Touch事件传递流程-小米 http://hanhailong.com/2015/09/24/Android-%E4%B8%89%E5%BC%A0%E5%9B%BE%E6%90%9E%E5%AE%9ATouch%E4%BA%8B%E4%BB%B6%E4%BC%A0%E9%80%92%E6%9C%BA%E5%88%B6/