Flutter Navigator 2.0 指南與原理解析

// Page
bool canUpdate(Page<dynamic> other) {
  return other.runtimeType == runtimeType &&
         other.key == key;
}

// Widget
static bool canUpdate(Widget oldWidget, Widget newWidget) {
  return oldWidget.runtimeType == newWidget.runtimeType
      && oldWidget.key == newWidget.key;
}

class _MyAppState extends State<MyApp> {
  final pages = [
    MyPage(
      key: Key('/'),
      name: '/',
      builder: (context) => HomeScreen(),
    ),
    MyPage(
      key: Key('/category/5'),
      name: '/category/5',
      builder: (context) => CategoryScreen(id: 5),
    ),
    MyPage(
      key: Key('/item/15'),
      name: '/item/15',
      builder: (context) => ItemScreen(id: 15),
    ),
  ];

  @override
  Widget build(BuildContext context) {
    return //...
      Navigator(
          key: _navigatorKey,
          pages: List.of(pages),
        ),
  }
}

void addPage(MyPage page) {
  setState(() => pages.add(page));
}

class _MyAppState extends State<MyApp> {
  bool _onPopPage(Route<dynamic> route, dynamic result) {
    setState(() => pages.remove(route.settings));
    return route.didPop(result);
  }

  @override
  Widget build(BuildContext context) {
    print('build: $pages');
    return // ...
      Navigator(
        key: _navigatorKey,
        onPopPage: _onPopPage,
        pages: List.of(pages),
      )
  }
}

bool _onPopPage(Route<dynamic> route, dynamic result) {
  // setState(() => pages.remove(route.settings));
  return route.didPop(result);
}

bool _onPopPage(Route<dynamic> route, dynamic result) {
  if (...) {
    return false;
  }
  setState(() => pages.remove(route.settings));
  return route.didPop(result);
}

List<Page> pages = <Page>[
  MaterialPage(
    key: ValueKey('VeggiesListPage'),
    child: VeggiesListScreen(
      veggies: veggies,
      onTapped: _handleVeggieTapped,
    ),
  ),
  if (show404)
    MaterialPage(key: ValueKey('UnknownPage'), child: UnknownScreen())
  else if (_selectedVeggie != null)
    VeggieDetailsPage(veggie: _selectedVeggie)
];

class MyPage extends Page {
  final Veggie veggie;

  MyPage({
    this.veggie,
  }) : super(key: ValueKey(veggie));

  Route createRoute(BuildContext context) {
    return MaterialPageRoute(
      settings: this,
      builder: (BuildContext context) {
        return VeggieDetailsScreen(veggie: veggie);
      },
    );
  }
}

void _pushPage() {
  MyRouteDelegate.of(context).push('Route$_counter');
}

MaterialApp.router(
  title: 'Flutter Demo',
  theme: ThemeData(
    primarySwatch: Colors.blue,
    visualDensity: VisualDensity.adaptivePlatformDensity,
  ),
  routeInformationParser: MyRouteParser(),
  routerDelegate: delegate,
)

class MyRouteDelegate extends RouterDelegate<String>
    with PopNavigatorRouterDelegateMixin<String>, ChangeNotifier {
  final _stack = <String>[];

  static MyRouteDelegate of(BuildContext context) {
    final delegate = Router.of(context).routerDelegate;
    assert(delegate is MyRouteDelegate, 'Delegate type must match');
    return delegate as MyRouteDelegate;
  }

  MyRouteDelegate({
    @required this.onGenerateRoute,
  });

  // ...
  @override
  Widget build(BuildContext context) {
    print('${describeIdentity(this)}.stack: $_stack');
    return Navigator(
      key: navigatorKey,
      onPopPage: _onPopPage,
      pages: [
        for (final name in _stack)
            MyPage(
              key: ValueKey(name),
              name: name,
              routeFactory: onGenerateRoute,
            ),
      ],
    );
  }
}

class MyRouteDelegate extends RouterDelegate<String>
    with PopNavigatorRouterDelegateMixin<String>, ChangeNotifier {
  final _stack = <String>[];

  static MyRouteDelegate of(BuildContext context) {
    final delegate = Router.of(context).routerDelegate;
    assert(delegate is MyRouteDelegate, 'Delegate type must match');
    return delegate as MyRouteDelegate;
  }

  MyRouteDelegate({
    @required this.onGenerateRoute,
  });

  final RouteFactory onGenerateRoute;

  @override
  GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();

  @override
  String get currentConfiguration => _stack.isNotEmpty ? _stack.last : null;

  List<String> get stack => List.unmodifiable(_stack);

  void push(String newRoute) {
    _stack.add(newRoute);
    notifyListeners();
  }

  void pop() {
    if (_stack.isNotEmpty) {
      _stack.remove(_stack.last);
    }
    notifyListeners();
  }

  @override
  Future<void> setInitialRoutePath(String configuration) {
    return setNewRoutePath(configuration);
  }

  @override
  Future<void> setNewRoutePath(String configuration) {
    print('setNewRoutePath $configuration');
    _stack
      ..clear()
      ..add(configuration);
    return SynchronousFuture<void>(null);
  }

  bool _onPopPage(Route<dynamic> route, dynamic result) {
    if (_stack.isNotEmpty) {
      if (_stack.last == route.settings.name) {
        _stack.remove(route.settings.name);
        notifyListeners();
      }
    }
    return route.didPop(result);
  }

  @override
  Widget build(BuildContext context) {
    print('${describeIdentity(this)}.stack: $_stack');
    return Navigator(
      key: navigatorKey,
      onPopPage: _onPopPage,
      pages: [
        for (final name in _stack)
            MyPage(
              key: ValueKey(name),
              name: name,
            ),
      ],
    );
  }
}

MyRouteDelegate.of(context).push('Route$_counter');

MyRouteDelegate.of(context).pop();

MaterialApp.router(
  title: 'Flutter Demo',
  routeInformationParser: MyRouteParser(), 	// 傳入 MyRouteParser
  routerDelegate: delegate,
)

class MyRouteParser extends RouteInformationParser<String> {
  @override
  Future<String> parseRouteInformation(RouteInformation routeInformation) {
    return SynchronousFuture(routeInformation.location);
  }

  @override
  RouteInformation restoreRouteInformation(String configuration) {
    return RouteInformation(location: configuration);
  }
}

@override
Future<void> setNewRoutePath(String configuration) {
  print('setNewRoutePath $configuration');
  _stack
    ..clear()
    ..add(configuration);
  return SynchronousFuture<void>(null);
}

import 'package:flutter/material.dart';
import 'package:flutter_navigator_v2/navigator_v2/model.dart';

class VeggieRouteInformationParser extends RouteInformationParser<VeggieRoutePath> {
  @override
  Future<VeggieRoutePath> parseRouteInformation(
      RouteInformation routeInformation) async {
    print("parseRouteInformation");
    final uri = Uri.parse(routeInformation.location);
    // Handle '/'
    if (uri.pathSegments.length == 0) {
      return VeggieRoutePath.home();
    }

    // Handle '/veggie/:id'
    if (uri.pathSegments.length == 2) {
      if (uri.pathSegments[0] != 'veggie') return VeggieRoutePath.unknown();
      var remaining = uri.pathSegments[1];
      var id = int.tryParse(remaining);
      if (id == null) return VeggieRoutePath.unknown();
      return VeggieRoutePath.details(id);
    }

    // Handle unknown routes
    return VeggieRoutePath.unknown();
  }

  @override
  RouteInformation restoreRouteInformation(VeggieRoutePath path) {
    print("restoreRouteInformation");
    if (path.isUnknown) {
      return RouteInformation(location: '/404');
    }
    if (path.isHomePage) {
      return RouteInformation(location: '/');
    }
    if (path.isDetailsPage) {
      return RouteInformation(location: '/veggie/${path.id}');
    }
    return null;
  }
}

class VeggieRoutePath {
  final int id;
  final bool isUnknown;

  VeggieRoutePath.home()
      : id = null,
        isUnknown = false;

  VeggieRoutePath.details(this.id) : isUnknown = false;

  VeggieRoutePath.unknown()
      : id = null,
        isUnknown = true;

  bool get isHomePage => id == null;

  bool get isDetailsPage => id != null;
}