private void setScrollingCacheEnabled(boolean enabled) {
        if (mScrollingCacheEnabled != enabled) {
            mScrollingCacheEnabled = enabled;
            if (USE_CACHE) {
                final int size = getChildCount();
                for (int i = 0; i < size; ++i) {
                    final View child = getChildAt(i);
                    if (child.getVisibility() != GONE) {
                        child.setDrawingCacheEnabled(enabled);
                    }
                }
            }
        }
    }
Returns true if a fake drag is in progress.

@return true if currently in a fake drag, false otherwise.
@see #beginFakeDrag()
@see #fakeDragBy(float)
@see #endFakeDrag()
dkplayer-sample/src/main/java/xyz/doikki/dkplayer/widget/VerticalViewPager.java