NestedScrollingChildHelper

Added in 1.1.0

class 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 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 view.

Public functions

Boolean
dispatchNestedFling(velocityX: Float, velocityY: Float, consumed: Boolean)

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

Boolean
dispatchNestedPreFling(velocityX: Float, velocityY: Float)

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

Boolean
dispatchNestedPreScroll(
    dx: Int,
    dy: Int,
    consumed: IntArray?,
    offsetInWindow: IntArray?
)

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

Boolean
dispatchNestedPreScroll(
    dx: Int,
    dy: Int,
    consumed: IntArray?,
    offsetInWindow: IntArray?,
    type: Int
)

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

Boolean
dispatchNestedScroll(
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    offsetInWindow: IntArray?
)

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

Boolean
dispatchNestedScroll(
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    offsetInWindow: IntArray?,
    type: Int
)

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

Unit
dispatchNestedScroll(
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    offsetInWindow: IntArray?,
    type: Int,
    consumed: IntArray?
)

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

Boolean

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

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

Boolean

Check if nested scrolling is enabled for this view.

Unit

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

Unit

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

Unit

Enable nested scrolling.

Boolean

Start a new nested scroll for this view.

Boolean
startNestedScroll(axes: Int, type: Int)

Start a new nested scroll for this view.

Unit

Stop a nested scroll in progress.

Unit

Stop a nested scroll in progress.

Public constructors

NestedScrollingChildHelper

Added in 1.1.0
NestedScrollingChildHelper(view: View)

Construct a new helper for a given view.

Public functions

dispatchNestedFling

Added in 1.1.0
fun dispatchNestedFling(velocityX: Float, velocityY: Float, consumed: Boolean): Boolean

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

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

Returns
Boolean

true if the parent consumed the nested fling

dispatchNestedPreFling

Added in 1.1.0
fun dispatchNestedPreFling(velocityX: Float, velocityY: Float): Boolean

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

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

Returns
Boolean

true if the parent consumed the nested fling

dispatchNestedPreScroll

Added in 1.1.0
fun dispatchNestedPreScroll(
    dx: Int,
    dy: Int,
    consumed: IntArray?,
    offsetInWindow: IntArray?
): Boolean

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/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.

Returns
Boolean

true if the parent consumed any of the nested scroll

dispatchNestedPreScroll

Added in 1.1.0
fun dispatchNestedPreScroll(
    dx: Int,
    dy: Int,
    consumed: IntArray?,
    offsetInWindow: IntArray?,
    type: Int
): Boolean

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/androidx.core.view.NestedScrollingChild2 interface method with the same signature to implement the standard policy.

Returns
Boolean

true if the parent consumed any of the nested scroll

dispatchNestedScroll

Added in 1.1.0
fun dispatchNestedScroll(
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    offsetInWindow: IntArray?
): Boolean

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/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.

Returns
Boolean

true if the parent consumed any of the nested scroll distance

dispatchNestedScroll

Added in 1.1.0
fun dispatchNestedScroll(
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    offsetInWindow: IntArray?,
    type: Int
): Boolean

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.

Returns
Boolean

true if the parent consumed any of the nested scroll distance

dispatchNestedScroll

Added in 1.1.0
fun dispatchNestedScroll(
    dxConsumed: Int,
    dyConsumed: Int,
    dxUnconsumed: Int,
    dyUnconsumed: Int,
    offsetInWindow: IntArray?,
    type: Int,
    consumed: IntArray?
): Unit

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.

hasNestedScrollingParent

Added in 1.1.0
fun hasNestedScrollingParent(): Boolean

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/androidx.core.view.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

Added in 1.1.0
fun hasNestedScrollingParent(type: Int): Boolean

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/androidx.core.view.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

isNestedScrollingEnabled

Added in 1.1.0
fun isNestedScrollingEnabled(): Boolean

Check if nested scrolling is enabled for this view.

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

Returns
Boolean

true if nested scrolling is enabled for this view

onDetachedFromWindow

Added in 1.1.0
fun onDetachedFromWindow(): Unit

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/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.

onStopNestedScroll

Added in 1.1.0
fun onStopNestedScroll(child: View): Unit

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

This is a delegate method. Call it from your View subclass method/androidx.core.view.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

Added in 1.1.0
fun setNestedScrollingEnabled(enabled: Boolean): Unit

Enable nested scrolling.

This is a delegate method. Call it from your View subclass method/androidx.core.view.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

Added in 1.1.0
fun startNestedScroll(axes: Int): Boolean

Start a new nested scroll for this view.

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

Parameters
axes: Int

Supported nested scroll axes. See startNestedScroll.

Returns
Boolean

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

startNestedScroll

Added in 1.1.0
fun startNestedScroll(axes: Int, type: Int): Boolean

Start a new nested scroll for this view.

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

Parameters
axes: Int

Supported nested scroll axes. See startNestedScroll.

type: Int

type of the scroll.

Returns
Boolean

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

stopNestedScroll

Added in 1.1.0
fun stopNestedScroll(): Unit

Stop a nested scroll in progress.

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

stopNestedScroll

Added in 1.1.0
fun stopNestedScroll(type: Int): Unit

Stop a nested scroll in progress.

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