StaggeredGridLayoutManager

Kotlin |Java

open class StaggeredGridLayoutManager : RecyclerView.LayoutManager, RecyclerView.SmoothScroller.ScrollVectorProvider

kotlin.Any
↳	androidx.recyclerview.widget.RecyclerView.LayoutManager
	↳	androidx.recyclerview.widget.StaggeredGridLayoutManager

A LayoutManager that lays out children in a staggered grid formation. It supports horizontal & vertical layout as well as an ability to layout children in reverse.

Staggered grids are likely to have gaps at the edges of the layout. To avoid these gaps, StaggeredGridLayoutManager can offset spans independently or move items between spans. You can control this behavior via setGapStrategy(int).

Summary

Nested classes
open	LayoutParams LayoutParams used by StaggeredGridLayoutManager.

Constants
static Int	GAP_HANDLING_LAZY
static Int	GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS When scroll state is changed to RecyclerView#SCROLL_STATE_IDLE, StaggeredGrid will check if there are gaps in the because of full span items.
static Int	GAP_HANDLING_NONE Does not do anything to hide gaps.
static Int	HORIZONTAL
static Int	VERTICAL

Public constructors
<init>(context: Context!, attrs: AttributeSet!, defStyleAttr: Int, defStyleRes: Int) Constructor used when layout manager is set in XML by RecyclerView attribute "layoutManager".
<init>(spanCount: Int, orientation: Int) Creates a StaggeredGridLayoutManager with given parameters.

Public methods
open Unit	assertNotInLayoutOrScroll(message: String!)
open Boolean	canScrollHorizontally()
open Boolean	canScrollVertically()
open Boolean	checkLayoutParams(lp: RecyclerView.LayoutParams!)
open Int	computeHorizontalScrollExtent(state: RecyclerView.State)
open Int	computeHorizontalScrollOffset(state: RecyclerView.State)
open Int	computeHorizontalScrollRange(state: RecyclerView.State)
open PointF?	computeScrollVectorForPosition(targetPosition: Int)
open Int	computeVerticalScrollExtent(state: RecyclerView.State)
open Int	computeVerticalScrollOffset(state: RecyclerView.State)
open Int	computeVerticalScrollRange(state: RecyclerView.State)
open IntArray!	findFirstCompletelyVisibleItemPositions(into: IntArray!) Returns the adapter position of the first completely visible view for each span.
open IntArray!	findFirstVisibleItemPositions(into: IntArray!) Returns the adapter position of the first visible view for each span.
open IntArray!	findLastCompletelyVisibleItemPositions(into: IntArray!) Returns the adapter position of the last completely visible view for each span.
open IntArray!	findLastVisibleItemPositions(into: IntArray!) Returns the adapter position of the last visible view for each span.
open RecyclerView.LayoutParams!	generateDefaultLayoutParams()
open RecyclerView.LayoutParams!	generateLayoutParams(c: Context!, attrs: AttributeSet!)
open RecyclerView.LayoutParams!	generateLayoutParams(lp: LayoutParams!)
open Int	getColumnCountForAccessibility(recycler: RecyclerView.Recycler, state: RecyclerView.State)
open Int	getGapStrategy() Returns the current gap handling strategy for StaggeredGridLayoutManager.
open Int	getOrientation()
open Boolean	getReverseLayout() Returns whether views are laid out in reverse order or not.
open Int	getRowCountForAccessibility(recycler: RecyclerView.Recycler, state: RecyclerView.State)
open Int	getSpanCount() Returns the number of spans laid out by StaggeredGridLayoutManager.
open Unit	invalidateSpanAssignments() For consistency, StaggeredGridLayoutManager keeps a mapping between spans and items.
open Boolean	isAutoMeasureEnabled()
open Unit	offsetChildrenHorizontal(dx: Int)
open Unit	offsetChildrenVertical(dy: Int)
open Unit	onDetachedFromWindow(view: RecyclerView!, recycler: RecyclerView.Recycler!)
open View?	onFocusSearchFailed(focused: View, direction: Int, recycler: RecyclerView.Recycler, state: RecyclerView.State)
open Unit	onInitializeAccessibilityEvent(event: AccessibilityEvent)
open Unit	onInitializeAccessibilityNodeInfoForItem(recycler: RecyclerView.Recycler, state: RecyclerView.State, host: View, info: AccessibilityNodeInfoCompat)
open Unit	onItemsAdded(recyclerView: RecyclerView, positionStart: Int, itemCount: Int)
open Unit	onItemsChanged(recyclerView: RecyclerView)
open Unit	onItemsMoved(recyclerView: RecyclerView, from: Int, to: Int, itemCount: Int)
open Unit	onItemsRemoved(recyclerView: RecyclerView, positionStart: Int, itemCount: Int)
open Unit	onItemsUpdated(recyclerView: RecyclerView, positionStart: Int, itemCount: Int, payload: Any?)
open Unit	onLayoutChildren(recycler: RecyclerView.Recycler!, state: RecyclerView.State!)
open Unit	onLayoutCompleted(state: RecyclerView.State!)
open Unit	onRestoreInstanceState(state: Parcelable!)
open Parcelable?	onSaveInstanceState()
open Unit	onScrollStateChanged(state: Int)
open Int	scrollHorizontallyBy(dx: Int, recycler: RecyclerView.Recycler!, state: RecyclerView.State!)
open Unit	scrollToPosition(position: Int)
open Unit	scrollToPositionWithOffset(position: Int, offset: Int) Scroll to the specified adapter position with the given offset from layout start.
open Int	scrollVerticallyBy(dy: Int, recycler: RecyclerView.Recycler!, state: RecyclerView.State!)
open Unit	setGapStrategy(gapStrategy: Int) Sets the gap handling strategy for StaggeredGridLayoutManager.
open Unit	setMeasuredDimension(childrenBounds: Rect!, wSpec: Int, hSpec: Int)
open Unit	setOrientation(orientation: Int) Sets the orientation of the layout.
open Unit	setReverseLayout(reverseLayout: Boolean) Sets whether LayoutManager should start laying out items from the end of the UI.
open Unit	setSpanCount(spanCount: Int) Sets the number of spans for the layout.
open Unit	smoothScrollToPosition(recyclerView: RecyclerView!, state: RecyclerView.State!, position: Int)
open Boolean	supportsPredictiveItemAnimations()

Inherited functions

From class LayoutManager Unit addDisappearingView(child: View!) To be called only during onLayoutChildren(Recycler, State) 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 getChildAt(int) or won't be included in getChildCount() method. Unit addDisappearingView(child: View!, index: Int) To be called only during onLayoutChildren(Recycler, State) 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 getChildAt(int) or won't be included in getChildCount() method. Unit addView(child: View!) Add a view to the currently attached RecyclerView if needed. LayoutManagers should use this method to add views obtained from a Recycler using Recycler#getViewForPosition(int). Unit addView(child: View!, index: Int) Add a view to the currently attached RecyclerView if needed. LayoutManagers should use this method to add views obtained from a Recycler using Recycler#getViewForPosition(int). Unit assertInLayoutOrScroll(message: String!) Checks if RecyclerView is in the middle of a layout or scroll and throws an IllegalStateException if it is not. Unit attachView(@NonNull child: View, index: Int, lp: RecyclerView.LayoutParams!) Reattach a previously detached view. This method should not be used to reattach views that were previously detachAndScrapView(android.view.View, RecyclerView.Recycler) scrapped}. Unit attachView(@NonNull child: View, index: Int) Reattach a previously detached view. This method should not be used to reattach views that were previously detachAndScrapView(android.view.View, RecyclerView.Recycler) scrapped}. Unit attachView(@NonNull child: View) Reattach a previously detached view. This method should not be used to reattach views that were previously detachAndScrapView(android.view.View, RecyclerView.Recycler) scrapped}. Unit calculateItemDecorationsForChild(@NonNull child: View, @NonNull outRect: Rect) 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#measure(int, int), you can use this method to get decorations. Int chooseSize(spec: Int, desired: Int, min: Int) Chooses a size from the given specs and parameters that is closest to the desired size and also complies with the spec. Unit collectInitialPrefetchPositions(adapterItemCount: Int, layoutPrefetchRegistry: 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 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. Unit detachAndScrapAttachedViews(@NonNull recycler: RecyclerView.Recycler) 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. Unit detachAndScrapView(@NonNull child: View, @NonNull recycler: RecyclerView.Recycler) 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. Unit detachAndScrapViewAt(index: Int, @NonNull recycler: RecyclerView.Recycler) 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. Unit detachView(@NonNull child: View) 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 detachAndScrapView(android.view.View, RecyclerView.Recycler) 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. Unit detachViewAt(index: Int) 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 detachAndScrapView(android.view.View, RecyclerView.Recycler) 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. Unit endAnimation(view: View!) Ends all animations on the view created by the ItemAnimator. View? findContainingItemView(@NonNull view: View) 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). View? findViewByPosition(position: Int) 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 ignoreView(View), it is also ignored by this method. Int getBaseline() Returns offset of the RecyclerView's text baseline from the its top boundary. Int getBottomDecorationHeight(@NonNull child: View) 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 calculateItemDecorationsForChild(View, Rect) is called. View? getChildAt(index: Int) Return the child view at the given index Int getChildCount() 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. Int getChildMeasureSpec(parentSize: Int, padding: Int, childDimension: Int, canScroll: Boolean) Calculate a MeasureSpec value for measuring a child view in one dimension. Int getChildMeasureSpec(parentSize: Int, parentMode: Int, padding: Int, childDimension: Int, canScroll: Boolean) Calculate a MeasureSpec value for measuring a child view in one dimension. Boolean getClipToPadding() Check if the RecyclerView is configured to clip child views to its padding. Int getDecoratedBottom(@NonNull child: View) Returns the bottom edge of the given child view within its parent, offset by any applied ItemDecorations. Unit getDecoratedBoundsWithMargins(@NonNull view: View, @NonNull outBounds: Rect) Returns the bounds of the view including its decoration and margins. Int getDecoratedLeft(@NonNull child: View) Returns the left edge of the given child view within its parent, offset by any applied ItemDecorations. Int getDecoratedMeasuredHeight(@NonNull child: View) Returns the measured height of the given child, plus the additional size of any insets applied by ItemDecorations. Int getDecoratedMeasuredWidth(@NonNull child: View) Returns the measured width of the given child, plus the additional size of any insets applied by ItemDecorations. Int getDecoratedRight(@NonNull child: View) Returns the right edge of the given child view within its parent, offset by any applied ItemDecorations. Int getDecoratedTop(@NonNull child: View) Returns the top edge of the given child view within its parent, offset by any applied ItemDecorations. View? getFocusedChild() Returns the item View which has or contains focus. Int getHeight() 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 android.view.View.MeasureSpec height if the 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. Int getHeightMode() 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 setAutoMeasureEnabled(boolean). When RecyclerView is running a layout, this value is always set to View.MeasureSpec#EXACTLY even if it was measured with a different spec mode. Int getItemCount() 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 State is available, you should use State#getItemCount() instead. For more details, check the documentation for State#getItemCount(). Int getItemViewType(@NonNull view: View) Returns the View type defined by the adapter. Int getLayoutDirection() Returns the resolved layout direction for this RecyclerView. Int getLeftDecorationWidth(@NonNull child: View) 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 calculateItemDecorationsForChild(View, Rect) is called. Int getMinimumHeight() Int getMinimumWidth() Int getPaddingBottom() Return the bottom padding of the parent RecyclerView Int getPaddingEnd() Return the end padding of the parent RecyclerView Int getPaddingLeft() Return the left padding of the parent RecyclerView Int getPaddingRight() Return the right padding of the parent RecyclerView Int getPaddingStart() Return the start padding of the parent RecyclerView Int getPaddingTop() Return the top padding of the parent RecyclerView Int getPosition(@NonNull view: View) 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. RecyclerView.LayoutManager.Properties! getProperties(@NonNull context: Context, @Nullable attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int) Parse the xml attributes to get the most common properties used by layout managers. android.R.attr#orientation androidx.recyclerview.R.attr#spanCount androidx.recyclerview.R.attr#reverseLayout androidx.recyclerview.R.attr#stackFromEnd Int getRightDecorationWidth(@NonNull child: View) 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 calculateItemDecorationsForChild(View, Rect) is called. Int getSelectionModeForAccessibility(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State) Returns the selection mode for accessibility. Should be AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE, AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_SINGLE or AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_MULTIPLE. Default implementation returns AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE. Int getTopDecorationHeight(@NonNull child: View) 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 calculateItemDecorationsForChild(View, Rect) is called. Unit getTransformedBoundingBox(@NonNull child: View, includeDecorInsets: Boolean, @NonNull out: Rect) 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. Int getWidth() 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 android.view.View.MeasureSpec width if the 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. Int getWidthMode() 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 setAutoMeasureEnabled(boolean). When RecyclerView is running a layout, this value is always set to View.MeasureSpec#EXACTLY even if it was measured with a different spec mode. Boolean hasFocus() Returns true if the RecyclerView this LayoutManager is bound to has or contains focus. Unit ignoreView(@NonNull view: View) 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 removeAndRecycleAllViews(Recycler) will ignore the child whereas removeAllViews() or offsetChildrenHorizontal(int) will not ignore the child. Before this child can be recycled again, you have to call stopIgnoringView(View). You can call this method only if your LayoutManger is in onLayout or onScroll callback. Boolean isAttachedToWindow() Returns whether LayoutManager is currently attached to a RecyclerView which is attached to a window. Boolean isFocused() Returns true if the RecyclerView this LayoutManager is bound to has focus. Boolean isItemPrefetchEnabled() Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames. Boolean isLayoutHierarchical(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State) Returns whether layout is hierarchical or not to be used for accessibility. Default implementation returns false. Boolean isMeasurementCacheEnabled() 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 setMeasurementCacheEnabled(boolean). Boolean isSmoothScrolling() Boolean isViewPartiallyVisible(@NonNull child: View, completelyVisible: Boolean, acceptEndPointInclusion: Boolean) 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. Unit layoutDecorated(@NonNull child: View, left: Int, top: Int, right: Int, bottom: Int) 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: layoutDecoratedWithMargins(View, int, int, int, int) getDecoratedBoundsWithMargins(View, Rect) measureChild(View, int, int) measureChildWithMargins(View, int, int) getDecoratedLeft(View) getDecoratedTop(View) getDecoratedRight(View) getDecoratedBottom(View) getDecoratedMeasuredWidth(View) getDecoratedMeasuredHeight(View) Unit layoutDecoratedWithMargins(@NonNull child: View, left: Int, top: Int, right: Int, bottom: 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: layoutDecorated(View, int, int, int, int) measureChild(View, int, int) measureChildWithMargins(View, int, int) getDecoratedLeft(View) getDecoratedTop(View) getDecoratedRight(View) getDecoratedBottom(View) getDecoratedMeasuredWidth(View) getDecoratedMeasuredHeight(View) Unit measureChild(@NonNull child: View, widthUsed: Int, heightUsed: Int) 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. Unit measureChildWithMargins(@NonNull child: View, widthUsed: Int, heightUsed: Int) 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. Unit moveView(fromIndex: Int, toIndex: Int) Moves a View from one position to another. Unit onAdapterChanged(@Nullable oldAdapter: RecyclerView.Adapter<RecyclerView.ViewHolder!>?, @Nullable newAdapter: RecyclerView.Adapter<RecyclerView.ViewHolder!>?) Called if the RecyclerView this LayoutManager is bound to has a different adapter set via RecyclerView#setAdapter(Adapter) or RecyclerView#swapAdapter(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. Boolean onAddFocusables(@NonNull recyclerView: RecyclerView, @NonNull views: ArrayList<View!>, direction: Int, focusableMode: Int) Called to populate focusable views within the RecyclerView. The LayoutManager implementation should return true if the default behavior of ViewGroup#addFocusables(java.util.ArrayList, int) should be suppressed. The default implementation returns false to trigger RecyclerView to fall back to the default ViewGroup behavior. Unit onAttachedToWindow(view: RecyclerView!) 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 onLayoutChildren(Recycler, State) 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. Unit onDetachedFromWindow(view: RecyclerView!) Unit onInitializeAccessibilityEvent(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State, @NonNull event: AccessibilityEvent) Called by the accessibility delegate to initialize an accessibility event. Default implementation adds item count and scroll information to the event. Unit onInitializeAccessibilityNodeInfo(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State, @NonNull info: AccessibilityNodeInfoCompat) Called by the AccessibilityDelegate when the information about the current layout should be populated. Default implementation adds a . You should override getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State) and getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State) for more accurate accessibility information. View? onInterceptFocusSearch(@NonNull focused: View, direction: Int) 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(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. Unit onItemsUpdated(@NonNull recyclerView: RecyclerView, positionStart: Int, itemCount: Int) Called when items have been changed in the adapter. To receive payload, override onItemsUpdated(RecyclerView, int, int, Object) instead, then this callback will not be invoked. Unit onMeasure(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State, widthSpec: Int, heightSpec: Int) Measure the attached RecyclerView. Implementations must call setMeasuredDimension(int, int) 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. Boolean onRequestChildFocus(@NonNull parent: RecyclerView, @NonNull child: View, @Nullable focused: View?) Boolean onRequestChildFocus(@NonNull parent: RecyclerView, @NonNull state: RecyclerView.State, @NonNull child: View, @Nullable focused: View?) 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. Boolean performAccessibilityAction(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State, action: Int, @Nullable args: Bundle?) Called by AccessibilityDelegate when an action is requested from the RecyclerView. Boolean performAccessibilityActionForItem(@NonNull recycler: RecyclerView.Recycler, @NonNull state: RecyclerView.State, @NonNull view: View, action: Int, @Nullable args: Bundle?) Called by AccessibilityDelegate when an accessibility action is requested on one of the children of LayoutManager. Default implementation does not do anything. Unit postOnAnimation(action: Runnable!) 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. Unit removeAllViews() 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. Unit removeAndRecycleAllViews(@NonNull recycler: RecyclerView.Recycler) Removes all views and recycles them using the given recycler. If you want to clean cached views as well, you should call Recycler#clear() too. If a View is marked as "ignored", it is not removed nor recycled. Unit removeAndRecycleView(@NonNull child: View, @NonNull recycler: RecyclerView.Recycler) Remove a child view and recycle it using the given Recycler. Unit removeAndRecycleViewAt(index: Int, @NonNull recycler: RecyclerView.Recycler) Remove a child view and recycle it using the given Recycler. Boolean removeCallbacks(action: Runnable!) Removes the specified Runnable from the message queue. Calling this method when LayoutManager is not attached to a RecyclerView has no effect. Unit removeDetachedView(@NonNull child: View) Finish removing a view that was previously temporarily detached. Unit removeView(child: View!) 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 Recycler#recycleView(android.view.View). Unit removeViewAt(index: Int) 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 Recycler#recycleView(android.view.View). Boolean requestChildRectangleOnScreen(@NonNull parent: RecyclerView, @NonNull child: View, @NonNull rect: Rect, immediate: Boolean) Called when a child of the RecyclerView wants a particular rectangle to be positioned onto the screen. See ViewParent#requestChildRectangleOnScreen(android.view.View, * android.graphics.Rect, boolean) 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. Boolean requestChildRectangleOnScreen(@NonNull parent: RecyclerView, @NonNull child: View, @NonNull rect: Rect, immediate: Boolean, focusedChildVisible: Boolean) 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. Unit requestLayout() Calls RecyclerView#requestLayout on the underlying RecyclerView Unit requestSimpleAnimationsInNextLayout() 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 ItemAnimator set, RecyclerView will not run any animations but will still clear this flag after the layout is complete. Unit setAutoMeasureEnabled(enabled: Boolean) 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 LayoutManager#onMeasure(Recycler, State, int, int). Unit setItemPrefetchEnabled(enabled: Boolean) 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. Unit setMeasuredDimension(widthSize: Int, heightSize: Int) Set the measured dimensions of the host RecyclerView. Unit setMeasurementCacheEnabled(measurementCacheEnabled: Boolean) Sets whether RecyclerView should use its own measurement cache for the children. This is a more aggressive cache than the framework uses. Unit startSmoothScroll(smoothScroller: RecyclerView.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. Unit stopIgnoringView(@NonNull view: 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.

Constants

GAP_HANDLING_LAZY

static val GAP_HANDLING_LAZY: Int

Deprecated: No longer supported.

Value: 1

GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS

static val GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS: Int

When scroll state is changed to RecyclerView#SCROLL_STATE_IDLE, StaggeredGrid will check if there are gaps in the because of full span items. If it finds, it will re-layout and move items to correct positions with animations.

For example, if LayoutManager ends up with the following layout due to adapter changes:

AAA
      _BC
      DDD
      

It will animate to the following state:

AAA
      BC_
      DDD
      

Value: 2

GAP_HANDLING_NONE

static val GAP_HANDLING_NONE: Int

Does not do anything to hide gaps.

Value: 0

HORIZONTAL

static val HORIZONTAL: Int

Value: RecyclerView.HORIZONTAL

VERTICAL

static val VERTICAL: Int

Value: RecyclerView.VERTICAL

Public constructors

<init>

StaggeredGridLayoutManager(context: Context!, attrs: AttributeSet!, defStyleAttr: Int, defStyleRes: Int)

Constructor used when layout manager is set in XML by RecyclerView attribute "layoutManager". Defaults to single column and vertical.

<init>

StaggeredGridLayoutManager(spanCount: Int, orientation: Int)

Creates a StaggeredGridLayoutManager with given parameters.

Parameters
spanCount	Int: If orientation is vertical, spanCount is number of columns. If orientation is horizontal, spanCount is number of rows.
orientation	Int: VERTICAL or HORIZONTAL

Public methods

assertNotInLayoutOrScroll

open fun assertNotInLayoutOrScroll(message: String!): Unit

canScrollHorizontally

open fun canScrollHorizontally(): Boolean

canScrollVertically

open fun canScrollVertically(): Boolean

checkLayoutParams

open fun checkLayoutParams(lp: RecyclerView.LayoutParams!): Boolean

computeHorizontalScrollExtent

open fun computeHorizontalScrollExtent(state: RecyclerView.State): Int

computeHorizontalScrollOffset

open fun computeHorizontalScrollOffset(state: RecyclerView.State): Int

computeHorizontalScrollRange

open fun computeHorizontalScrollRange(state: RecyclerView.State): Int

computeScrollVectorForPosition

open fun computeScrollVectorForPosition(targetPosition: Int): PointF?

computeVerticalScrollExtent

open fun computeVerticalScrollExtent(state: RecyclerView.State): Int

computeVerticalScrollOffset

open fun computeVerticalScrollOffset(state: RecyclerView.State): Int

computeVerticalScrollRange

open fun computeVerticalScrollRange(state: RecyclerView.State): Int

findFirstCompletelyVisibleItemPositions

open fun findFirstCompletelyVisibleItemPositions(into: IntArray!): IntArray!

Returns the adapter position of the first completely visible view for each span.

Note that, this value is not affected by layout orientation or item order traversal. (setReverseLayout(boolean)). Views are sorted by their positions in the adapter, not in the layout.

If RecyclerView has item decorators, they will be considered in calculations as well.

StaggeredGridLayoutManager may pre-cache some views that are not necessarily visible. Those views are ignored in this method.

Parameters
into	IntArray!: An array to put the results into. If you don't provide any, LayoutManager will create a new one.

Return
IntArray!: The adapter position of the first fully visible item in each span. If a span does not have any items, RecyclerView#NO_POSITION is returned for that span.

See Also

• #findFirstVisibleItemPositions(int[])#findLastCompletelyVisibleItemPositions(int[])

findFirstVisibleItemPositions

open fun findFirstVisibleItemPositions(into: IntArray!): IntArray!

Returns the adapter position of the first visible view for each span.

Note that, this value is not affected by layout orientation or item order traversal. (setReverseLayout(boolean)). Views are sorted by their positions in the adapter, not in the layout.

If RecyclerView has item decorators, they will be considered in calculations as well.

StaggeredGridLayoutManager may pre-cache some views that are not necessarily visible. Those views are ignored in this method.

Parameters
into	IntArray!: An array to put the results into. If you don't provide any, LayoutManager will create a new one.

Return
IntArray!: The adapter position of the first visible item in each span. If a span does not have any items, RecyclerView#NO_POSITION is returned for that span.

See Also

• #findFirstCompletelyVisibleItemPositions(int[])#findLastVisibleItemPositions(int[])

findLastCompletelyVisibleItemPositions

open fun findLastCompletelyVisibleItemPositions(into: IntArray!): IntArray!

Returns the adapter position of the last completely visible view for each span.

Note that, this value is not affected by layout orientation or item order traversal. (setReverseLayout(boolean)). Views are sorted by their positions in the adapter, not in the layout.

If RecyclerView has item decorators, they will be considered in calculations as well.

StaggeredGridLayoutManager may pre-cache some views that are not necessarily visible. Those views are ignored in this method.

Parameters
into	IntArray!: An array to put the results into. If you don't provide any, LayoutManager will create a new one.

Return
IntArray!: The adapter position of the last fully visible item in each span. If a span does not have any items, RecyclerView#NO_POSITION is returned for that span.

See Also

• #findFirstCompletelyVisibleItemPositions(int[])#findLastVisibleItemPositions(int[])

findLastVisibleItemPositions

open fun findLastVisibleItemPositions(into: IntArray!): IntArray!

Returns the adapter position of the last visible view for each span.

Note that, this value is not affected by layout orientation or item order traversal. (setReverseLayout(boolean)). Views are sorted by their positions in the adapter, not in the layout.

If RecyclerView has item decorators, they will be considered in calculations as well.

StaggeredGridLayoutManager may pre-cache some views that are not necessarily visible. Those views are ignored in this method.

Parameters
into	IntArray!: An array to put the results into. If you don't provide any, LayoutManager will create a new one.

Return
IntArray!: The adapter position of the last visible item in each span. If a span does not have any items, RecyclerView#NO_POSITION is returned for that span.

See Also

• #findLastCompletelyVisibleItemPositions(int[])#findFirstVisibleItemPositions(int[])

generateDefaultLayoutParams

open fun generateDefaultLayoutParams(): RecyclerView.LayoutParams!

generateLayoutParams

open fun generateLayoutParams(c: Context!, attrs: AttributeSet!): RecyclerView.LayoutParams!

generateLayoutParams

open fun generateLayoutParams(lp: LayoutParams!): RecyclerView.LayoutParams!

getColumnCountForAccessibility

open fun getColumnCountForAccessibility(recycler: RecyclerView.Recycler, state: RecyclerView.State): Int

getGapStrategy

open fun getGapStrategy(): Int

Returns the current gap handling strategy for StaggeredGridLayoutManager.

Staggered grid may have gaps in the layout due to changes in the adapter. To avoid gaps, StaggeredGridLayoutManager provides 2 options. Check GAP_HANDLING_NONE and GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS for details.

By default, StaggeredGridLayoutManager uses GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS.

Return
Int: Current gap handling strategy.

See Also

• #setGapStrategy(int)#GAP_HANDLING_NONE#GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS

getOrientation

open fun getOrientation(): Int

getReverseLayout

open fun getReverseLayout(): Boolean

Returns whether views are laid out in reverse order or not.

Not that this value is not affected by RecyclerView's layout direction.

Return
Boolean: True if layout is reversed, false otherwise

See Also

• #setReverseLayout(boolean)

getRowCountForAccessibility

open fun getRowCountForAccessibility(recycler: RecyclerView.Recycler, state: RecyclerView.State): Int

getSpanCount

open fun getSpanCount(): Int

Returns the number of spans laid out by StaggeredGridLayoutManager.

Return
Int: Number of spans in the layout

invalidateSpanAssignments

open fun invalidateSpanAssignments(): Unit

For consistency, StaggeredGridLayoutManager keeps a mapping between spans and items.

If you need to cancel current assignments, you can call this method which will clear all assignments and request a new layout.

isAutoMeasureEnabled

open fun isAutoMeasureEnabled(): Boolean

offsetChildrenHorizontal

open fun offsetChildrenHorizontal(dx: Int): Unit

offsetChildrenVertical

open fun offsetChildrenVertical(dy: Int): Unit

onDetachedFromWindow

open fun onDetachedFromWindow(view: RecyclerView!, recycler: RecyclerView.Recycler!): Unit

onFocusSearchFailed

@Nullable open fun onFocusSearchFailed(focused: View, direction: Int, recycler: RecyclerView.Recycler, state: RecyclerView.State): View?

onInitializeAccessibilityEvent

open fun onInitializeAccessibilityEvent(event: AccessibilityEvent): Unit

onInitializeAccessibilityNodeInfoForItem

open fun onInitializeAccessibilityNodeInfoForItem(recycler: RecyclerView.Recycler, state: RecyclerView.State, host: View, info: AccessibilityNodeInfoCompat): Unit

onItemsAdded

open fun onItemsAdded(recyclerView: RecyclerView, positionStart: Int, itemCount: Int): Unit

onItemsChanged

open fun onItemsChanged(recyclerView: RecyclerView): Unit

onItemsMoved

open fun onItemsMoved(recyclerView: RecyclerView, from: Int, to: Int, itemCount: Int): Unit

onItemsRemoved

open fun onItemsRemoved(recyclerView: RecyclerView, positionStart: Int, itemCount: Int): Unit

onItemsUpdated

open fun onItemsUpdated(recyclerView: RecyclerView, positionStart: Int, itemCount: Int, payload: Any?): Unit

onLayoutChildren

open fun onLayoutChildren(recycler: RecyclerView.Recycler!, state: RecyclerView.State!): Unit

onLayoutCompleted

open fun onLayoutCompleted(state: RecyclerView.State!): Unit

onRestoreInstanceState

open fun onRestoreInstanceState(state: Parcelable!): Unit

onSaveInstanceState

open fun onSaveInstanceState(): Parcelable?

onScrollStateChanged

open fun onScrollStateChanged(state: Int): Unit

scrollHorizontallyBy

open fun scrollHorizontallyBy(dx: Int, recycler: RecyclerView.Recycler!, state: RecyclerView.State!): Int

scrollToPosition

open fun scrollToPosition(position: Int): Unit

scrollToPositionWithOffset

open fun scrollToPositionWithOffset(position: Int, offset: Int): Unit

Scroll to the specified adapter position with the given offset from layout start.

Note that scroll position change will not be reflected until the next layout call.

If you are just trying to make a position visible, use scrollToPosition(int).

Parameters
position	Int: Index (starting at 0) of the reference item.
offset	Int: The distance (in pixels) between the start edge of the item view and start edge of the RecyclerView.

See Also

• #setReverseLayout(boolean)#scrollToPosition(int)

scrollVerticallyBy

open fun scrollVerticallyBy(dy: Int, recycler: RecyclerView.Recycler!, state: RecyclerView.State!): Int

setGapStrategy

open fun setGapStrategy(gapStrategy: Int): Unit

Sets the gap handling strategy for StaggeredGridLayoutManager. If the gapStrategy parameter is different than the current strategy, calling this method will trigger a layout request.

Parameters
gapStrategy	Int: The new gap handling strategy. Should be GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS or .

See Also

• #getGapStrategy()

setMeasuredDimension

open fun setMeasuredDimension(childrenBounds: Rect!, wSpec: Int, hSpec: Int): Unit

setOrientation

open fun setOrientation(orientation: Int): Unit

Sets the orientation of the layout. StaggeredGridLayoutManager will do its best to keep scroll position if this method is called after views are laid out.

Parameters
orientation	Int: HORIZONTAL or VERTICAL

setReverseLayout

open fun setReverseLayout(reverseLayout: Boolean): Unit

Sets whether LayoutManager should start laying out items from the end of the UI. The order items are traversed is not affected by this call.

For vertical layout, if it is set to true, first item will be at the bottom of the list.

For horizontal layouts, it depends on the layout direction. When set to true, If RecyclerView is LTR, than it will layout from RTL, if RecyclerView} is RTL, it will layout from LTR.

Parameters
reverseLayout	Boolean: Whether layout should be in reverse or not

setSpanCount

open fun setSpanCount(spanCount: Int): Unit

Sets the number of spans for the layout. This will invalidate all of the span assignments for Views.

Calling this method will automatically result in a new layout request unless the spanCount parameter is equal to current span count.

Parameters
spanCount	Int: Number of spans to layout

smoothScrollToPosition

open fun smoothScrollToPosition(recyclerView: RecyclerView!, state: RecyclerView.State!, position: Int): Unit

supportsPredictiveItemAnimations

open fun supportsPredictiveItemAnimations(): Boolean