Flutter——FloatingActionButton组件（浮动按钮组件）

FloatingActionButton 简称 FAB ,可以实现浮动按钮，也可以实现类似闲鱼 app 的地步凸起导航。

 

 

属性名称	属性值
child	子视图，一般为 Icon，不推荐使用文字
tooltip	FAB 被长按时显示，也是无障碍功能
backgroundColor	背景颜色
elevation	未点击的时候的阴影
hignlightElevation	点击时阴影值，默认 12.0
onPressed	点击事件回调
shape	可以定义 FAB 的形状等
mini	是否是 mini 类型默认 false

FloatingActionButton实现闲鱼APP底部凸起按钮：

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    title: "FloatingActionButton",
    home: MyApp(),
  ));
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  int _currentIndex = 0;
  List _pageList = [
    Page("闲鱼页面"),
    Page("鱼塘页面"),
    Page("发布页面"),
    Page("消息"),
    Page("我的")
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: _pageList[_currentIndex],
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _currentIndex,
        type: BottomNavigationBarType.fixed,
        fixedColor: Colors.yellow,
        onTap: (int index) {
          setState(() {
            this._currentIndex = index;
          });
        },
        items: [
          BottomNavigationBarItem(
              icon: Icon(Icons.home),
              title: Text("闲鱼", style: TextStyle(color: Colors.black54))),
          BottomNavigationBarItem(
              icon: Icon(Icons.category),
              title: Text("鱼塘", style: TextStyle(color: Colors.black54))),
          BottomNavigationBarItem(
              icon: Icon(Icons.settings),
              title: Text("发布", style: TextStyle(color: Colors.black54))),
          BottomNavigationBarItem(
              icon: Icon(Icons.message),
              title: Text("消息", style: TextStyle(color: Colors.black54))),
          BottomNavigationBarItem(
              icon: Icon(Icons.settings),
              title: Text("我的", style: TextStyle(color: Colors.black54))),
        ],
      ),
      floatingActionButton: Container(
        margin: EdgeInsets.only(top: 5),
        child: FloatingActionButton(
          child: Icon(Icons.add, color: Colors.black54),
          backgroundColor: Colors.yellow,
          onPressed: () {
            setState(() {
              this._currentIndex = 2;
            });
          },
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
    );
  }
}

class Page extends StatelessWidget {
  String text;

  Page(this.text);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Text(text),
    );
  }
}