFling(float velocityX, float velocityY, boolean consumed) Dispatch a nested fling operation to the current nested scrolling parent.
boolean	dispatchNestedPreFling(float velocityX, float velocityY) Dispatch a nested pre-fling operation to the current nested scrolling parent.
boolean	dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent.
boolean	dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow, int type) Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent.
void	dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow, int type, int[] consumed) Dispatch one step of a nested scrolling operation to the current nested scrolling parent.
boolean	dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow, int type) Dispatch one step of a nested scrolling operation to the current nested scrolling parent.
boolean	dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow) Dispatch one step of a nested scrolling operation to the current nested scrolling parent.
boolean	hasNestedScrollingParent() Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the type of touch.
boolean	hasNestedScrollingParent(int type) Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the given type.
boolean	isNestedScrollingEnabled() Check if nested scrolling is enabled for this view.
void	onDetachedFromWindow() View subclasses should always call this method on their NestedScrollingChildHelper when detached from a window.
void	onStopNestedScroll(View child) Called when a nested scrolling child stops its current nested scroll operation.
void	setNestedScrollingEnabled(boolean enabled) Enable nested scrolling.
boolean	startNestedScroll(int axes) Start a new nested scroll for this view.
boolean	startNestedScroll(int axes, int type) Start a new nested scroll for this view.
void	stopNestedScroll() Stop a nested scroll in progress.
void	stopNestedScroll(int type) Stop a nested scroll in progress.

Inherited methods
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait(long arg0, int arg1) final void wait(long arg0) final void wait()

Public constructors

NestedScrollingChildHelper

public NestedScrollingChildHelper (View view)

Construct a new helper for a given view.

Parameters
view	View

Public methods

dispatchNestedFling

public boolean dispatchNestedFling (float velocityX, 
                float velocityY, 
                boolean consumed)

Dispatch a nested fling operation to the current nested scrolling parent.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
velocityX	float
velocityY	float
consumed	boolean

Returns
boolean	true if the parent consumed the nested fling

dispatchNestedPreFling

public boolean dispatchNestedPreFling (float velocityX, 
                float velocityY)

Dispatch a nested pre-fling operation to the current nested scrolling parent.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
velocityX	float
velocityY	float

Returns
boolean	true if the parent consumed the nested fling

dispatchNestedPreScroll

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

Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
dx	int
dy	int
consumed	int
offsetInWindow	int

Returns
boolean	true if the parent consumed any of the nested scroll

dispatchNestedPreScroll

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

Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild2 interface method with the same signature to implement the standard policy.

Parameters
dx	int
dy	int
consumed	int
offsetInWindow	int
type	int

Returns
boolean	true if the parent consumed any of the nested scroll

dispatchNestedScroll

public void dispatchNestedScroll (int dxConsumed, 
                int dyConsumed, 
                int dxUnconsumed, 
                int dyUnconsumed, 
                int[] offsetInWindow, 
                int type, 
                int[] consumed)

Dispatch one step of a nested scrolling operation to the current nested scrolling parent.

This is a delegate method. Call it from your NestedScrollingChild3 interface method with the same signature to implement the standard policy.

Parameters
dxConsumed	int
dyConsumed	int
dxUnconsumed	int
dyUnconsumed	int
offsetInWindow	int
type	int
consumed	int

dispatchNestedScroll

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

Dispatch one step of a nested scrolling operation to the current nested scrolling parent.

This is a delegate method. Call it from your NestedScrollingChild2 interface method with the same signature to implement the standard policy.

Parameters
dxConsumed	int
dyConsumed	int
dxUnconsumed	int
dyUnconsumed	int
offsetInWindow	int
type	int

Returns
boolean	true if the parent consumed any of the nested scroll distance

dispatchNestedScroll

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

Dispatch one step of a nested scrolling operation to the current nested scrolling parent.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
dxConsumed	int
dyConsumed	int
dxUnconsumed	int
dyUnconsumed	int
offsetInWindow	int

Returns
boolean	true if the parent consumed any of the nested scroll distance

hasNestedScrollingParent

public boolean hasNestedScrollingParent ()

Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the type of touch.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Returns
boolean	true if this view has a nested scrolling parent, false otherwise

hasNestedScrollingParent

public boolean hasNestedScrollingParent (int type)

Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the given type.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
type	int

Returns
boolean	true if this view has a nested scrolling parent, false otherwise

isNestedScrollingEnabled

public boolean isNestedScrollingEnabled ()

Check if nested scrolling is enabled for this view.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Returns
boolean	true if nested scrolling is enabled for this view

onDetachedFromWindow

public void onDetachedFromWindow ()

View subclasses should always call this method on their NestedScrollingChildHelper when detached from a window.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

onStopNestedScroll

public void onStopNestedScroll (View child)

Called when a nested scrolling child stops its current nested scroll operation.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
child	View: Child view stopping its nested scroll. This may not be a direct child view.

setNestedScrollingEnabled

public void setNestedScrollingEnabled (boolean enabled)

Enable nested scrolling.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
enabled	boolean: true to enable nested scrolling dispatch from this view, false otherwise

startNestedScroll

public boolean startNestedScroll (int axes)

Start a new nested scroll for this view.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

Parameters
axes	int: Supported nested scroll axes. See NestedScrollingChild.startNestedScroll(int).

Returns
boolean	true if a cooperating parent view was found and nested scrolling started successfully

startNestedScroll

public boolean startNestedScroll (int axes, 
                int type)

Start a new nested scroll for this view.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild2 interface method with the same signature to implement the standard policy.

Parameters
axes	int: Supported nested scroll axes. See NestedScrollingChild2.startNestedScroll(int, int).
type	int

Returns
boolean	true if a cooperating parent view was found and nested scrolling started successfully

stopNestedScroll

public void stopNestedScroll ()

Stop a nested scroll in progress.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild interface method with the same signature to implement the standard policy.

stopNestedScroll

public void stopNestedScroll (int type)

Stop a nested scroll in progress.

This is a delegate method. Call it from your View subclass method/NestedScrollingChild2 interface method with the same signature to implement the standard policy.

Parameters
type	int

• Interfaces

  • ActionProvider.VisibilityListener
  • DragStartHelper.OnDragStartListener
  • LayoutInflaterFactory
  • MenuItemCompat.OnActionExpandListener
  • NestedScrollingChild
  • NestedScrollingChild2
  • NestedScrollingChild3
  • NestedScrollingParent
  • NestedScrollingParent2
  • NestedScrollingParent3
  • OnApplyWindowInsetsListener
  • ScrollingView
  • TintableBackgroundView
  • ViewCompat.OnUnhandledKeyEventListenerCompat
  • ViewPropertyAnimatorListener
  • ViewPropertyAnimatorUpdateListener

• Classes

  • AccessibilityDelegateCompat
  • ActionProvider
  • DisplayCutoutCompat
  • DragAndDropPermissionsCompat
  • DragStartHelper
  • GestureDetectorCompat
  • GravityCompat
  • InputDeviceCompat
  • LayoutInflaterCompat
  • MarginLayoutParamsCompat
  • MenuCompat
  • MenuItemCompat
  • MotionEventCompat
  • NestedScrollingChildHelper
  • NestedScrollingParentHelper
  • OneShotPreDrawListener
  • PointerIconCompat
  • ScaleGestureDetectorCompat
  • VelocityTrackerCompat
  • ViewCompat
  • ViewConfigurationCompat
  • ViewGroupCompat
  • ViewParentCompat
  • ViewPropertyAnimatorCompat
  • ViewPropertyAnimatorListenerAdapter
  • WindowCompat
  • WindowInsetsCompat