public class StaggeredGridLayoutManager extends RecyclerView.LayoutManager implements RecyclerView.SmoothScroller.ScrollVectorProvider
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)
.
Modifier and Type | Class and Description |
---|---|
static class |
StaggeredGridLayoutManager.LayoutParams
LayoutParams used by StaggeredGridLayoutManager.
|
static class |
StaggeredGridLayoutManager.SavedState |
RecyclerView.LayoutManager.Properties
Modifier and Type | Field and Description |
---|---|
static int |
GAP_HANDLING_LAZY
Deprecated.
No longer supported.
|
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 |
Constructor and Description |
---|
StaggeredGridLayoutManager(Context context,
AttributeSet attrs,
int defStyleAttr,
int defStyleRes)
Constructor used when layout manager is set in XML by RecyclerView attribute
"layoutManager".
|
StaggeredGridLayoutManager(int spanCount,
int orientation)
Creates a StaggeredGridLayoutManager with given parameters.
|
Modifier and Type | Method and Description |
---|---|
void |
assertNotInLayoutOrScroll(String message)
Checks if RecyclerView is in the middle of a layout or scroll and throws an
IllegalStateException if it is. |
boolean |
canScrollHorizontally()
Query if horizontal scrolling is currently supported.
|
boolean |
canScrollVertically()
Query if vertical scrolling is currently supported.
|
boolean |
checkLayoutParams(RecyclerView.LayoutParams lp)
Determines the validity of the supplied LayoutParams object.
|
int |
computeHorizontalScrollExtent(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 |
computeHorizontalScrollRange(RecyclerView.State state)
Override this method if you want to support scroll bars.
|
PointF |
computeScrollVectorForPosition(int targetPosition)
Should calculate the vector that points to the direction where the target position
can be found.
|
int |
computeVerticalScrollExtent(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.
|
int |
computeVerticalScrollRange(RecyclerView.State state)
Override this method if you want to support scroll bars.
|
int[] |
findFirstCompletelyVisibleItemPositions(int[] into)
Returns the adapter position of the first completely visible view for each span.
|
int[] |
findFirstVisibleItemPositions(int[] into)
Returns the adapter position of the first visible view for each span.
|
int[] |
findLastCompletelyVisibleItemPositions(int[] into)
Returns the adapter position of the last completely visible view for each span.
|
int[] |
findLastVisibleItemPositions(int[] into)
Returns the adapter position of the last visible view for each span.
|
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 from
an inflated layout resource.
|
RecyclerView.LayoutParams |
generateLayoutParams(ViewGroup.LayoutParams lp)
Create a LayoutParams object suitable for this LayoutManager, copying relevant
values from the supplied LayoutParams object if possible.
|
int |
getColumnCountForAccessibility(RecyclerView.Recycler recycler,
RecyclerView.State state)
Returns the number of columns for accessibility.
|
int |
getGapStrategy()
Returns the current gap handling strategy for StaggeredGridLayoutManager.
|
int |
getOrientation() |
boolean |
getReverseLayout()
Returns whether views are laid out in reverse order or not.
|
int |
getRowCountForAccessibility(RecyclerView.Recycler recycler,
RecyclerView.State state)
Returns the number of rows for accessibility.
|
int |
getSpanCount()
Returns the number of spans laid out by StaggeredGridLayoutManager.
|
void |
invalidateSpanAssignments()
For consistency, StaggeredGridLayoutManager keeps a mapping between spans and items.
|
void |
offsetChildrenHorizontal(int dx)
Offset all child views attached to the parent RecyclerView by dx pixels along
the horizontal axis.
|
void |
offsetChildrenVertical(int dy)
Offset all child views attached to the parent RecyclerView by dy pixels along
the vertical axis.
|
void |
onDetachedFromWindow(RecyclerView view,
RecyclerView.Recycler recycler)
Called when this LayoutManager is detached from its parent RecyclerView or when
its parent RecyclerView is detached from its window.
|
View |
onFocusSearchFailed(View focused,
int direction,
RecyclerView.Recycler recycler,
RecyclerView.State state)
Called when searching for a focusable view in the given direction has failed
for the current content of the RecyclerView.
|
void |
onInitializeAccessibilityEvent(AccessibilityEvent event) |
void |
onInitializeAccessibilityNodeInfoForItem(RecyclerView.Recycler recycler,
RecyclerView.State state,
View host,
AccessibilityNodeInfoCompat info)
Called by the AccessibilityDelegate when the accessibility information for a specific
item should be populated.
|
void |
onItemsAdded(RecyclerView recyclerView,
int positionStart,
int itemCount)
Called when items have been added to the adapter.
|
void |
onItemsChanged(RecyclerView recyclerView)
Called when
RecyclerView.Adapter.notifyDataSetChanged() is triggered instead of giving
detailed information on what has actually changed. |
void |
onItemsMoved(RecyclerView recyclerView,
int from,
int to,
int itemCount)
Called when an item is moved withing the adapter.
|
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 |
onLayoutChildren(RecyclerView.Recycler recycler,
RecyclerView.State state)
Lay out all relevant child views from the given adapter.
|
void |
onLayoutCompleted(RecyclerView.State state)
Called after a full layout calculation is finished.
|
void |
onRestoreInstanceState(Parcelable state) |
Parcelable |
onSaveInstanceState()
Called when the LayoutManager should save its state.
|
void |
onScrollStateChanged(int state)
RecyclerView calls this method to notify LayoutManager that scroll state has changed.
|
int |
scrollHorizontallyBy(int dx,
RecyclerView.Recycler recycler,
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.
|
void |
scrollToPositionWithOffset(int position,
int offset)
Scroll to the specified adapter position with the given offset from layout start.
|
int |
scrollVerticallyBy(int dy,
RecyclerView.Recycler recycler,
RecyclerView.State state)
Scroll vertically by dy pixels in screen coordinates and return the distance traveled.
|
void |
setGapStrategy(int gapStrategy)
Sets the gap handling strategy for StaggeredGridLayoutManager.
|
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
RecyclerView.onMeasure(int, int) . |
void |
setOrientation(int orientation)
Sets the orientation of the layout.
|
void |
setReverseLayout(boolean reverseLayout)
Sets whether LayoutManager should start laying out items from the end of the UI.
|
void |
setSpanCount(int spanCount)
Sets the number of spans for the layout.
|
void |
smoothScrollToPosition(RecyclerView recyclerView,
RecyclerView.State state,
int position)
Smooth scroll to the specified adapter position.
|
boolean |
supportsPredictiveItemAnimations()
Returns whether this LayoutManager supports automatic item animations.
|
addDisappearingView, addDisappearingView, addView, addView, assertInLayoutOrScroll, attachView, attachView, attachView, calculateItemDecorationsForChild, chooseSize, detachAndScrapAttachedViews, detachAndScrapView, detachAndScrapViewAt, detachView, detachViewAt, endAnimation, findContainingItemView, findViewByPosition, getBaseline, getBottomDecorationHeight, getChildAt, getChildCount, getChildMeasureSpec, getChildMeasureSpec, getClipToPadding, 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, getSelectionModeForAccessibility, getTopDecorationHeight, getTransformedBoundingBox, getWidth, getWidthMode, hasFocus, ignoreView, isAttachedToWindow, isAutoMeasureEnabled, isFocused, isItemPrefetchEnabled, isLayoutHierarchical, isMeasurementCacheEnabled, isSmoothScrolling, layoutDecorated, layoutDecoratedWithMargins, measureChild, measureChildWithMargins, moveView, onAdapterChanged, onAddFocusables, onAttachedToWindow, onDetachedFromWindow, onInitializeAccessibilityEvent, onInitializeAccessibilityNodeInfo, onInterceptFocusSearch, onItemsUpdated, onMeasure, onRequestChildFocus, onRequestChildFocus, performAccessibilityAction, performAccessibilityActionForItem, postOnAnimation, removeAllViews, removeAndRecycleAllViews, removeAndRecycleView, removeAndRecycleViewAt, removeCallbacks, removeDetachedView, removeView, removeViewAt, requestChildRectangleOnScreen, requestLayout, requestSimpleAnimationsInNextLayout, setAutoMeasureEnabled, setItemPrefetchEnabled, setMeasuredDimension, setMeasurementCacheEnabled, startSmoothScroll, stopIgnoringView
public static final int HORIZONTAL
public static final int VERTICAL
public static final int GAP_HANDLING_NONE
@Deprecated public static final int GAP_HANDLING_LAZY
public static final int GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS
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
public StaggeredGridLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
public StaggeredGridLayoutManager(int spanCount, int orientation)
spanCount
- If orientation is vertical, spanCount is number of columns. If
orientation is horizontal, spanCount is number of rows.orientation
- VERTICAL
or HORIZONTAL
public void onScrollStateChanged(int state)
RecyclerView.LayoutManager
onScrollStateChanged
in class RecyclerView.LayoutManager
state
- The new scroll state for RecyclerViewpublic void onDetachedFromWindow(RecyclerView view, RecyclerView.Recycler recycler)
RecyclerView.LayoutManager
LayoutManager should clear all of its View references as another LayoutManager might be assigned to the RecyclerView.
If the RecyclerView is re-attached with the same LayoutManager and Adapter, it may not
call #onLayoutChildren(Recycler, State)
if nothing has changed and a layout was
not requested on the RecyclerView while it was detached.
If your LayoutManager has View references that it cleans in on-detach, it should also
call RecyclerView.requestLayout()
to ensure that it is re-laid out when
RecyclerView is re-attached.
Subclass implementations should always call through to the superclass implementation.
onDetachedFromWindow
in class RecyclerView.LayoutManager
view
- The RecyclerView this LayoutManager is bound torecycler
- The recycler to use if you prefer to recycle your children instead of
keeping them around.RecyclerView.LayoutManager.onAttachedToWindow(RecyclerView)
public void setSpanCount(int spanCount)
Calling this method will automatically result in a new layout request unless the spanCount parameter is equal to current span count.
spanCount
- Number of spans to layoutpublic void setOrientation(int orientation)
orientation
- HORIZONTAL
or VERTICAL
public void setReverseLayout(boolean reverseLayout)
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.
reverseLayout
- Whether layout should be in reverse or notpublic int getGapStrategy()
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
.
setGapStrategy(int)
,
GAP_HANDLING_NONE
,
GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS
public void setGapStrategy(int gapStrategy)
gapStrategy
- The new gap handling strategy. Should be
GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS
or GAP_HANDLING_NONE
.getGapStrategy()
public void assertNotInLayoutOrScroll(String message)
RecyclerView.LayoutManager
IllegalStateException
if it is.assertNotInLayoutOrScroll
in class RecyclerView.LayoutManager
message
- The message for the exception. Can be null.RecyclerView.LayoutManager.assertInLayoutOrScroll(String)
public int getSpanCount()
public void invalidateSpanAssignments()
If you need to cancel current assignments, you can call this method which will clear all assignments and request a new layout.
public boolean getReverseLayout()
Not that this value is not affected by RecyclerView's layout direction.
setReverseLayout(boolean)
public void setMeasuredDimension(Rect childrenBounds, int wSpec, int hSpec)
RecyclerView.LayoutManager
RecyclerView.onMeasure(int, int)
. It is
called after the RecyclerView calls
LayoutManager#onLayoutChildren(Recycler, State)
during a measurement pass.
This method should call RecyclerView.LayoutManager.setMeasuredDimension(int, int)
.
The default implementation adds the RecyclerView's padding to the given bounding box then caps the value to be within the given measurement specs.
This method is only called if the LayoutManager opted into the auto measurement API.
setMeasuredDimension
in class RecyclerView.LayoutManager
childrenBounds
- The bounding box of all childrenwSpec
- The widthMeasureSpec that was passed into the RecyclerView.hSpec
- The heightMeasureSpec that was passed into the RecyclerView.RecyclerView.LayoutManager.setAutoMeasureEnabled(boolean)
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)
RecyclerView.LayoutManager
ItemAnimator
, and simple
item animations are enabled. This means that add/remove operations on the
adapter will result in animations to add new or appearing items, removed or
disappearing items, and moved items. If a LayoutManager returns false from
RecyclerView.LayoutManager.supportsPredictiveItemAnimations()
, which is the default, and runs a
normal layout operation during #onLayoutChildren(Recycler, State)
, the
RecyclerView will have enough information to run those animations in a simple
way. For example, the default ItemAnimator, DefaultItemAnimator
, will
simply fade views in and out, whether they are actually added/removed or whether
they are moved on or off the screen due to other add/remove operations.
A LayoutManager wanting a better item animation experience, where items can be
animated onto and off of the screen according to where the items exist when they
are not on screen, then the LayoutManager should return true from
RecyclerView.LayoutManager.supportsPredictiveItemAnimations()
and add additional logic to
#onLayoutChildren(Recycler, State)
. Supporting predictive animations
means that #onLayoutChildren(Recycler, State)
will be called twice;
once as a "pre" layout step to determine where items would have been prior to
a real layout, and again to do the "real" layout. In the pre-layout phase,
items will remember their pre-layout positions to allow them to be laid out
appropriately. Also, removed
items will
be returned from the scrap to help determine correct placement of other items.
These removed items should not be added to the child list, but should be used
to help calculate correct positioning of other views, including views that
were not previously onscreen (referred to as APPEARING views), but whose
pre-layout offscreen position can be determined given the extra
information about the pre-layout removed views.
The second layout pass is the real layout in which only non-removed views
will be used. The only additional requirement during this pass is, if
RecyclerView.LayoutManager.supportsPredictiveItemAnimations()
returns true, to note which
views exist in the child list prior to layout and which are not there after
layout (referred to as DISAPPEARING views), and to position/layout those views
appropriately, without regard to the actual bounds of the RecyclerView. This allows
the animation system to know the location to which to animate these disappearing
views.
The default LayoutManager implementations for RecyclerView handle all of these requirements for animations already. Clients of RecyclerView can either use one of these layout managers directly or look at their implementations of onLayoutChildren() to see how they account for the APPEARING and DISAPPEARING views.
onLayoutChildren
in class RecyclerView.LayoutManager
recycler
- Recycler to use for fetching potentially cached views for a
positionstate
- Transient state of RecyclerViewpublic void onLayoutCompleted(RecyclerView.State state)
RecyclerView.LayoutManager
#onLayoutChildren(Recycler, State)
calls due to animations or
layout measurement but it will include only one #onLayoutCompleted(State)
call.
This method will be called at the end of View.layout(int, int, int, int)
call.
This is a good place for the LayoutManager to do some cleanup like pending scroll position, saved state etc.
onLayoutCompleted
in class RecyclerView.LayoutManager
state
- Transient state of RecyclerViewpublic boolean supportsPredictiveItemAnimations()
RecyclerView.LayoutManager
#onLayoutChildren(Recycler, State)
.
The default return value is false
, so subclasses of LayoutManager
will not get predictive item animations by default.
Whether item animations are enabled in a RecyclerView is determined both
by 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 simple item animations will be enabled, in which
views that are moving onto or off of the screen are simply faded in/out. If
the RecyclerView has a non-null ItemAnimator and this method returns true,
then there will be two calls to #onLayoutChildren(Recycler, State)
to
setup up the information needed to more intelligently predict where appearing
and disappearing views should be animated from/to.
supportsPredictiveItemAnimations
in class RecyclerView.LayoutManager
public int[] findFirstVisibleItemPositions(int[] into)
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.
into
- An array to put the results into. If you don't provide any, LayoutManager will
create a new one.RecyclerView.NO_POSITION
is returned for that span.findFirstCompletelyVisibleItemPositions(int[])
,
findLastVisibleItemPositions(int[])
public int[] findFirstCompletelyVisibleItemPositions(int[] into)
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.
into
- An array to put the results into. If you don't provide any, LayoutManager will
create a new one.RecyclerView.NO_POSITION
is returned for that span.findFirstVisibleItemPositions(int[])
,
findLastCompletelyVisibleItemPositions(int[])
public int[] findLastVisibleItemPositions(int[] into)
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.
into
- An array to put the results into. If you don't provide any, LayoutManager will
create a new one.RecyclerView.NO_POSITION
is returned for that span.findLastCompletelyVisibleItemPositions(int[])
,
findFirstVisibleItemPositions(int[])
public int[] findLastCompletelyVisibleItemPositions(int[] into)
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.
into
- An array to put the results into. If you don't provide any, LayoutManager will
create a new one.RecyclerView.NO_POSITION
is returned for that span.findFirstCompletelyVisibleItemPositions(int[])
,
findLastVisibleItemPositions(int[])
public int computeHorizontalScrollOffset(RecyclerView.State state)
RecyclerView.LayoutManager
Override this method if you want to support scroll bars.
Read RecyclerView.computeHorizontalScrollOffset()
for details.
Default implementation returns 0.
computeHorizontalScrollOffset
in class RecyclerView.LayoutManager
state
- Current State of RecyclerView where you can find total item countRecyclerView.computeHorizontalScrollOffset()
public int computeVerticalScrollOffset(RecyclerView.State state)
RecyclerView.LayoutManager
Override this method if you want to support scroll bars.
Read RecyclerView.computeVerticalScrollOffset()
for details.
Default implementation returns 0.
computeVerticalScrollOffset
in class RecyclerView.LayoutManager
state
- Current State of RecyclerView where you can find total item countRecyclerView.computeVerticalScrollOffset()
public int computeHorizontalScrollExtent(RecyclerView.State state)
RecyclerView.LayoutManager
Override this method if you want to support scroll bars.
Read RecyclerView.computeHorizontalScrollExtent()
for details.
Default implementation returns 0.
computeHorizontalScrollExtent
in class RecyclerView.LayoutManager
state
- Current state of RecyclerViewRecyclerView.computeHorizontalScrollExtent()
public int computeVerticalScrollExtent(RecyclerView.State state)
RecyclerView.LayoutManager
Override this method if you want to support scroll bars.
Read RecyclerView.computeVerticalScrollExtent()
for details.
Default implementation returns 0.
computeVerticalScrollExtent
in class RecyclerView.LayoutManager
state
- Current state of RecyclerViewRecyclerView.computeVerticalScrollExtent()
public int computeHorizontalScrollRange(RecyclerView.State state)
RecyclerView.LayoutManager
Override this method if you want to support scroll bars.
Read RecyclerView.computeHorizontalScrollRange()
for details.
Default implementation returns 0.
computeHorizontalScrollRange
in class RecyclerView.LayoutManager
state
- Current State of RecyclerView where you can find total item countRecyclerView.computeHorizontalScrollRange()
public int computeVerticalScrollRange(RecyclerView.State state)
RecyclerView.LayoutManager
Override this method if you want to support scroll bars.
Read RecyclerView.computeVerticalScrollRange()
for details.
Default implementation returns 0.
computeVerticalScrollRange
in class RecyclerView.LayoutManager
state
- Current State of RecyclerView where you can find total item countRecyclerView.computeVerticalScrollRange()
public void onRestoreInstanceState(Parcelable state)
onRestoreInstanceState
in class RecyclerView.LayoutManager
public Parcelable onSaveInstanceState()
RecyclerView.LayoutManager
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.
onSaveInstanceState
in class RecyclerView.LayoutManager
public void onInitializeAccessibilityNodeInfoForItem(RecyclerView.Recycler recycler, RecyclerView.State state, View host, AccessibilityNodeInfoCompat info)
RecyclerView.LayoutManager
Default implementation adds basic positioning information about the item.
onInitializeAccessibilityNodeInfoForItem
in class RecyclerView.LayoutManager
recycler
- The Recycler that can be used to convert view positions into adapter
positionsstate
- The current state of RecyclerViewhost
- The child for which accessibility node info should be populatedinfo
- The info to fill out about the itemAbsListView.onInitializeAccessibilityNodeInfoForItem(View, int,
android.view.accessibility.AccessibilityNodeInfo)
public void onInitializeAccessibilityEvent(AccessibilityEvent event)
onInitializeAccessibilityEvent
in class RecyclerView.LayoutManager
public int getRowCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)
RecyclerView.LayoutManager
Default implementation returns the number of items in the adapter if LayoutManager supports vertical scrolling or 1 if LayoutManager does not support vertical scrolling.
getRowCountForAccessibility
in class RecyclerView.LayoutManager
recycler
- The Recycler that can be used to convert view positions into adapter
positionsstate
- The current state of RecyclerViewpublic int getColumnCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)
RecyclerView.LayoutManager
Default implementation returns the number of items in the adapter if LayoutManager supports horizontal scrolling or 1 if LayoutManager does not support horizontal scrolling.
getColumnCountForAccessibility
in class RecyclerView.LayoutManager
recycler
- The Recycler that can be used to convert view positions into adapter
positionsstate
- The current state of RecyclerViewpublic void offsetChildrenHorizontal(int dx)
RecyclerView.LayoutManager
offsetChildrenHorizontal
in class RecyclerView.LayoutManager
dx
- Pixels to offset bypublic void offsetChildrenVertical(int dy)
RecyclerView.LayoutManager
offsetChildrenVertical
in class RecyclerView.LayoutManager
dy
- Pixels to offset bypublic void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount)
RecyclerView.LayoutManager
onItemsRemoved
in class RecyclerView.LayoutManager
public void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount)
RecyclerView.LayoutManager
onItemsAdded
in class RecyclerView.LayoutManager
public void onItemsChanged(RecyclerView recyclerView)
RecyclerView.LayoutManager
RecyclerView.Adapter.notifyDataSetChanged()
is triggered instead of giving
detailed information on what has actually changed.onItemsChanged
in class RecyclerView.LayoutManager
public void onItemsMoved(RecyclerView recyclerView, int from, int to, int itemCount)
RecyclerView.LayoutManager
Note that, an item may also change position in response to another ADD/REMOVE/MOVE
operation. This callback is only called if and only if RecyclerView.Adapter.notifyItemMoved(int, int)
is called.
onItemsMoved
in class RecyclerView.LayoutManager
public void onItemsUpdated(RecyclerView recyclerView, int positionStart, int itemCount, Object payload)
RecyclerView.LayoutManager
RecyclerView.LayoutManager.onItemsUpdated(RecyclerView, int, int)
.onItemsUpdated
in class RecyclerView.LayoutManager
public boolean canScrollVertically()
RecyclerView.LayoutManager
canScrollVertically
in class RecyclerView.LayoutManager
public boolean canScrollHorizontally()
RecyclerView.LayoutManager
canScrollHorizontally
in class RecyclerView.LayoutManager
public int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state)
RecyclerView.LayoutManager
scrollHorizontallyBy
in class RecyclerView.LayoutManager
dx
- distance to scroll by in pixels. X increases as scroll position
approaches the right.recycler
- Recycler to use for fetching potentially cached views for a
positionstate
- Transient state of RecyclerViewMath.abs(result)
may be less than dx if a boundary was reached.public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state)
RecyclerView.LayoutManager
scrollVerticallyBy
in class RecyclerView.LayoutManager
dy
- distance to scroll in pixels. Y increases as scroll position
approaches the bottom.recycler
- Recycler to use for fetching potentially cached views for a
positionstate
- Transient state of RecyclerViewMath.abs(result)
may be less than dy if a boundary was reached.public PointF computeScrollVectorForPosition(int targetPosition)
RecyclerView.SmoothScroller.ScrollVectorProvider
This method is used by the LinearSmoothScroller
to initiate a scroll towards
the target position.
The magnitude of the vector is not important. It is always normalized before being
used by the LinearSmoothScroller
.
LayoutManager should not check whether the position exists in the adapter or not.
computeScrollVectorForPosition
in interface RecyclerView.SmoothScroller.ScrollVectorProvider
targetPosition
- the target position to which the returned vector should pointpublic void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position)
RecyclerView.LayoutManager
Smooth scroll to the specified adapter position.
To support smooth scrolling, override this method, create your RecyclerView.SmoothScroller
instance and call #startSmoothScroll(SmoothScroller)
.
smoothScrollToPosition
in class RecyclerView.LayoutManager
recyclerView
- The RecyclerView to which this layout manager is attachedstate
- Current State of RecyclerViewposition
- Scroll to this adapter position.public void scrollToPosition(int position)
RecyclerView.LayoutManager
scrollToPosition
in class RecyclerView.LayoutManager
position
- Scroll to this adapter position.public void scrollToPositionWithOffset(int position, int offset)
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)
.
position
- Index (starting at 0) of the reference item.offset
- The distance (in pixels) between the start edge of the item view and
start edge of the RecyclerView.setReverseLayout(boolean)
,
scrollToPosition(int)
public RecyclerView.LayoutParams generateDefaultLayoutParams()
RecyclerView.LayoutManager
LayoutParams
object for a child of the RecyclerView.
LayoutManagers will often want to use a custom LayoutParams
type
to store extra information specific to the layout. Client code should subclass
RecyclerView.LayoutParams
for this purpose.
Important: if you use your own custom LayoutParams
type
you must also override
ViewGroup.checkLayoutParams(LayoutParams)
,
RecyclerView.LayoutManager.generateLayoutParams(android.view.ViewGroup.LayoutParams)
and
RecyclerView.LayoutManager.generateLayoutParams(android.content.Context, android.util.AttributeSet)
.
generateDefaultLayoutParams
in class RecyclerView.LayoutManager
public RecyclerView.LayoutParams generateLayoutParams(Context c, AttributeSet attrs)
RecyclerView.LayoutManager
Important: if you use your own custom LayoutParams
type
you must also override
ViewGroup.checkLayoutParams(LayoutParams)
,
RecyclerView.LayoutManager.generateLayoutParams(android.view.ViewGroup.LayoutParams)
and
RecyclerView.LayoutManager.generateLayoutParams(android.content.Context, android.util.AttributeSet)
.
generateLayoutParams
in class RecyclerView.LayoutManager
c
- Context for obtaining styled attributesattrs
- AttributeSet describing the supplied argumentspublic RecyclerView.LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp)
RecyclerView.LayoutManager
Important: if you use your own custom LayoutParams
type
you must also override
ViewGroup.checkLayoutParams(LayoutParams)
,
RecyclerView.LayoutManager.generateLayoutParams(android.view.ViewGroup.LayoutParams)
and
RecyclerView.LayoutManager.generateLayoutParams(android.content.Context, android.util.AttributeSet)
.
generateLayoutParams
in class RecyclerView.LayoutManager
lp
- Source LayoutParams object to copy values frompublic boolean checkLayoutParams(RecyclerView.LayoutParams lp)
RecyclerView.LayoutManager
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.
checkLayoutParams
in class RecyclerView.LayoutManager
lp
- LayoutParams object to checkpublic int getOrientation()
@Nullable public View onFocusSearchFailed(View focused, int direction, RecyclerView.Recycler recycler, RecyclerView.State state)
RecyclerView.LayoutManager
This is the LayoutManager's opportunity to populate views in the given direction to fulfill the request if it can. The LayoutManager should attach and return the view to be focused. The default implementation returns null.
onFocusSearchFailed
in class RecyclerView.LayoutManager
focused
- The currently focused viewdirection
- One of View.FOCUS_UP
, View.FOCUS_DOWN
,
View.FOCUS_LEFT
, View.FOCUS_RIGHT
,
View.FOCUS_BACKWARD
, View.FOCUS_FORWARD
or 0 for not applicablerecycler
- The recycler to use for obtaining views for currently offscreen itemsstate
- Transient state of RecyclerView