belongs to Maven artifact com.android.support:support-compat:28.0.0-alpha1
NestedScrollingChild2
public
interface
NestedScrollingChild2
implements
NestedScrollingChild
android.support.v4.view.NestedScrollingChild2 |
Known Indirect Subclasses |
This interface should be implemented by View
subclasses that wish
to support dispatching nested scrolling operations to a cooperating parent
ViewGroup
.
Classes implementing this interface should create a final instance of a
NestedScrollingChildHelper
as a field and delegate any View methods to the
NestedScrollingChildHelper
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
boolean
|
dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow, int type)
Dispatch one step of a nested scroll in progress before this view consumes any portion of it. |
abstract
boolean
|
dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow, int type)
Dispatch one step of a nested scroll in progress. |
abstract
boolean
|
hasNestedScrollingParent(int type)
Returns true if this view has a nested scrolling parent for the given input type. |
abstract
boolean
|
startNestedScroll(int axes, int type)
Begin a nestable scroll operation along the given axes, for the given input type. |
abstract
void
|
stopNestedScroll(int type)
Stop a nested scroll in progress for the given input type. |
Inherited methods | |
---|---|
From
interface
android.support.v4.view.NestedScrollingChild
|
Public methods
dispatchNestedPreScroll
boolean dispatchNestedPreScroll (int dx, int dy, int[] consumed, int[] offsetInWindow, int type)
Dispatch one step of a nested scroll in progress before this view consumes any portion of it.
Nested pre-scroll events are to nested scroll events what touch intercept is to touch.
dispatchNestedPreScroll
offers an opportunity for the parent view in a nested
scrolling operation to consume some or all of the scroll operation before the child view
consumes it.
Parameters | |
---|---|
dx |
int : Horizontal scroll distance in pixels |
dy |
int : Vertical scroll distance in pixels |
consumed |
int : Output. If not null, consumed[0] will contain the consumed component of dx
and consumed[1] the consumed dy. |
offsetInWindow |
int : Optional. If not null, on return this will contain the offset
in local view coordinates of this view from before this operation
to after it completes. View implementations may use this to adjust
expected input coordinate tracking. |
type |
int : the type of input which cause this scroll event |
Returns | |
---|---|
boolean |
true if the parent consumed some or all of the scroll delta |
dispatchNestedScroll
boolean dispatchNestedScroll (int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow, int type)
Dispatch one step of a nested scroll in progress.
Implementations of views that support nested scrolling should call this to report
info about a scroll in progress to the current nested scrolling parent. If a nested scroll
is not currently in progress or nested scrolling is not
enabled
for this view this method does nothing.
Compatible View implementations should also call
dispatchNestedPreScroll
before
consuming a component of the scroll event themselves.
Parameters | |
---|---|
dxConsumed |
int : Horizontal distance in pixels consumed by this view during this scroll step |
dyConsumed |
int : Vertical distance in pixels consumed by this view during this scroll step |
dxUnconsumed |
int : Horizontal scroll distance in pixels not consumed by this view |
dyUnconsumed |
int : Horizontal scroll distance in pixels not consumed by this view |
offsetInWindow |
int : Optional. If not null, on return this will contain the offset
in local view coordinates of this view from before this operation
to after it completes. View implementations may use this to adjust
expected input coordinate tracking. |
type |
int : the type of input which cause this scroll event |
Returns | |
---|---|
boolean |
true if the event was dispatched, false if it could not be dispatched. |
hasNestedScrollingParent
boolean hasNestedScrollingParent (int type)
Returns true if this view has a nested scrolling parent for the given input type.
The presence of a nested scrolling parent indicates that this view has initiated a nested scroll and it was accepted by an ancestor view further up the view hierarchy.
Parameters | |
---|---|
type |
int : the type of input which cause this scroll event |
Returns | |
---|---|
boolean |
whether this view has a nested scrolling parent |
startNestedScroll
boolean startNestedScroll (int axes, int type)
Begin a nestable scroll operation along the given axes, for the given input type.
A view starting a nested scroll promises to abide by the following contract:
The view will call startNestedScroll upon initiating a scroll operation. In the case
of a touch scroll type this corresponds to the initial ACTION_DOWN
.
In the case of touch scrolling the nested scroll will be terminated automatically in
the same manner as requestDisallowInterceptTouchEvent(boolean)
.
In the event of programmatic scrolling the caller must explicitly call
stopNestedScroll(int)
to indicate the end of the nested scroll.
If startNestedScroll
returns true, a cooperative parent was found.
If it returns false the caller may ignore the rest of this contract until the next scroll.
Calling startNestedScroll while a nested scroll is already in progress will return true.
At each incremental step of the scroll the caller should invoke
dispatchNestedPreScroll
once it has calculated the requested scrolling delta. If it returns true the nested scrolling
parent at least partially consumed the scroll and the caller should adjust the amount it
scrolls by.
After applying the remainder of the scroll delta the caller should invoke
dispatchNestedScroll
, passing
both the delta consumed and the delta unconsumed. A nested scrolling parent may treat
these values differently. See
onNestedScroll(View, int, int, int, int, int)
.
Parameters | |
---|---|
axes |
int : Flags consisting of a combination of SCROLL_AXIS_HORIZONTAL
and/or SCROLL_AXIS_VERTICAL . |
type |
int : the type of input which cause this scroll event |
Returns | |
---|---|
boolean |
true if a cooperative parent was found and nested scrolling has been enabled for the current gesture. |
stopNestedScroll
void stopNestedScroll (int type)
Stop a nested scroll in progress for the given input type.
Calling this method when a nested scroll is not currently in progress is harmless.
Parameters | |
---|---|
type |
int : the type of input which cause this scroll event |
See also:
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