Subclasses:

WearableLinearLayoutManager, GridLayoutManager, GridLayoutManager, LinearLayoutManager, StaggeredGridLayoutManager

Overview

A LayoutManager is responsible for measuring and positioning item views within a RecyclerView as well as determining the policy for when to recycle item views that are no longer visible to the user. By changing the LayoutManager a RecyclerView can be used to implement a standard vertically scrolling list, a uniform grid, staggered grids, horizontally scrolling collections and more. Several stock layout managers are provided for general use.

If the LayoutManager specifies a default constructor or one with the signature (, , int, int), RecyclerView will instantiate and set the LayoutManager when being inflated. Most used properties can be then obtained from RecyclerView.LayoutManager.getProperties(Context, AttributeSet, int, int). In case a LayoutManager specifies both constructors, the non-default constructor will take precedence.

Summary

Constructors

Methods

Sets the measured dimensions from the given bounding box of the children and the measurement specs that were passed into RecyclerView.onMeasure(int, int). It is only called if a LayoutManager returns true from RecyclerView.LayoutManager.isAutoMeasureEnabled() and it is called after the RecyclerView calls RecyclerView.LayoutManager in the execution of RecyclerView.onMeasure(int, int).

This method must call RecyclerView.LayoutManager.setMeasuredDimension(int, int).

The default implementation adds the RecyclerView's padding to the given bounding box then caps the value to be within the given measurement specs.

Parameters:

childrenBounds: The bounding box of all children
wSpec: The widthMeasureSpec that was passed into the RecyclerView.
hSpec: The heightMeasureSpec that was passed into the RecyclerView.

See also: RecyclerView.LayoutManager.isAutoMeasureEnabled(), RecyclerView.LayoutManager.setMeasuredDimension(int, int)

Calls RecyclerView#requestLayout on the underlying RecyclerView

Checks if RecyclerView is in the middle of a layout or scroll and throws an java.lang.IllegalStateException if it is not.

Parameters:

message: The message for the exception. Can be null.

See also: RecyclerView.LayoutManager.assertNotInLayoutOrScroll(String)

Chooses a size from the given specs and parameters that is closest to the desired size and also complies with the spec.

Parameters:

spec: The measureSpec
desired: The preferred measurement
min: The minimum value

Returns:

A size that fits to the given specs

Checks if RecyclerView is in the middle of a layout or scroll and throws an java.lang.IllegalStateException if it is.

Parameters:

message: The message for the exception. Can be null.

See also: RecyclerView.LayoutManager.assertInLayoutOrScroll(String)

Deprecated: Implementors of LayoutManager should define whether or not it uses AutoMeasure by overriding RecyclerView.LayoutManager.isAutoMeasureEnabled().

Defines whether the measuring pass of layout should use the AutoMeasure mechanism of RecyclerView or if it should be done by the LayoutManager's implementation of RecyclerView.LayoutManager.

Parameters:

enabled: True if layout measurement should be done by the RecyclerView, false if it should be done by this LayoutManager.

See also: RecyclerView.LayoutManager.isAutoMeasureEnabled()

Returns whether the measuring pass of layout should use the AutoMeasure mechanism of RecyclerView or if it should be done by the LayoutManager's implementation of RecyclerView.LayoutManager.

This method returns false by default (it actually returns the value passed to the deprecated RecyclerView.LayoutManager.setAutoMeasureEnabled(boolean)) and should be overridden to return true if a LayoutManager wants to be auto measured by the RecyclerView.

If this method is overridden to return true, RecyclerView.LayoutManager should not be overridden.

AutoMeasure is a RecyclerView mechanism that handles the measuring pass of layout in a simple and contract satisfying way, including the wrapping of children laid out by LayoutManager. Simply put, it handles wrapping children by calling RecyclerView.LayoutManager during a call to RecyclerView.onMeasure(int, int), and then calculating desired dimensions based on children's dimensions and positions. It does this while supporting all existing animation capabilities of the RecyclerView.

More specifically:

1. When RecyclerView.onMeasure(int, int) is called, if the provided measure specs both have a mode of , RecyclerView will set its measured dimensions accordingly and return, allowing layout to continue as normal (Actually, RecyclerView will call RecyclerView.LayoutManager for backwards compatibility reasons but it should not be overridden if AutoMeasure is being used).
2. If one of the layout specs is not EXACT, the RecyclerView will start the layout process. It will first process all pending Adapter updates and then decide whether to run a predictive layout. If it decides to do so, it will first call RecyclerView.LayoutManager with RecyclerView.State.isPreLayout() set to true. At this stage, RecyclerView.LayoutManager.getWidth() and RecyclerView.LayoutManager.getHeight() will still return the width and height of the RecyclerView as of the last layout calculation.

   After handling the predictive case, RecyclerView will call RecyclerView.LayoutManager with RecyclerView.State.isMeasuring() set to true and RecyclerView.State.isPreLayout() set to false. The LayoutManager can access the measurement specs via RecyclerView.LayoutManager.getHeight(), RecyclerView.LayoutManager.getHeightMode(), RecyclerView.LayoutManager.getWidth() and RecyclerView.LayoutManager.getWidthMode().

3. After the layout calculation, RecyclerView sets the measured width & height by calculating the bounding box for the children (+ RecyclerView's padding). The LayoutManagers can override RecyclerView.LayoutManager.setMeasuredDimension(Rect, int, int) to choose different values. For instance, GridLayoutManager overrides this value to handle the case where if it is vertical and has 3 columns but only 2 items, it should still measure its width to fit 3 items, not 2.
4. Any following calls to RecyclerView.onMeasure(int, int) will run RecyclerView.LayoutManager with RecyclerView.State.isMeasuring() set to true and RecyclerView.State.isPreLayout() set to false. RecyclerView will take care of which views are actually added / removed / moved / changed for animations so that the LayoutManager should not worry about them and handle each RecyclerView.LayoutManager call as if it is the last one.
5. When measure is complete and RecyclerView's RecyclerView.onLayout(boolean, int, int, int, int) method is called, RecyclerView checks whether it already did layout calculations during the measure pass and if so, it re-uses that information. It may still decide to call RecyclerView.LayoutManager if the last measure spec was different from the final dimensions or adapter contents have changed between the measure call and the layout call.
6. Finally, animations are calculated and run as usual.

Returns:

True if the measuring pass of layout should use the AutoMeasure mechanism of RecyclerView or False if it should be done by the LayoutManager's implementation of RecyclerView.LayoutManager.

See also: RecyclerView.LayoutManager.setMeasuredDimension(Rect, int, int), RecyclerView.LayoutManager

Returns whether this LayoutManager supports "predictive item animations".

"Predictive item animations" are automatically created animations that show where items came from, and where they are going to, as items are added, removed, or moved within a layout.

A LayoutManager wishing to support predictive item animations must override this method to return true (the default implementation returns false) and must obey certain behavioral contracts outlined in RecyclerView.LayoutManager.

Whether item animations actually occur in a RecyclerView is actually determined by both the return value from this method and the ItemAnimator set on the RecyclerView itself. If the RecyclerView has a non-null ItemAnimator but this method returns false, then only "simple item animations" will be enabled in the RecyclerView, in which views whose position are changing are simply faded in/out. If the RecyclerView has a non-null ItemAnimator and this method returns true, then predictive item animations will be enabled in the RecyclerView.

Returns:

true if this LayoutManager supports predictive item animations, false otherwise.

Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames.

If enabled, the LayoutManager will be queried for items to inflate/bind in between view system traversals on devices running API 21 or greater. Default value is true.

On platforms API level 21 and higher, the UI thread is idle between passing a frame to RenderThread and the starting up its next frame at the next VSync pulse. By prefetching out of window views in this time period, delays from inflation and view binding are much less likely to cause jank and stuttering during scrolls and flings.

While prefetch is enabled, it will have the side effect of expanding the effective size of the View cache to hold prefetched views.

Parameters:

enabled: True if items should be prefetched in between traversals.

See also: RecyclerView.LayoutManager.isItemPrefetchEnabled()

Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames.

Returns:

true if item prefetch is enabled, false otherwise

See also: RecyclerView.LayoutManager.setItemPrefetchEnabled(boolean)

Gather all positions from the LayoutManager to be prefetched, given specified momentum.

If item prefetch is enabled, this method is called in between traversals to gather which positions the LayoutManager will soon need, given upcoming movement in subsequent traversals.

The LayoutManager should call RecyclerView.LayoutManager.LayoutPrefetchRegistry.addPosition(int, int) for each item to be prepared, and these positions will have their ViewHolders created and bound, if there is sufficient time available, in advance of being needed by a scroll or layout.

Parameters:

dx: X movement component.
dy: Y movement component.
state: State of RecyclerView
layoutPrefetchRegistry: PrefetchRegistry to add prefetch entries into.

See also: RecyclerView.LayoutManager.isItemPrefetchEnabled(), RecyclerView.LayoutManager.collectInitialPrefetchPositions(int, RecyclerView.LayoutManager.LayoutPrefetchRegistry)

Gather all positions from the LayoutManager to be prefetched in preperation for its RecyclerView to come on screen, due to the movement of another, containing RecyclerView.

This method is only called when a RecyclerView is nested in another RecyclerView.

If item prefetch is enabled for this LayoutManager, as well in another containing LayoutManager, this method is called in between draw traversals to gather which positions this LayoutManager will first need, once it appears on the screen.

For example, if this LayoutManager represents a horizontally scrolling list within a vertically scrolling LayoutManager, this method would be called when the horizontal list is about to come onscreen.

The LayoutManager should call RecyclerView.LayoutManager.LayoutPrefetchRegistry.addPosition(int, int) for each item to be prepared, and these positions will have their ViewHolders created and bound, if there is sufficient time available, in advance of being needed by a scroll or layout.

Parameters:

adapterItemCount: number of items in the associated adapter.
layoutPrefetchRegistry: PrefetchRegistry to add prefetch entries into.

See also: RecyclerView.LayoutManager.isItemPrefetchEnabled(), RecyclerView.LayoutManager

Returns whether LayoutManager is currently attached to a RecyclerView which is attached to a window.

Returns:

True if this LayoutManager is controlling a RecyclerView and the RecyclerView is attached to window.

Causes the Runnable to execute on the next animation time step. The runnable will be run on the user interface thread.

Calling this method when LayoutManager is not attached to a RecyclerView has no effect.

Parameters:

action: The Runnable that will be executed.

See also: RecyclerView.LayoutManager.removeCallbacks(Runnable)

Removes the specified Runnable from the message queue.

Calling this method when LayoutManager is not attached to a RecyclerView has no effect.

Parameters:

action: The Runnable to remove from the message handling queue

Returns:

true if RecyclerView could ask the Handler to remove the Runnable, false otherwise. When the returned value is true, the Runnable may or may not have been actually removed from the message queue (for instance, if the Runnable was not in the queue already.)

See also: RecyclerView.LayoutManager.postOnAnimation(Runnable)

Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView is attached to a window.

If the RecyclerView is re-attached with the same LayoutManager and Adapter, it may not call RecyclerView.LayoutManager if nothing has changed and a layout was not requested on the RecyclerView while it was detached.

Subclass implementations should always call through to the superclass implementation.

Parameters:

view: The RecyclerView this LayoutManager is bound to

See also: RecyclerView.LayoutManager

Deprecated: override RecyclerView.LayoutManager

Called when this LayoutManager is detached from its parent RecyclerView or when its parent RecyclerView is detached from its window.

LayoutManager should clear all of its View references as another LayoutManager might be assigned to the RecyclerView.

If the RecyclerView is re-attached with the same LayoutManager and Adapter, it may not call RecyclerView.LayoutManager if nothing has changed and a layout was not requested on the RecyclerView while it was detached.

If your LayoutManager has View references that it cleans in on-detach, it should also call RecyclerView.requestLayout() to ensure that it is re-laid out when RecyclerView is re-attached.

Subclass implementations should always call through to the superclass implementation.

Parameters:

view: The RecyclerView this LayoutManager is bound to
recycler: The recycler to use if you prefer to recycle your children instead of keeping them around.

See also: RecyclerView.LayoutManager.onAttachedToWindow(RecyclerView)

Check if the RecyclerView is configured to clip child views to its padding.

Returns:

true if this RecyclerView clips children to its padding, false otherwise

Lay out all relevant child views from the given adapter. The LayoutManager is in charge of the behavior of item animations. By default, RecyclerView has a non-null ItemAnimator, and simple item animations are enabled. This means that add/remove operations on the adapter will result in animations to add new or appearing items, removed or disappearing items, and moved items. If a LayoutManager returns false from RecyclerView.LayoutManager.supportsPredictiveItemAnimations(), which is the default, and runs a normal layout operation during RecyclerView.LayoutManager, the RecyclerView will have enough information to run those animations in a simple way. For example, the default ItemAnimator, DefaultItemAnimator, will simply fade views in and out, whether they are actually added/removed or whether they are moved on or off the screen due to other add/remove operations.

A LayoutManager wanting a better item animation experience, where items can be animated onto and off of the screen according to where the items exist when they are not on screen, then the LayoutManager should return true from RecyclerView.LayoutManager.supportsPredictiveItemAnimations() and add additional logic to RecyclerView.LayoutManager. Supporting predictive animations means that RecyclerView.LayoutManager will be called twice; once as a "pre" layout step to determine where items would have been prior to a real layout, and again to do the "real" layout. In the pre-layout phase, items will remember their pre-layout positions to allow them to be laid out appropriately. Also, removed items will be returned from the scrap to help determine correct placement of other items. These removed items should not be added to the child list, but should be used to help calculate correct positioning of other views, including views that were not previously onscreen (referred to as APPEARING views), but whose pre-layout offscreen position can be determined given the extra information about the pre-layout removed views.

The second layout pass is the real layout in which only non-removed views will be used. The only additional requirement during this pass is, if RecyclerView.LayoutManager.supportsPredictiveItemAnimations() returns true, to note which views exist in the child list prior to layout and which are not there after layout (referred to as DISAPPEARING views), and to position/layout those views appropriately, without regard to the actual bounds of the RecyclerView. This allows the animation system to know the location to which to animate these disappearing views.

The default LayoutManager implementations for RecyclerView handle all of these requirements for animations already. Clients of RecyclerView can either use one of these layout managers directly or look at their implementations of onLayoutChildren() to see how they account for the APPEARING and DISAPPEARING views.

Parameters:

recycler: Recycler to use for fetching potentially cached views for a position
state: Transient state of RecyclerView

Called after a full layout calculation is finished. The layout calculation may include multiple RecyclerView.LayoutManager calls due to animations or layout measurement but it will include only one RecyclerView.LayoutManager call. This method will be called at the end of View call.

This is a good place for the LayoutManager to do some cleanup like pending scroll position, saved state etc.

Parameters:

state: Transient state of RecyclerView

Create a default LayoutParams object for a child of the RecyclerView.

LayoutManagers will often want to use a custom LayoutParams type to store extra information specific to the layout. Client code should subclass RecyclerView.LayoutParams for this purpose.

Important: if you use your own custom LayoutParams type you must also override RecyclerView.LayoutManager, RecyclerView.LayoutManager and RecyclerView.LayoutManager.

Returns:

A new LayoutParams for a child view

Determines the validity of the supplied LayoutParams object.

This should check to make sure that the object is of the correct type and all values are within acceptable ranges. The default implementation returns true for non-null params.

Parameters:

lp: LayoutParams object to check

Returns:

true if this LayoutParams object is valid, false otherwise

Create a LayoutParams object suitable for this LayoutManager, copying relevant values from the supplied LayoutParams object if possible.

Important: if you use your own custom LayoutParams type you must also override RecyclerView.LayoutManager, RecyclerView.LayoutManager and RecyclerView.LayoutManager.

Parameters:

lp: Source LayoutParams object to copy values from

Returns:

a new LayoutParams object

Create a LayoutParams object suitable for this LayoutManager from an inflated layout resource.

Important: if you use your own custom LayoutParams type you must also override RecyclerView.LayoutManager, RecyclerView.LayoutManager and RecyclerView.LayoutManager.

Parameters:

c: Context for obtaining styled attributes
attrs: AttributeSet describing the supplied arguments

Returns:

a new LayoutParams object

Scroll horizontally by dx pixels in screen coordinates and return the distance traveled. The default implementation does nothing and returns 0.

Parameters:

dx: distance to scroll by in pixels. X increases as scroll position approaches the right.
recycler: Recycler to use for fetching potentially cached views for a position
state: Transient state of RecyclerView

Returns:

The actual distance scrolled. The return value will be negative if dx was negative and scrolling proceeeded in that direction. Math.abs(result) may be less than dx if a boundary was reached.

Scroll vertically by dy pixels in screen coordinates and return the distance traveled. The default implementation does nothing and returns 0.

Parameters:

dy: distance to scroll in pixels. Y increases as scroll position approaches the bottom.
recycler: Recycler to use for fetching potentially cached views for a position
state: Transient state of RecyclerView

Returns:

The actual distance scrolled. The return value will be negative if dy was negative and scrolling proceeeded in that direction. Math.abs(result) may be less than dy if a boundary was reached.

Query if horizontal scrolling is currently supported. The default implementation returns false.

Returns:

True if this LayoutManager can scroll the current contents horizontally

Query if vertical scrolling is currently supported. The default implementation returns false.

Returns:

True if this LayoutManager can scroll the current contents vertically

Scroll to the specified adapter position. Actual position of the item on the screen depends on the LayoutManager implementation.

Parameters:

position: Scroll to this adapter position.

Smooth scroll to the specified adapter position.

To support smooth scrolling, override this method, create your RecyclerView.SmoothScroller instance and call RecyclerView.LayoutManager.

Parameters:

recyclerView: The RecyclerView to which this layout manager is attached
state: Current State of RecyclerView
position: Scroll to this adapter position.

Starts a smooth scroll using the provided RecyclerView.SmoothScroller.

Each instance of SmoothScroller is intended to only be used once. Provide a new SmoothScroller instance each time this method is called.

Calling this method will cancel any previous smooth scroll request.

Parameters:

smoothScroller: Instance which defines how smooth scroll should be animated

Returns:

true if RecyclerView is currently in the state of smooth scrolling.

Returns the resolved layout direction for this RecyclerView.

Returns:

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

Ends all animations on the view created by the RecyclerView.ItemAnimator.

Parameters:

view: The View for which the animations should be ended.

See also: RecyclerView.ItemAnimator.endAnimations()

To be called only during RecyclerView.LayoutManager to add a view to the layout that is known to be going away, either because it has been removed or because it is actually not in the visible portion of the container but is being laid out in order to inform RecyclerView in how to animate the item out of view.

Views added via this method are going to be invisible to LayoutManager after the dispatchLayout pass is complete. They cannot be retrieved via RecyclerView.LayoutManager.getChildAt(int) or won't be included in RecyclerView.LayoutManager.getChildCount() method.

Parameters:

child: View to add and then remove with animation.

To be called only during RecyclerView.LayoutManager to add a view to the layout that is known to be going away, either because it has been removed or because it is actually not in the visible portion of the container but is being laid out in order to inform RecyclerView in how to animate the item out of view.

Views added via this method are going to be invisible to LayoutManager after the dispatchLayout pass is complete. They cannot be retrieved via RecyclerView.LayoutManager.getChildAt(int) or won't be included in RecyclerView.LayoutManager.getChildCount() method.

Parameters:

child: View to add and then remove with animation.
index: Index of the view.

Add a view to the currently attached RecyclerView if needed. LayoutManagers should use this method to add views obtained from a RecyclerView.Recycler using RecyclerView.Recycler.getViewForPosition(int).

Parameters:

child: View to add

Add a view to the currently attached RecyclerView if needed. LayoutManagers should use this method to add views obtained from a RecyclerView.Recycler using RecyclerView.Recycler.getViewForPosition(int).

Parameters:

child: View to add
index: Index to add child at

Remove a view from the currently attached RecyclerView if needed. LayoutManagers should use this method to completely remove a child view that is no longer needed. LayoutManagers should strongly consider recycling removed views using RecyclerView.Recycler.

Parameters:

child: View to remove

Remove a view from the currently attached RecyclerView if needed. LayoutManagers should use this method to completely remove a child view that is no longer needed. LayoutManagers should strongly consider recycling removed views using RecyclerView.Recycler.

Parameters:

index: Index of the child view to remove

Remove all views from the currently attached RecyclerView. This will not recycle any of the affected views; the LayoutManager is responsible for doing so if desired.

Returns offset of the RecyclerView's text baseline from the its top boundary.

Returns:

The offset of the RecyclerView's text baseline from the its top boundary; -1 if there is no baseline.

Returns the adapter position of the item represented by the given View. This does not contain any adapter changes that might have happened after the last layout.

Parameters:

view: The view to query

Returns:

The adapter position of the item which is rendered by this View.

Returns the View type defined by the adapter.

Parameters:

view: The view to query

Returns:

The type of the view assigned by the adapter.

Traverses the ancestors of the given view and returns the item view that contains it and also a direct child of the LayoutManager.

Note that this method may return null if the view is a child of the RecyclerView but not a child of the LayoutManager (e.g. running a disappear animation).

Parameters:

view: The view that is a descendant of the LayoutManager.

Returns:

The direct child of the LayoutManager which contains the given view or null if the provided view is not a descendant of this LayoutManager.

See also: RecyclerView.getChildViewHolder(View), RecyclerView.findContainingViewHolder(View)

Finds the view which represents the given adapter position.

This method traverses each child since it has no information about child order. Override this method to improve performance if your LayoutManager keeps data about child views.

If a view is ignored via RecyclerView.LayoutManager.ignoreView(View), it is also ignored by this method.

Parameters:

position: Position of the item in adapter

Returns:

The child view that represents the given position or null if the position is not laid out

Temporarily detach a child view.

LayoutManagers may want to perform a lightweight detach operation to rearrange views currently attached to the RecyclerView. Generally LayoutManager implementations will want to use RecyclerView.LayoutManager so that the detached view may be rebound and reused.

If a LayoutManager uses this method to detach a view, it must reattach or fully remove the detached view before the LayoutManager entry point method called by RecyclerView returns.

Parameters:

child: Child to detach

Temporarily detach a child view.

LayoutManagers may want to perform a lightweight detach operation to rearrange views currently attached to the RecyclerView. Generally LayoutManager implementations will want to use RecyclerView.LayoutManager so that the detached view may be rebound and reused.

If a LayoutManager uses this method to detach a view, it must reattach or fully remove the detached view before the LayoutManager entry point method called by RecyclerView returns.

Parameters:

index: Index of the child to detach

Reattach a previously detached view. This method should not be used to reattach views that were previously RecyclerView.LayoutManager scrapped}.

Parameters:

child: Child to reattach
index: Intended child index for child
lp: LayoutParams for child

Reattach a previously detached view. This method should not be used to reattach views that were previously RecyclerView.LayoutManager scrapped}.

Parameters:

child: Child to reattach
index: Intended child index for child

Reattach a previously detached view. This method should not be used to reattach views that were previously RecyclerView.LayoutManager scrapped}.

Parameters:

child: Child to reattach

Finish removing a view that was previously temporarily detached.

Parameters:

child: Detached child to remove

Moves a View from one position to another.

Parameters:

fromIndex: The View's initial index
toIndex: The View's target index

Detach a child view and add it to a Recycler's scrap heap.

Scrapping a view allows it to be rebound and reused to show updated or different data.

Parameters:

child: Child to detach and scrap
recycler: Recycler to deposit the new scrap view into

Detach a child view and add it to a Recycler's scrap heap.

Scrapping a view allows it to be rebound and reused to show updated or different data.

Parameters:

index: Index of child to detach and scrap
recycler: Recycler to deposit the new scrap view into

Remove a child view and recycle it using the given Recycler.

Parameters:

child: Child to remove and recycle
recycler: Recycler to use to recycle child

Remove a child view and recycle it using the given Recycler.

Parameters:

index: Index of child to remove and recycle
recycler: Recycler to use to recycle child

Return the current number of child views attached to the parent RecyclerView. This does not include child views that were temporarily detached and/or scrapped.

Returns:

Number of attached children

Return the child view at the given index

Parameters:

index: Index of child to return

Returns:

Child view at index

Return the width measurement spec mode that is currently relevant to the LayoutManager.

This value is set only if the LayoutManager opts into the AutoMeasure api via RecyclerView.LayoutManager.setAutoMeasureEnabled(boolean).

When RecyclerView is running a layout, this value is always set to even if it was measured with a different spec mode.

Returns:

Width measure spec mode

See also:

Return the height measurement spec mode that is currently relevant to the LayoutManager.

This value is set only if the LayoutManager opts into the AutoMeasure api via RecyclerView.LayoutManager.setAutoMeasureEnabled(boolean).

When RecyclerView is running a layout, this value is always set to even if it was measured with a different spec mode.

Returns:

Height measure spec mode

See also:

Returns the width that is currently relevant to the LayoutManager.

This value is usually equal to the laid out width of the RecyclerView but may reflect the current width if the RecyclerView.LayoutManager is using AutoMeasure and the RecyclerView is in the process of measuring. The LayoutManager must always use this method to retrieve the width relevant to it at any given time.

Returns:

Width in pixels

Returns the height that is currently relevant to the LayoutManager.

This value is usually equal to the laid out height of the RecyclerView but may reflect the current height if the RecyclerView.LayoutManager is using AutoMeasure and the RecyclerView is in the process of measuring. The LayoutManager must always use this method to retrieve the height relevant to it at any given time.

Returns:

Height in pixels

Return the left padding of the parent RecyclerView

Returns:

Padding in pixels

Return the top padding of the parent RecyclerView

Returns:

Padding in pixels

Return the right padding of the parent RecyclerView

Returns:

Padding in pixels

Return the bottom padding of the parent RecyclerView

Returns:

Padding in pixels

Return the start padding of the parent RecyclerView

Returns:

Padding in pixels

Return the end padding of the parent RecyclerView

Returns:

Padding in pixels

Returns true if the RecyclerView this LayoutManager is bound to has focus.

Returns:

True if the RecyclerView has focus, false otherwise.

See also: View

Returns true if the RecyclerView this LayoutManager is bound to has or contains focus.

Returns:

true if the RecyclerView has or contains focus

See also: View

Returns the item View which has or contains focus.

Returns:

A direct child of RecyclerView which has focus or contains the focused child.

Returns the number of items in the adapter bound to the parent RecyclerView.

Note that this number is not necessarily equal to State#getItemCount(). In methods where RecyclerView.State is available, you should use State#getItemCount() instead. For more details, check the documentation for State#getItemCount().

Returns:

The number of items in the bound adapter

See also: RecyclerView.State.getItemCount()

Offset all child views attached to the parent RecyclerView by dx pixels along the horizontal axis.

Parameters:

dx: Pixels to offset by

Offset all child views attached to the parent RecyclerView by dy pixels along the vertical axis.

Parameters:

dy: Pixels to offset by

Flags a view so that it will not be scrapped or recycled.

Scope of ignoring a child is strictly restricted to position tracking, scrapping and recyling. Methods like RecyclerView.LayoutManager will ignore the child whereas RecyclerView.LayoutManager.removeAllViews() or RecyclerView.LayoutManager.offsetChildrenHorizontal(int) will not ignore the child.

Before this child can be recycled again, you have to call RecyclerView.LayoutManager.stopIgnoringView(View).

You can call this method only if your LayoutManger is in onLayout or onScroll callback.

Parameters:

view: View to ignore.

See also: RecyclerView.LayoutManager.stopIgnoringView(View)

View can be scrapped and recycled again.

Note that calling this method removes all information in the view holder.

You can call this method only if your LayoutManger is in onLayout or onScroll callback.

Parameters:

view: View to ignore.

Temporarily detach and scrap all currently attached child views. Views will be scrapped into the given Recycler. The Recycler may prefer to reuse scrap views before other views that were previously recycled.

Parameters:

recycler: Recycler to scrap views into

Measure a child view using standard measurement policy, taking the padding of the parent RecyclerView and any added item decorations into account.

If the RecyclerView can be scrolled in either dimension the caller may pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.

Parameters:

child: Child view to measure
widthUsed: Width in pixels currently consumed by other views, if relevant
heightUsed: Height in pixels currently consumed by other views, if relevant

In addition to the View Framework's measurement cache, RecyclerView uses its own additional measurement cache for its children to avoid re-measuring them when not necessary. It is on by default but it can be turned off via RecyclerView.LayoutManager.setMeasurementCacheEnabled(boolean).

Returns:

True if measurement cache is enabled, false otherwise.

See also: RecyclerView.LayoutManager.setMeasurementCacheEnabled(boolean)

Sets whether RecyclerView should use its own measurement cache for the children. This is a more aggressive cache than the framework uses.

Parameters:

measurementCacheEnabled: True to enable the measurement cache, false otherwise.

See also: RecyclerView.LayoutManager.isMeasurementCacheEnabled()

Measure a child view using standard measurement policy, taking the padding of the parent RecyclerView, any added item decorations and the child margins into account.

If the RecyclerView can be scrolled in either dimension the caller may pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.

Parameters:

child: Child view to measure
widthUsed: Width in pixels currently consumed by other views, if relevant
heightUsed: Height in pixels currently consumed by other views, if relevant

Deprecated: use RecyclerView.LayoutManager.getChildMeasureSpec(int, int, int, int, boolean)

Calculate a MeasureSpec value for measuring a child view in one dimension.

Parameters:

parentSize: Size of the parent view where the child will be placed
padding: Total space currently consumed by other elements of the parent
childDimension: Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT. Generally obtained from the child view's LayoutParams
canScroll: true if the parent RecyclerView can scroll in this dimension

Returns:

a MeasureSpec value for the child view

Calculate a MeasureSpec value for measuring a child view in one dimension.

Parameters:

parentSize: Size of the parent view where the child will be placed
parentMode: The measurement spec mode of the parent
padding: Total space currently consumed by other elements of parent
childDimension: Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT. Generally obtained from the child view's LayoutParams
canScroll: true if the parent RecyclerView can scroll in this dimension

Returns:

a MeasureSpec value for the child view

Returns the measured width of the given child, plus the additional size of any insets applied by ItemDecorations.

Parameters:

child: Child view to query

Returns:

child's measured width plus ItemDecoration insets

See also: View

Returns the measured height of the given child, plus the additional size of any insets applied by ItemDecorations.

Parameters:

child: Child view to query

Returns:

child's measured height plus ItemDecoration insets

See also: View

Lay out the given child view within the RecyclerView using coordinates that include any current ItemDecorations.

LayoutManagers should prefer working in sizes and coordinates that include item decoration insets whenever possible. This allows the LayoutManager to effectively ignore decoration insets within measurement and layout code. See the following methods:

• RecyclerView.LayoutManager.layoutDecoratedWithMargins(View, int, int, int, int)
• RecyclerView.LayoutManager.getDecoratedBoundsWithMargins(View, Rect)
• RecyclerView.LayoutManager.measureChild(View, int, int)
• RecyclerView.LayoutManager.measureChildWithMargins(View, int, int)
• RecyclerView.LayoutManager.getDecoratedLeft(View)
• RecyclerView.LayoutManager.getDecoratedTop(View)
• RecyclerView.LayoutManager.getDecoratedRight(View)
• RecyclerView.LayoutManager.getDecoratedBottom(View)
• RecyclerView.LayoutManager.getDecoratedMeasuredWidth(View)
• RecyclerView.LayoutManager.getDecoratedMeasuredHeight(View)

Parameters:

child: Child to lay out
left: Left edge, with item decoration insets included
top: Top edge, with item decoration insets included
right: Right edge, with item decoration insets included
bottom: Bottom edge, with item decoration insets included

See also: View, RecyclerView.LayoutManager.layoutDecoratedWithMargins(View, int, int, int, int)

Lay out the given child view within the RecyclerView using coordinates that include any current ItemDecorations and margins.

LayoutManagers should prefer working in sizes and coordinates that include item decoration insets whenever possible. This allows the LayoutManager to effectively ignore decoration insets within measurement and layout code. See the following methods:

• RecyclerView.LayoutManager.layoutDecorated(View, int, int, int, int)
• RecyclerView.LayoutManager.measureChild(View, int, int)
• RecyclerView.LayoutManager.measureChildWithMargins(View, int, int)
• RecyclerView.LayoutManager.getDecoratedLeft(View)
• RecyclerView.LayoutManager.getDecoratedTop(View)
• RecyclerView.LayoutManager.getDecoratedRight(View)
• RecyclerView.LayoutManager.getDecoratedBottom(View)
• RecyclerView.LayoutManager.getDecoratedMeasuredWidth(View)
• RecyclerView.LayoutManager.getDecoratedMeasuredHeight(View)

Parameters:

child: Child to lay out
left: Left edge, with item decoration insets and left margin included
top: Top edge, with item decoration insets and top margin included
right: Right edge, with item decoration insets and right margin included
bottom: Bottom edge, with item decoration insets and bottom margin included

See also: View, RecyclerView.LayoutManager.layoutDecorated(View, int, int, int, int)

Calculates the bounding box of the View while taking into account its matrix changes (translation, scale etc) with respect to the RecyclerView.

If includeDecorInsets is true, they are applied first before applying the View's matrix so that the decor offsets also go through the same transformation.

Parameters:

child: The ItemView whose bounding box should be calculated.
includeDecorInsets: True if the decor insets should be included in the bounding box
out: The rectangle into which the output will be written.

Returns the bounds of the view including its decoration and margins.

Parameters:

view: The view element to check
outBounds: A rect that will receive the bounds of the element including its decoration and margins.

Returns the left edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters:

child: Child to query

Returns:

Child left edge with offsets applied

See also: RecyclerView.LayoutManager.getLeftDecorationWidth(View)

Returns the top edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters:

child: Child to query

Returns:

Child top edge with offsets applied

See also: RecyclerView.LayoutManager.getTopDecorationHeight(View)

Returns the right edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters:

child: Child to query

Returns:

Child right edge with offsets applied

See also: RecyclerView.LayoutManager.getRightDecorationWidth(View)

Returns the bottom edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters:

child: Child to query

Returns:

Child bottom edge with offsets applied

See also: RecyclerView.LayoutManager.getBottomDecorationHeight(View)

Calculates the item decor insets applied to the given child and updates the provided Rect instance with the inset values.

• The Rect's left is set to the total width of left decorations.
• The Rect's top is set to the total height of top decorations.
• The Rect's right is set to the total width of right decorations.
• The Rect's bottom is set to total height of bottom decorations.

Note that item decorations are automatically calculated when one of the LayoutManager's measure child methods is called. If you need to measure the child with custom specs via View, you can use this method to get decorations.

Parameters:

child: The child view whose decorations should be calculated
outRect: The Rect to hold result values

Returns the total height of item decorations applied to child's top.

Note that this value is not updated until the View is measured or RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect) is called.

Parameters:

child: Child to query

Returns:

The total height of item decorations applied to the child's top.

See also: RecyclerView.LayoutManager.getDecoratedTop(View), RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect)

Returns the total height of item decorations applied to child's bottom.

Note that this value is not updated until the View is measured or RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect) is called.

Parameters:

child: Child to query

Returns:

The total height of item decorations applied to the child's bottom.

See also: RecyclerView.LayoutManager.getDecoratedBottom(View), RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect)

Returns the total width of item decorations applied to child's left.

Note that this value is not updated until the View is measured or RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect) is called.

Parameters:

child: Child to query

Returns:

The total width of item decorations applied to the child's left.

See also: RecyclerView.LayoutManager.getDecoratedLeft(View), RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect)

Returns the total width of item decorations applied to child's right.

Note that this value is not updated until the View is measured or RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect) is called.

Parameters:

child: Child to query

Returns:

The total width of item decorations applied to the child's right.

See also: RecyclerView.LayoutManager.getDecoratedRight(View), RecyclerView.LayoutManager.calculateItemDecorationsForChild(View, Rect)

Called when searching for a focusable view in the given direction has failed for the current content of the RecyclerView.

This is the LayoutManager's opportunity to populate views in the given direction to fulfill the request if it can. The LayoutManager should attach and return the view to be focused, if a focusable view in the given direction is found. Otherwise, if all the existing (or the newly populated views) are unfocusable, it returns the next unfocusable view to become visible on the screen. This unfocusable view is typically the first view that's either partially or fully out of RV's padded bounded area in the given direction. The default implementation returns null.

Parameters:

focused: The currently focused view
direction: One of View, View, View, View, View, View or 0 for not applicable
recycler: The recycler to use for obtaining views for currently offscreen items
state: Transient state of RecyclerView

Returns:

The chosen view to be focused if a focusable view is found, otherwise an unfocusable view to become visible onto the screen, else null.

This method gives a LayoutManager an opportunity to intercept the initial focus search before the default behavior of is used. If this method returns null FocusFinder will attempt to find a focusable child view. If it fails then RecyclerView.LayoutManager.onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State) will be called to give the LayoutManager an opportunity to add new views for items that did not have attached views representing them. The LayoutManager should not add or remove views from this method.

Parameters:

focused: The currently focused view
direction: One of View, View, View, View, View, View

Returns:

A descendant view to focus or null to fall back to default behavior. The default implementation returns null.

Called when a child of the RecyclerView wants a particular rectangle to be positioned onto the screen. See for more details.

The base implementation will attempt to perform a standard programmatic scroll to bring the given rect into view, within the padded area of the RecyclerView.

Parameters:

child: The direct child making the request.
rect: The rectangle in the child's coordinates the child wishes to be on the screen.
immediate: True to forbid animated or delayed scrolling, false otherwise

Returns:

Whether the group scrolled to handle the operation

Requests that the given child of the RecyclerView be positioned onto the screen. This method can be called for both unfocusable and focusable child views. For unfocusable child views, focusedChildVisible is typically true in which case, layout manager makes the child view visible only if the currently focused child stays in-bounds of RV.

Parameters:

parent: The parent RecyclerView.
child: The direct child making the request.
rect: The rectangle in the child's coordinates the child wishes to be on the screen.
immediate: True to forbid animated or delayed scrolling, false otherwise
focusedChildVisible: Whether the currently focused view must stay visible.

Returns:

Whether the group scrolled to handle the operation

Returns whether the given child view is partially or fully visible within the padded bounded area of RecyclerView, depending on the input parameters. A view is partially visible if it has non-zero overlap with RV's padded bounded area. If acceptEndPointInclusion flag is set to true, it's also considered partially visible if it's located outside RV's bounds and it's hitting either RV's start or end bounds.

Parameters:

child: The child view to be examined.
completelyVisible: If true, the method returns true if and only if the child is completely visible. If false, the method returns true if and only if the child is only partially visible (that is it will return false if the child is either completely visible or out of RV's bounds).
acceptEndPointInclusion: If the view's endpoint intersection with RV's start of end bounds is enough to consider it partially visible, false otherwise.

Returns:

True if the given child is partially or fully visible, false otherwise.

Deprecated: Use RecyclerView.LayoutManager

Called when a descendant view of the RecyclerView requests focus.

A LayoutManager wishing to keep focused views aligned in a specific portion of the view may implement that behavior in an override of this method.

If the LayoutManager executes different behavior that should override the default behavior of scrolling the focused child on screen instead of running alongside it, this method should return true.

Parameters:

parent: The RecyclerView hosting this LayoutManager
state: Current state of RecyclerView
child: Direct child of the RecyclerView containing the newly focused view
focused: The newly focused view. This may be the same view as child or it may be null

Returns:

true if the default scroll behavior should be suppressed

Called if the RecyclerView this LayoutManager is bound to has a different adapter set via RecyclerView.setAdapter(RecyclerView.Adapter) or RecyclerView.swapAdapter(RecyclerView.Adapter, boolean). The LayoutManager may use this opportunity to clear caches and configure state such that it can relayout appropriately with the new data and potentially new view types.

The default implementation removes all currently attached views.

Parameters:

oldAdapter: The previous adapter instance. Will be null if there was previously no adapter.
newAdapter: The new adapter instance. Might be null if RecyclerView.setAdapter(RecyclerView.Adapter) is called with null.

Called to populate focusable views within the RecyclerView.

The LayoutManager implementation should return true if the default behavior of ViewGroup should be suppressed.

The default implementation returns false to trigger RecyclerView to fall back to the default ViewGroup behavior.

Parameters:

recyclerView: The RecyclerView hosting this LayoutManager
views: List of output views. This method should add valid focusable views to this list.
direction: One of View, View, View, View, View, View
focusableMode: The type of focusables to be added.

Returns:

true to suppress the default behavior, false to add default focusables after this method returns.

See also: RecyclerView.LayoutManager, RecyclerView.LayoutManager

Called in response to a call to RecyclerView.Adapter.notifyDataSetChanged() or RecyclerView.swapAdapter(RecyclerView.Adapter, boolean) ()} and signals that the the entire data set has changed.

Called when items have been added to the adapter. The LayoutManager may choose to requestLayout if the inserted items would require refreshing the currently visible set of child views. (e.g. currently empty space would be filled by appended items, etc.)

Called when items have been removed from the adapter.

Called when items have been changed in the adapter. To receive payload, override RecyclerView.LayoutManager.onItemsUpdated(RecyclerView, int, int, Object) instead, then this callback will not be invoked.

Called when items have been changed in the adapter and with optional payload. Default implementation calls RecyclerView.LayoutManager.onItemsUpdated(RecyclerView, int, int).

Called when an item is moved withing the adapter.

Note that, an item may also change position in response to another ADD/REMOVE/MOVE operation. This callback is only called if and only if RecyclerView.Adapter.notifyItemMoved(int, int) is called.

Override this method if you want to support scroll bars.

Read RecyclerView.computeHorizontalScrollExtent() for details.

Default implementation returns 0.

Parameters:

state: Current state of RecyclerView

Returns:

The horizontal extent of the scrollbar's thumb

See also: RecyclerView.computeHorizontalScrollExtent()

Override this method if you want to support scroll bars.

Read RecyclerView.computeHorizontalScrollOffset() for details.

Default implementation returns 0.

Parameters:

state: Current State of RecyclerView where you can find total item count

Returns:

The horizontal offset of the scrollbar's thumb

See also: RecyclerView.computeHorizontalScrollOffset()

Override this method if you want to support scroll bars.

Read RecyclerView.computeHorizontalScrollRange() for details.

Default implementation returns 0.

Parameters:

state: Current State of RecyclerView where you can find total item count

Returns:

The total horizontal range represented by the vertical scrollbar

See also: RecyclerView.computeHorizontalScrollRange()

Override this method if you want to support scroll bars.

Read RecyclerView.computeVerticalScrollExtent() for details.

Default implementation returns 0.

Parameters:

state: Current state of RecyclerView

Returns:

The vertical extent of the scrollbar's thumb

See also: RecyclerView.computeVerticalScrollExtent()

Override this method if you want to support scroll bars.

Read RecyclerView.computeVerticalScrollOffset() for details.

Default implementation returns 0.

Parameters:

state: Current State of RecyclerView where you can find total item count

Returns:

The vertical offset of the scrollbar's thumb

See also: RecyclerView.computeVerticalScrollOffset()

Override this method if you want to support scroll bars.

Read RecyclerView.computeVerticalScrollRange() for details.

Default implementation returns 0.

Parameters:

state: Current State of RecyclerView where you can find total item count

Returns:

The total vertical range represented by the vertical scrollbar

See also: RecyclerView.computeVerticalScrollRange()

Measure the attached RecyclerView. Implementations must call RecyclerView.LayoutManager.setMeasuredDimension(int, int) before returning.

It is strongly advised to use the AutoMeasure mechanism by overriding RecyclerView.LayoutManager.isAutoMeasureEnabled() to return true as AutoMeasure handles all the standard measure cases including when the RecyclerView's layout_width or layout_height have been set to wrap_content. If RecyclerView.LayoutManager.isAutoMeasureEnabled() is overridden to return true, this method should not be overridden.

The default implementation will handle EXACTLY measurements and respect the minimum width and height properties of the host RecyclerView if measured as UNSPECIFIED. AT_MOST measurements will be treated as EXACTLY and the RecyclerView will consume all available space.

Parameters:

recycler: Recycler
state: Transient state of RecyclerView
widthSpec: Width
heightSpec: Height

See also: RecyclerView.LayoutManager.isAutoMeasureEnabled(), RecyclerView.LayoutManager.setMeasuredDimension(int, int)

Set the measured dimensions of the host RecyclerView.

Parameters:

widthSize: Measured width
heightSize: Measured height

Returns:

The host RecyclerView's View

Returns:

The host RecyclerView's View

Called when the LayoutManager should save its state. This is a good time to save your scroll position, configuration and anything else that may be required to restore the same layout state if the LayoutManager is recreated.

RecyclerView does NOT verify if the LayoutManager has changed between state save and restore. This will let you share information between your LayoutManagers but it is also your responsibility to make sure they use the same parcelable class.

Returns:

Necessary information for LayoutManager to be able to restore its state

Called when the RecyclerView is ready to restore the state based on a previous RecyclerView. Notice that this might happen after an actual layout, based on how Adapter prefers to restore State. See RecyclerView.Adapter.getStateRestorationPolicy() for more information.

Parameters:

state: The parcelable that was returned by the previous LayoutManager's RecyclerView.LayoutManager.onSaveInstanceState() method.

RecyclerView calls this method to notify LayoutManager that scroll state has changed.

Parameters:

state: The new scroll state for RecyclerView

Removes all views and recycles them using the given recycler.

If you want to clean cached views as well, you should call RecyclerView.Recycler.clear() too.

If a View is marked as "ignored", it is not removed nor recycled.

Parameters:

recycler: Recycler to use to recycle children

See also: RecyclerView.LayoutManager, RecyclerView.LayoutManager, RecyclerView.LayoutManager.ignoreView(View)

Called by the AccessibilityDelegate when the information about the current layout should be populated.

Default implementation adds a AccessibilityNodeInfoCompat.CollectionInfoCompat.

You should override RecyclerView.LayoutManager.getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), RecyclerView.LayoutManager.getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), RecyclerView.LayoutManager.isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State) and RecyclerView.LayoutManager.getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State) for more accurate accessibility information.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView
info: The info that should be filled by the LayoutManager

See also: View, RecyclerView.LayoutManager.getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), RecyclerView.LayoutManager.getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), RecyclerView.LayoutManager.isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State), RecyclerView.LayoutManager.getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State)

Called by the accessibility delegate to initialize an accessibility event.

Default implementation adds item count and scroll information to the event.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView
event: The event instance to initialize

See also: View

Called by the AccessibilityDelegate when the accessibility information for a specific item should be populated.

Default implementation adds basic positioning information about the item.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView
host: The child for which accessibility node info should be populated
info: The info to fill out about the item

See also: android.widget.AbsListView

A LayoutManager can call this method to force RecyclerView to run simple animations in the next layout pass, even if there is not any trigger to do so. (e.g. adapter data change).

Note that, calling this method will not guarantee that RecyclerView will run animations at all. For example, if there is not any RecyclerView.ItemAnimator set, RecyclerView will not run any animations but will still clear this flag after the layout is complete.

Returns the selection mode for accessibility. Should be , or .

Default implementation returns .

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView

Returns:

Selection mode for accessibility. Default implementation returns .

Returns the number of rows for accessibility.

Default implementation returns the number of items in the adapter if LayoutManager supports vertical scrolling or 1 if LayoutManager does not support vertical scrolling.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView

Returns:

The number of rows in LayoutManager for accessibility.

Returns the number of columns for accessibility.

Default implementation returns the number of items in the adapter if LayoutManager supports horizontal scrolling or 1 if LayoutManager does not support horizontal scrolling.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView

Returns:

The number of rows in LayoutManager for accessibility.

Returns whether layout is hierarchical or not to be used for accessibility.

Default implementation returns false.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView

Returns:

True if layout is hierarchical.

Called by AccessibilityDelegate when an action is requested from the RecyclerView.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView
action: The action to perform
args: Optional action arguments

See also: View

Called by AccessibilityDelegate when an accessibility action is requested on one of the children of LayoutManager.

Default implementation does not do anything.

Parameters:

recycler: The Recycler that can be used to convert view positions into adapter positions
state: The current state of RecyclerView
view: The child view on which the action is performed
action: The action to perform
args: Optional action arguments

Returns:

true if action is handled

See also: View

Parse the xml attributes to get the most common properties used by layout managers.

Returns:

an object containing the properties as specified in the attrs.