フラッタエラー:mediaquery.of ()は、mediaquery - fluttercornerを含まないコンテキストで呼び出されます.コム

return new Container(
      height: MediaQuery.of(context).size.height,
      decoration: BoxDecoration(
        color: backgroundColor,
      ),
      child:   DecoratedBox(
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          mainAxisSize: MainAxisSize.max,
          children: <Widget>[
            Center(

                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Container(height: 120.0, color: Colors.yellow, child: new ColorLoader2(color1: Colors.redAccent, color2: Colors.deepPurple, color3: Colors.green),),

                ],
      ),
            )
        ],
      ),
        decoration: BoxDecoration(
          color: Colors.redAccent,
        ),
      )
    );
  }
}