ViewParentCompat

Artifact: androidx.core:core

View Source

Added in 1.1.0

---

Kotlin |Java

public final class ViewParentCompat

---

Helper for accessing features in ViewParent.

Summary

Public methods
static void	@ReplaceWith(expression = "parent.notifySubtreeAccessibilityStateChanged(child, source, changeType)") notifySubtreeAccessibilityStateChanged(     @NonNull ViewParent parent,     @NonNull View child,     @NonNull View source,     int changeType ) This method is deprecated. Call notifySubtreeAccessibilityStateChanged directly.
static boolean	onNestedFling(     @NonNull ViewParent parent,     @NonNull View target,     float velocityX,     float velocityY,     boolean consumed ) Request a fling from a nested scroll.
static boolean	onNestedPreFling(     @NonNull ViewParent parent,     @NonNull View target,     float velocityX,     float velocityY ) React to a nested fling before the target view consumes it.
static void	onNestedPreScroll(     @NonNull ViewParent parent,     @NonNull View target,     int dx,     int dy,     @NonNull int[] consumed ) React to a nested scroll in progress before the target view consumes a portion of the scroll.
static void	onNestedPreScroll(     @NonNull ViewParent parent,     @NonNull View target,     int dx,     int dy,     @NonNull int[] consumed,     int type ) React to a nested scroll in progress before the target view consumes a portion of the scroll.
static void	onNestedScroll(     @NonNull ViewParent parent,     @NonNull View target,     int dxConsumed,     int dyConsumed,     int dxUnconsumed,     int dyUnconsumed ) React to a nested scroll in progress.
static void	onNestedScroll(     @NonNull ViewParent parent,     @NonNull View target,     int dxConsumed,     int dyConsumed,     int dxUnconsumed,     int dyUnconsumed,     int type ) React to a nested scroll in progress.
static void	onNestedScroll(     @NonNull ViewParent parent,     @NonNull View target,     int dxConsumed,     int dyConsumed,     int dxUnconsumed,     int dyUnconsumed,     int type,     @NonNull int[] consumed ) React to a nested scroll in progress.
static void	onNestedScrollAccepted(     @NonNull ViewParent parent,     @NonNull View child,     @NonNull View target,     int nestedScrollAxes ) React to the successful claiming of a nested scroll operation.
static void	onNestedScrollAccepted(     @NonNull ViewParent parent,     @NonNull View child,     @NonNull View target,     int nestedScrollAxes,     int type ) React to the successful claiming of a nested scroll operation.
static boolean	onStartNestedScroll(     @NonNull ViewParent parent,     @NonNull View child,     @NonNull View target,     int nestedScrollAxes ) React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.
static boolean	onStartNestedScroll(     @NonNull ViewParent parent,     @NonNull View child,     @NonNull View target,     int nestedScrollAxes,     int type ) React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.
static void	onStopNestedScroll(@NonNull ViewParent parent, @NonNull View target) React to a nested scroll operation ending.
static void	onStopNestedScroll(     @NonNull ViewParent parent,     @NonNull View target,     int type ) React to a nested scroll operation ending.
static boolean	@ReplaceWith(expression = "parent.requestSendAccessibilityEvent(child, event)") requestSendAccessibilityEvent(     ViewParent parent,     View child,     AccessibilityEvent event ) This method is deprecated. Use requestSendAccessibilityEvent directly.

Public methods

notifySubtreeAccessibilityStateChanged

Added in 1.1.0

Deprecated in 1.15.0

@ReplaceWith(expression = "parent.notifySubtreeAccessibilityStateChanged(child, source, changeType)")
public static void notifySubtreeAccessibilityStateChanged(
    @NonNull ViewParent parent,
    @NonNull View child,
    @NonNull View source,
    int changeType
)

This method is deprecated.

Call notifySubtreeAccessibilityStateChanged directly.

Notifies a view parent that the accessibility state of one of its descendants has changed and that the structure of the subtree is different.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View child	The direct child whose subtree has changed.
@NonNull View source	The descendant view that changed.
int changeType	A bit mask of the types of changes that occurred. One or more of: CONTENT_CHANGE_TYPE_CONTENT_DESCRIPTION CONTENT_CHANGE_TYPE_SUBTREE CONTENT_CHANGE_TYPE_TEXT CONTENT_CHANGE_TYPE_UNDEFINED

onNestedFling

Added in 1.1.0

public static boolean onNestedFling(
    @NonNull ViewParent parent,
    @NonNull View target,
    float velocityX,
    float velocityY,
    boolean consumed
)

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.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	View that initiated the nested scroll
float velocityX	Horizontal velocity in pixels per second
float velocityY	Vertical velocity in pixels per second
boolean consumed	true if the child consumed the fling, false otherwise

Returns
boolean	true if this parent consumed or otherwise reacted to the fling

onNestedPreFling

Added in 1.1.0

public static boolean onNestedPreFling(
    @NonNull ViewParent parent,
    @NonNull View target,
    float velocityX,
    float velocityY
)

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.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	View that initiated the nested scroll
float velocityX	Horizontal velocity in pixels per second
float velocityY	Vertical velocity in pixels per second

Returns
boolean	true if this parent consumed the fling ahead of the target view

onNestedPreScroll

Added in 1.1.0

public static void onNestedPreScroll(
    @NonNull ViewParent parent,
    @NonNull View target,
    int dx,
    int dy,
    @NonNull int[] consumed
)

React to a nested scroll in progress before the target view consumes a portion of the scroll.

This version of the method just calls onNestedPreScroll using the touch input type.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	View that initiated the nested scroll
int dx	Horizontal scroll distance in pixels
int dy	Vertical scroll distance in pixels
@NonNull int[] consumed	Output. The horizontal and vertical scroll distance consumed by this parent

onNestedPreScroll

Added in 1.1.0

public static void onNestedPreScroll(
    @NonNull ViewParent parent,
    @NonNull View target,
    int dx,
    int dy,
    @NonNull int[] consumed,
    int type
)

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 dispatchNestedPreScroll. 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
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	View that initiated the nested scroll
int dx	Horizontal scroll distance in pixels
int dy	Vertical scroll distance in pixels
@NonNull int[] consumed	Output. The horizontal and vertical scroll distance consumed by this parent
int type	the type of input which cause this scroll event

onNestedScroll

Added in 1.1.0

public static void onNestedScroll(
    @NonNull ViewParent parent,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed
)

React to a nested scroll in progress.

This version of the method just calls onNestedScroll using the touch input type.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	The descendent view controlling the nested scroll
int dxConsumed	Horizontal scroll distance in pixels already consumed by target
int dyConsumed	Vertical scroll distance in pixels already consumed by target
int dxUnconsumed	Horizontal scroll distance in pixels not consumed by target
int dyUnconsumed	Vertical scroll distance in pixels not consumed by target

onNestedScroll

Added in 1.1.0

public static void onNestedScroll(
    @NonNull ViewParent parent,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int type
)

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.

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
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	The descendant view controlling the nested scroll
int dxConsumed	Horizontal scroll distance in pixels already consumed by target
int dyConsumed	Vertical scroll distance in pixels already consumed by target
int dxUnconsumed	Horizontal scroll distance in pixels not consumed by target
int dyUnconsumed	Vertical scroll distance in pixels not consumed by target
int type	the type of input which cause this scroll event

onNestedScroll

Added in 1.1.0

public static void onNestedScroll(
    @NonNull ViewParent parent,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int type,
    @NonNull int[] consumed
)

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.

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
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	The descendent view controlling the nested scroll
int dxConsumed	Horizontal scroll distance in pixels already consumed by target
int dyConsumed	Vertical scroll distance in pixels already consumed by target
int dxUnconsumed	Horizontal scroll distance in pixels not consumed by target
int dyUnconsumed	Vertical scroll distance in pixels not consumed by target
int type	the type of input which cause this scroll event
@NonNull int[] consumed	Output. If not null, 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.

onNestedScrollAccepted

Added in 1.1.0

public static void onNestedScrollAccepted(
    @NonNull ViewParent parent,
    @NonNull View child,
    @NonNull View target,
    int nestedScrollAxes
)

React to the successful claiming of a nested scroll operation.

This version of the method just calls onNestedScrollAccepted using the touch input type.

Parameters
@NonNull ViewParent parent	ViewParent that contains the child view.
@NonNull View child	Direct child of this ViewParent containing target
@NonNull View target	View that initiated the nested scroll
int nestedScrollAxes	Flags consisting of SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL or both

onNestedScrollAccepted

Added in 1.1.0

public static void onNestedScrollAccepted(
    @NonNull ViewParent parent,
    @NonNull View child,
    @NonNull View target,
    int nestedScrollAxes,
    int type
)

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.

Parameters
@NonNull ViewParent parent	ViewParent that contains the child view.
@NonNull View child	Direct child of this ViewParent containing target
@NonNull View target	View that initiated the nested scroll
int nestedScrollAxes	Flags consisting of SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL or both
int type	the type of input which cause this scroll event

See also
onStartNestedScroll
onStopNestedScroll

onStartNestedScroll

Added in 1.1.0

public static boolean onStartNestedScroll(
    @NonNull ViewParent parent,
    @NonNull View child,
    @NonNull View target,
    int nestedScrollAxes
)

React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.

This version of the method just calls onStartNestedScroll using the touch input type.

Parameters
@NonNull ViewParent parent	ViewParent that contains the child view.
@NonNull View child	Direct child of this ViewParent containing target
@NonNull View target	View that initiated the nested scroll
int nestedScrollAxes	Flags consisting of SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL or both

Returns
boolean	true if this ViewParent accepts the nested scroll operation

onStartNestedScroll

Added in 1.1.0

public static boolean onStartNestedScroll(
    @NonNull ViewParent parent,
    @NonNull View child,
    @NonNull View target,
    int nestedScrollAxes,
    int type
)

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 startNestedScroll. 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.

Parameters
@NonNull ViewParent parent	ViewParent that contains the child view.
@NonNull View child	Direct child of this ViewParent containing target
@NonNull View target	View that initiated the nested scroll
int nestedScrollAxes	Flags consisting of SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL or both
int type	the type of input which cause this scroll event

Returns
boolean	true if this ViewParent accepts the nested scroll operation

onStopNestedScroll

Added in 1.1.0

public static void onStopNestedScroll(@NonNull ViewParent parent, @NonNull View target)

React to a nested scroll operation ending.

This version of the method just calls onStopNestedScroll using the touch input type.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	View that initiated the nested scroll

onStopNestedScroll

Added in 1.1.0

public static void onStopNestedScroll(
    @NonNull ViewParent parent,
    @NonNull View target,
    int type
)

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 ACTION_UP or ACTION_CANCEL event. Implementations of this method should always call their superclass's implementation of this method if one is present.

Parameters
@NonNull ViewParent parent	ViewParent that contains the target view.
@NonNull View target	View that initiated the nested scroll
int type	the type of input which cause this scroll event

requestSendAccessibilityEvent

Added in 1.1.0

Deprecated in 1.1.0

@ReplaceWith(expression = "parent.requestSendAccessibilityEvent(child, event)")
public static boolean requestSendAccessibilityEvent(
    ViewParent parent,
    View child,
    AccessibilityEvent event
)

This method is deprecated.

Use requestSendAccessibilityEvent directly.

Called by a child to request from its parent to send an AccessibilityEvent. The child has already populated a record for itself in the event and is delegating to its parent to send the event. The parent can optionally add a record for itself.

Note: An accessibility event is fired by an individual view which populates the event with a record for its state and requests from its parent to perform the sending. The parent can optionally add a record for itself before dispatching the request to its parent. A parent can also choose not to respect the request for sending the event. The accessibility event is sent by the topmost view in the view tree.

Parameters
ViewParent parent	The parent whose method to invoke.
View child	The child which requests sending the event.
AccessibilityEvent event	The event to be sent.

Returns
boolean	True if the event was sent.