Package 

Interface NestedScrollingChild2

  • All Implemented Interfaces:
    tds.androidx.core.view.NestedScrollingChild 
    
public interface NestedScrollingChild2
 implements NestedScrollingChild

    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.

    • Method Summary

      Modifier and Type Method Description
      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.
      abstract boolean hasNestedScrollingParent(int type) Returns true if this view has a nested scrolling parent for the given input type.
      abstract boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, @Nullable() Array<int> offsetInWindow, int type) Dispatch one step of a nested scroll in progress.
      abstract boolean dispatchNestedPreScroll(int dx, int dy, @Nullable() Array<int> consumed, @Nullable() Array<int> offsetInWindow, int type) Dispatch one step of a nested scroll in progress before this view consumes any portion of it.

      • Methods inherited from class tds.androidx.core.view.NestedScrollingChild

        dispatchNestedFling, dispatchNestedPreFling, dispatchNestedPreScroll, dispatchNestedScroll, hasNestedScrollingParent, isNestedScrollingEnabled, setNestedScrollingEnabled, startNestedScroll, stopNestedScroll

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • startNestedScroll

         abstract 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 caseof a touch scroll type this corresponds to the initial ACTION_DOWN.In the case of touch scrolling the nested scroll will be terminated automatically inthe same manner as requestDisallowInterceptTouchEvent.In the event of programmatic scrolling the caller must explicitly call stopNestedScroll 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 scrollingparent at least partially consumed the scroll and the caller should adjust the amount itscrolls by.

        After applying the remainder of the scroll delta the caller should invoke dispatchNestedScroll, passingboth the delta consumed and the delta unconsumed. A nested scrolling parent may treatthese values differently. See onNestedScroll.

        Parameters:
        axes - Flags consisting of a combination of SCROLL_AXIS_HORIZONTAL and/or SCROLL_AXIS_VERTICAL.
        type - the type of input which cause this scroll event

      • stopNestedScroll

         abstract 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 - the type of input which cause this scroll event

      • hasNestedScrollingParent

         abstract 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 initiateda nested scroll and it was accepted by an ancestor view further up the view hierarchy.

        Parameters:
        type - the type of input which cause this scroll event

      • dispatchNestedScroll

         abstract boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, @Nullable() Array<int> offsetInWindow, int type)

        Dispatch one step of a nested scroll in progress.

        Implementations of views that support nested scrolling should call this to reportinfo about a scroll in progress to the current nested scrolling parent. If a nested scrollis not currently in progress or nested scrolling is not enabled for this view this method does nothing.

        Compatible View implementations should also call dispatchNestedPreScroll beforeconsuming a component of the scroll event themselves.

        Parameters:
        dxConsumed - Horizontal distance in pixels consumed by this view during this scroll step
        dyConsumed - Vertical distance in pixels consumed by this view during this scroll step
        dxUnconsumed - Horizontal scroll distance in pixels not consumed by this view
        dyUnconsumed - Horizontal scroll distance in pixels not consumed by this view
        offsetInWindow - Optional.
        type - the type of input which cause this scroll event

      • dispatchNestedPreScroll

         abstract boolean dispatchNestedPreScroll(int dx, int dy, @Nullable() Array<int> consumed, @Nullable() Array<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 nestedscrolling operation to consume some or all of the scroll operation before the child viewconsumes it.

        Parameters:
        dx - Horizontal scroll distance in pixels
        dy - Vertical scroll distance in pixels
        consumed - Output.
        offsetInWindow - Optional.
        type - the type of input which cause this scroll event