Nested navigator tabs

Easy to use and highly configurable nested navigator with named routes and custom BottomBar support. It is not limited to MaterialPageRoute and you are not forced to use the default BottomNavigationBar.

Route aware events for the tabs

The multiple navigation stack is implemented by using Navigators inside an IndexedStack. Only the selected tab's navigator is visible but all of them are active, so implementing a route observer won't work for tracking tabs. To overcome this, a fake(empty) page is pushed to the not visible navigators and popped on the active one. When the main tab page isn't visible the empty route is pushed to all of the inner stacks.

Getting Started

dependencies:
  nested_navigator_tabs: ^0.2.0

Usage

For basic usage you have to specify the tabs and the generator (Routes.generateRoute()) method:

class TabPage extends StatelessWidget {
  const TabPage({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return NestedNavigatorTabs(
      generator: generateRoute,
      tabs: [
        NavigatorTab(
            defaultRouteName: "page1",
            navItem: BottomNavigationBarItem(
                icon: Icon(Icons.mail_outline),
                activeIcon: Icon(Icons.mail),
                title: Text("Mail"))),
        NavigatorTab(
            defaultRouteName: "page2",
            navItem: BottomNavigationBarItem(
                icon: Icon(Icons.person_outline),
                activeIcon: Icon(Icons.person),
                title: Text("Person"))),
      ],
    );
  }
}

For proper route detection (Route aware events) inside the tabs, a route observer of the root navigator is needed. You have to create a RouteObserver and register as a navigatorObserver. Then use the RouteObserverProvider widget to make it accessible through the Context.

final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>();

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      navigatorObservers: [routeObserver],
      builder: (context, child) => RouteObserverProvider(routeObserver: routeObserver, child: child,),
      initialRoute: '/',
      onGenerateRoute: generateRoute,
    );
  }
}

The route observer can be obtained through the context by calling:

    RouteObserver<PageRoute> routeObserver = RouteObserverProvider.of(context).routeObserver;

To track the visibility of a page, there is a VisibilityObserver widget:

VisibilityObserver(
    onVisible: (fromPop) {
        //fromPop is false if this page was pushed
    },
    onInvisible: (isPopped) {
      // true if the back has been pressed and the page is being popped and false if a new route has been pushed over this
    },
    child:...
)

Other properties

clearStackOnDoubleTap

Clears the current navigator if you tap on the selected tab(default: true)

popNestedRouteOnBack

Automatically handles the back events and pops the current nested route(default: true)

initialTab

Defines the default tab(default: 0)

backMode

Defines the backstack strategy and switches between the tabs according to it.

• stayOnTab: never switches tabs
• switchTabWhenEmpty: switches to the previously visited tab when the current navigator's stack is empty
• globalStack: goes back and switches between the tabs as they were visited.

onGlobalStackChanged

Get notified when the current tab or any route changes

void Function({@required int tab, @required String routeName, @required StackEvent type}) onGlobalStackChanged;

Advanced usage

bottomBarBuilder

You can specify your own bottom bar instead of the default BottomNavigationBar:

 Widget Function(
      BuildContext context,
      List<BottomNavigationBarItem> navItems,
      int selectedIndex,
      Function(int) onIndexSelected) bottomBarBuilder;

layoutBuilder

It is possible to re-implement the whole layout including the Scaffold.

Widget Function(BuildContext context, IndexedStack container,
      Widget bottomBar, int currentIndex) layoutBuilder;

The container holds the nested Navigators. The bottomBar is the widget built by the bottomBarBuilder.

Static methods

NestedNavigatorTabs.of(BuildContext context, bool isNullOk)

You can access to the whole navigator state. If no state found in the provided context it can return null or throw and exception.

NestedNavigatorTabs.switchTabTo(BuildContext context,int tabIndex)

Selects the tab with the given index.

NestedNavigatorTabs.navigateTo(BuildContext context,int tabIndex, Route route)

You can push any kind of route to the tabIndex tab (or to the current tab if null)

NestedNavigatorTabs.tabNavigatorOf(BuildContext context,int tabIndex, bool setToCurrent)

Gets the nested Navigator of the tabIndex tab and switches to that tab if setToCurrent is true

NestedNavigatorTabs.back(BuildContext context)

Use this instead of Navigator.of(context).back() when you want to follow the globalStack navigation. (For example when a page from the first tab is pushed to the second tab, the Navigator's back just pops the new page but doesn't switch back to the first tab.)