flutter 仿京东首页 吸顶功能

直接上代码

CustomScrollView(
        slivers: <Widget>[
          SliverAppBar(
            pinned: true,
            expandedHeight: 200.0,
            centerTitle: true,
          automaticallyImplyLeading: true,
          primary: true,
              leading: Icon(Icons.invert_colors_on_sharp),
              actions: [
                Icon(Icons.ac_unit_rounded),
                Container(
                  child: Icon(Icons.access_alarm_outlined),
                  margin: EdgeInsets.symmetric(horizontal: 10.w),
                )
              ],
            iconTheme: colorTheme.iconTheme,
            titleSpacing: 50,
            flexibleSpace: FlexibleSpaceBar(
              centerTitle: true,
              collapseMode: CollapseMode.pin,
              title: ConstrainedBox(
                constraints: BoxConstraints(
                  maxWidth: MediaQuery.of(context).size.width / 1.5,
                ),

                child: Container(
                  margin: EdgeInsets.only(right: 20, left: 20 / 1.5),
                  // padding: EdgeInsets.only(right: 10, left: 10),
                  height: 25,
                  // alignment: Alignment.centerLeft,
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(16.r),
                    color: Colors.white,
                  ),
                ),
              ),
            ),
          ),
          SliverGrid.count(crossAxisCount: 4,children: List.generate(8, (index){
            return Container(
              color: Colors.primaries[index%Colors.primaries.length],
              alignment: Alignment.center,
              child: Text('$index',style: TextStyle(color: Colors.white,fontSize: 20),),
            );
          }).toList(),),
          SliverList(
            delegate: SliverChildBuilderDelegate((content, index) {
              return Container(
                height: 85,
                alignment: Alignment.center,
                color: Colors.primaries[index % Colors.primaries.length],
                child: Text('$index',style: TextStyle(color: Colors.white,fontSize: 20),),
              );
            }, childCount: 25),
          )
          // Header(),
          // Body(),
        ],
      ),
    )```