V
- The View type that this Behavior operates onpublic abstract static class CoordinatorLayout.Behavior<V extends View> extends Object
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.
Constructor and Description |
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Behavior()
Default constructor for instantiating Behaviors.
|
Behavior(Context context,
AttributeSet attrs)
Default constructor for inflating Behaviors from layout.
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Modifier and Type | Method and Description |
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boolean |
blocksInteractionBelow(CoordinatorLayout parent,
V child)
Determine whether interaction with views behind the given child in the child order
should be blocked.
|
boolean |
getInsetDodgeRect(CoordinatorLayout parent,
V child,
Rect rect)
Called when a view is set to dodge view insets.
|
int |
getScrimColor(CoordinatorLayout parent,
V child)
Supply a scrim color that will be painted behind the associated child view.
|
float |
getScrimOpacity(CoordinatorLayout parent,
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.
|
static Object |
getTag(View child)
Get the behavior-specific tag object with the given child view.
|
boolean |
isDirty(CoordinatorLayout parent,
V child)
Deprecated.
this method is not called anymore. You can safely remove all usages
and implementations. This method will be removed in a future release.
|
boolean |
layoutDependsOn(CoordinatorLayout parent,
V child,
View dependency)
Determine whether the supplied child view has another specific sibling view as a
layout dependency.
|
WindowInsetsCompat |
onApplyWindowInsets(CoordinatorLayout coordinatorLayout,
V child,
WindowInsetsCompat insets)
Called when the window insets have changed.
|
void |
onAttachedToLayoutParams(CoordinatorLayout.LayoutParams params)
Called when the Behavior has been attached to a LayoutParams instance.
|
boolean |
onDependentViewChanged(CoordinatorLayout parent,
V child,
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.
|
void |
onDependentViewRemoved(CoordinatorLayout parent,
V child,
View dependency)
Respond to a child's dependent view being removed.
|
void |
onDetachedFromLayoutParams()
Called when the Behavior has been detached from its holding LayoutParams instance.
|
boolean |
onInterceptTouchEvent(CoordinatorLayout parent,
V child,
MotionEvent ev)
Respond to CoordinatorLayout touch events before they are dispatched to child views.
|
boolean |
onLayoutChild(CoordinatorLayout parent,
V child,
int layoutDirection)
Called when the parent CoordinatorLayout is about the lay out the given child view.
|
boolean |
onMeasureChild(CoordinatorLayout parent,
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(CoordinatorLayout coordinatorLayout,
V child,
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(CoordinatorLayout coordinatorLayout,
V child,
View target,
float velocityX,
float velocityY)
Called when a nested scrolling child is about to start a fling.
|
void |
onNestedPreScroll(CoordinatorLayout coordinatorLayout,
V child,
View target,
int dx,
int dy,
int[] consumed)
Called when a nested scroll in progress is about to update, before the target has
consumed any of the scrolled distance.
|
void |
onNestedScroll(CoordinatorLayout coordinatorLayout,
V child,
View target,
int dxConsumed,
int dyConsumed,
int dxUnconsumed,
int dyUnconsumed)
Called when a nested scroll in progress has updated and the target has scrolled or
attempted to scroll.
|
void |
onNestedScrollAccepted(CoordinatorLayout coordinatorLayout,
V child,
View directTargetChild,
View target,
int nestedScrollAxes)
Called when a nested scroll has been accepted by the CoordinatorLayout.
|
boolean |
onRequestChildRectangleOnScreen(CoordinatorLayout coordinatorLayout,
V child,
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(CoordinatorLayout parent,
V child,
Parcelable state)
Hook allowing a behavior to re-apply a representation of its internal state that had
previously been generated by
onSaveInstanceState(android.support.design.widget.CoordinatorLayout, V) . |
Parcelable |
onSaveInstanceState(CoordinatorLayout parent,
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.
|
boolean |
onStartNestedScroll(CoordinatorLayout coordinatorLayout,
V child,
View directTargetChild,
View target,
int nestedScrollAxes)
Called when a descendant of the CoordinatorLayout attempts to initiate a nested scroll.
|
void |
onStopNestedScroll(CoordinatorLayout coordinatorLayout,
V child,
View target)
Called when a nested scroll has ended.
|
boolean |
onTouchEvent(CoordinatorLayout parent,
V child,
MotionEvent ev)
Respond to CoordinatorLayout touch events after this Behavior has started
intercepting them. |
static void |
setTag(View child,
Object tag)
Associate a Behavior-specific tag object with the given child view.
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public Behavior()
public Behavior(Context context, AttributeSet attrs)
context
- attrs
- public void onAttachedToLayoutParams(@NonNull CoordinatorLayout.LayoutParams params)
This will be called after the LayoutParams has been instantiated and can be modified.
params
- the LayoutParams instance that this Behavior has been attached topublic void onDetachedFromLayoutParams()
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.
public boolean onInterceptTouchEvent(CoordinatorLayout parent, V child, MotionEvent ev)
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(android.support.design.widget.CoordinatorLayout, V, android.view.MotionEvent)
method.
The default implementation of this method always returns false.
parent
- the parent view currently receiving this touch eventchild
- the child view associated with this Behaviorev
- the MotionEvent describing the touch event being processedpublic boolean onTouchEvent(CoordinatorLayout parent, V child, MotionEvent ev)
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.
parent
- the parent view currently receiving this touch eventchild
- the child view associated with this Behaviorev
- the MotionEvent describing the touch event being processedpublic int getScrimColor(CoordinatorLayout parent, V child)
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
.
parent
- the parent view of the given childchild
- the child view above the scrimColor.BLACK
.getScrimOpacity(CoordinatorLayout, android.view.View)
public float getScrimOpacity(CoordinatorLayout parent, V child)
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.
parent
- the parent view of the given childchild
- the child view above the scrimpublic boolean blocksInteractionBelow(CoordinatorLayout parent, V child)
The default implementation returns true if
getScrimOpacity(CoordinatorLayout, android.view.View)
would return > 0.0f.
parent
- the parent view of the given childchild
- the child view to testgetScrimOpacity(CoordinatorLayout, android.view.View)
would
return > 0.0f.public boolean layoutDependsOn(CoordinatorLayout parent, V child, View 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:
onDependentViewChanged(android.support.design.widget.CoordinatorLayout, V, android.view.View)
when the dependency view's layout or
position changes.parent
- the parent view of the given childchild
- the child view to testdependency
- the proposed dependency of childonDependentViewChanged(CoordinatorLayout, android.view.View, android.view.View)
public boolean onDependentViewChanged(CoordinatorLayout parent, V child, View dependency)
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, android.view.View, android.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.
parent
- the parent view of the given childchild
- the child view to manipulatedependency
- the dependent view that changedpublic void onDependentViewRemoved(CoordinatorLayout parent, V child, View dependency)
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, android.view.View, android.view.View)
or
if child
has set another view as it's anchor.
parent
- the parent view of the given childchild
- the child view to manipulatedependency
- the dependent view that has been removed@Deprecated public boolean isDirty(CoordinatorLayout parent, V child)
public boolean onMeasureChild(CoordinatorLayout parent, V child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed)
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
.
parent
- the parent CoordinatorLayoutchild
- the child to measureparentWidthMeasureSpec
- the width requirements for this viewwidthUsed
- extra space that has been used up by the parent
horizontally (possibly by other children of the parent)parentHeightMeasureSpec
- the height requirements for this viewheightUsed
- extra space that has been used up by the parent
vertically (possibly by other children of the parent)public boolean onLayoutChild(CoordinatorLayout parent, V child, int layoutDirection)
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, android.view.View, android.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.
parent
- the parent CoordinatorLayoutchild
- child view to lay outlayoutDirection
- the resolved layout direction for the CoordinatorLayout, such as
ViewCompat.LAYOUT_DIRECTION_LTR
or
ViewCompat.LAYOUT_DIRECTION_RTL
.public static void setTag(View child, Object tag)
child
- child view to set tag withtag
- tag object to setpublic static Object getTag(View child)
child
- child view to get tag withpublic boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, V child, View directTargetChild, View target, int nestedScrollAxes)
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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withdirectTargetChild
- the child view of the CoordinatorLayout that either is or
contains the target of the nested scroll operationtarget
- the descendant view of the CoordinatorLayout initiating the nested scrollnestedScrollAxes
- the axes that this nested scroll applies to. See
ViewCompat.SCROLL_AXIS_HORIZONTAL
,
ViewCompat.SCROLL_AXIS_VERTICAL
NestedScrollingParent.onStartNestedScroll(View, View, int)
public void onNestedScrollAccepted(CoordinatorLayout coordinatorLayout, V child, View directTargetChild, View target, int nestedScrollAxes)
Any Behavior associated with any direct child of the CoordinatorLayout may elect
to accept the nested scroll as part of onStartNestedScroll(android.support.design.widget.CoordinatorLayout, V, android.view.View, android.view.View, int)
. Each Behavior
that returned true will receive subsequent nested scroll events for that nested scroll.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withdirectTargetChild
- the child view of the CoordinatorLayout that either is or
contains the target of the nested scroll operationtarget
- the descendant view of the CoordinatorLayout initiating the nested scrollnestedScrollAxes
- the axes that this nested scroll applies to. See
ViewCompat.SCROLL_AXIS_HORIZONTAL
,
ViewCompat.SCROLL_AXIS_VERTICAL
NestedScrollingParent.onNestedScrollAccepted(View, View, int)
public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, V child, View target)
Any Behavior associated with any direct child of the CoordinatorLayout may elect
to accept the nested scroll as part of onStartNestedScroll(android.support.design.widget.CoordinatorLayout, V, android.view.View, android.view.View, int)
. 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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withtarget
- the descendant view of the CoordinatorLayout that initiated
the nested scrollNestedScrollingParent.onStopNestedScroll(View)
public void onNestedScroll(CoordinatorLayout coordinatorLayout, V child, View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed)
Any Behavior associated with the direct child of the CoordinatorLayout may elect
to accept the nested scroll as part of onStartNestedScroll(android.support.design.widget.CoordinatorLayout, V, android.view.View, android.view.View, int)
. 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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withtarget
- the descendant view of the CoordinatorLayout performing the nested scrolldxConsumed
- horizontal pixels consumed by the target's own scrolling operationdyConsumed
- vertical pixels consumed by the target's own scrolling operationdxUnconsumed
- horizontal pixels not consumed by the target's own scrolling
operation, but requested by the userdyUnconsumed
- vertical pixels not consumed by the target's own scrolling operation,
but requested by the userNestedScrollingParent.onNestedScroll(View, int, int, int, int)
public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, V child, View target, int dx, int dy, int[] consumed)
Any Behavior associated with the direct child of the CoordinatorLayout may elect
to accept the nested scroll as part of onStartNestedScroll(android.support.design.widget.CoordinatorLayout, V, android.view.View, android.view.View, int)
. 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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withtarget
- the descendant view of the CoordinatorLayout performing the nested scrolldx
- the raw horizontal number of pixels that the user attempted to scrolldy
- the raw vertical number of pixels that the user attempted to scrollconsumed
- 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 consumedNestedScrollingParent.onNestedPreScroll(View, int, int, int[])
public boolean onNestedFling(CoordinatorLayout coordinatorLayout, V child, View target, float velocityX, float velocityY, boolean consumed)
Any Behavior associated with the direct child of the CoordinatorLayout may elect
to accept the nested scroll as part of onStartNestedScroll(android.support.design.widget.CoordinatorLayout, V, android.view.View, android.view.View, int)
. 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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withtarget
- the descendant view of the CoordinatorLayout performing the nested scrollvelocityX
- horizontal velocity of the attempted flingvelocityY
- vertical velocity of the attempted flingconsumed
- true if the nested child view consumed the flingNestedScrollingParent.onNestedFling(View, float, float, boolean)
public boolean onNestedPreFling(CoordinatorLayout coordinatorLayout, V child, View target, float velocityX, float velocityY)
Any Behavior associated with the direct child of the CoordinatorLayout may elect
to accept the nested scroll as part of onStartNestedScroll(android.support.design.widget.CoordinatorLayout, V, android.view.View, android.view.View, int)
. 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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withtarget
- the descendant view of the CoordinatorLayout performing the nested scrollvelocityX
- horizontal velocity of the attempted flingvelocityY
- vertical velocity of the attempted flingNestedScrollingParent.onNestedPreFling(View, float, float)
@NonNull public WindowInsetsCompat onApplyWindowInsets(CoordinatorLayout coordinatorLayout, V child, WindowInsetsCompat insets)
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.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withinsets
- the new window insets.public boolean onRequestChildRectangleOnScreen(CoordinatorLayout coordinatorLayout, V child, Rect rectangle, boolean immediate)
The contract for this method is the same as
ViewParent.requestChildRectangleOnScreen(View, Rect, boolean)
.
coordinatorLayout
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is
associated withrectangle
- The rectangle which the child wishes to be on the screen
in the child's coordinatesimmediate
- true to forbid animated or delayed scrolling, false otherwiseViewParent.requestChildRectangleOnScreen(View, Rect, boolean)
public void onRestoreInstanceState(CoordinatorLayout parent, V child, Parcelable state)
onSaveInstanceState(android.support.design.widget.CoordinatorLayout, V)
. This function will never
be called with a null state.parent
- the parent CoordinatorLayoutchild
- child view to restore fromstate
- The frozen state that had previously been returned by
onSaveInstanceState(android.support.design.widget.CoordinatorLayout, V)
.CoordinatorLayout.onSaveInstanceState()
public Parcelable onSaveInstanceState(CoordinatorLayout parent, V child)
Behavior state is only saved when both the parent CoordinatorLayout
and
a view using this behavior have valid IDs set.
parent
- the parent CoordinatorLayoutchild
- child view to restore fromCoordinatorLayout.onRestoreInstanceState(android.os.Parcelable)
,
View.onSaveInstanceState()
public boolean getInsetDodgeRect(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull Rect rect)
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.
parent
- the CoordinatorLayout parent of the view this Behavior is
associated withchild
- the child view of the CoordinatorLayout this Behavior is associated withrect
- the rect to update with the dodge rectangle