NestedScrollingChildHelper
public class NestedScrollingChildHelper
Helper class for implementing nested scrolling child views compatible with Android platform versions earlier than Android 5.0 Lollipop (API 21).
View subclasses should instantiate a final instance of this class as a field at construction. For each View method that has a matching method signature in this class, delegate the operation to the helper instance in an overridden method implementation. This implements the standard framework policy for nested scrolling.
Views invoking nested scrolling functionality should always do so from the relevant androidx.core.view.ViewCompat, androidx.core.view.ViewGroupCompat or androidx.core.view.ViewParentCompat compatibility shim static methods. This ensures interoperability with nested scrolling views on Android 5.0 Lollipop and newer.
Summary
Public constructors |
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Construct a new helper for a given view. |
Public methods |
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boolean |
dispatchNestedFling(float velocityX, float velocityY, boolean consumed)Dispatch a nested fling operation to the current nested scrolling parent. |
boolean |
dispatchNestedPreFling(float velocityX, float velocityY)Dispatch a nested pre-fling operation to the current nested scrolling parent. |
boolean |
dispatchNestedPreScroll(Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent. |
boolean |
dispatchNestedPreScroll(Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent. |
boolean |
dispatchNestedScroll(Dispatch one step of a nested scrolling operation to the current nested scrolling parent. |
boolean |
dispatchNestedScroll(Dispatch one step of a nested scrolling operation to the current nested scrolling parent. |
void |
dispatchNestedScroll(Dispatch one step of a nested scrolling operation to the current nested scrolling parent. |
boolean |
Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the type of touch. |
boolean |
hasNestedScrollingParent(int type)Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the given type. |
boolean |
Check if nested scrolling is enabled for this view. |
void |
View subclasses should always call this method on their |
void |
onStopNestedScroll(@NonNull View child)Called when a nested scrolling child stops its current nested scroll operation. |
void |
setNestedScrollingEnabled(boolean enabled)Enable nested scrolling. |
boolean |
startNestedScroll(int axes)Start a new nested scroll for this view. |
boolean |
startNestedScroll(int axes, int type)Start a new nested scroll for this view. |
void |
Stop a nested scroll in progress. |
void |
stopNestedScroll(int type)Stop a nested scroll in progress. |
Public constructors
NestedScrollingChildHelper
public NestedScrollingChildHelper(@NonNull View view)
Construct a new helper for a given view.
Public methods
dispatchNestedFling
public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed)
Dispatch a nested fling operation to the current nested scrolling parent.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if the parent consumed the nested fling |
dispatchNestedPreFling
public boolean dispatchNestedPreFling(float velocityX, float velocityY)
Dispatch a nested pre-fling operation to the current nested scrolling parent.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if the parent consumed the nested fling |
dispatchNestedPreScroll
public boolean dispatchNestedPreScroll(
int dx,
int dy,
@Nullable int[] consumed,
@Nullable int[] offsetInWindow
)
Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if the parent consumed any of the nested scroll |
dispatchNestedPreScroll
public boolean dispatchNestedPreScroll(
int dx,
int dy,
@Nullable int[] consumed,
@Nullable int[] offsetInWindow,
int type
)
Dispatch one step of a nested pre-scrolling operation to the current nested scrolling parent.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild2 interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if the parent consumed any of the nested scroll |
dispatchNestedScroll
public boolean dispatchNestedScroll(
int dxConsumed,
int dyConsumed,
int dxUnconsumed,
int dyUnconsumed,
@Nullable int[] offsetInWindow
)
Dispatch one step of a nested scrolling operation to the current nested scrolling parent.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
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dispatchNestedScroll
public boolean dispatchNestedScroll(
int dxConsumed,
int dyConsumed,
int dxUnconsumed,
int dyUnconsumed,
@Nullable int[] offsetInWindow,
int type
)
Dispatch one step of a nested scrolling operation to the current nested scrolling parent.
This is a delegate method. Call it from your NestedScrollingChild2 interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
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dispatchNestedScroll
public void dispatchNestedScroll(
int dxConsumed,
int dyConsumed,
int dxUnconsumed,
int dyUnconsumed,
@Nullable int[] offsetInWindow,
int type,
@Nullable int[] consumed
)
Dispatch one step of a nested scrolling operation to the current nested scrolling parent.
This is a delegate method. Call it from your NestedScrollingChild3 interface method with the same signature to implement the standard policy.
hasNestedScrollingParent
public boolean hasNestedScrollingParent()
Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the type of touch.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if this view has a nested scrolling parent, false otherwise |
hasNestedScrollingParent
public boolean hasNestedScrollingParent(int type)
Check if this view has a nested scrolling parent view currently receiving events for a nested scroll in progress with the given type.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if this view has a nested scrolling parent, false otherwise |
isNestedScrollingEnabled
public boolean isNestedScrollingEnabled()
Check if nested scrolling is enabled for this view.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Returns | |
|---|---|
boolean |
true if nested scrolling is enabled for this view |
onDetachedFromWindow
public void onDetachedFromWindow()
View subclasses should always call this method on their NestedScrollingChildHelper when detached from a window.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
onStopNestedScroll
public void onStopNestedScroll(@NonNull View child)
Called when a nested scrolling child stops its current nested scroll operation.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
setNestedScrollingEnabled
public void setNestedScrollingEnabled(boolean enabled)
Enable nested scrolling.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Parameters | |
|---|---|
boolean enabled |
true to enable nested scrolling dispatch from this view, false otherwise |
startNestedScroll
public boolean startNestedScroll(int axes)
Start a new nested scroll for this view.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
| Parameters | |
|---|---|
int axes |
Supported nested scroll axes. See |
| Returns | |
|---|---|
boolean |
true if a cooperating parent view was found and nested scrolling started successfully |
startNestedScroll
public boolean startNestedScroll(int axes, int type)
Start a new nested scroll for this view.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild2 interface method with the same signature to implement the standard policy.
| Parameters | |
|---|---|
int axes |
Supported nested scroll axes. See |
int type |
type of the scroll. |
| Returns | |
|---|---|
boolean |
true if a cooperating parent view was found and nested scrolling started successfully |
stopNestedScroll
public void stopNestedScroll()
Stop a nested scroll in progress.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild interface method with the same signature to implement the standard policy.
stopNestedScroll
public void stopNestedScroll(int type)
Stop a nested scroll in progress.
This is a delegate method. Call it from your View subclass method/androidx.core.view.NestedScrollingChild2 interface method with the same signature to implement the standard policy.