WearableLinearLayoutManager

Added in 1.1.0

class WearableLinearLayoutManager : 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 functions

WearableLinearLayoutManager.LayoutCallback?
Unit
onLayoutChildren(
    recycler: RecyclerView.Recycler!,
    state: RecyclerView.State!
)

Lay out all relevant child views from the given adapter.

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

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

Unit

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

Inherited Constants

From androidx.recyclerview.widget.LinearLayoutManager
const Int
const Int
INVALID_OFFSET = -2147483648
const Int

Inherited functions

From androidx.recyclerview.widget.LinearLayoutManager
Unit

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

Unit
calculateExtraLayoutSpace(
    state: RecyclerView.State,
    extraLayoutSpace: IntArray
)

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

Boolean
Boolean
Unit
collectAdjacentPrefetchPositions(
    dx: Int,
    dy: Int,
    state: RecyclerView.State!,
    layoutPrefetchRegistry: RecyclerView.LayoutManager.LayoutPrefetchRegistry!
)

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

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.

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!

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!

Finds the view which represents the given adapter position.

RecyclerView.LayoutParams!

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

Int

This function 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.

Unit

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

View!
onFocusSearchFailed(
    focused: View!,
    direction: Int,
    recycler: RecyclerView.Recycler!,
    state: RecyclerView.State!
)

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

Unit
Unit

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

Unit

Called after a full layout calculation is finished.

Unit

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

Parcelable!

Called when the LayoutManager should save its state.

Unit
prepareForDrop(view: View, target: View, x: Int, y: Int)

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

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

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

Unit
scrollToPosition(position: Int)

Scroll the RecyclerView to make the position visible.

Unit
scrollToPositionWithOffset(position: Int, offset: Int)

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

Unit

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.

Unit
setOrientation(orientation: Int)

Sets the orientation of the layout.

Unit
setRecycleChildrenOnDetach(recycleChildrenOnDetach: Boolean)

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

Unit
setReverseLayout(reverseLayout: Boolean)

Used to reverse item traversal and layout order.

Unit

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.

Unit
setStackFromEnd(stackFromEnd: Boolean)

Compatibility support for setStackFromBottom

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

Smooth scroll to the specified adapter position.

Boolean

Returns whether this LayoutManager supports "predictive item animations".

From androidx.recyclerview.widget.RecyclerView.LayoutManager
Unit

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.

Unit
addDisappearingView(child: View!, index: Int)

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.

Unit
addView(child: View!)

Add a view to the currently attached RecyclerView if needed.

Unit
addView(child: View!, index: Int)

Add a view to the currently attached RecyclerView if needed.

Unit

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

Unit
attachView(child: View)

Reattach a previously detached view.

Unit
attachView(child: View, index: Int)

Reattach a previously detached view.

Unit
attachView(child: View, index: Int, lp: RecyclerView.LayoutParams!)

Reattach a previously detached view.

Unit

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.

java-static 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
collectAdjacentPrefetchPositions(
    dx: Int,
    dy: Int,
    state: RecyclerView.State!,
    layoutPrefetchRegistry: RecyclerView.LayoutManager.LayoutPrefetchRegistry!
)

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

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.

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.

Unit

Temporarily detach and scrap all currently attached child views.

Unit

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

Unit

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

Unit
detachView(child: View)

Temporarily detach a child view.

Unit
detachViewAt(index: Int)

Temporarily detach a child view.

Unit

Ends all animations on the view created by the ItemAnimator.

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.

View?
getChildAt(index: Int)

Return the child view at the given index

Int

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

java-static Int
getChildMeasureSpec(
    parentSize: Int,
    padding: Int,
    childDimension: Int,
    canScroll: Boolean
)

This function is deprecated.

use getChildMeasureSpec

java-static 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

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.

Unit

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.

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.

java-static RecyclerView.LayoutManager.Properties!
getProperties(
    context: Context,
    attrs: AttributeSet?,
    defStyleAttr: Int,
    defStyleRes: Int
)

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.

Unit
getTransformedBoundingBox(
    child: View,
    includeDecorInsets: Boolean,
    out: Rect
)

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.

Unit

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.

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(
    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.

Unit
layoutDecorated(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.

Unit
layoutDecoratedWithMargins(
    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.

Unit
measureChild(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.

Unit
measureChildWithMargins(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.

Unit
moveView(fromIndex: Int, toIndex: Int)

Moves a View from one position to another.

Unit

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

Unit

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

Unit
onAdapterChanged(
    oldAdapter: RecyclerView.Adapter?,
    newAdapter: RecyclerView.Adapter?
)

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

Boolean
onAddFocusables(
    recyclerView: RecyclerView,
    views: ArrayList<View!>,
    direction: Int,
    focusableMode: Int
)

Called to populate focusable views within the RecyclerView.

Unit

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

Unit

This function is deprecated.

override onDetachedFromWindow

Unit

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

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

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

Unit
Unit

Called by the accessibility delegate to initialize an accessibility event.

Unit

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

Unit

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

View?
onInterceptFocusSearch(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.

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

Called when items have been added to the adapter.

Unit

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

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

Called when an item is moved withing the adapter.

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

Called when items have been removed from the adapter.

Unit
onItemsUpdated(
    recyclerView: RecyclerView,
    positionStart: Int,
    itemCount: Int
)

Called when items have been changed in the adapter.

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

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

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

Lay out all relevant child views from the given adapter.

Unit

Called after a full layout calculation is finished.

Unit
onMeasure(
    recycler: RecyclerView.Recycler,
    state: RecyclerView.State,
    widthSpec: Int,
    heightSpec: Int
)

Measure the attached RecyclerView.

Boolean
onRequestChildFocus(parent: RecyclerView, child: View, focused: View?)

This function is deprecated.

Use onRequestChildFocus

Boolean
onRequestChildFocus(
    parent: RecyclerView,
    state: RecyclerView.State,
    child: View,
    focused: View?
)

Called when a descendant view of the RecyclerView requests focus.

Unit

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

Boolean
performAccessibilityAction(
    recycler: RecyclerView.Recycler,
    state: RecyclerView.State,
    action: Int,
    args: Bundle?
)

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

Boolean
performAccessibilityActionForItem(
    recycler: RecyclerView.Recycler,
    state: RecyclerView.State,
    view: View,
    action: Int,
    args: Bundle?
)

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

Unit

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

Unit

Remove all views from the currently attached RecyclerView.

Unit

Removes all views and recycles them using the given recycler.

Unit

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

Unit

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

Boolean

Removes the specified Runnable from the message queue.

Unit

Finish removing a view that was previously temporarily detached.

Unit
removeView(child: View!)

Remove a view from the currently attached RecyclerView if needed.

Unit
removeViewAt(index: Int)

Remove a view from the currently attached RecyclerView if needed.

Boolean
requestChildRectangleOnScreen(
    parent: RecyclerView,
    child: View,
    rect: Rect,
    immediate: Boolean
)

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

Boolean
requestChildRectangleOnScreen(
    parent: RecyclerView,
    child: View,
    rect: Rect,
    immediate: Boolean,
    focusedChildVisible: Boolean
)

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

Unit

Calls RecyclerView#requestLayout on the underlying RecyclerView

Unit

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

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

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

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

Unit

This function is deprecated.

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

Unit

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

Unit
setMeasuredDimension(widthSize: Int, heightSize: Int)

Set the measured dimensions of the host RecyclerView.

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

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

Unit
setMeasurementCacheEnabled(measurementCacheEnabled: Boolean)

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

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

Smooth scroll to the specified adapter position.

Unit

Starts a smooth scroll using the provided SmoothScroller.

Unit

View can be scrapped and recycled again.

Public constructors

WearableLinearLayoutManager

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

Creates a WearableLinearLayoutManager for a vertical list.

Parameters
context: Context!

Current context, will be used to access resources.

layoutCallback: WearableLinearLayoutManager.LayoutCallback!

Callback to be associated with this WearableLinearLayoutManager

Public functions

onLayoutChildren

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

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

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

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
fun setLayoutCallback(
    layoutCallback: WearableLinearLayoutManager.LayoutCallback?
): Unit

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

Parameters
layoutCallback: WearableLinearLayoutManager.LayoutCallback?