startNestedScroll
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. 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 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.
Return
true if a cooperative parent was found and nested scrolling has been enabled for the current gesture.
Parameters
Flags consisting of a combination of SCROLL_AXIS_HORIZONTAL and/or SCROLL_AXIS_VERTICAL.
the type of input which cause this scroll event