private void enableLayers(boolean enable) {
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final int layerType = enable ?
                    ViewCompat.LAYER_TYPE_HARDWARE : ViewCompat.LAYER_TYPE_NONE;
            ViewCompat.setLayerType(getChildAt(i), layerType, null);
        }
    }
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.
dkplayer-sample/src/main/java/xyz/doikki/dkplayer/widget/VerticalViewPager.java