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Added in API level 1

ViewParent

public interface ViewParent

android.view.ViewParent
Known Indirect Subclasses


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).

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)

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

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

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 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.

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 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)

Bring up a context menu for the specified view or its ancestors.

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 TYPE_PRIMARY.

Public methods

bringChildToFront

Added in API level 1
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 KITKAT this method should be followed by calls to requestLayout() and 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
boolean canResolveLayoutDirection ()

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

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

canResolveTextAlignment

Added in API level 19
boolean canResolveTextAlignment ()

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

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

canResolveTextDirection

Added in API level 19
boolean canResolveTextDirection ()

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

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

childDrawableStateChanged

Added in API level 1
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.

childHasTransientStateChanged

Added in API level 19
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
hasTransientState boolean: true if this child has transient state

clearChildFocus

Added in API level 1
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
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

focusSearch

Added in API level 1
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
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
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
int getLayoutDirection ()

Return this view parent layout direction. See getLayoutDirection()

Returns
int LAYOUT_DIRECTION_RTL if the layout direction is RTL or returns LAYOUT_DIRECTION_LTR if the layout direction is not RTL.

getParent

Added in API level 1
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
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
int getTextAlignment ()

Return this view parent text alignment. See getTextAlignment()

Returns
int the resolved text alignment. Returns one of: TEXT_ALIGNMENT_GRAVITY, TEXT_ALIGNMENT_CENTER, TEXT_ALIGNMENT_TEXT_START, TEXT_ALIGNMENT_TEXT_END, TEXT_ALIGNMENT_VIEW_START, TEXT_ALIGNMENT_VIEW_END

getTextDirection

Added in API level 19
int getTextDirection ()

Return this view parent text direction. See getTextDirection()

Returns
int the resolved text direction. Returns one of: TEXT_DIRECTION_FIRST_STRONG TEXT_DIRECTION_ANY_RTL, TEXT_DIRECTION_LTR, TEXT_DIRECTION_RTL, TEXT_DIRECTION_LOCALE

invalidateChild

Added in API level 1
void invalidateChild (View child, 
                Rect r)

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
ViewParent invalidateChildInParent (int[] location, 
                Rect r)

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
boolean isLayoutDirectionResolved ()

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

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

isLayoutRequested

Added in API level 1
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
boolean isTextAlignmentResolved ()

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

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

isTextDirectionResolved

Added in API level 19
boolean isTextDirectionResolved ()

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

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

notifySubtreeAccessibilityStateChanged

Added in API level 19
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
child View: The direct child whose subtree has changed.
source View: The descendant view that changed.
changeType int: A bit mask of the types of changes that occurred. One or more of:

onNestedFling

Added in API level 21
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
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
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
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
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 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
action int: Action being performed; see AccessibilityNodeInfo
arguments Bundle: Optional action arguments
Returns
boolean true if the action was consumed by this ViewParent

onNestedPreScroll

Added in API level 21
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 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
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

onNestedScroll

Added in API level 21
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(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
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
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
target View: View that initiated the nested scroll
nestedScrollAxes int: Flags consisting of SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL or both

See also:

onStartNestedScroll

Added in API level 21
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 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(View).

Parameters
child View: Direct child of this ViewParent containing target
target View: View that initiated the nested scroll
nestedScrollAxes int: Flags consisting of SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL or both
Returns
boolean true if this ViewParent accepts the nested scroll operation

onStopNestedScroll

Added in API level 21
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 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
target View: View that initiated the nested scroll

recomputeViewAttributes

Added in API level 1
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
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
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 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.
      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
void requestDisallowInterceptTouchEvent (boolean disallowIntercept)

Called when a child does not want this parent and its ancestors to intercept touch events with 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
void requestFitSystemWindows ()

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

requestLayout

Added in API level 1
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
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.
event AccessibilityEvent: The event to be sent.
Returns
boolean True if the event was sent.

requestTransparentRegion

Added in API level 1
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
boolean showContextMenuForChild (View originalView)

Bring up a 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, 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 a context menu was displayed

startActionModeForChild

Added in API level 23
ActionMode startActionModeForChild (View originalView, 
                ActionMode.Callback callback, 
                int type)

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, 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 TYPE_PRIMARY or TYPE_FLOATING.
Returns
ActionMode The new action mode if it was started, null otherwise

startActionModeForChild

Added in API level 11
ActionMode startActionModeForChild (View originalView, 
                ActionMode.Callback callback)

Start an action mode for the specified view with the default type 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, 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
Returns
ActionMode The new action mode if it was started, null otherwise

See also:

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