polaris/ui/lib/navdrawer.dart

import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:ui/activity.dart';
import 'package:ui/system_settings.dart';
import 'package:ui/weclome.dart';

class NavDrawer extends StatefulWidget {
  const NavDrawer({super.key});

  @override
  State<StatefulWidget> createState() {
    return _NavDrawerState();
  }
}

class _NavDrawerState extends State<NavDrawer> {
  var _counter = 0;

  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
        constraints: const BoxConstraints(maxWidth: 220),
        child: Row(
            mainAxisAlignment: MainAxisAlignment.start,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Flexible(
                  child: NavigationRail(
                selectedIndex: _counter,
                onDestinationSelected: (value) {
                  setState(() {
                    _counter = value;
                  });
                  if (value == 0) {
                    context.go(WelcomePage.route);
                  } else if (value == 1) {
                    context.go(ActivityPage.route);
                  } else if (value == 2) {
                    context.go(SystemSettingsPage.route);
                  }
                },
                extended: MediaQuery.of(context).size.width >= 850,
                unselectedIconTheme: const IconThemeData(color: Colors.grey),
                destinations: const <NavigationRailDestination>[
                  NavigationRailDestination(
                    icon: Icon(Icons.live_tv),
                    label: Text('电视剧'),
                  ),
                  NavigationRailDestination(
                    icon: Icon(Icons.download),
                    label: Text('活动'),
                  ),
                  NavigationRailDestination(
                    icon: Icon(Icons.settings),
                    label: Text('设置'),
                  ),
                  NavigationRailDestination(
                    icon: Icon(Icons.computer),
                    label: Text('系统'),
                  ),
                ],
                //groupAlignment: -1,
                minWidth: 56,
              ))
            ]));
  }
}