listview 监听顶部滚动的距离的方法

getListViewScrollY.java

 private Dictionary<Integer, Integer> listViewItemHeights = new Hashtable<Integer, Integer>();
    private int getListViewScrollY(AbsListView view) {
        View c = view.getChildAt(0);
        int scrollY = -c.getTop();
        listViewItemHeights.put(view.getFirstVisiblePosition(), c.getHeight());
        for (int i = 0; i < view.getFirstVisiblePosition(); ++i) {
            if (listViewItemHeights.get(i) != null)
                scrollY += listViewItemHeights.get(i); //顶部消失的所有Item的高度
        }
        return scrollY;
    }