Added in API level 1

Summary: Methods

ViewParent

Kotlin |Java

public interface ViewParent

android.view.ViewParent

Known indirect subclasses

AbsListView, AbsSpinner, AbsoluteLayout, ActionMenuView, AdapterView<T extends Adapter>, AdapterViewAnimator, AdapterViewFlipper, AppWidgetHostView, CalendarView, DatePicker, DialerFilter, ExpandableListView, FragmentBreadCrumbs, FrameLayout, Gallery, and 34 others.

AbsListView	Base class that can be used to implement virtualized lists of items.
AbsSpinner	An abstract base class for spinner widgets.
AbsoluteLayout	This class was deprecated in API level 3. Use `FrameLayout`, `RelativeLayout` or a custom layout instead.
ActionMenuView	ActionMenuView is a presentation of a series of menu options as a View.
AdapterView<T extends Adapter>	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 class was deprecated in API level 26. Use a custom view or layout to handle this functionality instead
ExpandableListView	A view that shows items in a vertically scrolling two-level list.
FragmentBreadCrumbs	This class was deprecated in API level 21. This widget is no longer supported.
FrameLayout	FrameLayout is designed to block out an area on the screen to display a single item.
Gallery	This class was deprecated in API level 16. This widget is no longer supported. Other horizontally scrolling widgets include `HorizontalScrollView` and `ViewPager` from the support library.
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	This class was deprecated in API level 17. This class is not supported anymore. It is recommended you base your own implementation on the source code for the Android Open Source Project if you must use it in your application.
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	This class was deprecated in API level 30. new applications should use fragment APIs instead of this class: Use TabLayout and ViewPager instead.
TabWidget	This class was deprecated in API level 30. new applications should use fragment APIs instead of this class: Use TabLayout and ViewPager instead.
TableLayout	A layout that arranges its children into rows and columns.
TableRow	A layout that arranges its children horizontally.
TextSwitcher	Specialized `ViewSwitcher` that contains only children of type `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	This class was deprecated in API level 17. This class can be implemented easily by apps using a `RelativeLayout` or a `LinearLayout`.
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.
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.
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	This class was deprecated in API level 29. This functionality and UI is better handled with custom views and layouts rather than a dedicated zoom-control widget

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 void`	`bringChildToFront(View child)` 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 void`	`childDrawableStateChanged(View child)` This method is called on the parent when a child's drawable state has changed.
`abstract void`	`childHasTransientStateChanged(View child, boolean hasTransientState)` Called when a child view now has or no longer is tracking transient state.
`abstract void`	`clearChildFocus(View child)` Called when a child of this parent is giving up focus
`abstract void`	`createContextMenu(ContextMenu menu)` Have the parent populate the specified context menu if it has anything to add (and then recurse on its parent).
`default OnBackInvokedDispatcher`	`findOnBackInvokedDispatcherForChild(View child, View requester)` Walk up the View hierarchy to find the nearest `OnBackInvokedDispatcher`.
`abstract View`	`focusSearch(View v, int direction)` Find the nearest view in the specified direction that wants to take focus
`abstract void`	`focusableViewAvailable(View v)` Tells the parent that a new focusable view has become available.
`abstract boolean`	`getChildVisibleRect(View child, Rect r, Point offset)` 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 void`	`invalidateChild(View child, Rect r)` This method was deprecated in API level 26. Use `onDescendantInvalidated(android.view.View, android.view.View)` instead.
`abstract ViewParent`	`invalidateChildInParent(int[] location, Rect r)` This method was deprecated in API level 26. Use `onDescendantInvalidated(android.view.View, android.view.View)` instead.
`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(View currentCluster, int direction)` Find the nearest keyboard navigation cluster in the specified direction.
`abstract void`	`notifySubtreeAccessibilityStateChanged(View child, View source, int changeType)` Notifies a view parent that the accessibility state of one of its descendants has changed and that the structure of the subtree is different.
`default void`	`onDescendantInvalidated(View child, View target)` The target View has been invalidated, or has had a drawing property changed that requires the hierarchy to re-render.
`abstract boolean`	`onNestedFling(View target, float velocityX, float velocityY, boolean consumed)` Request a fling from a nested scroll.
`abstract boolean`	`onNestedPreFling(View target, float velocityX, float velocityY)` React to a nested fling before the target view consumes it.
`abstract boolean`	`onNestedPrePerformAccessibilityAction(View target, int action, Bundle arguments)` React to an accessibility action delegated by a target descendant view before the target processes it.
`abstract void`	`onNestedPreScroll(View target, int dx, int dy, int[] consumed)` React to a nested scroll in progress before the target view consumes a portion of the scroll.
`abstract void`	`onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed)` React to a nested scroll in progress.
`abstract void`	`onNestedScrollAccepted(View child, View target, int nestedScrollAxes)` React to the successful claiming of a nested scroll operation.
`abstract boolean`	`onStartNestedScroll(View child, View target, int nestedScrollAxes)` React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.
`abstract void`	`onStopNestedScroll(View target)` React to a nested scroll operation ending.
`abstract void`	`recomputeViewAttributes(View child)` Tell view hierarchy that the global view attributes need to be re-evaluated.
`abstract void`	`requestChildFocus(View child, View focused)` Called when a child of this parent wants focus
`abstract boolean`	`requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate)` Called when a child of this group wants a particular rectangle to be positioned onto the screen.
`abstract void`	`requestDisallowInterceptTouchEvent(boolean disallowIntercept)` Called when a child does not want this parent and its ancestors to intercept touch events with `ViewGroup#onInterceptTouchEvent(MotionEvent)`.
`abstract void`	`requestFitSystemWindows()` Ask that a new dispatch of `View.fitSystemWindows(Rect)` be performed.
`abstract void`	`requestLayout()` Called when something has changed which has invalidated the layout of a child of this view parent.
`abstract boolean`	`requestSendAccessibilityEvent(View child, AccessibilityEvent event)` Called by a child to request from its parent to send an `AccessibilityEvent`.
`abstract void`	`requestTransparentRegion(View child)` Called when a child wants the view hierarchy to gather and report transparent regions to the window compositor.
`abstract boolean`	`showContextMenuForChild(View originalView)` Shows the context menu for the specified view or its ancestors.
`abstract boolean`	`showContextMenuForChild(View originalView, float x, float y)` Shows the context menu for the specified view or its ancestors anchored to the specified view-relative coordinate.
`abstract ActionMode`	`startActionModeForChild(View originalView, ActionMode.Callback callback, int type)` Start an action mode of a specific type for the specified view.
`abstract ActionMode`	`startActionModeForChild(View originalView, ActionMode.Callback callback)` Start an action mode for the specified view with the default type `ActionMode#TYPE_PRIMARY`.

Public methods

bringChildToFront

Added in API level 1

public abstract void bringChildToFront (View child)

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 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

public abstract boolean canResolveLayoutDirection ()

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

Returns
`boolean`	True if this view parent can resolve the layout direction.

canResolveTextAlignment

Added in API level 19

public abstract boolean canResolveTextAlignment ()

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

Returns
`boolean`	True if this view parent can resolve the text alignment.

canResolveTextDirection

Added in API level 19

public abstract boolean canResolveTextDirection ()

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

Returns
`boolean`	True if this view parent can resolve the text direction.

childDrawableStateChanged

Added in API level 1

public abstract void childDrawableStateChanged (View child)

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

public abstract void childHasTransientStateChanged (View child, 
                boolean hasTransientState)

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

public abstract void clearChildFocus (View child)

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

public abstract void createContextMenu (ContextMenu menu)

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

public OnBackInvokedDispatcher findOnBackInvokedDispatcherForChild (View child, 
                View requester)

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`.

Returns
`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

public abstract View focusSearch (View v, 
                int direction)

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

Returns
`View`

focusableViewAvailable

Added in API level 1

public abstract void focusableViewAvailable (View v)

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

public abstract boolean getChildVisibleRect (View child, 
                Rect r, 
                Point offset)

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)

Returns
`boolean`	true if the resulting rectangle is not empty, false otherwise

getLayoutDirection

Added in API level 19

public abstract int getLayoutDirection ()

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

Returns
`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

public abstract ViewParent getParent ()

Returns the parent if it exists, or null.

Returns
`ViewParent`	a ViewParent or null if this ViewParent does not have a parent

getParentForAccessibility

Added in API level 16

public abstract ViewParent getParentForAccessibility ()

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.

Returns
`ViewParent`	The parent or `null` if no such is found.

getTextAlignment

Added in API level 19

public abstract int getTextAlignment ()

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

Returns
`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

public abstract int getTextDirection ()

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

Returns
`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

public abstract void invalidateChild (View child, 
                Rect r)

This method was deprecated in API level 26.
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

public abstract ViewParent invalidateChildInParent (int[] location, 
                Rect r)

This method was deprecated in API level 26.
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`	`int`: 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

Returns
`ViewParent`	the parent of this ViewParent or null

isLayoutDirectionResolved

Added in API level 19

public abstract boolean isLayoutDirectionResolved ()

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

Returns
`boolean`	True if this view parent layout direction is resolved.

isLayoutRequested

Added in API level 1

public abstract boolean isLayoutRequested ()

Indicates whether layout was requested on this view parent.

Returns
`boolean`	true if layout was requested, false otherwise

isTextAlignmentResolved

Added in API level 19

public abstract boolean isTextAlignmentResolved ()

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

Returns
`boolean`	True if this view parent text alignment is resolved.

isTextDirectionResolved

Added in API level 19

public abstract boolean isTextDirectionResolved ()

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

Returns
`boolean`	True if this view parent text direction is resolved.

keyboardNavigationClusterSearch

Added in API level 26

public abstract View keyboardNavigationClusterSearch (View currentCluster, 
                int direction)

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

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

notifySubtreeAccessibilityStateChanged

Added in API level 19

public abstract void notifySubtreeAccessibilityStateChanged (View child, 
                View source, 
                int changeType)

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

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`

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:

onDescendantInvalidated

Added in API level 26

public void onDescendantInvalidated (View child, 
                View target)

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

public abstract boolean onNestedFling (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
`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

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

onNestedPreFling

Added in API level 21

public abstract boolean onNestedPreFling (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
`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

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

onNestedPrePerformAccessibilityAction

Added in API level 22

public abstract boolean onNestedPrePerformAccessibilityAction (View target, 
                int action, 
                Bundle arguments)

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 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 `AccessibilityNodeInfo`
`arguments`	`Bundle`: Optional action arguments This value may be `null`.

Returns
`boolean`	true if the action was consumed by this ViewParent

onNestedPreScroll

Added in API level 21

public abstract void onNestedPreScroll (View target, 
                int dx, 
                int dy, 
                int[] consumed)

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`	`int`: Output. The horizontal and vertical scroll distance consumed by this parent This value cannot be `null`.

onNestedScroll

Added in API level 21

public abstract void onNestedScroll (View target, 
                int dxConsumed, 
                int dyConsumed, 
                int dxUnconsumed, 
                int dyUnconsumed)

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

public abstract void onNestedScrollAccepted (View child, 
                View target, 
                int nestedScrollAxes)

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

Added in API level 21

public abstract boolean onStartNestedScroll (View child, 
                View target, 
                int nestedScrollAxes)

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

Returns
`boolean`	true if this ViewParent accepts the nested scroll operation

onStopNestedScroll

Added in API level 21

public abstract void onStopNestedScroll (View target)

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

public abstract void recomputeViewAttributes (View child)

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

public abstract void requestChildFocus (View child, 
                View focused)

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

public abstract boolean requestChildRectangleOnScreen (View child, 
                Rect rectangle, 
                boolean immediate)

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

Returns
`boolean`	Whether the group scrolled to handle the operation

requestDisallowInterceptTouchEvent

Added in API level 1

public abstract void requestDisallowInterceptTouchEvent (boolean disallowIntercept)

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

public abstract void requestFitSystemWindows ()

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

requestLayout

Added in API level 1

public abstract void requestLayout ()

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

public abstract boolean requestSendAccessibilityEvent (View child, 
                AccessibilityEvent event)

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.

Returns
`boolean`	True if the event was sent.

requestTransparentRegion

Added in API level 1

public abstract void requestTransparentRegion (View child)

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

public abstract boolean showContextMenuForChild (View originalView)

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

Returns
`boolean`	`true` if the context menu was shown, `false` otherwise

See also:

showContextMenuForChild(View, float, float)

showContextMenuForChild

Added in API level 24

public abstract boolean showContextMenuForChild (View originalView, 
                float x, 
                float y)

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

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

Returns
`boolean`	`true` if the context menu was shown, `false` otherwise

startActionModeForChild

Added in API level 23

public abstract ActionMode startActionModeForChild (View originalView, 
                ActionMode.Callback callback, 
                int type)

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

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`.

Returns
`ActionMode`	The new action mode if it was started, null otherwise

startActionModeForChild

Added in API level 11

public abstract ActionMode startActionModeForChild (View originalView, 
                ActionMode.Callback callback)

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

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

Returns
`ActionMode`	The new action mode if it was started, null otherwise

See also:

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