用百分比将小部件放在堆栈中

您可以将

Positioned.fill

LayoutBuilder

    new Stack(    children: <Widget>[      new Positioned.fill(        child: new LayoutBuilder(          builder: (context, constraints) { return new Padding(   padding: new EdgeInsets.only(top: constraints.biggest.height * .59, bottom: constraints.biggest.height * .31),   child: new Text("toto", textAlign: TextAlign.center,), );          },        ),      )    ],  ),