private void requestParentDisallowInterceptTouchEvent(boolean disallowIntercept) {
        final ViewParent parent = getParent();
        if (parent != null) {
            parent.requestDisallowInterceptTouchEvent(disallowIntercept);
        }
    }
This method will be invoked when the current page is scrolled, either as part
of a programmatically initiated smooth scroll or a user initiated touch scroll.
If you override this method you must call through to the superclass implementation
(e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
returns.

@param position Position index of the first page currently being displayed.
                Page position+1 will be visible if positionOffset is nonzero.
@param offset Value from [0, 1) indicating the offset from the page at position.
@param offsetPixels Value in pixels indicating the offset from position.
library/src/main/java/com/daimajia/slider/library/Tricks/ViewPagerEx.java