@Override
    public int getScrollDistance() {
        View c = getChildAt(0);
        if (c == null) {
            return 0;
        }
        int firstVisiblePosition = getFirstVisiblePosition();
        int top = c.getTop();
        int scrollY = -top + firstVisiblePosition * c.getHeight();
        return scrollY;
    }
@author: Kongzue
@github: https://github.com/kongzue/
@homepage: http://kongzue.com/
@mail: myzcxhh@live.cn
@createTime: 2020/10/6 23:42
DialogX/src/main/java/com/kongzue/dialogx/util/views/DialogListView.java