belongs to Maven artifact com.android.support:support-compat:28.0.0-alpha1
NestedScrollingParent2
public
interface
NestedScrollingParent2
implements
NestedScrollingParent
android.support.v4.view.NestedScrollingParent2 |
Known Indirect Subclasses |
This interface should be implemented by ViewGroup
subclasses
that wish to support scrolling operations delegated by a nested child view.
Classes implementing this interface should create a final instance of a
NestedScrollingParentHelper
as a field and delegate any View or ViewGroup methods
to the NestedScrollingParentHelper
methods of the same signature.
Views invoking nested scrolling functionality should always do so from the relevant
ViewCompat
, ViewGroupCompat
or ViewParentCompat
compatibility
shim static methods. This ensures interoperability with nested scrolling views on all versions
of Android.
Summary
Public methods | |
---|---|
abstract
void
|
onNestedPreScroll(View target, int dx, int dy, int[] consumed, int type)
React to a nested scroll in progress before the target view consumes a portion of the scroll. |
abstract
void
|
onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type)
React to a nested scroll in progress. |
abstract
void
|
onNestedScrollAccepted(View child, View target, int axes, int type)
React to the successful claiming of a nested scroll operation. |
abstract
boolean
|
onStartNestedScroll(View child, View target, int axes, int type)
React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate. |
abstract
void
|
onStopNestedScroll(View target, int type)
React to a nested scroll operation ending. |
Inherited methods | |
---|---|
From
interface
android.support.v4.view.NestedScrollingParent
|
Public methods
onNestedPreScroll
void onNestedPreScroll (View target, int dx, int dy, int[] consumed, int type)
React to a nested scroll in progress before the target view consumes a portion of the scroll.
When working with nested scrolling often the parent view may want an opportunity to consume the scroll before the nested scrolling child does. An example of this is a drawer that contains a scrollable list. The user will want to be able to scroll the list fully into view before the list itself begins scrolling.
onNestedPreScroll
is called when a nested scrolling child invokes
dispatchNestedPreScroll(int, int, int[], int[])
. The implementation should
report how any pixels of the scroll reported by dx, dy were consumed in the
consumed
array. Index 0 corresponds to dx and index 1 corresponds to dy.
This parameter will never be null. Initial values for consumed[0] and consumed[1]
will always be 0.
Parameters | |
---|---|
target |
View : View that initiated the nested scroll |
dx |
int : Horizontal scroll distance in pixels |
dy |
int : Vertical scroll distance in pixels |
consumed |
int : Output. The horizontal and vertical scroll distance consumed by this parent |
type |
int : the type of input which cause this scroll event
|
onNestedScroll
void onNestedScroll (View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type)
React to a nested scroll in progress.
This method will be called when the ViewParent's current nested scrolling child view
dispatches a nested scroll event. To receive calls to this method the ViewParent must have
previously returned true
for a call to
onStartNestedScroll(View, View, int, int)
.
Both the consumed and unconsumed portions of the scroll distance are reported to the ViewParent. An implementation may choose to use the consumed portion to match or chase scroll position of multiple child elements, for example. The unconsumed portion may be used to allow continuous dragging of multiple scrolling or draggable elements, such as scrolling a list within a vertical drawer where the drawer begins dragging once the edge of inner scrolling content is reached.
Parameters | |
---|---|
target |
View : The descendent view controlling the nested scroll |
dxConsumed |
int : Horizontal scroll distance in pixels already consumed by target |
dyConsumed |
int : Vertical scroll distance in pixels already consumed by target |
dxUnconsumed |
int : Horizontal scroll distance in pixels not consumed by target |
dyUnconsumed |
int : Vertical scroll distance in pixels not consumed by target |
type |
int : the type of input which cause this scroll event
|
onNestedScrollAccepted
void onNestedScrollAccepted (View child, View target, int axes, int type)
React to the successful claiming of a nested scroll operation.
This method will be called after
onStartNestedScroll
returns true. It
offers an opportunity for the view and its superclasses to perform initial configuration
for the nested scroll. Implementations of this method should always call their superclass's
implementation of this method if one is present.
Parameters | |
---|---|
child |
View : Direct child of this ViewParent containing target |
target |
View : View that initiated the nested scroll |
axes |
int : Flags consisting of SCROLL_AXIS_HORIZONTAL ,
SCROLL_AXIS_VERTICAL or both |
type |
int : the type of input which cause this scroll event |
onStartNestedScroll
boolean onStartNestedScroll (View child, View target, int axes, int type)
React to a descendant view initiating a nestable scroll operation, claiming the nested scroll operation if appropriate.
This method will be called in response to a descendant view invoking
startNestedScroll(View, int)
. Each parent up the view hierarchy will be
given an opportunity to respond and claim the nested scrolling operation by returning
true
.
This method may be overridden by ViewParent implementations to indicate when the view
is willing to support a nested scrolling operation that is about to begin. If it returns
true, this ViewParent will become the target view's nested scrolling parent for the duration
of the scroll operation in progress. When the nested scroll is finished this ViewParent
will receive a call to onStopNestedScroll(View, int)
.
Parameters | |
---|---|
child |
View : Direct child of this ViewParent containing target |
target |
View : View that initiated the nested scroll |
axes |
int : Flags consisting of SCROLL_AXIS_HORIZONTAL ,
SCROLL_AXIS_VERTICAL or both |
type |
int : the type of input which cause this scroll event |
Returns | |
---|---|
boolean |
true if this ViewParent accepts the nested scroll operation |
onStopNestedScroll
void onStopNestedScroll (View target, int type)
React to a nested scroll operation ending.
Perform cleanup after a nested scrolling operation.
This method will be called when a nested scroll stops, for example when a nested touch
scroll ends with a ACTION_UP
or ACTION_CANCEL
event.
Implementations of this method should always call their superclass's implementation of this
method if one is present.
Parameters | |
---|---|
target |
View : View that initiated the nested scroll |
type |
int : the type of input which cause this scroll event
|
Annotations
Interfaces
- ActionProvider.VisibilityListener
- AsyncLayoutInflater.OnInflateFinishedListener
- LayoutInflaterFactory
- MenuItemCompat.OnActionExpandListener
- NestedScrollingChild
- NestedScrollingChild2
- NestedScrollingParent
- NestedScrollingParent2
- OnApplyWindowInsetsListener
- ScrollingView
- TintableBackgroundView
- ViewPager.OnAdapterChangeListener
- ViewPager.OnPageChangeListener
- ViewPager.PageTransformer
- ViewPropertyAnimatorListener
- ViewPropertyAnimatorUpdateListener
Classes
- AbsSavedState
- AccessibilityDelegateCompat
- ActionProvider
- AsyncLayoutInflater
- GestureDetectorCompat
- GravityCompat
- InputDeviceCompat
- LayoutInflaterCompat
- MarginLayoutParamsCompat
- MenuCompat
- MenuItemCompat
- MotionEventCompat
- NestedScrollingChildHelper
- NestedScrollingParentHelper
- PagerAdapter
- PagerTabStrip
- PagerTitleStrip
- PointerIconCompat
- ScaleGestureDetectorCompat
- VelocityTrackerCompat
- ViewCompat
- ViewConfigurationCompat
- ViewGroupCompat
- ViewPager
- ViewPager.LayoutParams
- ViewPager.SavedState
- ViewPager.SimpleOnPageChangeListener
- ViewParentCompat
- ViewPropertyAnimatorCompat
- ViewPropertyAnimatorListenerAdapter
- WindowCompat
- WindowInsetsCompat