CoordinatorLayout.Behavior

public abstract class CoordinatorLayout.Behavior<V extends View>


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.

Parameters
<V extends View>

The View type that this Behavior operates on

Summary

Public constructors

Default constructor for instantiating Behaviors.

Default constructor for inflating Behaviors from layout.

Public methods

boolean

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

boolean
getInsetDodgeRect(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull Rect rect
)

Called when a view is set to dodge view insets.

@ColorInt int

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

@FloatRange(from = 0, to = 1) float

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

static @Nullable Object

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

boolean
layoutDependsOn(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull View dependency
)

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

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

Called when the window insets have changed.

void

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

boolean
onDependentViewChanged(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull View dependency
)

Respond to a change in a child's dependent view

void
onDependentViewRemoved(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull View dependency
)

Respond to a child's dependent view being removed.

void

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

boolean
onInterceptTouchEvent(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull MotionEvent ev
)

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

boolean
onLayoutChild(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    int layoutDirection
)

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

boolean
onMeasureChild(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    int parentWidthMeasureSpec,
    int widthUsed,
    int parentHeightMeasureSpec,
    int heightUsed
)

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

boolean
onNestedFling(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    float velocityX,
    float velocityY,
    boolean consumed
)

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

boolean
onNestedPreFling(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    float velocityX,
    float velocityY
)

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

void
onNestedPreScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dx,
    int dy,
    @NonNull int[] consumed
)

This method is deprecated.

You should now override onNestedPreScroll.

void
onNestedPreScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dx,
    int dy,
    @NonNull int[] consumed,
    int type
)

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

void
onNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed
)

This method is deprecated.

You should now override onNestedScroll.

void
onNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int type
)

This method is deprecated.

You should now override onNestedScroll.

void
onNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int type,
    @NonNull int[] consumed
)

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

void
onNestedScrollAccepted(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes
)

This method is deprecated.

You should now override onNestedScrollAccepted.

void
onNestedScrollAccepted(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes,
    int type
)

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

boolean
onRequestChildRectangleOnScreen(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull Rect rectangle,
    boolean immediate
)

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

void
onRestoreInstanceState(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull Parcelable state
)

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

@Nullable 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.

boolean
onStartNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes
)

This method is deprecated.

You should now override onStartNestedScroll.

boolean
onStartNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes,
    int type
)

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

void
onStopNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target
)

This method is deprecated.

You should now override onStopNestedScroll.

void
onStopNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int type
)

Called when a nested scroll has ended.

boolean
onTouchEvent(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull MotionEvent ev
)

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

static void
setTag(@NonNull View child, @Nullable Object tag)

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

Public constructors

Behavior

Added in 1.1.0
public Behavior()

Default constructor for instantiating Behaviors.

Behavior

Added in 1.1.0
public Behavior(@NonNull Context context, @Nullable AttributeSet attrs)

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
@NonNull Context context
@Nullable AttributeSet attrs

Public methods

blocksInteractionBelow

Added in 1.1.0
public boolean blocksInteractionBelow(@NonNull CoordinatorLayout parent, @NonNull V child)

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

The default implementation returns true if getScrimOpacity would return >0.0f.

Parameters
@NonNull CoordinatorLayout parent

the parent view of the given child

@NonNull V child

the child view to test

Returns
boolean

true if getScrimOpacity would return >0.0f.

getInsetDodgeRect

Added in 1.1.0
public boolean getInsetDodgeRect(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull Rect rect
)

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
@NonNull CoordinatorLayout parent

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull Rect rect

the rect to update with the dodge rectangle

Returns
boolean

true the rect was updated, false if we should use the child's bounds

getScrimColor

Added in 1.1.0
public @ColorInt int getScrimColor(@NonNull CoordinatorLayout parent, @NonNull V child)

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 BLACK.

Parameters
@NonNull CoordinatorLayout parent

the parent view of the given child

@NonNull V child

the child view above the scrim

Returns
@ColorInt int

the desired scrim color in 0xAARRGGBB format. The default return value is BLACK.

See also
getScrimOpacity

getScrimOpacity

Added in 1.1.0
public @FloatRange(from = 0, to = 1) float getScrimOpacity(@NonNull CoordinatorLayout parent, @NonNull V child)

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
@NonNull CoordinatorLayout parent

the parent view of the given child

@NonNull V child

the child view above the scrim

Returns
@FloatRange(from = 0, to = 1) float

the desired scrim opacity from 0.0f to 1.0f. The default return value is 0.0f.

getTag

Added in 1.1.0
public static @Nullable Object getTag(@NonNull View child)

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

Parameters
@NonNull View child

child view to get tag with

Returns
@Nullable Object

the previously stored tag object

layoutDependsOn

Added in 1.1.0
public boolean layoutDependsOn(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull View dependency
)

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
@NonNull CoordinatorLayout parent

the parent view of the given child

@NonNull V child

the child view to test

@NonNull View dependency

the proposed dependency of child

Returns
boolean

true if child's layout depends on the proposed dependency's layout, false otherwise

onApplyWindowInsets

Added in 1.1.0
public @NonNull WindowInsetsCompat onApplyWindowInsets(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull WindowInsetsCompat insets
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull WindowInsetsCompat insets

the new window insets.

Returns
@NonNull WindowInsetsCompat

The insets supplied, minus any insets that were consumed

onAttachedToLayoutParams

Added in 1.1.0
public void onAttachedToLayoutParams(@NonNull CoordinatorLayout.LayoutParams params)

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
@NonNull CoordinatorLayout.LayoutParams params

the LayoutParams instance that this Behavior has been attached to

onDependentViewChanged

Added in 1.1.0
public boolean onDependentViewChanged(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull View dependency
)

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 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
@NonNull CoordinatorLayout parent

the parent view of the given child

@NonNull V child

the child view to manipulate

@NonNull View dependency

the dependent view that changed

Returns
boolean

true if the Behavior changed the child view's size or position, false otherwise

onDependentViewRemoved

Added in 1.1.0
public void onDependentViewRemoved(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull View dependency
)

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 or if child has set another view as it's anchor.

Parameters
@NonNull CoordinatorLayout parent

the parent view of the given child

@NonNull V child

the child view to manipulate

@NonNull View dependency

the dependent view that has been removed

onDetachedFromLayoutParams

Added in 1.1.0
public void onDetachedFromLayoutParams()

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 setBehavior. It will not be called if the associated view is removed from the CoordinatorLayout or similar.

onInterceptTouchEvent

Added in 1.1.0
public boolean onInterceptTouchEvent(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull MotionEvent ev
)

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 isShown on the given child.

The default implementation of this method always returns false.

Parameters
@NonNull CoordinatorLayout parent

the parent view currently receiving this touch event

@NonNull V child

the child view associated with this Behavior

@NonNull MotionEvent ev

the MotionEvent describing the touch event being processed

Returns
boolean

true if this Behavior would like to intercept and take over the event stream. The default always returns false.

onLayoutChild

Added in 1.1.0
public boolean onLayoutChild(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    int layoutDirection
)

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 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
@NonNull CoordinatorLayout parent

the parent CoordinatorLayout

@NonNull V child

child view to lay out

int layoutDirection

the resolved layout direction for the CoordinatorLayout, such as LAYOUT_DIRECTION_LTR or LAYOUT_DIRECTION_RTL.

Returns
boolean

true if the Behavior performed layout of the child view, false to request default layout behavior

onMeasureChild

Added in 1.1.0
public boolean onMeasureChild(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    int parentWidthMeasureSpec,
    int widthUsed,
    int parentHeightMeasureSpec,
    int heightUsed
)

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
@NonNull CoordinatorLayout parent

the parent CoordinatorLayout

@NonNull V child

the child to measure

int parentWidthMeasureSpec

the width requirements for this view

int widthUsed

extra space that has been used up by the parent horizontally (possibly by other children of the parent)

int parentHeightMeasureSpec

the height requirements for this view

int heightUsed

extra space that has been used up by the parent vertically (possibly by other children of the parent)

Returns
boolean

true if the Behavior measured the child view, false if the CoordinatorLayout should perform its default measurement

onNestedFling

Added in 1.1.0
public boolean onNestedFling(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    float velocityX,
    float velocityY,
    boolean consumed
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View target

the descendant view of the CoordinatorLayout performing the nested scroll

float velocityX

horizontal velocity of the attempted fling

float velocityY

vertical velocity of the attempted fling

boolean consumed

true if the nested child view consumed the fling

Returns
boolean

true if the Behavior consumed the fling

See also
onNestedFling

onNestedPreFling

Added in 1.1.0
public boolean onNestedPreFling(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    float velocityX,
    float velocityY
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View target

the descendant view of the CoordinatorLayout performing the nested scroll

float velocityX

horizontal velocity of the attempted fling

float velocityY

vertical velocity of the attempted fling

Returns
boolean

true if the Behavior consumed the fling

See also
onNestedPreFling

onNestedPreScroll

Added in 1.1.0
Deprecated in 1.1.0
public void onNestedPreScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dx,
    int dy,
    @NonNull int[] consumed
)

onNestedPreScroll

Added in 1.1.0
public void onNestedPreScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dx,
    int dy,
    @NonNull int[] consumed,
    int type
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View target

the descendant view of the CoordinatorLayout performing the nested scroll

int dx

the raw horizontal number of pixels that the user attempted to scroll

int dy

the raw vertical number of pixels that the user attempted to scroll

@NonNull int[] consumed

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

int type

the type of input which cause this scroll event

onNestedScroll

Added in 1.1.0
Deprecated in 1.1.0
public void onNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed
)

onNestedScroll

Added in 1.1.0
Deprecated in 1.1.0
public void onNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int type
)

onNestedScroll

Added in 1.1.0
public void onNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int type,
    @NonNull int[] consumed
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View target

the descendant view of the CoordinatorLayout performing the nested scroll

int dxConsumed

horizontal pixels consumed by the target's own scrolling operation

int dyConsumed

vertical pixels consumed by the target's own scrolling operation

int dxUnconsumed

horizontal pixels not consumed by the target's own scrolling operation, but requested by the user

int dyUnconsumed

vertical pixels not consumed by the target's own scrolling operation, but requested by the user

int type

the type of input which cause this scroll event

@NonNull int[] consumed

output. Upon this method returning, should contain the scroll distances consumed by this Behavior

See also
onNestedScroll

onNestedScrollAccepted

Added in 1.1.0
Deprecated in 1.1.0
public void onNestedScrollAccepted(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes
)

onNestedScrollAccepted

Added in 1.1.0
public void onNestedScrollAccepted(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes,
    int type
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View directTargetChild

the child view of the CoordinatorLayout that either is or contains the target of the nested scroll operation

@NonNull View target

the descendant view of the CoordinatorLayout initiating the nested scroll

int axes

the axes that this nested scroll applies to. See SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL

int type

the type of input which cause this scroll event

onRequestChildRectangleOnScreen

Added in 1.1.0
public boolean onRequestChildRectangleOnScreen(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull Rect rectangle,
    boolean immediate
)

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 requestChildRectangleOnScreen.

Parameters
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull Rect rectangle

The rectangle which the child wishes to be on the screen in the child's coordinates

boolean immediate

true to forbid animated or delayed scrolling, false otherwise

Returns
boolean

true if the Behavior handled the request

onRestoreInstanceState

Added in 1.1.0
public void onRestoreInstanceState(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull Parcelable state
)

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
@NonNull CoordinatorLayout parent

the parent CoordinatorLayout

@NonNull V child

child view to restore from

@NonNull Parcelable state

The frozen state that had previously been returned by onSaveInstanceState.

onSaveInstanceState

Added in 1.1.0
public @Nullable Parcelable onSaveInstanceState(@NonNull CoordinatorLayout parent, @NonNull V child)

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
@NonNull CoordinatorLayout parent

the parent CoordinatorLayout

@NonNull V child

child view to restore from

Returns
@Nullable Parcelable

Returns a Parcelable object containing the behavior's current dynamic state.

onStartNestedScroll

Added in 1.1.0
Deprecated in 1.1.0
public boolean onStartNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes
)

onStartNestedScroll

Added in 1.1.0
public boolean onStartNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View directTargetChild,
    @NonNull View target,
    int axes,
    int type
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View directTargetChild

the child view of the CoordinatorLayout that either is or contains the target of the nested scroll operation

@NonNull View target

the descendant view of the CoordinatorLayout initiating the nested scroll

int axes

the axes that this nested scroll applies to. See SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL

int type

the type of input which cause this scroll event

Returns
boolean

true if the Behavior wishes to accept this nested scroll

onStopNestedScroll

Added in 1.1.0
Deprecated in 1.1.0
public void onStopNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target
)

onStopNestedScroll

Added in 1.1.0
public void onStopNestedScroll(
    @NonNull CoordinatorLayout coordinatorLayout,
    @NonNull V child,
    @NonNull View target,
    int type
)

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
@NonNull CoordinatorLayout coordinatorLayout

the CoordinatorLayout parent of the view this Behavior is associated with

@NonNull V child

the child view of the CoordinatorLayout this Behavior is associated with

@NonNull View target

the descendant view of the CoordinatorLayout that initiated the nested scroll

int type

the type of input which cause this scroll event

onTouchEvent

Added in 1.1.0
public boolean onTouchEvent(
    @NonNull CoordinatorLayout parent,
    @NonNull V child,
    @NonNull MotionEvent ev
)

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 isShown on the given child.

Parameters
@NonNull CoordinatorLayout parent

the parent view currently receiving this touch event

@NonNull V child

the child view associated with this Behavior

@NonNull MotionEvent ev

the MotionEvent describing the touch event being processed

Returns
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

Added in 1.1.0
public static void setTag(@NonNull View child, @Nullable Object tag)

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

Parameters
@NonNull View child

child view to set tag with

@Nullable Object tag

tag object to set