16.APP首页框架搭建-Scaffold与PageView

APP首页框架搭建

• 实现首页导航需要哪些材料？

• 什么是Scaffold widget？

• 什么是PageView？

• 实现首页导航

实现首页导航需要哪些材料?

• Scaffold

• • BottomNavigationBar

• PageView

• • PageController

什么是Scaffold widget？

Scaffold是一个实现了基本的material design的布局结构。

class Scaffold extends StatefulWidget {
  /// Creates a visual scaffold for material design widgets.
  const Scaffold({
    Key key,
    this.appBar,
    this.body,
    this.floatingActionButton,
    this.floatingActionButtonLocation,
    this.floatingActionButtonAnimator,
    this.persistentFooterButtons,
    this.drawer,
    this.endDrawer,
    this.bottomNavigationBar,
    this.bottomSheet,
    this.backgroundColor,
    this.resizeToAvoidBottomPadding = true,
    this.primary = true,
  }) : assert(primary != null), super(key: key);
...

顶部导航

image

import 'package:flutter/material.dart';

class TabbedAppBarSample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DefaultTabController(
        length: choices.length,
        child: Scaffold(
          appBar: AppBar(
            title: const Text('Tabbed AppBar'),
            bottom: TabBar(
              isScrollable: true,
              tabs: choices.map((Choice choice) {
                return Tab(
                  text: choice.title,
                  icon: Icon(choice.icon),
                );
              }).toList(),
            ),
          ),
          body: TabBarView(
            children: choices.map((Choice choice) {
              return Padding(
                padding: const EdgeInsets.all(16.0),
                child: ChoiceCard(choice: choice),
              );
            }).toList(),
          ),
        ),
      ),
    );
  }
}

class Choice {
  const Choice({this.title, this.icon});
  final String title;
  final IconData icon;
}

const List<Choice> choices = const <Choice>[
  const Choice(title: 'CAR', icon: Icons.directions_car),
  const Choice(title: 'BICYCLE', icon: Icons.directions_bike),
  const Choice(title: 'BOAT', icon: Icons.directions_boat),
  const Choice(title: 'BUS', icon: Icons.directions_bus),
  const Choice(title: 'TRAIN', icon: Icons.directions_railway),
  const Choice(title: 'WALK', icon: Icons.directions_walk),
];

class ChoiceCard extends StatelessWidget {
  const ChoiceCard({Key key, this.choice}) : super(key: key);
  final Choice choice;

  @override
  Widget build(BuildContext context) {
    final TextStyle textStyle = Theme.of(context).textTheme.display1;
    return Card(
      color: Colors.white,
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Icon(choice.icon, size: 128.0, color: textStyle.color),
            Text(choice.title, style: textStyle),
          ],
        ),
      ),
    );
  }
}
void main() {
  runApp(TabbedAppBarSample());
}

底部导航菜单

image

import 'package:flutter/material.dart';
import 'package:flutter_app/pages/home_page.dart';
import 'package:flutter_app/pages/my_page.dart';
import 'package:flutter_app/pages/search_page.dart';
import 'package:flutter_app/pages/travel_page.dart';

class TabNavigator extends StatefulWidget {
  @override
  _TabNavigatorState createState() => _TabNavigatorState();
}

class _TabNavigatorState extends State<TabNavigator>
    with SingleTickerProviderStateMixin {
  final _defaultColor = Colors.grey;
  final _activeColor = Colors.blue;
  int _currentIndex = 0;
  var _controller = PageController(
    initialPage: 0,
  );

  @override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView(
        controller: _controller,
        children: <Widget>[HomePage(), SearchPage(), TravelPage(), MyPage()],
        physics: NeverScrollableScrollPhysics(),
      ),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _currentIndex,
        onTap: (index) {
          _controller.jumpToPage(index);
          setState(() {
            _currentIndex = index;
          });
        },
        type: BottomNavigationBarType.fixed,
        items: [
          BottomNavigationBarItem(
            icon: Icon(
              Icons.home,
              color: _defaultColor,
            ),
            activeIcon: Icon(
              Icons.home,
              color: _activeColor,
            ),
            title: Text(
              '首页',
              style: TextStyle(
                  color: _currentIndex != 0 ? _defaultColor : _activeColor),
            ),
          ),
          BottomNavigationBarItem(
              icon: Icon(
                Icons.search,
                color: _defaultColor,
              ),
              activeIcon: Icon(
                Icons.search,
                color: _activeColor,
              ),
              title: Text(
                '搜索',
                style: TextStyle(
                    color: _currentIndex != 1 ? _defaultColor : _activeColor),
              )),
          BottomNavigationBarItem(
              icon: Icon(
                Icons.camera_alt,
                color: _defaultColor,
              ),
              activeIcon: Icon(
                Icons.camera_alt,
                color: _activeColor,
              ),
              title: Text(
                '旅拍',
                style: TextStyle(
                    color: _currentIndex != 2 ? _defaultColor : _activeColor),
              )),
          BottomNavigationBarItem(
              icon: Icon(
                Icons.account_circle,
                color: _defaultColor,
              ),
              activeIcon: Icon(
                Icons.account_circle,
                color: _activeColor,
              ),
              title: Text(
                '我的',
                style: TextStyle(
                    color: _currentIndex != 3 ? _defaultColor : _activeColor),
              )),
        ],
      ),
    );
  }
}

侧拉栏菜单

image

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  final appTitle = 'Drawer Demo';
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: appTitle,
      home: MyHomePage(title: appTitle),
    );
  }
}

class MyHomePage extends StatelessWidget {
  final String title;
  MyHomePage({Key key, this.title}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(title)),
      body: Center(child: Text('My Page!')),
      drawer: Drawer(
        // Add a ListView to the drawer. This ensures the user can scroll
        // through the options in the Drawer if there isn't enough vertical
        // space to fit everything.
        child: ListView(
          // Important: Remove any padding from the ListView.
          padding: EdgeInsets.zero,
          children: <Widget>[
            DrawerHeader(
              child: Text('Drawer Header'),
              decoration: BoxDecoration(
                color: Colors.blue,
              ),
            ),
            ListTile(
              title: Text('Item 1'),
              onTap: () {
                // Update the state of the app
                // ...
                // Then close the drawer
                Navigator.pop(context);
              },
            ),
            ListTile(
              title: Text('Item 2'),
              onTap: () {
                // Update the state of the app
                // ...
                // Then close the drawer
                Navigator.pop(context);
              },
            ),
          ],
        ),
      ),
    );
  }
}

什么是PageView？

PageView是一个可以完成页面之间滚动的widget。 类似于Android中的ViewPager

class PageView extends StatefulWidget {
   PageView({
    Key key,
    this.scrollDirection = Axis.horizontal, //滚动的方向，支持水平和垂直两个方向
    this.reverse = false, //是否反方向滚动
    PageController controller, //PageView的控制类
    this.physics, //手势滚动逻辑，支持不滚动，总是滚动，与滚动到边缘时是否有bounce
    this.pageSnapping = true,//设置为false以禁用页面捕捉，对自定义滚动行为很有用。
    this.onPageChanged,//页面切换时调用
    List<Widget> children = const <Widget>[],
  }) : controller = controller ?? _defaultPageController,
       childrenDelegate = SliverChildListDelegate(children),
       super(key: key);
...