Flutter flutter_screenutil 實現屏幕適配

1. 在pubspec.yaml文件導入:

   flutter_screenutil: ^0.6.0

2. 初始化:   美工提供的UI設計尺寸ScreenUtil.instance = ScreenUtil(width: 1080, height: 2160)..init(context);
3. 字體大小： Text( list[index].mallName, style: TextStyle(fontSize: ScreenUtil().setSp(24)), ),
4. 適配屏幕尺寸：

   height: ScreenUtil().setHeight(80),
   width: ScreenUtil().setWidth(570),