实现代码如下
double itemHeight=40.0;
Widget left=ListView.builder(
shrinkWrap:true,
itemExtent:itemHeight,//确定每一个item的高度 会让item加载更加高效
controller: _scrollController,
itemCount: widget.data==null?0:widget.data.length,
itemBuilder: (context,index){
Widget list=InkWell(
child:Container(
width: 83.0,
height: itemHeight,
child: Center(
child: Text(widget.data[index].name,
overflow: TextOverflow.ellipsis,
style: TextStyle(fontSize: 16.0),
),
),
),
onTap: (){
setState(() {
activeIndex=index;
});
///屏幕高度减AppBar高度和底部高度
double mediaHeight=(MediaQuery.of(context).size.height)-75.0-50.0;
///Item总数
int itemCount=widget.data.length;
///滚动高度
double scrollHeight=itemCount*itemHeight;
///公式如下：当前点击的Item/Item总数*滚动高度-屏幕高度/2+Item的高度/2
double _top=activeIndex/itemCount*scrollHeight-mediaHeight/2+itemHeight/2;
// print("Top值：$_top 当前Item$activeIndex Item总数$itemCount 滚动条高度：$scrollHeight 屏幕高度$mediaHeight Item的高度：$itemHeight");
_scrollController.animateTo(_top,duration: Duration(milliseconds: 300,),curve: Curves.fastOutSlowIn);
widget.onSelected(widget.data[index].children);
},
);
list=Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
decoration: BoxDecoration(color: activeIndex==index? AppTheme.color_red:AppTheme.backageColor),
height: 30.0,
width: 3.0,
),
Material(type: MaterialType.transparency,child: list)
],
);
return list;
},
);
