ViewParent

bringChildToFront

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.

canResolveLayoutDirection

abstract fun canResolveLayoutDirection(): Boolean

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

canResolveTextAlignment

abstract fun canResolveTextAlignment(): Boolean

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

canResolveTextDirection

abstract fun canResolveTextDirection(): Boolean

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

childDrawableStateChanged

abstract fun childDrawableStateChanged(child: View): Unit

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

childHasTransientStateChanged

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.

clearChildFocus

abstract fun clearChildFocus(child: View!): Unit

Called when a child of this parent is giving up focus

createContextMenu

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).

findOnBackInvokedDispatcherForChild

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

Walk up the View hierarchy to find the nearest OnBackInvokedDispatcher.

focusSearch

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

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

focusableViewAvailable

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.

getChildVisibleRect

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.

getLayoutDirection

abstract fun getLayoutDirection(): Int

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

getParent

abstract fun getParent(): ViewParent!

Returns the parent if it exists, or null.

getParentForAccessibility

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.

getTextAlignment

abstract fun getTextAlignment(): Int

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

getTextDirection

abstract fun getTextDirection(): Int

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

invalidateChild

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.

invalidateChildInParent

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.

isLayoutDirectionResolved

abstract fun isLayoutDirectionResolved(): Boolean

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

isLayoutRequested

abstract fun isLayoutRequested(): Boolean

Indicates whether layout was requested on this view parent.

isTextAlignmentResolved

abstract fun isTextAlignmentResolved(): Boolean

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

isTextDirectionResolved

abstract fun isTextDirectionResolved(): Boolean

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

keyboardNavigationClusterSearch

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.

notifySubtreeAccessibilityStateChanged

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.

onDescendantInvalidated

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.

onNestedFling

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.

onNestedPreFling

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.

onNestedPrePerformAccessibilityAction

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.

onNestedPreScroll

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.

onNestedScroll

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.

onNestedScrollAccepted

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.

onStartNestedScroll

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).

onStopNestedScroll

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.

recomputeViewAttributes

abstract fun recomputeViewAttributes(child: View!): Unit

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

requestChildFocus

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

Called when a child of this parent wants focus

requestChildRectangleOnScreen

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

requestDisallowInterceptTouchEvent

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.

requestFitSystemWindows

abstract fun requestFitSystemWindows(): Unit

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

requestLayout

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

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.

requestTransparentRegion

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.

showContextMenuForChild

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.

showContextMenuForChild

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).

startActionModeForChild

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.

startActionModeForChild

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.