如何在 Flutter 底部导航栏中的特定选项卡中加载数据

Question

I am using an Animated Container in Bottom Nav Bar to Hide the Bottom Navbar While Scrolling(Similar to Pinterest). I want to display The data of particular tab in the Same Page. (refer the GIF)

https://i.stack.imgur.com/xlOsy.gif

I Want to display the Content In the Screen of the tab and I don't want to route to other Screen leaving the main Screen. I have 4 rows with different Icons. How Can I achieve this?

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  double yTransValue = 0;

  @override
  Widget build(BuildContext context) {
    return NotificationListener<ScrollUpdateNotification>(
      onNotification: (notification) {
        print(notification.metrics.axisDirection);
        print(notification.metrics.axis);

        if (notification.scrollDelta.sign == 1) {
          setState(() {
            yTransValue = 100;
          });
        } else if (notification.scrollDelta.sign == -1) {
          setState(() {
            yTransValue = 0;
          });
        }
      },
      child: Scaffold(
        body: ListView.builder(
          itemBuilder: (BuildContext context, int index) {
            return SizedBox(
              height: 260,
              child: Card(
                child: Center(child: Text('Item #$index')),
              ),
            );
          },
        ),
        bottomNavigationBar: AnimatedContainer(
          duration: Duration(milliseconds: 300),
          transform: Matrix4.translationValues(0, yTransValue, 0),
          child: SizedBox(
            height: 60,
            child: Card(
              color: Colors.grey,
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  Icon(Icons.home),
                  Icon(Icons.search),
                  Icon(Icons.favorite_border),
                  Icon(Icons.person_rounded),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}

I had tried Wrapping the Icons With 'Gesture Detector' But when the Icon is pressed a data is loaded in new Screen.

Answer 1

Use the following code:

import 'package:flutter/material.dart';

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

/// This is the main application widget.
class MyApp extends StatelessWidget {
  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: MyStatefulWidget(),
    );
  }
}

/// This is the stateful widget that the main application instantiates.
class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key key}) : super(key: key);

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

/// This is the private State class that goes with MyStatefulWidget.
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  static const TextStyle optionStyle =
      TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  static const List<Widget> _widgetOptions = <Widget>[
    Text(
      'Index 0: Home',
      style: optionStyle,
    ),
    Text(
      'Index 1: Business',
      style: optionStyle,
    ),
    Text(
      'Index 2: School',
      style: optionStyle,
    ),
  ];

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('BottomNavigationBar Sample'),
      ),
      body: Center(
        child: _widgetOptions.elementAt(_selectedIndex),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.business),
            label: 'Business',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.school),
            label: 'School',
          ),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.amber[800],
        onTap: _onItemTapped,
      ),
    );
  }
}