Added in API level 1

ViewParent

---

Kotlin |Java

interface ViewParent

android.view.ViewParent

Known Direct Subclasses ViewGroup ViewGroup A ViewGroup is a special view that can contain other views (called children.) The view group is the base class for layouts and views containers.

Known Indirect Subclasses AbsListView, AbsSpinner, AbsoluteLayout, ActionMenuView, AdapterView, AdapterViewAnimator, AdapterViewFlipper, AppWidgetHostView, CalendarView, DatePicker, DialerFilter, ExpandableListView, and 36 others. AbsListView Base class that can be used to implement virtualized lists of items. AbsSpinner An abstract base class for spinner widgets. AbsoluteLayout A layout that lets you specify exact locations (x/y coordinates) of its children. ActionMenuView ActionMenuView is a presentation of a series of menu options as a View. AdapterView An AdapterView is a view whose children are determined by an Adapter. AdapterViewAnimator Base class for a AdapterView that will perform animations when switching between its views. AdapterViewFlipper Simple ViewAnimator that will animate between two or more views that have been added to it. AppWidgetHostView Provides the glue to show AppWidget views. CalendarView This class is a calendar widget for displaying and selecting dates. DatePicker Provides a widget for selecting a date. DialerFilter This widget is a layout that contains several specifically-named child views that handle keyboard entry interpreted as standard phone dialpad digits. ExpandableListView A view that shows items in a vertically scrolling two-level list. FragmentBreadCrumbs Helper class for showing "bread crumbs" representing the fragment stack in an activity. FrameLayout FrameLayout is designed to block out an area on the screen to display a single item. Gallery A view that shows items in a center-locked, horizontally scrolling list. GestureOverlayView A transparent overlay for gesture input that can be placed on top of other widgets or contain other widgets. GridLayout A layout that places its children in a rectangular grid. GridView A view that shows items in two-dimensional scrolling grid. HorizontalScrollView Layout container for a view hierarchy that can be scrolled by the user, allowing it to be larger than the physical display. ImageSwitcher ViewSwitcher that switches between two ImageViews when a new image is set on it. InlineContentView This class represents a view that holds opaque content from another app that you can inline in your UI. LinearLayout A layout that arranges other views either horizontally in a single column or vertically in a single row. ListView Displays a vertically-scrollable collection of views, where each view is positioned immediatelybelow the previous view in the list. MediaController A view containing controls for a MediaPlayer. NumberPicker A widget that enables the user to select a number from a predefined range. RadioGroup This class is used to create a multiple-exclusion scope for a set of radio buttons. RelativeLayout A Layout where the positions of the children can be described in relation to each other or to the parent. ScrollView A view group that allows the view hierarchy placed within it to be scrolled. SearchView A widget that provides a user interface for the user to enter a search query and submit a request to a search provider. SlidingDrawer SlidingDrawer hides content out of the screen and allows the user to drag a handle to bring the content on screen. Spinner A view that displays one child at a time and lets the user pick among them. SplashScreenView The view which allows an activity to customize its splash screen exit animation. StackView TabHost Container for a tabbed window view. TabWidget Displays a list of tab labels representing each page in the parent's tab collection. TableLayout A layout that arranges its children into rows and columns. TableRow A layout that arranges its children horizontally. TextSwitcher Specialized android.widget.ViewSwitcher that contains only children of type android.widget.TextView. TimePicker A widget for selecting the time of day, in either 24-hour or AM/PM mode. Toolbar A standard toolbar for use within application content. TvInteractiveAppView Displays contents of interactive TV applications. TvView Displays TV contents. TwoLineListItem A view group with two children, intended for use in ListViews. ViewAnimator Base class for a FrameLayout container that will perform animations when switching between its views. ViewFlipper Simple ViewAnimator that will animate between two or more views that have been added to it. ViewSwitcher ViewAnimator that switches between two views, and has a factory from which these views are created. WebView A View that displays web pages. ZoomControls The ZoomControls class displays a simple set of controls used for zooming and provides callbacks to register for events.

Defines the responsibilities for a class that will be a parent of a View. This is the API that a view sees when it wants to interact with its parent.

Summary

Public methods
abstract Unit	bringChildToFront(child: View!) Change the z order of the child so it's on top of all other children.
abstract Boolean	canResolveLayoutDirection() Tells if this view parent can resolve the layout direction.
abstract Boolean	canResolveTextAlignment() Tells if this view parent can resolve the text alignment.
abstract Boolean	canResolveTextDirection() Tells if this view parent can resolve the text direction.
abstract Unit	childDrawableStateChanged(child: View) This method is called on the parent when a child's drawable state has changed.
abstract Unit	childHasTransientStateChanged(child: View, hasTransientState: Boolean) Called when a child view now has or no longer is tracking transient state.
abstract Unit	clearChildFocus(child: View!) Called when a child of this parent is giving up focus
abstract Unit	createContextMenu(menu: ContextMenu!) Have the parent populate the specified context menu if it has anything to add (and then recurse on its parent).
open OnBackInvokedDispatcher?	findOnBackInvokedDispatcherForChild(child: View, requester: View) Walk up the View hierarchy to find the nearest OnBackInvokedDispatcher.
abstract View!	focusSearch(v: View!, direction: Int) Find the nearest view in the specified direction that wants to take focus
abstract Unit	focusableViewAvailable(v: View!) Tells the parent that a new focusable view has become available.
abstract Boolean	getChildVisibleRect(child: View!, r: Rect!, offset: Point!) Compute the visible part of a rectangular region defined in terms of a child view's coordinates.
abstract Int	getLayoutDirection() Return this view parent layout direction.
abstract ViewParent!	getParent() Returns the parent if it exists, or null.
abstract ViewParent!	getParentForAccessibility() Gets the parent of a given View for accessibility.
abstract Int	getTextAlignment() Return this view parent text alignment.
abstract Int	getTextDirection() Return this view parent text direction.
abstract Unit	invalidateChild(child: View!, r: Rect!) All or part of a child is dirty and needs to be redrawn.
abstract ViewParent!	invalidateChildInParent(location: IntArray!, r: Rect!) All or part of a child is dirty and needs to be redrawn.
abstract Boolean	isLayoutDirectionResolved() Tells if this view parent layout direction is resolved.
abstract Boolean	isLayoutRequested() Indicates whether layout was requested on this view parent.
abstract Boolean	isTextAlignmentResolved() Tells if this view parent text alignment is resolved.
abstract Boolean	isTextDirectionResolved() Tells if this view parent text direction is resolved.
abstract View!	keyboardNavigationClusterSearch(currentCluster: View!, direction: Int) Find the nearest keyboard navigation cluster in the specified direction.
abstract Unit	notifySubtreeAccessibilityStateChanged(child: View, source: View, changeType: Int) Notifies a view parent that the accessibility state of one of its descendants has changed and that the structure of the subtree is different.
open Unit	onDescendantInvalidated(child: View, target: View) The target View has been invalidated, or has had a drawing property changed that requires the hierarchy to re-render.
abstract Boolean	onNestedFling(target: View, velocityX: Float, velocityY: Float, consumed: Boolean) Request a fling from a nested scroll.
abstract Boolean	onNestedPreFling(target: View, velocityX: Float, velocityY: Float) React to a nested fling before the target view consumes it.
abstract Boolean	onNestedPrePerformAccessibilityAction(target: View, action: Int, arguments: Bundle?) React to an accessibility action delegated by a target descendant view before the target processes it.
abstract Unit	onNestedPreScroll(target: View, dx: Int, dy: Int, consumed: IntArray) React to a nested scroll in progress before the target view consumes a portion of the scroll.
abstract Unit	onNestedScroll(target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int) React to a nested scroll in progress.
abstract Unit	onNestedScrollAccepted(child: View, target: View, nestedScrollAxes: Int) React to the successful claiming of a nested scroll operation.
abstract Boolean	onStartNestedScroll(child: View, target: View, nestedScrollAxes: Int) React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.
abstract Unit	onStopNestedScroll(target: View) React to a nested scroll operation ending.
abstract Unit	recomputeViewAttributes(child: View!) Tell view hierarchy that the global view attributes need to be re-evaluated.
abstract Unit	requestChildFocus(child: View!, focused: View!) Called when a child of this parent wants focus
abstract Boolean	requestChildRectangleOnScreen(child: View, rectangle: Rect!, immediate: Boolean) Called when a child of this group wants a particular rectangle to be positioned onto the screen.
abstract Unit	requestDisallowInterceptTouchEvent(disallowIntercept: Boolean) Called when a child does not want this parent and its ancestors to intercept touch events with ViewGroup#onInterceptTouchEvent(MotionEvent).
abstract Unit	requestFitSystemWindows() Ask that a new dispatch of View.fitSystemWindows(Rect) be performed.
abstract Unit	requestLayout() Called when something has changed which has invalidated the layout of a child of this view parent.
abstract Boolean	requestSendAccessibilityEvent(child: View, event: AccessibilityEvent!) Called by a child to request from its parent to send an AccessibilityEvent.
abstract Unit	requestTransparentRegion(child: View!) Called when a child wants the view hierarchy to gather and report transparent regions to the window compositor.
abstract Boolean	showContextMenuForChild(originalView: View!) Shows the context menu for the specified view or its ancestors.
abstract Boolean	showContextMenuForChild(originalView: View!, x: Float, y: Float) Shows the context menu for the specified view or its ancestors anchored to the specified view-relative coordinate.
abstract ActionMode!	startActionModeForChild(originalView: View!, callback: ActionMode.Callback!) Start an action mode for the specified view with the default type ActionMode#TYPE_PRIMARY.
abstract ActionMode!	startActionModeForChild(originalView: View!, callback: ActionMode.Callback!, type: Int) Start an action mode of a specific type for the specified view.

Public methods

bringChildToFront

Added in API level 1

abstract fun bringChildToFront(child: View!): Unit

Change the z order of the child so it's on top of all other children. This ordering change may affect layout, if this container uses an order-dependent layout scheme (e.g., LinearLayout). Prior to android.os.Build.VERSION_CODES#KITKAT this method should be followed by calls to requestLayout() and View#invalidate() on this parent to force the parent to redraw with the new child ordering.

Parameters
child	View!: The child to bring to the top of the z order

canResolveLayoutDirection

Added in API level 19

abstract fun canResolveLayoutDirection(): Boolean

Tells if this view parent can resolve the layout direction. See View#setLayoutDirection(int)

Return
Boolean	True if this view parent can resolve the layout direction.

canResolveTextAlignment

Added in API level 19

abstract fun canResolveTextAlignment(): Boolean

Tells if this view parent can resolve the text alignment. See View#setTextAlignment(int)

Return
Boolean	True if this view parent can resolve the text alignment.

canResolveTextDirection

Added in API level 19

abstract fun canResolveTextDirection(): Boolean

Tells if this view parent can resolve the text direction. See View#setTextDirection(int)

Return
Boolean	True if this view parent can resolve the text direction.

childDrawableStateChanged

Added in API level 1

abstract fun childDrawableStateChanged(child: View): Unit

This method is called on the parent when a child's drawable state has changed.

Parameters
child	View: The child whose drawable state has changed. This value cannot be null.

childHasTransientStateChanged

Added in API level 19

abstract fun childHasTransientStateChanged(
    child: View, 
    hasTransientState: Boolean
): Unit

Called when a child view now has or no longer is tracking transient state.

"Transient state" is any state that a View might hold that is not expected to be reflected in the data model that the View currently presents. This state only affects the presentation to the user within the View itself, such as the current state of animations in progress or the state of a text selection operation.

Transient state is useful for hinting to other components of the View system that a particular view is tracking something complex but encapsulated. A ListView for example may acknowledge that list item Views with transient state should be preserved within their position or stable item ID instead of treating that view as trivially replaceable by the backing adapter. This allows adapter implementations to be simpler instead of needing to track the state of item view animations in progress such that they could be restored in the event of an unexpected recycling and rebinding of attached item views.

This method is called on a parent view when a child view or a view within its subtree begins or ends tracking of internal transient state.

Parameters
child	View: Child view whose state has changed This value cannot be null.
hasTransientState	Boolean: true if this child has transient state

clearChildFocus

Added in API level 1

abstract fun clearChildFocus(child: View!): Unit

Called when a child of this parent is giving up focus

Parameters
child	View!: The view that is giving up focus

createContextMenu

Added in API level 1

abstract fun createContextMenu(menu: ContextMenu!): Unit

Have the parent populate the specified context menu if it has anything to add (and then recurse on its parent).

Parameters
menu	ContextMenu!: The menu to populate

findOnBackInvokedDispatcherForChild

Added in API level 33

open fun findOnBackInvokedDispatcherForChild(
    child: View, 
    requester: View
): OnBackInvokedDispatcher?

Walk up the View hierarchy to find the nearest OnBackInvokedDispatcher.

Parameters
child	View: The direct child of this view for which to find a dispatcher. This value cannot be null.
requester	View: The requester that will use the dispatcher. Can be the same as child. This value cannot be null.

Return
OnBackInvokedDispatcher?	The OnBackInvokedDispatcher from this or the nearest ancestor, or null if the view is both not attached and have no ancestor providing an OnBackInvokedDispatcher.

focusSearch

Added in API level 1

abstract fun focusSearch(
    v: View!, 
    direction: Int
): View!

Find the nearest view in the specified direction that wants to take focus

Parameters
v	View!: The view that currently has focus
direction	Int: One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT

focusableViewAvailable

Added in API level 1

abstract fun focusableViewAvailable(v: View!): Unit

Tells the parent that a new focusable view has become available. This is to handle transitions from the case where there are no focusable views to the case where the first focusable view appears.

Parameters
v	View!: The view that has become newly focusable

getChildVisibleRect

Added in API level 1

abstract fun getChildVisibleRect(
    child: View!, 
    r: Rect!, 
    offset: Point!
): Boolean

Compute the visible part of a rectangular region defined in terms of a child view's coordinates.

Returns the clipped visible part of the rectangle r, defined in the child's local coordinate system. r is modified by this method to contain the result, expressed in the global (root) coordinate system.

The resulting rectangle is always axis aligned. If a rotation is applied to a node in the View hierarchy, the result is the axis-aligned bounding box of the visible rectangle.

Parameters
child	View!: A child View, whose rectangular visible region we want to compute
r	Rect!: The input rectangle, defined in the child coordinate system. Will be overwritten to contain the resulting visible rectangle, expressed in global (root) coordinates
offset	Point!: The input coordinates of a point, defined in the child coordinate system. As with the r parameter, this will be overwritten to contain the global (root) coordinates of that point. A null value is valid (in case you are not interested in this result)

Return
Boolean	true if the resulting rectangle is not empty, false otherwise

getLayoutDirection

Added in API level 19

abstract fun getLayoutDirection(): Int

Return this view parent layout direction. See View#getLayoutDirection()

Return
Int	View#LAYOUT_DIRECTION_RTL if the layout direction is RTL or returns View#LAYOUT_DIRECTION_LTR if the layout direction is not RTL.

getParent

Added in API level 1

abstract fun getParent(): ViewParent!

Returns the parent if it exists, or null.

Return
ViewParent!	a ViewParent or null if this ViewParent does not have a parent

getParentForAccessibility

Added in API level 16

abstract fun getParentForAccessibility(): ViewParent!

Gets the parent of a given View for accessibility. Since some Views are not exposed to the accessibility layer the parent for accessibility is not necessarily the direct parent of the View, rather it is a predecessor.

Return
ViewParent!	The parent or null if no such is found.

getTextAlignment

Added in API level 19

abstract fun getTextAlignment(): Int

Return this view parent text alignment. See android.view.View#getTextAlignment()

Return
Int	the resolved text alignment. Returns one of: View#TEXT_ALIGNMENT_GRAVITY, View#TEXT_ALIGNMENT_CENTER, View#TEXT_ALIGNMENT_TEXT_START, View#TEXT_ALIGNMENT_TEXT_END, View#TEXT_ALIGNMENT_VIEW_START, View#TEXT_ALIGNMENT_VIEW_END

getTextDirection

Added in API level 19

abstract fun getTextDirection(): Int

Return this view parent text direction. See View#getTextDirection()

Return
Int	the resolved text direction. Returns one of: View#TEXT_DIRECTION_FIRST_STRONG View#TEXT_DIRECTION_ANY_RTL, View#TEXT_DIRECTION_LTR, View#TEXT_DIRECTION_RTL, View#TEXT_DIRECTION_LOCALE

invalidateChild

Added in API level 1
Deprecated in API level 26

abstract fun invalidateChild(
    child: View!, 
    r: Rect!
): Unit

Deprecated: Use onDescendantInvalidated(android.view.View,android.view.View) instead.

All or part of a child is dirty and needs to be redrawn.

Parameters
child	View!: The child which is dirty
r	Rect!: The area within the child that is invalid

invalidateChildInParent

Added in API level 1
Deprecated in API level 26

abstract fun invalidateChildInParent(
    location: IntArray!, 
    r: Rect!
): ViewParent!

Deprecated: Use onDescendantInvalidated(android.view.View,android.view.View) instead.

All or part of a child is dirty and needs to be redrawn.

The location array is an array of two int values which respectively define the left and the top position of the dirty child.

This method must return the parent of this ViewParent if the specified rectangle must be invalidated in the parent. If the specified rectangle does not require invalidation in the parent or if the parent does not exist, this method must return null.

When this method returns a non-null value, the location array must have been updated with the left and top coordinates of this ViewParent.

Parameters
location	IntArray!: An array of 2 ints containing the left and top coordinates of the child to invalidate
r	Rect!: The area within the child that is invalid

Return
ViewParent!	the parent of this ViewParent or null

isLayoutDirectionResolved

Added in API level 19

abstract fun isLayoutDirectionResolved(): Boolean

Tells if this view parent layout direction is resolved. See View#setLayoutDirection(int)

Return
Boolean	True if this view parent layout direction is resolved.

isLayoutRequested

Added in API level 1

abstract fun isLayoutRequested(): Boolean

Indicates whether layout was requested on this view parent.

Return
Boolean	true if layout was requested, false otherwise

isTextAlignmentResolved

Added in API level 19

abstract fun isTextAlignmentResolved(): Boolean

Tells if this view parent text alignment is resolved. See View#setTextAlignment(int)

Return
Boolean	True if this view parent text alignment is resolved.

isTextDirectionResolved

Added in API level 19

abstract fun isTextDirectionResolved(): Boolean

Tells if this view parent text direction is resolved. See View#setTextDirection(int)

Return
Boolean	True if this view parent text direction is resolved.

keyboardNavigationClusterSearch

Added in API level 26

abstract fun keyboardNavigationClusterSearch(
    currentCluster: View!, 
    direction: Int
): View!

Find the nearest keyboard navigation cluster in the specified direction. This does not actually give focus to that cluster.

Parameters
currentCluster	View!: The starting point of the search. Null means the current cluster is not found yet
direction	Int: Direction to look

Return
View!	The nearest keyboard navigation cluster in the specified direction, or null if none can be found

notifySubtreeAccessibilityStateChanged

Added in API level 19

abstract fun notifySubtreeAccessibilityStateChanged(
    child: View, 
    source: View, 
    changeType: Int
): Unit

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
child	View: The direct child whose subtree has changed. This value cannot be null.
source	View: The descendant view that changed. May not be null.
changeType	Int: A bit mask of the types of changes that occurred. One or more of: AccessibilityEvent#CONTENT_CHANGE_TYPE_CONTENT_DESCRIPTION AccessibilityEvent#CONTENT_CHANGE_TYPE_STATE_DESCRIPTION AccessibilityEvent#CONTENT_CHANGE_TYPE_SUBTREE AccessibilityEvent#CONTENT_CHANGE_TYPE_TEXT AccessibilityEvent#CONTENT_CHANGE_TYPE_UNDEFINED AccessibilityEvent#CONTENT_CHANGE_TYPE_DRAG_STARTED AccessibilityEvent#CONTENT_CHANGE_TYPE_DRAG_CANCELLED AccessibilityEvent#CONTENT_CHANGE_TYPE_DRAG_DROPPED

onDescendantInvalidated

Added in API level 26

open fun onDescendantInvalidated(
    child: View, 
    target: View
): Unit

The target View has been invalidated, or has had a drawing property changed that requires the hierarchy to re-render. This method is called by the View hierarchy to signal ancestors that a View either needs to re-record its drawing commands, or drawing properties have changed. This is how Views schedule a drawing traversal. This signal is generally only dispatched for attached Views, since only they need to draw.

Parameters
child	View: Direct child of this ViewParent containing target This value cannot be null.
target	View: The view that needs to redraw This value cannot be null.

onNestedFling

Added in API level 21

abstract fun onNestedFling(
    target: View, 
    velocityX: Float, 
    velocityY: Float, 
    consumed: Boolean
): 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.

Parameters
target	View: View that initiated the nested scroll This value cannot be null.
velocityX	Float: Horizontal velocity in pixels per second
velocityY	Float: Vertical velocity in pixels per second
consumed	Boolean: true if the child consumed the fling, false otherwise

Return
Boolean	true if this parent consumed or otherwise reacted to the fling

onNestedPreFling

Added in API level 21

abstract fun onNestedPreFling(
    target: View, 
    velocityX: Float, 
    velocityY: Float
): Boolean

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
target	View: View that initiated the nested scroll This value cannot be null.
velocityX	Float: Horizontal velocity in pixels per second
velocityY	Float: Vertical velocity in pixels per second

Return
Boolean	true if this parent consumed the fling ahead of the target view

onNestedPrePerformAccessibilityAction

Added in API level 22

abstract fun onNestedPrePerformAccessibilityAction(
    target: View, 
    action: Int, 
    arguments: Bundle?
): Boolean

React to an accessibility action delegated by a target descendant view before the target processes it.

This method may be called by a target descendant view if the target wishes to give a view in its parent chain a chance to react to the event before normal processing occurs. Most commonly this will be a scroll event such as android.view.accessibility.AccessibilityNodeInfo#ACTION_SCROLL_FORWARD. A ViewParent that supports acting as a nested scrolling parent should override this method and act accordingly to implement scrolling via accesibility systems.

Parameters
target	View: The target view dispatching this action This value cannot be null.
action	Int: Action being performed; see android.view.accessibility.AccessibilityNodeInfo
arguments	Bundle?: Optional action arguments This value may be null.

Return
Boolean	true if the action was consumed by this ViewParent

onNestedPreScroll

Added in API level 21

abstract fun onNestedPreScroll(
    target: View, 
    dx: Int, 
    dy: Int, 
    consumed: IntArray
): 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 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.

Parameters
target	View: View that initiated the nested scroll This value cannot be null.
dx	Int: Horizontal scroll distance in pixels
dy	Int: Vertical scroll distance in pixels
consumed	IntArray: Output. The horizontal and vertical scroll distance consumed by this parent This value cannot be null.

onNestedScroll

Added in API level 21

abstract fun onNestedScroll(
    target: View, 
    dxConsumed: Int, 
    dyConsumed: Int, 
    dxUnconsumed: Int, 
    dyUnconsumed: 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 onStartNestedScroll(android.view.View,android.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.

Parameters
target	View: The descendent view controlling the nested scroll This value cannot be null.
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

onNestedScrollAccepted

Added in API level 21

abstract fun onNestedScrollAccepted(
    child: View, 
    target: View, 
    nestedScrollAxes: Int
): Unit

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
child	View: Direct child of this ViewParent containing target This value cannot be null.
target	View: View that initiated the nested scroll This value cannot be null.
nestedScrollAxes	Int: Flags consisting of View#SCROLL_AXIS_HORIZONTAL, View#SCROLL_AXIS_VERTICAL or both

See Also

• #onStartNestedScroll(View, View, int)
• #onStopNestedScroll(View)

onStartNestedScroll

Added in API level 21

abstract fun onStartNestedScroll(
    child: View, 
    target: View, 
    nestedScrollAxes: 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 View#startNestedScroll(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(android.view.View).

Parameters
child	View: Direct child of this ViewParent containing target This value cannot be null.
target	View: View that initiated the nested scroll This value cannot be null.
nestedScrollAxes	Int: Flags consisting of View#SCROLL_AXIS_HORIZONTAL, View#SCROLL_AXIS_VERTICAL or both

Return
Boolean	true if this ViewParent accepts the nested scroll operation

onStopNestedScroll

Added in API level 21

abstract fun onStopNestedScroll(target: View): 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 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.

Parameters
target	View: View that initiated the nested scroll This value cannot be null.

recomputeViewAttributes

Added in API level 1

abstract fun recomputeViewAttributes(child: View!): Unit

Tell view hierarchy that the global view attributes need to be re-evaluated.

Parameters
child	View!: View whose attributes have changed.

requestChildFocus

Added in API level 1

abstract fun requestChildFocus(
    child: View!, 
    focused: View!
): Unit

Called when a child of this parent wants focus

Parameters
child	View!: The child of this ViewParent that wants focus. This view will contain the focused view. It is not necessarily the view that actually has focus.
focused	View!: The view that is a descendant of child that actually has focus

requestChildRectangleOnScreen

Added in API level 3

abstract fun requestChildRectangleOnScreen(
    child: View, 
    rectangle: Rect!, 
    immediate: Boolean
): Boolean

Called when a child of this group wants a particular rectangle to be positioned onto the screen. ViewGroups overriding this can trust that:

• child will be a direct child of this group
• rectangle will be in the child's content coordinates

ViewGroups overriding this should uphold the contract:

• nothing will change if the rectangle is already visible
• the view port will be scrolled only just enough to make the rectangle visible

Parameters
child	View: The direct child making the request. This value cannot be null.
rectangle	Rect!: The rectangle in the child's coordinates the child wishes to be on the screen.
immediate	Boolean: True to forbid animated or delayed scrolling, false otherwise

Return
Boolean	Whether the group scrolled to handle the operation

requestDisallowInterceptTouchEvent

Added in API level 1

abstract fun requestDisallowInterceptTouchEvent(disallowIntercept: Boolean): Unit

Called when a child does not want this parent and its ancestors to intercept touch events with ViewGroup#onInterceptTouchEvent(MotionEvent).

This parent should pass this call onto its parents. This parent must obey this request for the duration of the touch (that is, only clear the flag after this parent has received an up or a cancel.

Parameters
disallowIntercept	Boolean: True if the child does not want the parent to intercept touch events.

requestFitSystemWindows

Added in API level 16

abstract fun requestFitSystemWindows(): Unit

Ask that a new dispatch of View.fitSystemWindows(Rect) be performed.

requestLayout

Added in API level 1

abstract fun requestLayout(): Unit

Called when something has changed which has invalidated the layout of a child of this view parent. This will schedule a layout pass of the view tree.

requestSendAccessibilityEvent

Added in API level 14

abstract fun requestSendAccessibilityEvent(
    child: View, 
    event: AccessibilityEvent!
): Boolean

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
child	View: The child which requests sending the event. This value cannot be null.
event	AccessibilityEvent!: The event to be sent.

Return
Boolean	True if the event was sent.

requestTransparentRegion

Added in API level 1

abstract fun requestTransparentRegion(child: View!): Unit

Called when a child wants the view hierarchy to gather and report transparent regions to the window compositor. Views that "punch" holes in the view hierarchy, such as SurfaceView can use this API to improve performance of the system. When no such a view is present in the hierarchy, this optimization in unnecessary and might slightly reduce the view hierarchy performance.

Parameters
child	View!: the view requesting the transparent region computation

showContextMenuForChild

Added in API level 1

abstract fun showContextMenuForChild(originalView: View!): Boolean

Shows the context menu for the specified view or its ancestors.

In most cases, a subclass does not need to override this. However, if the subclass is added directly to the window manager (for example, ViewManager#addView(View, android.view.ViewGroup.LayoutParams)) then it should override this and show the context menu.

Parameters
originalView	View!: the source view where the context menu was first invoked

Return
Boolean	true if the context menu was shown, false otherwise

See Also

• #showContextMenuForChild(View, float, float)

showContextMenuForChild

Added in API level 24

abstract fun showContextMenuForChild(
    originalView: View!, 
    x: Float, 
    y: Float
): Boolean

Shows the context menu for the specified view or its ancestors anchored to the specified view-relative coordinate.

In most cases, a subclass does not need to override this. However, if the subclass is added directly to the window manager (for example, ViewManager#addView(View, android.view.ViewGroup.LayoutParams)) then it should override this and show the context menu.

If a subclass overrides this method it should also override showContextMenuForChild(android.view.View).

Parameters
originalView	View!: the source view where the context menu was first invoked
x	Float: the X coordinate in pixels relative to the original view to which the menu should be anchored, or Float#NaN to disable anchoring
y	Float: the Y coordinate in pixels relative to the original view to which the menu should be anchored, or Float#NaN to disable anchoring

Return
Boolean	true if the context menu was shown, false otherwise

startActionModeForChild

Added in API level 11

abstract fun startActionModeForChild(
    originalView: View!, 
    callback: ActionMode.Callback!
): ActionMode!

Start an action mode for the specified view with the default type ActionMode#TYPE_PRIMARY.

In most cases, a subclass does not need to override this. However, if the subclass is added directly to the window manager (for example, ViewManager#addView(View, android.view.ViewGroup.LayoutParams)) then it should override this and start the action mode.

Parameters
originalView	View!: The source view where the action mode was first invoked
callback	ActionMode.Callback!: The callback that will handle lifecycle events for the action mode

Return
ActionMode!	The new action mode if it was started, null otherwise

See Also

• #startActionModeForChild(View, android.view.ActionMode.Callback, int)

startActionModeForChild

Added in API level 23

abstract fun startActionModeForChild(
    originalView: View!, 
    callback: ActionMode.Callback!, 
    type: Int
): ActionMode!

Start an action mode of a specific type for the specified view.

In most cases, a subclass does not need to override this. However, if the subclass is added directly to the window manager (for example, ViewManager#addView(View, android.view.ViewGroup.LayoutParams)) then it should override this and start the action mode.

Parameters
originalView	View!: The source view where the action mode was first invoked
callback	ActionMode.Callback!: The callback that will handle lifecycle events for the action mode
type	Int: One of ActionMode#TYPE_PRIMARY or ActionMode#TYPE_FLOATING.

Return
ActionMode!	The new action mode if it was started, null otherwise