flutter布局容器

Row | Column

Row | Column( 
  mainAxisAlignment: MainAxisAlignment.center, //主轴对齐方式
  crossAxisAlignment: CrossAxisAlignment.center, //交叉轴对齐方式
  children: <Widget>[] //子部件
}

Stack

Stack( //使子部件重叠(必须要有父容器)
 alignment: Alignment(0,0), //子部件为对齐的对齐方式
 children: <Widget>[] //子部件
)

Positioned

Positioned(
  top //上偏移
  right //右偏移
  bottom //下偏移
  left //左偏移
  child //子部件

AspectRatio

AspectRatio( //子部件纵横比
  aspectRatio: 1 / 1,//宽高比
  child: Container(
    decoration: BoxDecoration(color: Color(0xFFff0000)),
  ),
)

ConstrainedBox

ConstrainedBox( //约束子部件大小
  constraints: BoxConstraints(
    maxHeight: 200,
    minWidth: 10,
  ),
  child: Container(
    decoration: BoxDecoration(color: Color(0xFFff0000)),
  ),
)