flutter 中监听滑动事件

Listener({
 Key key,
 this.onPointerDown, //手指按下回调
 this.onPointerMove, //手指移动回调
 this.onPointerUp,//手指抬起回调
 this.onPointerCancel,//触摸事件取消回调
 this.behavior = HitTestBehavior.deferToChild, //在命中测试期间如何表现
 Widget child
})

Listener(
 onPointerDown: (dowPointEvent){},
 onPointerMove: (movePointEvent){},
 onPointerUp: (upPointEvent){},
 child: Container(
   child: Text('Listener的监听')
 )
);

 /// 下拉刷新，这里必须使用async，不然会报错
 Future<Null> _refresh() async {
  final Completer<Null> completer = new Completer<Null>();
  _dataList.clear(); // 清空数据
  setState(() {
   page = 1;
  });
  loadData(completer); // 加载数据
  return completer.future;
 }

ScrollController _scrollController = new ScrollController(); // 初始化滚动监听器，加载更多使用

_scrollController.addListener(() {
   // 如果滑动到底部
   if (_scrollController.position.pixels == _scrollController.position.maxScrollExtent) {
      // do something
   }
 });

RefreshIndicator(
  onRefresh: _refresh, // 下拉刷新
  child: ListView.builder(
    padding: EdgeInsets.only(bottom: Adapt.px(40)),
    shrinkWrap: true,
    controller: _scrollController,
    physics: AlwaysScrollableScrollPhysics(),
    itemCount: _dataList.length,
    itemBuilder: (context, item) {
       return listCard(_dataList[item]);
     }
   )
)

new Listener(
  onPointerMove: (event) {
    var position = event.position.distance;
    var detal = position - lastDownY;
    if (detal > 0) {
     print("================向下移动================");
    } else {
      // 所摸点长度 +滑动距离 = IistView的长度 说明到达底部
      print("================向上移动================");
      print("scrollController==滑动距离=======${(position - downY)}");
      var scrollExtent = scrollController.position.maxScrollExtent;
      print("scrollController==ListView最大长度===${scrollExtent}");
      print("scrollController==所摸点长度===${scrollController.offset}");
      print("scrollController==所摸点离屏幕距离===${position}");
      var result = scrollController.offset +(position - downY).abs();
      if (result >= scrollExtent) {
        print("scrollController====到达底部");
         lastListLength = scrollExtent;
         loadMore(); // 加载更多数据
       }
    }
   lastDownY = position;
   },
   child: new ListView.builder(
    controller: scrollController,
    itemCount: datas == null ? 0 : datas.length,
    itemBuilder: (BuildContext context, int index) {
        return Container(child: Text('列表${index}') )
    }
   )
 );

FocusScope.of(context).requestFocus(FocusNode());
// 或者
FocusNode _foucusNode = new FocusNode();
_foucusNode.unfocus();
使用 Listener 监听，在滑动屏幕的时候关闭键盘

Listener(
  onPointerMove: (movePointEvent){
    _foucusNode.unfocus();
  },
  child: return SingleChildScrollView(
    controller: _scrollController,
    child: Column(
     children: <Widget>[
      // some widget
     ],
    )
  )
)