GridLayoutManager


public final class GridLayoutManager extends RecyclerView.LayoutManager


A RecyclerView.LayoutManager implementation that lays out items in a grid for leanback VerticalGridView and HorizontalGridView.

Summary

Public constructors

Public methods

boolean

Query if horizontal scrolling is currently supported.

boolean

Query if vertical scrolling is currently supported.

boolean

Determines the validity of the supplied LayoutParams object.

void
collectAdjacentPrefetchPositions(
    int dx,
    int dy,
    @NonNull RecyclerView.State state,
    @NonNull RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry
)

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

void
collectInitialPrefetchPositions(
    int adapterItemCount,
    @NonNull RecyclerView.LayoutManager.LayoutPrefetchRegistry 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.

@NonNull RecyclerView.LayoutParams

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

@NonNull RecyclerView.LayoutParams

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

@NonNull RecyclerView.LayoutParams

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

int

Returns the number of columns for accessibility.

int

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

void

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

int

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

int

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

int

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

int

Returns the number of rows for accessibility.

void

Called if the RecyclerView this LayoutManager is bound to has a different adapter set via setAdapter or swapAdapter.

boolean
onAddFocusables(
    @NonNull RecyclerView recyclerView,
    @NonNull ArrayList<View> views,
    int direction,
    int focusableMode
)

Called to populate focusable views within the RecyclerView.

void

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

void

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

@Nullable View
onInterceptFocusSearch(@Nullable View focused, int direction)

This method gives a LayoutManager an opportunity to intercept the initial focus search before the default behavior of FocusFinder is used.

void
onItemsAdded(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount
)

Called when items have been added to the adapter.

void

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

void
onItemsMoved(
    @NonNull RecyclerView recyclerView,
    int fromPosition,
    int toPosition,
    int itemCount
)

Called when an item is moved withing the adapter.

void
onItemsRemoved(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount
)

Called when items have been removed from the adapter.

void
onItemsUpdated(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount
)

Called when items have been changed in the adapter.

void

Lay out all relevant child views from the given adapter.

void

Called after a full layout calculation is finished.

void
onMeasure(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    int widthSpec,
    int heightSpec
)

Measure the attached RecyclerView.

boolean
onRequestChildFocus(
    @NonNull RecyclerView parent,
    @NonNull RecyclerView.State state,
    @NonNull View child,
    @Nullable View focused
)

Called when a descendant view of the RecyclerView requests focus.

void

Called when the RecyclerView is ready to restore the state based on a previous RecyclerView.

@NonNull Parcelable

Called when the LayoutManager should save its state.

boolean
performAccessibilityAction(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    int action,
    @Nullable Bundle args
)

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

void

Removes all views and recycles them using the given recycler.

boolean
requestChildRectangleOnScreen(
    @NonNull RecyclerView parent,
    @NonNull View child,
    @NonNull Rect rect,
    boolean immediate
)

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

int
scrollHorizontallyBy(
    int dx,
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

Scroll horizontally by dx pixels in screen coordinates and return the distance traveled.

void
scrollToPosition(int position)

Scroll to the specified adapter position.

int
scrollVerticallyBy(
    int dy,
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

Scroll vertically by dy pixels in screen coordinates and return the distance traveled.

void
setFocusOutAllowed(boolean throughFront, boolean throughBack)

Sets whether focus can move out from the front and/or back of the grid view.

void
setOrientation(int orientation)

Sets grid view orientation.

void
smoothScrollToPosition(
    @NonNull RecyclerView recyclerView,
    @NonNull RecyclerView.State state,
    int position
)

Smooth scroll to the specified adapter position.

void

Starts a smooth scroll using the provided SmoothScroller.

boolean

Returns whether this LayoutManager supports "predictive item animations".

Inherited methods

From androidx.recyclerview.widget.RecyclerView.LayoutManager
void

To be called only during onLayoutChildren 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.

void
addDisappearingView(View child, int index)

To be called only during onLayoutChildren 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.

void
addView(View child)

Add a view to the currently attached RecyclerView if needed.

void
addView(View child, int index)

Add a view to the currently attached RecyclerView if needed.

void

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

void

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

void

Reattach a previously detached view.

void
attachView(@NonNull View child, int index)

Reattach a previously detached view.

void
attachView(@NonNull View child, int index, RecyclerView.LayoutParams lp)

Reattach a previously detached view.

void
calculateItemDecorationsForChild(
    @NonNull View child,
    @NonNull Rect outRect
)

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

static int
chooseSize(int spec, int desired, int min)

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

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

void

Temporarily detach and scrap all currently attached child views.

void
detachAndScrapView(
    @NonNull View child,
    @NonNull RecyclerView.Recycler recycler
)

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

void

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

void

Temporarily detach a child view.

void
detachViewAt(int index)

Temporarily detach a child view.

void

Ends all animations on the view created by the ItemAnimator.

@Nullable View

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

@Nullable View
findViewByPosition(int position)

Finds the view which represents the given adapter position.

int

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

int

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

@Nullable View
getChildAt(int index)

Return the child view at the given index

int

Return the current number of child views attached to the parent RecyclerView.

static int
getChildMeasureSpec(
    int parentSize,
    int padding,
    int childDimension,
    boolean canScroll
)

This method is deprecated.

use getChildMeasureSpec

static int
getChildMeasureSpec(
    int parentSize,
    int parentMode,
    int padding,
    int childDimension,
    boolean canScroll
)

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

boolean

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

int

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

int

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

@Nullable View

Returns the item View which has or contains focus.

@Px int

Returns the height that is currently relevant to the LayoutManager.

int

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

int

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

int

Returns the View type defined by the adapter.

int

Returns the resolved layout direction for this RecyclerView.

int

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

@Px int
@Px int
@Px int

Return the bottom padding of the parent RecyclerView

@Px int

Return the end padding of the parent RecyclerView

@Px int

Return the left padding of the parent RecyclerView

@Px int

Return the right padding of the parent RecyclerView

@Px int

Return the start padding of the parent RecyclerView

@Px int

Return the top padding of the parent RecyclerView

int

Returns the adapter position of the item represented by the given View.

static RecyclerView.LayoutManager.Properties
getProperties(
    @NonNull Context context,
    @Nullable AttributeSet attrs,
    int defStyleAttr,
    int defStyleRes
)

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

int

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

int

Returns the selection mode for accessibility.

int

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

void
getTransformedBoundingBox(
    @NonNull View child,
    boolean includeDecorInsets,
    @NonNull Rect out
)

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

@Px int

Returns the width that is currently relevant to the LayoutManager.

int

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

boolean

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

void

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

boolean

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

boolean

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 onMeasure.

boolean

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

final boolean

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

boolean

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

boolean

Query if the layout is in reverse order.

boolean

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.

boolean
boolean
isViewPartiallyVisible(
    @NonNull View child,
    boolean completelyVisible,
    boolean acceptEndPointInclusion
)

Returns whether the given child view is partially or fully visible within the padded bounded area of RecyclerView, depending on the input parameters.

void
layoutDecorated(
    @NonNull View child,
    int left,
    int top,
    int right,
    int bottom
)

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

void
layoutDecoratedWithMargins(
    @NonNull View child,
    int left,
    int top,
    int right,
    int bottom
)

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

void
measureChild(@NonNull View child, int widthUsed, int heightUsed)

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

void
measureChildWithMargins(
    @NonNull View child,
    int widthUsed,
    int heightUsed
)

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.

void
moveView(int fromIndex, int toIndex)

Moves a View from one position to another.

void

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

void

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

void

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

void

This method is deprecated.

override onDetachedFromWindow

void

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

@Nullable View
onFocusSearchFailed(
    @NonNull View focused,
    int direction,
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

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

void
void

Called by the accessibility delegate to initialize an accessibility event.

void
onItemsUpdated(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount,
    @Nullable Object payload
)

Called when items have been changed in the adapter and with optional payload.

boolean
onRequestChildFocus(
    @NonNull RecyclerView parent,
    @NonNull View child,
    @Nullable View focused
)

This method is deprecated.

Use onRequestChildFocus

void

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

boolean
performAccessibilityActionForItem(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    @NonNull View view,
    int action,
    @Nullable Bundle args
)

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

void

Causes the Runnable to execute on the next animation time step.

void

Remove all views from the currently attached RecyclerView.

void
removeAndRecycleView(
    @NonNull View child,
    @NonNull RecyclerView.Recycler recycler
)

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

void
removeAndRecycleViewAt(
    int index,
    @NonNull RecyclerView.Recycler recycler
)

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

boolean

Removes the specified Runnable from the message queue.

void

Finish removing a view that was previously temporarily detached.

void

Remove a view from the currently attached RecyclerView if needed.

void
removeViewAt(int index)

Remove a view from the currently attached RecyclerView if needed.

boolean
requestChildRectangleOnScreen(
    @NonNull RecyclerView parent,
    @NonNull View child,
    @NonNull Rect rect,
    boolean immediate,
    boolean focusedChildVisible
)

Requests that the given child of the RecyclerView be positioned onto the screen.

void

Calls RecyclerView#requestLayout on the underlying RecyclerView

void

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.

void
setAutoMeasureEnabled(boolean enabled)

This method is deprecated.

Implementors of LayoutManager should define whether or not it uses AutoMeasure by overriding isAutoMeasureEnabled.

final void
setItemPrefetchEnabled(boolean enabled)

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

void
setMeasuredDimension(int widthSize, int heightSize)

Set the measured dimensions of the host RecyclerView.

void
setMeasuredDimension(Rect childrenBounds, int wSpec, int hSpec)

Sets the measured dimensions from the given bounding box of the children and the measurement specs that were passed into onMeasure.

void
setMeasurementCacheEnabled(boolean measurementCacheEnabled)

Sets whether RecyclerView should use its own measurement cache for the children.

void

View can be scrapped and recycled again.

Public constructors

GridLayoutManager

Added in 1.0.0-alpha03
public GridLayoutManager()

Public methods

canScrollHorizontally

public boolean canScrollHorizontally()

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

Returns
boolean

True if this LayoutManager can scroll the current contents horizontally

canScrollVertically

public boolean canScrollVertically()

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

Returns
boolean

True if this LayoutManager can scroll the current contents vertically

checkLayoutParams

public boolean checkLayoutParams(@Nullable RecyclerView.LayoutParams lp)

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
@Nullable RecyclerView.LayoutParams lp

LayoutParams object to check

Returns
boolean

true if this LayoutParams object is valid, false otherwise

collectAdjacentPrefetchPositions

public void collectAdjacentPrefetchPositions(
    int dx,
    int dy,
    @NonNull RecyclerView.State state,
    @NonNull RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry
)

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 addPosition 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
int dx

X movement component.

int dy

Y movement component.

@NonNull RecyclerView.State state

State of RecyclerView

@NonNull RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry

PrefetchRegistry to add prefetch entries into.

collectInitialPrefetchPositions

public void collectInitialPrefetchPositions(
    int adapterItemCount,
    @NonNull RecyclerView.LayoutManager.LayoutPrefetchRegistry 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 addPosition 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
int adapterItemCount

number of items in the associated adapter.

@NonNull RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry

PrefetchRegistry to add prefetch entries into.

generateDefaultLayoutParams

Added in 1.0.0-alpha03
public @NonNull RecyclerView.LayoutParams generateDefaultLayoutParams()

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 for this purpose.

Important: if you use your own custom LayoutParams type you must also override #checkLayoutParams(LayoutParams), #generateLayoutParams(android.view.ViewGroup.LayoutParams) and #generateLayoutParams(android.content.Context, android.util.AttributeSet).

generateLayoutParams

public @NonNull RecyclerView.LayoutParams generateLayoutParams(@NonNull ViewGroup.LayoutParams lp)

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 #checkLayoutParams(LayoutParams), #generateLayoutParams(android.view.ViewGroup.LayoutParams) and #generateLayoutParams(android.content.Context, android.util.AttributeSet).

generateLayoutParams

public @NonNull RecyclerView.LayoutParams generateLayoutParams(@NonNull Context context, @NonNull AttributeSet attrs)

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 #checkLayoutParams(LayoutParams), #generateLayoutParams(android.view.ViewGroup.LayoutParams) and #generateLayoutParams(android.content.Context, android.util.AttributeSet).

getColumnCountForAccessibility

public int getColumnCountForAccessibility(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

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
@NonNull RecyclerView.Recycler recycler

The Recycler that can be used to convert view positions into adapter positions

@NonNull RecyclerView.State state

The current state of RecyclerView

Returns
int

The number of rows in LayoutManager for accessibility.

getDecoratedBottom

public int getDecoratedBottom(@NonNull View child)

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

Parameters
@NonNull View child

Child to query

Returns
int

Child bottom edge with offsets applied

getDecoratedBoundsWithMargins

public void getDecoratedBoundsWithMargins(@NonNull View view, @NonNull Rect outBounds)

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

Parameters
@NonNull View view

The view element to check

@NonNull Rect outBounds

A rect that will receive the bounds of the element including its decoration and margins.

getDecoratedLeft

public int getDecoratedLeft(@NonNull View child)

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

Parameters
@NonNull View child

Child to query

Returns
int

Child left edge with offsets applied

getDecoratedRight

public int getDecoratedRight(@NonNull View child)

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

Parameters
@NonNull View child

Child to query

Returns
int

Child right edge with offsets applied

getDecoratedTop

public int getDecoratedTop(@NonNull View child)

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

Parameters
@NonNull View child

Child to query

Returns
int

Child top edge with offsets applied

getRowCountForAccessibility

public int getRowCountForAccessibility(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

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
@NonNull RecyclerView.Recycler recycler

The Recycler that can be used to convert view positions into adapter positions

@NonNull RecyclerView.State state

The current state of RecyclerView

Returns
int

The number of rows in LayoutManager for accessibility.

onAdapterChanged

public void onAdapterChanged(
    @Nullable RecyclerView.Adapter oldAdapter,
    @Nullable RecyclerView.Adapter newAdapter
)

Called if the RecyclerView this LayoutManager is bound to has a different adapter set via setAdapter or swapAdapter. 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
@Nullable RecyclerView.Adapter oldAdapter

The previous adapter instance. Will be null if there was previously no adapter.

@Nullable RecyclerView.Adapter newAdapter

The new adapter instance. Might be null if setAdapter is called with null.

onAddFocusables

public boolean onAddFocusables(
    @NonNull RecyclerView recyclerView,
    @NonNull ArrayList<View> views,
    int direction,
    int focusableMode
)

Called to populate focusable views within the RecyclerView.

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

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

Parameters
@NonNull RecyclerView recyclerView

The RecyclerView hosting this LayoutManager

@NonNull ArrayList<View> views

List of output views. This method should add valid focusable views to this list.

int direction

One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_BACKWARD, FOCUS_FORWARD

int focusableMode

The type of focusables to be added.

Returns
boolean

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

onInitializeAccessibilityNodeInfo

public void onInitializeAccessibilityNodeInfo(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    @NonNull AccessibilityNodeInfoCompat info
)

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

Default implementation adds a .

You should override getRowCountForAccessibility, getColumnCountForAccessibility, isLayoutHierarchical and getSelectionModeForAccessibility for more accurate accessibility information.

Parameters
@NonNull RecyclerView.Recycler recycler

The Recycler that can be used to convert view positions into adapter positions

@NonNull RecyclerView.State state

The current state of RecyclerView

@NonNull AccessibilityNodeInfoCompat info

The info that should be filled by the LayoutManager

onInitializeAccessibilityNodeInfoForItem

public void onInitializeAccessibilityNodeInfoForItem(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    @NonNull View host,
    @NonNull AccessibilityNodeInfoCompat info
)

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
@NonNull RecyclerView.Recycler recycler

The Recycler that can be used to convert view positions into adapter positions

@NonNull RecyclerView.State state

The current state of RecyclerView

@NonNull View host

The child for which accessibility node info should be populated

@NonNull AccessibilityNodeInfoCompat info

The info to fill out about the item

onInterceptFocusSearch

public @Nullable View onInterceptFocusSearch(@Nullable View focused, int direction)

This method gives a LayoutManager an opportunity to intercept the initial focus search before the default behavior of FocusFinder is used. If this method returns null FocusFinder will attempt to find a focusable child view. If it fails then onFocusSearchFailed 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
@Nullable View focused

The currently focused view

int direction

One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_BACKWARD, FOCUS_FORWARD

Returns
@Nullable View

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

onItemsAdded

public void onItemsAdded(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount
)

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.)

onItemsChanged

public void onItemsChanged(@NonNull RecyclerView recyclerView)

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

onItemsMoved

public void onItemsMoved(
    @NonNull RecyclerView recyclerView,
    int fromPosition,
    int toPosition,
    int itemCount
)

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 notifyItemMoved is called.

onItemsRemoved

public void onItemsRemoved(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount
)

Called when items have been removed from the adapter.

onItemsUpdated

public void onItemsUpdated(
    @NonNull RecyclerView recyclerView,
    int positionStart,
    int itemCount
)

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

onLayoutChildren

public void onLayoutChildren(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

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 supportsPredictiveItemAnimations, which is the default, and runs a normal layout operation during onLayoutChildren, 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 supportsPredictiveItemAnimations and add additional logic to onLayoutChildren. Supporting predictive animations means that onLayoutChildren 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 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
@NonNull RecyclerView.Recycler recycler

Recycler to use for fetching potentially cached views for a position

@NonNull RecyclerView.State state

Transient state of RecyclerView

onLayoutCompleted

public void onLayoutCompleted(@NonNull RecyclerView.State state)

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

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

Parameters
@NonNull RecyclerView.State state

Transient state of RecyclerView

onMeasure

public void onMeasure(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    int widthSpec,
    int heightSpec
)

Measure the attached RecyclerView. Implementations must call setMeasuredDimension before returning.

It is strongly advised to use the AutoMeasure mechanism by overriding 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 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
@NonNull RecyclerView.Recycler recycler

Recycler

@NonNull RecyclerView.State state

Transient state of RecyclerView

int widthSpec

Width android.view.View.MeasureSpec

int heightSpec

Height android.view.View.MeasureSpec

onRequestChildFocus

public boolean onRequestChildFocus(
    @NonNull RecyclerView parent,
    @NonNull RecyclerView.State state,
    @NonNull View child,
    @Nullable View focused
)

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
@NonNull RecyclerView parent

The RecyclerView hosting this LayoutManager

@NonNull RecyclerView.State state

Current state of RecyclerView

@NonNull View child

Direct child of the RecyclerView containing the newly focused view

@Nullable View focused

The newly focused view. This may be the same view as child or it may be null

Returns
boolean

true if the default scroll behavior should be suppressed

onRestoreInstanceState

public void onRestoreInstanceState(@Nullable Parcelable 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 getStateRestorationPolicy for more information.

Parameters
@Nullable Parcelable state

The parcelable that was returned by the previous LayoutManager's onSaveInstanceState method.

onSaveInstanceState

public @NonNull Parcelable onSaveInstanceState()

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
@NonNull Parcelable

Necessary information for LayoutManager to be able to restore its state

performAccessibilityAction

public boolean performAccessibilityAction(
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state,
    int action,
    @Nullable Bundle args
)

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

Parameters
@NonNull RecyclerView.Recycler recycler

The Recycler that can be used to convert view positions into adapter positions

@NonNull RecyclerView.State state

The current state of RecyclerView

int action

The action to perform

@Nullable Bundle args

Optional action arguments

removeAndRecycleAllViews

public void removeAndRecycleAllViews(@NonNull RecyclerView.Recycler recycler)

Removes all views and recycles them using the given recycler.

If you want to clean cached views as well, you should call clear too.

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

Parameters
@NonNull RecyclerView.Recycler recycler

Recycler to use to recycle children

requestChildRectangleOnScreen

public boolean requestChildRectangleOnScreen(
    @NonNull RecyclerView parent,
    @NonNull View child,
    @NonNull Rect rect,
    boolean immediate
)

Called when a child of the RecyclerView wants a particular rectangle to be positioned onto the screen. See requestChildRectangleOnScreen 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
@NonNull RecyclerView parent

The parent RecyclerView.

@NonNull View child

The direct child making the request.

@NonNull Rect rect

The rectangle in the child's coordinates the child wishes to be on the screen.

boolean immediate

True to forbid animated or delayed scrolling, false otherwise

Returns
boolean

Whether the group scrolled to handle the operation

scrollHorizontallyBy

public int scrollHorizontallyBy(
    int dx,
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

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

Parameters
int dx

distance to scroll by in pixels. X increases as scroll position approaches the right.

@NonNull RecyclerView.Recycler recycler

Recycler to use for fetching potentially cached views for a position

@NonNull RecyclerView.State state

Transient state of RecyclerView

Returns
int

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.

scrollToPosition

public void scrollToPosition(int position)

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

Parameters
int position

Scroll to this adapter position.

scrollVerticallyBy

public int scrollVerticallyBy(
    int dy,
    @NonNull RecyclerView.Recycler recycler,
    @NonNull RecyclerView.State state
)

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

Parameters
int dy

distance to scroll in pixels. Y increases as scroll position approaches the bottom.

@NonNull RecyclerView.Recycler recycler

Recycler to use for fetching potentially cached views for a position

@NonNull RecyclerView.State state

Transient state of RecyclerView

Returns
int

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.

setFocusOutAllowed

Added in 1.0.0-alpha03
public void setFocusOutAllowed(boolean throughFront, boolean throughBack)

Sets whether focus can move out from the front and/or back of the grid view.

Parameters
boolean throughFront

For the vertical orientation, this controls whether focus can move out from the top of the grid. For the horizontal orientation, this controls whether focus can move out the front side of the grid.

boolean throughBack

For the vertical orientation, this controls whether focus can move out from the bottom of the grid. For the horizontal orientation, this controls whether focus can move out the back side of the grid.

setOrientation

Added in 1.0.0-alpha03
public void setOrientation(int orientation)

Sets grid view orientation.

smoothScrollToPosition

public void smoothScrollToPosition(
    @NonNull RecyclerView recyclerView,
    @NonNull RecyclerView.State state,
    int position
)

Smooth scroll to the specified adapter position.

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

Parameters
@NonNull RecyclerView recyclerView

The RecyclerView to which this layout manager is attached

@NonNull RecyclerView.State state

Current State of RecyclerView

int position

Scroll to this adapter position.

startSmoothScroll

public void startSmoothScroll(@NonNull RecyclerView.SmoothScroller smoothScroller)

Starts a smooth scroll using the provided 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
@NonNull RecyclerView.SmoothScroller smoothScroller

Instance which defines how smooth scroll should be animated

supportsPredictiveItemAnimations

public boolean supportsPredictiveItemAnimations()

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 onLayoutChildren.

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
boolean

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