Package 

Class GridLayoutManager

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      public abstract class GridLayoutManager.SpanSizeLookup

      A helper class to provide the number of spans each item occupies.

      Default implementation sets each item to occupy exactly 1 span.
      public final class GridLayoutManager.DefaultSpanSizeLookup

      Default implementation for SpanSizeLookup. Each item occupies 1 span.
      public class GridLayoutManager.LayoutParams

      LayoutParams used by GridLayoutManager.

      Note that if the orientation is VERTICAL, the width parameter is ignored and if theorientation is HORIZONTAL the height parameter is ignored because child view isexpected to fill all of the space given to it.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      public final static int DEFAULT_SPAN_COUNT

    • Method Summary

      Modifier and Type Method Description
      void setStackFromEnd(boolean stackFromEnd) stackFromEnd is not supported by GridLayoutManager.
      int getRowCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state) Returns the number of rows for accessibility.
      int getColumnCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state) Returns the number of columns for accessibility.
      void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) Lay out all relevant child views from the given adapter.The LayoutManager is in charge of the behavior of item animations.
      void onLayoutCompleted(RecyclerView.State state) Called after a full layout calculation is finished.
      void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount) Called when items have been added to the adapter.
      void onItemsChanged(RecyclerView recyclerView) Called in response to a call to notifyDataSetChanged or swapAdapter ()} and signals that the the entiredata set has changed.
      void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount) Called when items have been removed from the adapter.
      void onItemsUpdated(RecyclerView recyclerView, int positionStart, int itemCount, Object payload) Called when items have been changed in the adapter and with optional payload.
      void onItemsMoved(RecyclerView recyclerView, int from, int to, int itemCount) Called when an item is moved withing the adapter.
      RecyclerView.LayoutParams generateDefaultLayoutParams() Create a default LayoutParams object for a child of the RecyclerView.
      RecyclerView.LayoutParams generateLayoutParams(Context c, AttributeSet attrs) Create a LayoutParams object suitable for this LayoutManager froman inflated layout resource.
      RecyclerView.LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp) Create a LayoutParams object suitable for this LayoutManager, copying relevantvalues from the supplied LayoutParams object if possible.
      boolean checkLayoutParams(RecyclerView.LayoutParams lp) Determines the validity of the supplied LayoutParams object.
      void setSpanSizeLookup(GridLayoutManager.SpanSizeLookup spanSizeLookup) Sets the source to get the number of spans occupied by each item in the adapter.
      GridLayoutManager.SpanSizeLookup getSpanSizeLookup() Returns the current SpanSizeLookup used by the GridLayoutManager.
      void setMeasuredDimension(Rect childrenBounds, int wSpec, int hSpec) Sets the measured dimensions from the given bounding box of the children and themeasurement specs that were passed into onMeasure.
      int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state) Scroll horizontally by dx pixels in screen coordinates and return the distance traveled.The default implementation does nothing and returns 0.
      int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state) Scroll vertically by dy pixels in screen coordinates and return the distance traveled.The default implementation does nothing and returns 0.
      int getSpanCount() Returns the number of spans laid out by this grid.
      void setSpanCount(int spanCount) Sets the number of spans to be laid out.
      View onFocusSearchFailed(View focused, int focusDirection, RecyclerView.Recycler recycler, RecyclerView.State state) Called when searching for a focusable view in the given direction has failedfor the current content of the RecyclerView.
      boolean supportsPredictiveItemAnimations() Returns whether this LayoutManager supports "predictive item animations".
      int computeHorizontalScrollRange(RecyclerView.State state) Override this method if you want to support scroll bars.
      int computeVerticalScrollRange(RecyclerView.State state) Override this method if you want to support scroll bars.
      int computeHorizontalScrollOffset(RecyclerView.State state) Override this method if you want to support scroll bars.
      int computeVerticalScrollOffset(RecyclerView.State state) Override this method if you want to support scroll bars.
      void setUsingSpansToEstimateScrollbarDimensions(boolean useSpansToEstimateScrollBarDimensions) When this flag is set, the scroll offset and scroll range calculations will take accountof span information.
      boolean isUsingSpansToEstimateScrollbarDimensions() Returns true if the scroll offset and scroll range calculations take account of spaninformation.

      • Methods inherited from class tds.androidx.recyclerview.widget.LinearLayoutManager

        assertNotInLayoutOrScroll, canScrollHorizontally, canScrollVertically, collectAdjacentPrefetchPositions, collectInitialPrefetchPositions, computeHorizontalScrollExtent, computeScrollVectorForPosition, computeVerticalScrollExtent, findFirstCompletelyVisibleItemPosition, findFirstVisibleItemPosition, findLastCompletelyVisibleItemPosition, findLastVisibleItemPosition, findViewByPosition, getInitialPrefetchItemCount, getOrientation, getRecycleChildrenOnDetach, getReverseLayout, getStackFromEnd, isAutoMeasureEnabled, isSmoothScrollbarEnabled, onDetachedFromWindow, onInitializeAccessibilityEvent, onRestoreInstanceState, onSaveInstanceState, prepareForDrop, scrollToPosition, scrollToPositionWithOffset, setInitialPrefetchItemCount, setOrientation, setRecycleChildrenOnDetach, setReverseLayout, setSmoothScrollbarEnabled, smoothScrollToPosition

      • Methods inherited from class tds.androidx.recyclerview.widget.RecyclerView.LayoutManager

        addDisappearingView, addDisappearingView, addView, addView, assertInLayoutOrScroll, attachView, attachView, attachView, calculateItemDecorationsForChild, checkLayoutParams, chooseSize, collectAdjacentPrefetchPositions, collectInitialPrefetchPositions, computeHorizontalScrollExtent, computeHorizontalScrollOffset, computeHorizontalScrollRange, computeVerticalScrollExtent, computeVerticalScrollOffset, computeVerticalScrollRange, detachAndScrapAttachedViews, detachAndScrapView, detachAndScrapViewAt, detachView, detachViewAt, endAnimation, findContainingItemView, getBaseline, getBottomDecorationHeight, getChildAt, getChildCount, getChildMeasureSpec, getChildMeasureSpec, getClipToPadding, getColumnCountForAccessibility, getDecoratedBottom, getDecoratedBoundsWithMargins, getDecoratedLeft, getDecoratedMeasuredHeight, getDecoratedMeasuredWidth, getDecoratedRight, getDecoratedTop, getFocusedChild, getHeight, getHeightMode, getItemCount, getItemViewType, getLayoutDirection, getLeftDecorationWidth, getMinimumHeight, getMinimumWidth, getPaddingBottom, getPaddingEnd, getPaddingLeft, getPaddingRight, getPaddingStart, getPaddingTop, getPosition, getProperties, getRightDecorationWidth, getRowCountForAccessibility, getTopDecorationHeight, getTransformedBoundingBox, getWidth, getWidthMode, hasFocus, ignoreView, isAttachedToWindow, isFocused, isItemPrefetchEnabled, isLayoutHierarchical, isMeasurementCacheEnabled, isSmoothScrolling, isViewPartiallyVisible, layoutDecorated, layoutDecoratedWithMargins, measureChild, measureChildWithMargins, moveView, offsetChildrenHorizontal, offsetChildrenVertical, onAdapterChanged, onAddFocusables, onAttachedToWindow, onDetachedFromWindow, onDetachedFromWindow, onFocusSearchFailed, onInitializeAccessibilityEvent, onInitializeAccessibilityEvent, onInterceptFocusSearch, onItemsAdded, onItemsChanged, onItemsMoved, onItemsRemoved, onItemsUpdated, onItemsUpdated, onLayoutChildren, onLayoutCompleted, onMeasure, onRequestChildFocus, onRequestChildFocus, onScrollStateChanged, postOnAnimation, removeAllViews, removeAndRecycleAllViews, removeAndRecycleView, removeAndRecycleViewAt, removeCallbacks, removeDetachedView, removeView, removeViewAt, requestChildRectangleOnScreen, requestChildRectangleOnScreen, requestLayout, requestSimpleAnimationsInNextLayout, scrollHorizontallyBy, scrollVerticallyBy, setAutoMeasureEnabled, setItemPrefetchEnabled, setMeasuredDimension, setMeasurementCacheEnabled, smoothScrollToPosition, startSmoothScroll, stopIgnoringView

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • GridLayoutManager

        GridLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
        Constructor used when layout manager is set in XML by RecyclerView attribute"layoutManager".

      • GridLayoutManager

        GridLayoutManager(Context context, int spanCount)
        Creates a vertical GridLayoutManager
        Parameters:
        context - Current context, will be used to access resources.
        spanCount - The number of columns in the grid

      • GridLayoutManager

        GridLayoutManager(Context context, int spanCount, int orientation, boolean reverseLayout)
        Parameters:
        context - Current context, will be used to access resources.
        spanCount - The number of columns or rows in the grid
        orientation - Layout orientation.
        reverseLayout - When set to true, layouts from end to start.

    • Method Detail

      • getRowCountForAccessibility

         int getRowCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)

        Returns the number of rows for accessibility.

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

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

      • getColumnCountForAccessibility

         int getColumnCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)

        Returns the number of columns for accessibility.

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

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

      • onLayoutChildren

         void onLayoutChildren(RecyclerView.Recycler recycler, 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 #getItemAnimator() ItemAnimator, and simpleitem animations are enabled. This means that add/remove operations on theadapter will result in animations to add new or appearing items, removed ordisappearing items, and moved items. If a LayoutManager returns false from #supportsPredictiveItemAnimations(), which is the default, and runs anormal layout operation during #onLayoutChildren(Recycler, State), theRecyclerView will have enough information to run those animations in a simpleway. For example, the default ItemAnimator, , willsimply fade views in and out, whether they are actually added/removed or whetherthey are moved on or off the screen due to other add/remove operations.

        A LayoutManager wanting a better item animation experience, where items can beanimated onto and off of the screen according to where the items exist when theyare not on screen, then the LayoutManager should return true from #supportsPredictiveItemAnimations() and add additional logic to #onLayoutChildren(Recycler, State). Supporting predictive animationsmeans that #onLayoutChildren(Recycler, State) will be called twice;once as a "pre" layout step to determine where items would have been prior toa 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 outappropriately. Also, LayoutParams#isItemRemoved() removed items willbe 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 usedto help calculate correct positioning of other views, including views thatwere not previously onscreen (referred to as APPEARING views), but whosepre-layout offscreen position can be determined given the extrainformation about the pre-layout removed views.

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

        The default LayoutManager implementations for RecyclerView handle all of theserequirements for animations already. Clients of RecyclerView can either use oneof these layout managers directly or look at their implementations ofonLayoutChildren() to see how they account for the APPEARING andDISAPPEARING views.

      • onLayoutCompleted

         void onLayoutCompleted(RecyclerView.State state)

        Called after a full layout calculation is finished. The layout calculation may includemultiple onLayoutChildren calls due to animations orlayout 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 scrollposition, saved state etc.

        Parameters:
        state - Transient state of RecyclerView

      • onItemsAdded

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

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

      • onItemsRemoved

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

        Called when items have been removed from the adapter.

      • onItemsUpdated

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

        Called when items have been changed in the adapter and with optional payload.Default implementation calls onItemsUpdated.

      • onItemsMoved

         void onItemsMoved(RecyclerView recyclerView, int from, int to, 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/MOVEoperation. This callback is only called if and only if notifyItemMoved is called.

      • generateDefaultLayoutParams

         RecyclerView.LayoutParams generateDefaultLayoutParams()

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

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

        Important: if you use your own custom LayoutParams typeyou must also override #checkLayoutParams(LayoutParams), #generateLayoutParams(ViewGroup.LayoutParams) and #generateLayoutParams(Context, AttributeSet).

      • checkLayoutParams

         boolean checkLayoutParams(RecyclerView.LayoutParams lp)

        Determines the validity of the supplied LayoutParams object.

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

        Parameters:
        lp - LayoutParams object to check

      • setMeasuredDimension

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

        Sets the measured dimensions from the given bounding box of the children and themeasurement specs that were passed into onMeasure. It isonly called if a LayoutManager returns true from isAutoMeasureEnabled and it is called after the RecyclerView calls onLayoutChildren in the execution of onMeasure.

        This method must call setMeasuredDimension.

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

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

      • getSpanCount

         int getSpanCount()

        Returns the number of spans laid out by this grid.

      • onFocusSearchFailed

         View onFocusSearchFailed(View focused, int focusDirection, RecyclerView.Recycler recycler, RecyclerView.State state)

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

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

        Parameters:
        focused - The currently focused view
        recycler - The recycler to use for obtaining views for currently offscreen items
        state - Transient state of RecyclerView

      • supportsPredictiveItemAnimations

         boolean supportsPredictiveItemAnimations()

        Returns whether this LayoutManager supports "predictive item animations".

        "Predictive item animations" are automatically created animations that showwhere 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 thismethod to return true (the default implementation returns false) and must obey certainbehavioral contracts outlined in onLayoutChildren.

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

      • setUsingSpansToEstimateScrollbarDimensions

         void setUsingSpansToEstimateScrollbarDimensions(boolean useSpansToEstimateScrollBarDimensions)

        When this flag is set, the scroll offset and scroll range calculations will take accountof span information.

        This is will increase the accuracy of the scroll bar's size and offset but will requiremore calls to getSpanGroupIndex".

        This additional accuracy may or may not be needed, depending on the characteristics ofyour layout. You will likely benefit from this accuracy when:

        • The variation in item span sizes is large.
        • The size of your data set is small (if your data set is large, the scrollbar willlikely be very small anyway, and thus the increased accuracy has less impact).
        • Calls to getSpanGroupIndex are fast.

        If you decide to enable this feature, you should be sure that calls to getSpanGroupIndex are fast, that set span group indexcaching is set to true via a call to and span index caching is also enabled via a call to { }.