Behavior

abstract class Behavior<V : View!>
kotlin.Any
   ↳ androidx.coordinatorlayout.widget.CoordinatorLayout.Behavior

Interaction behavior plugin for child views of CoordinatorLayout.

A Behavior implements one or more interactions that a user can take on a child view. These interactions may include drags, swipes, flings, or any other gestures.

Summary

Public constructors

Default constructor for instantiating Behaviors.

<init>(context: Context!, attrs: AttributeSet!)

Default constructor for inflating Behaviors from layout.

Public methods

open Boolean
blocksInteractionBelow(@NonNull parent: CoordinatorLayout, @NonNull child: V)

Determine whether interaction with views behind the given child in the child order should be blocked.

open Boolean
getInsetDodgeRect(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull rect: Rect)

Called when a view is set to dodge view insets.

open Int
getScrimColor(@NonNull parent: CoordinatorLayout, @NonNull child: V)

Supply a scrim color that will be painted behind the associated child view.

open Float
getScrimOpacity(@NonNull parent: CoordinatorLayout, @NonNull child: V)

Determine the current opacity of the scrim behind a given child view

open static Any?
getTag(@NonNull child: View)

Get the behavior-specific tag object with the given child view.

open Boolean
layoutDependsOn(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull dependency: View)

Determine whether the supplied child view has another specific sibling view as a layout dependency.

open WindowInsetsCompat
onApplyWindowInsets(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull insets: WindowInsetsCompat)

Called when the window insets have changed.

open Unit

Called when the Behavior has been attached to a LayoutParams instance.

open Boolean
onDependentViewChanged(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull dependency: View)

Respond to a change in a child's dependent view

open Unit
onDependentViewRemoved(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull dependency: View)

Respond to a child's dependent view being removed.

open Unit

Called when the Behavior has been detached from its holding LayoutParams instance.

open Boolean
onInterceptTouchEvent(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull ev: MotionEvent)

Respond to CoordinatorLayout touch events before they are dispatched to child views.

open Boolean
onLayoutChild(@NonNull parent: CoordinatorLayout, @NonNull child: V, layoutDirection: Int)

Called when the parent CoordinatorLayout is about the lay out the given child view.

open Boolean
onMeasureChild(@NonNull parent: CoordinatorLayout, @NonNull child: V, parentWidthMeasureSpec: Int, widthUsed: Int, parentHeightMeasureSpec: Int, heightUsed: Int)

Called when the parent CoordinatorLayout is about to measure the given child view.

open Boolean
onNestedFling(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, velocityX: Float, velocityY: Float, consumed: Boolean)

Called when a nested scrolling child is starting a fling or an action that would be a fling.

open Boolean
onNestedPreFling(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, velocityX: Float, velocityY: Float)

Called when a nested scrolling child is about to start a fling.

open Unit
onNestedPreScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dx: Int, dy: Int, @NonNull consumed: IntArray)

open Unit
onNestedPreScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dx: Int, dy: Int, @NonNull consumed: IntArray, type: Int)

Called when a nested scroll in progress is about to update, before the target has consumed any of the scrolled distance.

open Unit
onNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int)

open Unit
onNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int)

open Unit
onNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int, @NonNull consumed: IntArray)

Called when a nested scroll in progress has updated and the target has scrolled or attempted to scroll.

open Unit
onNestedScrollAccepted(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int)

open Unit
onNestedScrollAccepted(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int, type: Int)

Called when a nested scroll has been accepted by the CoordinatorLayout.

open Boolean
onRequestChildRectangleOnScreen(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull rectangle: Rect, immediate: Boolean)

Called when a child of the view associated with this behavior wants a particular rectangle to be positioned onto the screen.

open Unit
onRestoreInstanceState(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull state: Parcelable)

Hook allowing a behavior to re-apply a representation of its internal state that had previously been generated by onSaveInstanceState.

open Parcelable?
onSaveInstanceState(@NonNull parent: CoordinatorLayout, @NonNull child: V)

Hook allowing a behavior to generate a representation of its internal state that can later be used to create a new instance with that same state.

open Boolean
onStartNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int)

open Boolean
onStartNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int, type: Int)

Called when a descendant of the CoordinatorLayout attempts to initiate a nested scroll.

open Unit
onStopNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View)

open Unit
onStopNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, type: Int)

Called when a nested scroll has ended.

open Boolean
onTouchEvent(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull ev: MotionEvent)

Respond to CoordinatorLayout touch events after this Behavior has started intercepting them.

open static Unit
setTag(@NonNull child: View, @Nullable tag: Any?)

Associate a Behavior-specific tag object with the given child view.

Public constructors

<init>

Behavior()

Default constructor for instantiating Behaviors.

<init>

Behavior(context: Context!, attrs: AttributeSet!)

Default constructor for inflating Behaviors from layout. The Behavior will have the opportunity to parse specially defined layout parameters. These parameters will appear on the child view tag.

Parameters
context Context!:
attrs Context!:

Public methods

blocksInteractionBelow

open fun blocksInteractionBelow(@NonNull parent: CoordinatorLayout, @NonNull child: V): Boolean

Determine whether interaction with views behind the given child in the child order should be blocked.

The default implementation returns true if getScrimOpacity(CoordinatorLayout, View) would return > 0.0f.

Parameters
parent CoordinatorLayout: the parent view of the given child
child CoordinatorLayout: the child view to test
Return
Boolean: true if getScrimOpacity(CoordinatorLayout, View) would return > 0.0f.

getInsetDodgeRect

open fun getInsetDodgeRect(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull rect: Rect): Boolean

Called when a view is set to dodge view insets.

This method allows a behavior to update the rectangle that should be dodged. The rectangle should be in the parent's coordinate system and within the child's bounds. If not, a IllegalArgumentException is thrown.

Parameters
parent CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
rect CoordinatorLayout: the rect to update with the dodge rectangle
Return
Boolean: true the rect was updated, false if we should use the child's bounds

getScrimColor

open fun getScrimColor(@NonNull parent: CoordinatorLayout, @NonNull child: V): Int

Supply a scrim color that will be painted behind the associated child view.

A scrim may be used to indicate that the other elements beneath it are not currently interactive or actionable, drawing user focus and attention to the views above the scrim.

The default implementation returns Color#BLACK.

Parameters
parent CoordinatorLayout: the parent view of the given child
child CoordinatorLayout: the child view above the scrim
Return
Int: the desired scrim color in 0xAARRGGBB format. The default return value is Color#BLACK.

getScrimOpacity

open fun getScrimOpacity(@NonNull parent: CoordinatorLayout, @NonNull child: V): Float

Determine the current opacity of the scrim behind a given child view

A scrim may be used to indicate that the other elements beneath it are not currently interactive or actionable, drawing user focus and attention to the views above the scrim.

The default implementation returns 0.0f.

Parameters
parent CoordinatorLayout: the parent view of the given child
child CoordinatorLayout: the child view above the scrim
Return
Float: the desired scrim opacity from 0.0f to 1.0f. The default return value is 0.0f.

getTag

@Nullable open static fun getTag(@NonNull child: View): Any?

Get the behavior-specific tag object with the given child view. This object is stored with the child view's LayoutParams.

Parameters
child View: child view to get tag with
Return
Any?: the previously stored tag object

layoutDependsOn

open fun layoutDependsOn(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull dependency: View): Boolean

Determine whether the supplied child view has another specific sibling view as a layout dependency.

This method will be called at least once in response to a layout request. If it returns true for a given child and dependency view pair, the parent CoordinatorLayout will:

  1. Always lay out this child after the dependent child is laid out, regardless of child order.
  2. Call onDependentViewChanged when the dependency view's layout or position changes.
Parameters
parent CoordinatorLayout: the parent view of the given child
child CoordinatorLayout: the child view to test
dependency CoordinatorLayout: the proposed dependency of child
Return
Boolean: true if child's layout depends on the proposed dependency's layout, false otherwise

onApplyWindowInsets

@NonNull open fun onApplyWindowInsets(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull insets: WindowInsetsCompat): WindowInsetsCompat

Called when the window insets have changed.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to handle the window inset change on behalf of it's associated view.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
insets CoordinatorLayout: the new window insets.
Return
WindowInsetsCompat: The insets supplied, minus any insets that were consumed

onAttachedToLayoutParams

open fun onAttachedToLayoutParams(@NonNull params: CoordinatorLayout.LayoutParams): Unit

Called when the Behavior has been attached to a LayoutParams instance.

This will be called after the LayoutParams has been instantiated and can be modified.

Parameters
params CoordinatorLayout.LayoutParams: the LayoutParams instance that this Behavior has been attached to

onDependentViewChanged

open fun onDependentViewChanged(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull dependency: View): Boolean

Respond to a change in a child's dependent view

This method is called whenever a dependent view changes in size or position outside of the standard layout flow. A Behavior may use this method to appropriately update the child view in response.

A view's dependency is determined by layoutDependsOn(CoordinatorLayout, View, View) or if child has set another view as it's anchor.

Note that if a Behavior changes the layout of a child via this method, it should also be able to reconstruct the correct position in onLayoutChild. onDependentViewChanged will not be called during normal layout since the layout of each child view will always happen in dependency order.

If the Behavior changes the child view's size or position, it should return true. The default implementation returns false.

Parameters
parent CoordinatorLayout: the parent view of the given child
child CoordinatorLayout: the child view to manipulate
dependency CoordinatorLayout: the dependent view that changed
Return
Boolean: true if the Behavior changed the child view's size or position, false otherwise

onDependentViewRemoved

open fun onDependentViewRemoved(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull dependency: View): Unit

Respond to a child's dependent view being removed.

This method is called after a dependent view has been removed from the parent. A Behavior may use this method to appropriately update the child view in response.

A view's dependency is determined by layoutDependsOn(CoordinatorLayout, View, View) or if child has set another view as it's anchor.

Parameters
parent CoordinatorLayout: the parent view of the given child
child CoordinatorLayout: the child view to manipulate
dependency CoordinatorLayout: the dependent view that has been removed

onDetachedFromLayoutParams

open fun onDetachedFromLayoutParams(): Unit

Called when the Behavior has been detached from its holding LayoutParams instance.

This will only be called if the Behavior has been explicitly removed from the LayoutParams instance via LayoutParams#setBehavior(Behavior). It will not be called if the associated view is removed from the CoordinatorLayout or similar.

onInterceptTouchEvent

open fun onInterceptTouchEvent(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull ev: MotionEvent): Boolean

Respond to CoordinatorLayout touch events before they are dispatched to child views.

Behaviors can use this to monitor inbound touch events until one decides to intercept the rest of the event stream to take an action on its associated child view. This method will return false until it detects the proper intercept conditions, then return true once those conditions have occurred.

Once a Behavior intercepts touch events, the rest of the event stream will be sent to the onTouchEvent method.

This method will be called regardless of the visibility of the associated child of the behavior. If you only wish to handle touch events when the child is visible, you should add a check to View#isShown() on the given child.

The default implementation of this method always returns false.

Parameters
parent CoordinatorLayout: the parent view currently receiving this touch event
child CoordinatorLayout: the child view associated with this Behavior
ev CoordinatorLayout: the MotionEvent describing the touch event being processed
Return
Boolean: true if this Behavior would like to intercept and take over the event stream. The default always returns false.

onLayoutChild

open fun onLayoutChild(@NonNull parent: CoordinatorLayout, @NonNull child: V, layoutDirection: Int): Boolean

Called when the parent CoordinatorLayout is about the lay out the given child view.

This method can be used to perform custom or modified layout of a child view in place of the default child layout behavior. The Behavior's implementation can delegate to the standard CoordinatorLayout measurement behavior by calling parent.onLayoutChild.

If a Behavior implements onDependentViewChanged(CoordinatorLayout, View, View) to change the position of a view in response to a dependent view changing, it should also implement onLayoutChild in such a way that respects those dependent views. onLayoutChild will always be called for a dependent view after its dependency has been laid out.

Parameters
parent CoordinatorLayout: the parent CoordinatorLayout
child CoordinatorLayout: child view to lay out
layoutDirection CoordinatorLayout: the resolved layout direction for the CoordinatorLayout, such as ViewCompat#LAYOUT_DIRECTION_LTR or ViewCompat#LAYOUT_DIRECTION_RTL.
Return
Boolean: true if the Behavior performed layout of the child view, false to request default layout behavior

onMeasureChild

open fun onMeasureChild(@NonNull parent: CoordinatorLayout, @NonNull child: V, parentWidthMeasureSpec: Int, widthUsed: Int, parentHeightMeasureSpec: Int, heightUsed: Int): Boolean

Called when the parent CoordinatorLayout is about to measure the given child view.

This method can be used to perform custom or modified measurement of a child view in place of the default child measurement behavior. The Behavior's implementation can delegate to the standard CoordinatorLayout measurement behavior by calling parent.onMeasureChild.

Parameters
parent CoordinatorLayout: the parent CoordinatorLayout
child CoordinatorLayout: the child to measure
parentWidthMeasureSpec CoordinatorLayout: the width requirements for this view
widthUsed CoordinatorLayout: extra space that has been used up by the parent horizontally (possibly by other children of the parent)
parentHeightMeasureSpec CoordinatorLayout: the height requirements for this view
heightUsed CoordinatorLayout: extra space that has been used up by the parent vertically (possibly by other children of the parent)
Return
Boolean: true if the Behavior measured the child view, false if the CoordinatorLayout should perform its default measurement

onNestedFling

open fun onNestedFling(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, velocityX: Float, velocityY: Float, consumed: Boolean): Boolean

Called when a nested scrolling child is starting a fling or an action that would be a fling.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll. Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedFling is called when the current nested scrolling child view detects the proper conditions for a fling. It reports if the child itself consumed the fling. If it did not, the child is expected to show some sort of overscroll indication. This method should return true if it consumes the fling, so that a child that did not itself take an action in response can choose not to show an overfling indication.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
target CoordinatorLayout: the descendant view of the CoordinatorLayout performing the nested scroll
velocityX CoordinatorLayout: horizontal velocity of the attempted fling
velocityY CoordinatorLayout: vertical velocity of the attempted fling
consumed CoordinatorLayout: true if the nested child view consumed the fling
Return
Boolean: true if the Behavior consumed the fling

onNestedPreFling

open fun onNestedPreFling(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, velocityX: Float, velocityY: Float): Boolean

Called when a nested scrolling child is about to start a fling.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll. Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedPreFling is called when the current nested scrolling child view detects the proper conditions for a fling, but it has not acted on it yet. A Behavior can return true to indicate that it consumed the fling. If at least one Behavior returns true, the fling should not be acted upon by the child.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
target CoordinatorLayout: the descendant view of the CoordinatorLayout performing the nested scroll
velocityX CoordinatorLayout: horizontal velocity of the attempted fling
velocityY CoordinatorLayout: vertical velocity of the attempted fling
Return
Boolean: true if the Behavior consumed the fling

onNestedPreScroll

open fun onNestedPreScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dx: Int, dy: Int, @NonNull consumed: IntArray): Unit

Deprecated: You should now override onNestedPreScroll(CoordinatorLayout, View, View, int, int, int[], int). This method will still continue to be called if the type is ViewCompat#TYPE_TOUCH.

onNestedPreScroll

open fun onNestedPreScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dx: Int, dy: Int, @NonNull consumed: IntArray, type: Int): Unit

Called when a nested scroll in progress is about to update, before the target has consumed any of the scrolled distance.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll. Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedPreScroll is called each time the nested scroll is updated by the nested scrolling child, before the nested scrolling child has consumed the scroll distance itself. Each Behavior responding to the nested scroll will receive the same values. The CoordinatorLayout will report as consumed the maximum number of pixels in either direction that any Behavior responding to the nested scroll reported as consumed.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
target CoordinatorLayout: the descendant view of the CoordinatorLayout performing the nested scroll
dx CoordinatorLayout: the raw horizontal number of pixels that the user attempted to scroll
dy CoordinatorLayout: the raw vertical number of pixels that the user attempted to scroll
consumed CoordinatorLayout: out parameter. consumed[0] should be set to the distance of dx that was consumed, consumed[1] should be set to the distance of dy that was consumed
type CoordinatorLayout: the type of input which cause this scroll event

onNestedScroll

open fun onNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int): Unit

Deprecated: You should now override onNestedScroll(CoordinatorLayout, View, View, int, int, int, int, int, int[]). This method will still continue to be called if neither onNestedScroll(CoordinatorLayout, View, View, int, int, int, int, int, int[]) nor onNestedScroll(View, int, int, int, int, int) are overridden and the type is ViewCompat#TYPE_TOUCH.

onNestedScroll

open fun onNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int): Unit

Deprecated: You should now override onNestedScroll(CoordinatorLayout, View, View, int, int, int, int, int, int[]). This method will still continue to be called if onNestedScroll(CoordinatorLayout, View, View, int, int, int, int, int, int[]) is not overridden.

onNestedScroll

open fun onNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int, @NonNull consumed: IntArray): Unit

Called when a nested scroll in progress has updated and the target has scrolled or attempted to scroll.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll. Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedScroll is called each time the nested scroll is updated by the nested scrolling child, with both consumed and unconsumed components of the scroll supplied in pixels. Each Behavior responding to the nested scroll will receive the same values.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
target CoordinatorLayout: the descendant view of the CoordinatorLayout performing the nested scroll
dxConsumed CoordinatorLayout: horizontal pixels consumed by the target's own scrolling operation
dyConsumed CoordinatorLayout: vertical pixels consumed by the target's own scrolling operation
dxUnconsumed CoordinatorLayout: horizontal pixels not consumed by the target's own scrolling operation, but requested by the user
dyUnconsumed CoordinatorLayout: vertical pixels not consumed by the target's own scrolling operation, but requested by the user
type CoordinatorLayout: the type of input which cause this scroll event
consumed CoordinatorLayout: output. Upon this method returning, should contain the scroll distances consumed by this Behavior

onNestedScrollAccepted

open fun onNestedScrollAccepted(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int): Unit

Deprecated: You should now override onNestedScrollAccepted(CoordinatorLayout, View, View, View, int, int). This method will still continue to be called if the type is ViewCompat#TYPE_TOUCH.

onNestedScrollAccepted

open fun onNestedScrollAccepted(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int, type: Int): Unit

Called when a nested scroll has been accepted by the CoordinatorLayout.

Any Behavior associated with any direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll. Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
directTargetChild CoordinatorLayout: the child view of the CoordinatorLayout that either is or contains the target of the nested scroll operation
target CoordinatorLayout: the descendant view of the CoordinatorLayout initiating the nested scroll
axes CoordinatorLayout: the axes that this nested scroll applies to. See ViewCompat#SCROLL_AXIS_HORIZONTAL, ViewCompat#SCROLL_AXIS_VERTICAL
type CoordinatorLayout: the type of input which cause this scroll event

onRequestChildRectangleOnScreen

open fun onRequestChildRectangleOnScreen(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull rectangle: Rect, immediate: Boolean): Boolean

Called when a child of the view associated with this behavior wants a particular rectangle to be positioned onto the screen.

The contract for this method is the same as ViewParent#requestChildRectangleOnScreen(View, Rect, boolean).

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
rectangle CoordinatorLayout: The rectangle which the child wishes to be on the screen in the child's coordinates
immediate CoordinatorLayout: true to forbid animated or delayed scrolling, false otherwise
Return
Boolean: true if the Behavior handled the request

onRestoreInstanceState

open fun onRestoreInstanceState(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull state: Parcelable): Unit

Hook allowing a behavior to re-apply a representation of its internal state that had previously been generated by onSaveInstanceState. This function will never be called with a null state.

Parameters
parent CoordinatorLayout: the parent CoordinatorLayout
child CoordinatorLayout: child view to restore from
state CoordinatorLayout: The frozen state that had previously been returned by onSaveInstanceState.

onSaveInstanceState

@Nullable open fun onSaveInstanceState(@NonNull parent: CoordinatorLayout, @NonNull child: V): Parcelable?

Hook allowing a behavior to generate a representation of its internal state that can later be used to create a new instance with that same state. This state should only contain information that is not persistent or can not be reconstructed later.

Behavior state is only saved when both the parent CoordinatorLayout and a view using this behavior have valid IDs set.

Parameters
parent CoordinatorLayout: the parent CoordinatorLayout
child CoordinatorLayout: child view to restore from
Return
Parcelable?: Returns a Parcelable object containing the behavior's current dynamic state.

onStartNestedScroll

open fun onStartNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int): Boolean

Deprecated: You should now override onStartNestedScroll(CoordinatorLayout, View, View, View, int, int). This method will still continue to be called if the type is ViewCompat#TYPE_TOUCH.

onStartNestedScroll

open fun onStartNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull directTargetChild: View, @NonNull target: View, axes: Int, type: Int): Boolean

Called when a descendant of the CoordinatorLayout attempts to initiate a nested scroll.

Any Behavior associated with any direct child of the CoordinatorLayout may respond to this event and return true to indicate that the CoordinatorLayout should act as a nested scrolling parent for this scroll. Only Behaviors that return true from this method will receive subsequent nested scroll events.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
directTargetChild CoordinatorLayout: the child view of the CoordinatorLayout that either is or contains the target of the nested scroll operation
target CoordinatorLayout: the descendant view of the CoordinatorLayout initiating the nested scroll
axes CoordinatorLayout: the axes that this nested scroll applies to. See ViewCompat#SCROLL_AXIS_HORIZONTAL, ViewCompat#SCROLL_AXIS_VERTICAL
type CoordinatorLayout: the type of input which cause this scroll event
Return
Boolean: true if the Behavior wishes to accept this nested scroll

onStopNestedScroll

open fun onStopNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View): Unit

Deprecated: You should now override onStopNestedScroll(CoordinatorLayout, View, View, int). This method will still continue to be called if the type is ViewCompat#TYPE_TOUCH.

onStopNestedScroll

open fun onStopNestedScroll(@NonNull coordinatorLayout: CoordinatorLayout, @NonNull child: V, @NonNull target: View, type: Int): Unit

Called when a nested scroll has ended.

Any Behavior associated with any direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll. Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onStopNestedScroll marks the end of a single nested scroll event sequence. This is a good place to clean up any state related to the nested scroll.

Parameters
coordinatorLayout CoordinatorLayout: the CoordinatorLayout parent of the view this Behavior is associated with
child CoordinatorLayout: the child view of the CoordinatorLayout this Behavior is associated with
target CoordinatorLayout: the descendant view of the CoordinatorLayout that initiated the nested scroll
type CoordinatorLayout: the type of input which cause this scroll event

onTouchEvent

open fun onTouchEvent(@NonNull parent: CoordinatorLayout, @NonNull child: V, @NonNull ev: MotionEvent): Boolean

Respond to CoordinatorLayout touch events after this Behavior has started intercepting them.

Behaviors may intercept touch events in order to help the CoordinatorLayout manipulate its child views. For example, a Behavior may allow a user to drag a UI pane open or closed. This method should perform actual mutations of view layout state.

This method will be called regardless of the visibility of the associated child of the behavior. If you only wish to handle touch events when the child is visible, you should add a check to View#isShown() on the given child.

Parameters
parent CoordinatorLayout: the parent view currently receiving this touch event
child CoordinatorLayout: the child view associated with this Behavior
ev CoordinatorLayout: the MotionEvent describing the touch event being processed
Return
Boolean: true if this Behavior handled this touch event and would like to continue receiving events in this stream. The default always returns false.

setTag

open static fun setTag(@NonNull child: View, @Nullable tag: Any?): Unit

Associate a Behavior-specific tag object with the given child view. This object will be stored with the child view's LayoutParams.

Parameters
child View: child view to set tag with
tag View: tag object to set