WearableLinearLayoutManager

Added in 1.1.0

public class WearableLinearLayoutManager extends LinearLayoutManager


This wear-specific implementation of LinearLayoutManager provides basic offsetting logic for updating child layout. For round devices it offsets the children horizontally to make them appear to travel around a circle. For square devices it aligns them in a straight list. This functionality is provided by the CurvingLayoutCallback which is set when constructing the this class with its default constructor WearableLinearLayoutManager.

Summary

Nested types

Callback for interacting with layout passes.

Public constructors

Creates a WearableLinearLayoutManager for a vertical list.

Creates a WearableLinearLayoutManager for a vertical list.

Public methods

@Nullable WearableLinearLayoutManager.LayoutCallback
void

Lay out all relevant child views from the given adapter.

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

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

void

Set a particular instance of the layout callback for this WearableLinearLayoutManager.

Inherited Constants

From androidx.recyclerview.widget.LinearLayoutManager
static final int
static final int
INVALID_OFFSET = -2147483648
static final int

Inherited methods

From androidx.recyclerview.widget.LinearLayoutManager
void

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

void
calculateExtraLayoutSpace(
    @NonNull RecyclerView.State state,
    @NonNull int[] extraLayoutSpace
)

Calculates the amount of extra space (in pixels) that should be laid out by and stores the result in extraLayoutSpace.

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

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

void
collectInitialPrefetchPositions(
    int adapterItemCount,
    RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry
)

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

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

PointF
computeScrollVectorForPosition(int targetPosition)

Should calculate the vector that points to the direction where the target position can be found.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Returns the adapter position of the first fully visible view.

int

Returns the adapter position of the first visible view.

int

Returns the adapter position of the last fully visible view.

int

Returns the adapter position of the last visible view.

View
findViewByPosition(int position)

Finds the view which represents the given adapter position.

RecyclerView.LayoutParams

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

int

This method is deprecated.

Use calculateExtraLayoutSpace instead.

int

Gets the number of items to prefetch in collectInitialPrefetchPositions, which defines how many inner items should be prefetched when this LayoutManager's RecyclerView is nested inside another RecyclerView.

int

Returns the current orientation of the layout.

boolean

Returns whether LayoutManager will recycle its children when it is detached from RecyclerView.

boolean

Returns if views are laid out from the opposite direction of the layout.

boolean
boolean

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

boolean
boolean

Query if the layout is in reverse order.

boolean

Returns the current state of the smooth scrollbar feature.

void

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
void

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

void

Called after a full layout calculation is finished.

void

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

Parcelable

Called when the LayoutManager should save its state.

void
prepareForDrop(@NonNull View view, @NonNull View target, int x, int y)

Called by the after a View is dropped over another View.

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 the RecyclerView to make the position visible.

void
scrollToPositionWithOffset(int position, int offset)

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

void

Sets the number of items to prefetch in collectInitialPrefetchPositions, which defines how many inner items should be prefetched when this LayoutManager's RecyclerView is nested inside another RecyclerView.

void
setOrientation(int orientation)

Sets the orientation of the layout.

void
setRecycleChildrenOnDetach(boolean recycleChildrenOnDetach)

Set whether LayoutManager will recycle its children when it is detached from RecyclerView.

void
setReverseLayout(boolean reverseLayout)

Used to reverse item traversal and layout order.

void
setSmoothScrollbarEnabled(boolean enabled)

When smooth scrollbar is enabled, the position and size of the scrollbar thumb is computed based on the number of visible pixels in the visible items.

void
setStackFromEnd(boolean stackFromEnd)

Compatibility support for setStackFromBottom

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

Smooth scroll to the specified adapter position.

boolean

Returns whether this LayoutManager supports "predictive item animations".

From androidx.recyclerview.widget.RecyclerView.LayoutManager
void

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

void
addDisappearingView(View child, int index)

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

void
addView(View child)

Add a view to the currently attached RecyclerView if needed.

void
addView(View child, int index)

Add a view to the currently attached RecyclerView if needed.

void

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

void

Reattach a previously detached view.

void
attachView(@NonNull View child, int index)

Reattach a previously detached view.

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

Reattach a previously detached view.

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

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

boolean

Determines the validity of the supplied LayoutParams object.

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

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

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

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

void
collectInitialPrefetchPositions(
    int adapterItemCount,
    RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry
)

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

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

int

Override this method if you want to support scroll bars.

void

Temporarily detach and scrap all currently attached child views.

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

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

void

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

void

Temporarily detach a child view.

void
detachViewAt(int index)

Temporarily detach a child view.

void

Ends all animations on the view created by the ItemAnimator.

@Nullable View

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

RecyclerView.LayoutParams

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

RecyclerView.LayoutParams

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

int

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

int

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

@Nullable View
getChildAt(int index)

Return the child view at the given index

int

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

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

This method is deprecated.

use getChildMeasureSpec

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

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

boolean

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

int

Returns the number of columns for accessibility.

int

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

void

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

int

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

int

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

int

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

int

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

int

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

@Nullable View

Returns the item View which has or contains focus.

@Px int

Returns the height that is currently relevant to the LayoutManager.

int

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

int

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

int

Returns the View type defined by the adapter.

int

Returns the resolved layout direction for this RecyclerView.

int

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

@Px int
@Px int
@Px int

Return the bottom padding of the parent RecyclerView

@Px int

Return the end padding of the parent RecyclerView

@Px int

Return the left padding of the parent RecyclerView

@Px int

Return the right padding of the parent RecyclerView

@Px int

Return the start padding of the parent RecyclerView

@Px int

Return the top padding of the parent RecyclerView

int

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

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

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

int

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

int

Returns the number of rows for accessibility.

int

Returns the selection mode for accessibility.

int

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

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

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

@Px int

Returns the width that is currently relevant to the LayoutManager.

int

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

boolean

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

void

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

boolean

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

boolean

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

final boolean

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

boolean

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

boolean

In addition to the View Framework's measurement cache, RecyclerView uses its own additional measurement cache for its children to avoid re-measuring them when not necessary.

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

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

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

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

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

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

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

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

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

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

void
moveView(int fromIndex, int toIndex)

Moves a View from one position to another.

void

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

void

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

void

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

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

Called to populate focusable views within the RecyclerView.

void

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

void

This method is deprecated.

override onDetachedFromWindow

void

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

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

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

void
void

Called by the accessibility delegate to initialize an accessibility event.

void

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

void

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

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

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

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

Called when items have been added to the adapter.

void

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

void
onItemsMoved(
    @NonNull RecyclerView recyclerView,
    int from,
    int to,
    int itemCount
)

Called when an item is moved withing the adapter.

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

Called when items have been removed from the adapter.

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

Called when items have been changed in the adapter.

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

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

void

Lay out all relevant child views from the given adapter.

void

Called after a full layout calculation is finished.

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

Measure the attached RecyclerView.

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

This method is deprecated.

Use onRequestChildFocus

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

Called when a descendant view of the RecyclerView requests focus.

void

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

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

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

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

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

void

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

void

Remove all views from the currently attached RecyclerView.

void

Removes all views and recycles them using the given recycler.

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

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

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

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

boolean

Removes the specified Runnable from the message queue.

void

Finish removing a view that was previously temporarily detached.

void

Remove a view from the currently attached RecyclerView if needed.

void
removeViewAt(int index)

Remove a view from the currently attached RecyclerView if needed.

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

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

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

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

void

Calls RecyclerView#requestLayout on the underlying RecyclerView

void

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

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

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

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

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

void
setAutoMeasureEnabled(boolean enabled)

This method is deprecated.

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

final void
setItemPrefetchEnabled(boolean enabled)

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

void
setMeasuredDimension(int widthSize, int heightSize)

Set the measured dimensions of the host RecyclerView.

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

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

void
setMeasurementCacheEnabled(boolean measurementCacheEnabled)

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

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

Smooth scroll to the specified adapter position.

void

Starts a smooth scroll using the provided SmoothScroller.

void

View can be scrapped and recycled again.

Public constructors

WearableLinearLayoutManager

Added in 1.1.0
public WearableLinearLayoutManager(Context context)

Creates a WearableLinearLayoutManager for a vertical list.

Parameters
Context context

Current context, will be used to access resources.

WearableLinearLayoutManager

Added in 1.1.0
public WearableLinearLayoutManager(
    Context context,
    WearableLinearLayoutManager.LayoutCallback layoutCallback
)

Creates a WearableLinearLayoutManager for a vertical list.

Parameters
Context context

Current context, will be used to access resources.

WearableLinearLayoutManager.LayoutCallback layoutCallback

Callback to be associated with this WearableLinearLayoutManager

Public methods

onLayoutChildren

public 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 simple item animations are enabled. This means that add/remove operations on the adapter will result in animations to add new or appearing items, removed or disappearing items, and moved items. If a LayoutManager returns false from #supportsPredictiveItemAnimations(), which is the default, and runs a normal layout operation during #onLayoutChildren(Recycler, State), the RecyclerView will have enough information to run those animations in a simple way. For example, the default ItemAnimator, , will simply fade views in and out, whether they are actually added/removed or whether they are moved on or off the screen due to other add/remove operations.

A LayoutManager wanting a better item animation experience, where items can be animated onto and off of the screen according to where the items exist when they are not on screen, then the LayoutManager should return true from #supportsPredictiveItemAnimations() and add additional logic to #onLayoutChildren(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, LayoutParams#isItemRemoved() removed items will be returned from the scrap to help determine correct placement of other items. These removed items should not be added to the child list, but should be used to help calculate correct positioning of other views, including views that were not previously onscreen (referred to as APPEARING views), but whose pre-layout offscreen position can be determined given the extra information about the pre-layout removed views.

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

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

scrollVerticallyBy

public 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.

setLayoutCallback

Added in 1.1.0
public void setLayoutCallback(
    @Nullable WearableLinearLayoutManager.LayoutCallback layoutCallback
)

Set a particular instance of the layout callback for this WearableLinearLayoutManager. The callback will be called on the Ui thread.