@Override
        public void onScrollChanged(int l, int t, int oldL, int oldT) {
            if (null == mScrollView) return;
            if (null != onScrollChangedListener)
                onScrollChangedListener.onChildScroll(oldT);
            if (mScrollView.getScrollY() == 0) {
                setDraggable(true);
            } else {
                setDraggable(false);
            }
        }
Layout that can scroll down to a max offset and can tell the scroll progress by
OnScrollProgressListener.
scrolllayout/src/main/java/com/yinglan/scrolllayout/ScrollLayout.java