gg_router 1.0.1

Create nested routes in Flutter. Sync app state and browser URL. Navigate absolutely and relatively. Animate route transitions. Save and restore application state. Manage URI query parameters.

example/lib/main.dart

// @license
// Copyright (c) 2019 - 2021 Dr. Gabriel Gatzsche. All Rights Reserved.
//
// Use of this source code is governed by terms that can be
// found in the LICENSE file in the root of this package.

import 'dart:async';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:gg_router/gg_router.dart';
import 'package:gg_value/gg_value.dart';
import 'package:shared_preferences/shared_preferences.dart';

import 'configure_nonweb.dart' if (dart.library.html) 'configure_web.dart';

void main() {
  configureApp();
  runApp(GgRouterExample());
}

const debugShowCheckedModeBanner = false;

// .............................................................................
class GgRouterExample extends StatelessWidget {
  GgRouterExample({Key? key}) : super(key: key);

  // ...........................................................................
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      title: "GgRouterExample",
      routerDelegate: GgRouterDelegate(
        child: _appContent,
        saveState: _saveState,
        restoreState: _restoreState,
        defaultRoute: '/sports/basketball',
      ),
      routeInformationParser: GgRouteInformationParser(),
      themeMode: ThemeMode.dark,
      darkTheme: ThemeData(brightness: Brightness.dark),
      theme: ThemeData(brightness: Brightness.light),
      debugShowCheckedModeBanner: debugShowCheckedModeBanner,
    );
  }

  // ...........................................................................
  Widget get _appContent {
    return Scaffold(
      appBar: AppBar(
        title: Text('GgRouter'),
        actions: <Widget>[
          _routeButton('Sports', 'sports'),
          _routeButton('Transportation', 'transportation'),
          _routeButton('Places', 'places'),
          Container(
            width: debugShowCheckedModeBanner ? 50 : 0,
          ),
        ],
      ),
      body: Builder(
        builder: (context) {
          _initErrorHandler(context);
          return GgRouter(
            {
              '_INDEX_': _indexPage,
              'sports': _sportsPage,
              'transportation': _transportationPage,
              'places': _placesPage,
              '*': _wildCardPage,
            },
            key: ValueKey('mainRouter'),
            inAnimation: _zoomIn,
            outAnimation: _zoomOut,
          );
        },
      ),
    );
  }

  // ...........................................................................
  _initErrorHandler(BuildContext context) {
    final node = GgRouter.of(context).node;
    node.errorHandler = null;
    node.errorHandler = (error) {
      final snackBar = SnackBar(
        content: Text(error.message),
        duration: Duration(seconds: 6),
        backgroundColor: Colors.red,
      );

      scheduleMicrotask(
          () => ScaffoldMessenger.of(context).showSnackBar(snackBar));
    };
  }

  // ...........................................................................
  Widget _text(String text, BuildContext context, bool isStaged) {
    final theme = Theme.of(context);
    final onPrimary = theme.colorScheme.onPrimary;
    final onPrimaryInactive = onPrimary.withAlpha(120);
    return Padding(
      padding: EdgeInsets.fromLTRB(20, 0, 20, 0),
      child: Text(
        text,
        style: TextStyle(color: isStaged ? onPrimary : onPrimaryInactive),
      ),
    );
  }

  // ...........................................................................
  Widget _bigIcon(BuildContext context, IconData icon) {
    return Center(
      child: Icon(
        icon,
        size: 200,
        color: Color(0x33FFFFFF),
      ),
    );
  }

  // ...........................................................................
  Widget _routeButton(String title, String route) {
    return Builder(builder: (context) {
      final router = GgRouter.of(context);

      return StreamBuilder(
        stream: router.onActiveChildChange,
        builder: (context, snapshot) {
          final isStaged = router.routeNameOfActiveChild == route;
          return TextButton(
            key: ValueKey(route),
            onPressed: () => router.navigateTo('$route/_LAST_'),
            child: _text(title, context, isStaged),
          );
        },
      );
    });
  }

  // ...........................................................................
  Widget _dialog(BuildContext context) {
    return Dialog(
      child: Stack(
        children: [
          Align(
            alignment: Alignment.topRight,
            child: IconButton(
              key: ValueKey('dialogCloseButton'),
              icon: Icon(Icons.close),
              onPressed: () {
                GgRouter.of(context).navigateTo('..');
              },
            ),
          ),
          Center(
            child: Column(
              children: [
                Expanded(child: Container()),
                _checkBox(context),
                Expanded(child: Container()),
              ],
            ),
          ),
        ],
      ),
    );
  }

  // ...........................................................................
  Widget _checkBox(BuildContext context) {
    final GgValue param = GgRouter.of(context).param('visit')!;

    return Row(children: [
      Expanded(child: Container()),
      SizedBox(
        width: 200,
        height: 50,
        child: Container(
          color: Color(0x11FFFFFF),
          child: StreamBuilder(
            stream: param.stream,
            builder: (context, snapshot) {
              return CheckboxListTile(
                title: Text("Visit Event"),
                value: param.value,
                onChanged: (newValue) => param.value = newValue as bool,
              );
            },
          ),
        ),
      ),
      Expanded(child: Container()),
    ]);
  }

  // ...........................................................................
  Widget _indexPage(BuildContext context) {
    return Center(
      key: ValueKey('indexPage'),
      child: Text(
        'GgRouter',
        style: Theme.of(context).textTheme.headline2,
      ),
    );
  }

  // ...........................................................................
  Widget _wildCardPage(BuildContext context) {
    final routeName = GgRouter.of(context).routeName;

    return Center(
      key: ValueKey('wildCardPage'),
      child: Text(
        'Wildcard: $routeName',
        key: ValueKey('WildCardText: $routeName'),
        style: Theme.of(context).textTheme.headline2,
      ),
    );
  }

  // ...........................................................................
  Widget _sportsPage(BuildContext context) {
    final router = GgRouter.of(context);

    return Scaffold(
      key: ValueKey('sportsPage'),
      bottomNavigationBar: StreamBuilder(
          stream: router.onActiveChildChange,
          builder: (context, snapshot) {
            final index = router.indexOfActiveChild ?? 0;

            return BottomNavigationBar(
              currentIndex: index,
              items: [
                BottomNavigationBarItem(
                  label: 'Basketball',
                  icon: Icon(Icons.sports_basketball),
                ),
                BottomNavigationBarItem(
                  label: 'Football',
                  icon: Icon(Icons.sports_football),
                ),
                BottomNavigationBarItem(
                  label: 'Handball',
                  icon: Icon(Icons.sports_handball),
                ),
              ],
              onTap: (index) {
                switch (index) {
                  case 0:
                    router.navigateTo('basketball/_LAST_');
                    break;
                  case 1:
                    router.navigateTo('football/_LAST_');
                    break;
                  case 2:
                    router.navigateTo('handball/_LAST_');
                    break;
                }
              },
            );
          }),
      body: GgRouter(
        {
          'basketball': (context) {
            return GgRouteParams(
              params: {
                'visit': GgRouteParam<bool>(seed: false),
              },
              child: GgPopoverRoute(
                key: ValueKey('dialog'),
                name: 'popover',
                base: Listener(
                  child: _bigIcon(context, Icons.sports_basketball),
                  onPointerUp: (_) =>
                      GgRouter.of(context).navigateTo('./popover'),
                ),
                popover: _dialog,
                inAnimation: _rotateIn,
                outAnimation: _rotateOut,
              ),
            );
          },
          'football': (c) => _bigIcon(c, Icons.sports_football),
          'handball': (c) => _bigIcon(c, Icons.sports_handball),
        },
        key: ValueKey('sportsRouter'),
        defaultRoute: 'basketball',
        inAnimation: _moveIn,
        outAnimation: _moveOut,
      ),
    );
  }

  // ...........................................................................
  Widget _transportationPage(BuildContext context) {
    final router = GgRouter.of(context);

    return Scaffold(
      key: ValueKey('transportationPage'),
      bottomNavigationBar: StreamBuilder(
          stream: router.onActiveChildChange,
          builder: (context, snapshot) {
            final index = router.indexOfActiveChild ?? 0;

            return BottomNavigationBar(
              currentIndex: index,
              items: [
                BottomNavigationBarItem(
                  label: 'Bus',
                  icon: Icon(Icons.directions_bus),
                ),
                BottomNavigationBarItem(
                  label: 'Bike',
                  icon: Icon(Icons.directions_bike),
                ),
                BottomNavigationBarItem(
                  label: 'Car',
                  icon: Icon(Icons.directions_car),
                ),
              ],
              onTap: (index) {
                switch (index) {
                  case 0:
                    router.navigateTo('bus');
                    break;
                  case 1:
                    router.navigateTo('bike');
                    break;
                  case 2:
                    router.navigateTo('car');
                    break;
                }
              },
            );
          }),
      body: GgRouter(
        {
          'bus': (c) => _bigIcon(c, Icons.directions_bus),
          'bike': (c) => _bigIcon(c, Icons.directions_bike),
          'car': (c) => _bigIcon(c, Icons.directions_car),
        },
        key: ValueKey('/transportation'),
        defaultRoute: 'bus',
        inAnimation: _moveIn,
        outAnimation: _moveOut,
      ),
    );
  }

// ...........................................................................
  Widget _placesPage(BuildContext context) {
    final router = GgRouter.of(context);
    // return Container(color: Colors.green);

    return Scaffold(
      bottomNavigationBar: StreamBuilder(
          key: ValueKey('placesPage'),
          stream: router.onActiveChildChange,
          builder: (context, snapshot) {
            final index = router.indexOfActiveChild ?? 0;

            return BottomNavigationBar(
              currentIndex: index,
              items: [
                BottomNavigationBarItem(
                  label: 'Airpot',
                  icon: Icon(Icons.airplanemode_active),
                ),
                BottomNavigationBarItem(
                  label: 'Park',
                  icon: Icon(Icons.park),
                ),
                BottomNavigationBarItem(
                  label: 'Hospital',
                  icon: Icon(Icons.local_hospital),
                ),
              ],
              onTap: (index) {
                switch (index) {
                  case 0:
                    router.navigateTo('airport');
                    break;
                  case 1:
                    router.navigateTo('park');
                    break;
                  case 2:
                    router.navigateTo('hospital');
                    break;
                }
              },
            );
          }),
      body: GgRouter(
        {
          'airport': (c) => _bigIcon(c, Icons.airplanemode_active),
          'park': (c) => _bigIcon(c, Icons.park),
          'hospital': (c) => _bigIcon(c, Icons.local_hospital),
        },
        key: ValueKey('/places'),
        defaultRoute: 'airport',
        inAnimation: _moveIn,
        outAnimation: _moveOut,
      ),
    );
  }

  // ...........................................................................
  _saveState(String state) async {
    (await (SharedPreferences.getInstance()))
        .setString('lastApplicationState', state);
  }

  // ...........................................................................
  Future<String?> _restoreState() async {
    final result = (await (SharedPreferences.getInstance()))
        .getString('lastApplicationState');
    return result;
  }

  // ...........................................................................
  Widget _zoomOut(
    BuildContext context,
    Animation animation,
    Widget child,
  ) {
    // In the first part of the animation the old widget is faded out
    final scale = animation.value < 0.5
        ? Curves.easeInOut.transform(1.0 - (animation.value * 2.0))
        : 0.0;

    return Transform.scale(
      scale: scale,
      child: child,
    );
  }

  // ...........................................................................
  Widget _zoomIn(
    BuildContext context,
    Animation animation,
    Widget child,
  ) {
    // In the second part of the animation the new widget is faded in
    final scale = animation.value >= 0.5
        ? Curves.easeInOut.transform(((animation.value - 0.5) * 2.0))
        : 0.0;

    return Transform.scale(
      scale: scale,
      child: child,
    );
  }

  // ...........................................................................
  Widget _moveIn(
    BuildContext context,
    Animation animation,
    Widget child,
  ) {
    final w = MediaQuery.of(context).size.width;
    final h = MediaQuery.of(context).size.height;
    final index = GgRouter.of(context).indexOfChildAnimatingIn;

    final fromLeft = Offset(-w * (1.0 - animation.value), 0);
    final fromBottom = Offset(0, h * (1.0 - animation.value));
    final fromRight = Offset(w * (1.0 - animation.value), 0);

    Offset offset = index == 0
        ? fromLeft
        : index == 1
            ? fromBottom
            : fromRight;

    return Transform.translate(
      offset: offset,
      child: child,
    );
  }

  // ...........................................................................
  Widget _moveOut(
    BuildContext context,
    Animation animation,
    Widget child,
  ) {
    final w = MediaQuery.of(context).size.width;
    final h = MediaQuery.of(context).size.height;
    final index = GgRouter.of(context).indexOfChildAnimatingOut;

    final toRight = Offset(w * (animation.value), 0);
    final toBottom = Offset(0, h * (animation.value));
    final toLeft = Offset(w * (-animation.value), 0);

    Offset offset = index == 0
        ? toLeft
        : index == 1
            ? toBottom
            : toRight;

    return Transform.translate(
      offset: offset,
      child: child,
    );
  }

  // ...........................................................................
  Widget _rotateIn(
    BuildContext context,
    Animation animation,
    Widget child,
  ) {
    final scale = animation.value;
    final angle = 2 * pi * animation.value;
    final fade = animation.value;

    return Transform.scale(
      scale: scale,
      child: Transform.rotate(
        angle: angle,
        child: Opacity(
          opacity: fade,
          child: child,
        ),
      ),
    );
  }

  // ...........................................................................
  Widget _rotateOut(
    BuildContext context,
    Animation animation,
    Widget child,
  ) {
    final scale = 1.0 - animation.value;
    final angle = -2 * pi * animation.value;
    final fade = 1.0 - animation.value;

    return Transform.scale(
      scale: scale,
      child: Transform.rotate(
        angle: angle,
        child: Opacity(
          opacity: fade,
          child: child,
        ),
      ),
    );
  }
}