Flutter Algin 对齐布局

import 'package:flutter/material.dart';

void main() => runApp(new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: new Text("对齐"),
        ),
        body: new Stack(
          children: [
            Align(
              //左上
              alignment: new FractionalOffset(0.0, 0.0),
              child: new Image.asset("images/1.jpeg", width: 120, height: 120),
            ),
            Align(
              //右上
              alignment: FractionalOffset.topRight,
              child: new Image.asset("images/1.jpeg", width: 120, height: 120),
            ),
            Align(
              //水平居中
              alignment: new FractionalOffset(0.5, 0.5),
              child: new Image.asset("images/1.jpeg", width: 120, height: 120),
            ),
            Align(
              //左下角
              alignment:FractionalOffset.bottomLeft,
              child: new Image.asset("images/1.jpeg", width: 120, height: 120),
            ),
            Align(
              //右下角
              alignment:FractionalOffset.bottomRight,
              child: new Image.asset("images/1.jpeg", width: 120, height: 120),
            ),
            Align(
              //左中
              alignment:FractionalOffset.centerLeft,
              child: new Image.asset("images/a.jpg", width: 120, height: 120),
            ),
            Align(
              //左中
              alignment:FractionalOffset.centerRight,
              child: new Image.asset("images/a.jpg", width: 120, height: 120),
            ),
            Align(
              //上中
              alignment:FractionalOffset.topCenter,
              child: new Image.asset("images/a.jpg", width: 120, height: 120),
            ),
            Align(
              //下中
              alignment:FractionalOffset.bottomCenter,
              child: new Image.asset("images/a.jpg", width: 120, height: 120),
            ),
          ],
        ),
      ),
    ));

参考：Flutter 技术入门与实战