Support Nested Navigator Back Button

Author: dangngocduc

lib/pages/authorization/authorization_navigation.dart

@@ -1,5 +1,6 @@
 import 'dart:developer' as developer;
 import 'package:cubit_app_flow/pages/authorization/sign_in/sign_in_page.dart';
+import 'package:cubit_app_flow/utils/navigator/navigator_support.dart';
 import 'package:flutter/material.dart';
 
 class AuthorizationNavigation extends StatefulWidget {
@@ -12,7 +13,7 @@ class _AuthorizationNavigationState extends State<AuthorizationNavigation> {
   static const TAG = 'AuthorizationNavigation';
   @override
   Widget build(BuildContext context) {
-    return Navigator(
+    return NavigatorSupport(
       initialRoute: SignInPage.ROUTE_NAME,
       onGenerateRoute: (settings) {
         switch(settings.name) {

lib/pages/authorized/authorized_navigation.dart

@@ -1,6 +1,7 @@
 import 'dart:developer' as developer;
 import 'package:cubit_app_flow/pages/authorized/home/home_page.dart';
 import 'package:cubit_app_flow/pages/authorized/profile/profile_edit_page.dart';
+import 'package:cubit_app_flow/utils/navigator/navigator_support.dart';
 import 'package:flutter/material.dart';
 
 import 'module1/module1_navigation.dart';
@@ -16,7 +17,7 @@ class _AuthorizedNavigationState extends State<AuthorizedNavigation> {
   GlobalKey<NavigatorState> navigationKey = GlobalKey(debugLabel: 'AuthorizedNavigation');
   @override
   Widget build(BuildContext context) {
-    return Navigator(
+    return NavigatorSupport(
       key: navigationKey,
       initialRoute: HomePage.ROUTE_NAME,
       onGenerateRoute: (settings) {
@@ -28,7 +29,7 @@ class _AuthorizedNavigationState extends State<AuthorizedNavigation> {
             );
           case Module1Navigation.ROUTE_NAME:
             return MaterialPageRoute(
-                builder: (context) => Module1Navigation(navigationKey),
+                builder: (context) => Module1Navigation(),
                 settings: settings
             );
           default:

lib/pages/authorized/module1/module1_navigation.dart

@@ -1,12 +1,10 @@
 import 'dart:developer' as developer;
 import 'package:cubit_app_flow/pages/authorized/module1/root_module1_page.dart';
+import 'package:cubit_app_flow/utils/navigator/navigator_support.dart';
 import 'package:flutter/material.dart';
 
 class Module1Navigation extends StatefulWidget {
   static const ROUTE_NAME = 'Module1Navigation';
-  final GlobalKey<NavigatorState> parentNavigation;
-
-  Module1Navigation(this.parentNavigation);
 
   @override
   _Module1NavigationState createState() => _Module1NavigationState();
@@ -16,17 +14,13 @@ class _Module1NavigationState extends State<Module1Navigation> {
   static const TAG = 'Module1Navigation';
   @override
   Widget build(BuildContext context) {
-    return Navigator(
+    return NavigatorSupport(
       initialRoute: RootModule1Page.ROUTE_NAME,
       onGenerateRoute: (settings) {
         switch(settings.name) {
           default:
             return MaterialPageRoute(
-                builder: (context) => RootModule1Page(
-                    () {
-                      widget.parentNavigation.currentState?.pop();
-                    }
-                ),
+                builder: (context) => RootModule1Page(),
             );
         }
       },

lib/pages/authorized/module1/root_module1_page.dart

@@ -1,11 +1,10 @@
 import 'dart:developer' as developer;
+import 'package:cubit_app_flow/utils/navigator/navigator_support.dart';
 import 'package:flutter/material.dart';
 
 class RootModule1Page extends StatefulWidget {
   static const ROUTE_NAME = 'RootModule1Page';
-  final VoidCallback onBackRoot;
-
-  RootModule1Page(this.onBackRoot);
+  RootModule1Page();
 
   @override
   _RootModule1PageState createState() => _RootModule1PageState();
@@ -18,7 +17,9 @@ class _RootModule1PageState extends State<RootModule1Page> {
     return Scaffold(
       appBar: AppBar(
         leading: BackButton(
-          onPressed: widget.onBackRoot,
+          onPressed: () {
+            NavigatorSupport.of(context).parent.pop();
+          },
         ),
         title: Text('Root Module1 Page'),
       ),

lib/utils/navigator/navigator_support.dart

@@ -0,0 +1,87 @@
+import 'package:flutter/material.dart';
+
+/// Support Nested Navigation Back Android
+class NavigatorSupport extends StatefulWidget {
+  static const ROUTE_NAME = 'NavigatorSupport';
+
+  final List<Page<dynamic>> pages;
+  final PopPageCallback onPopPage;
+  final String initialRoute;
+  final RouteFactory onGenerateRoute;
+  final RouteFactory onUnknownRoute;
+  final List<NavigatorObserver> observers;
+  static const String defaultRouteName = '/';
+  final RouteListFactory onGenerateInitialRoutes;
+  final TransitionDelegate<dynamic> transitionDelegate;
+
+  NavigatorSupport({
+    Key key,
+    this.pages = const <Page<dynamic>>[],
+    this.onPopPage,
+    this.initialRoute,
+    this.onGenerateInitialRoutes = Navigator.defaultGenerateInitialRoutes,
+    this.onGenerateRoute,
+    this.onUnknownRoute,
+    this.transitionDelegate = const DefaultTransitionDelegate<dynamic>(),
+    this.observers = const <NavigatorObserver>[],
+  }): super(key: key);
+
+  @override
+  NavigatorSupportState createState() => NavigatorSupportState();
+
+  static NavigatorSupportState of(
+      BuildContext context) {
+    // Handles the case where the input context is a navigator element.
+    NavigatorSupportState navigator;
+    if (context is StatefulElement && context.state is NavigatorSupportState) {
+      navigator = context.state as NavigatorSupportState;
+    }
+    navigator = navigator ?? context.findAncestorStateOfType<NavigatorSupportState>();
+    return navigator;
+  }
+
+}
+
+class NavigatorSupportState extends State<NavigatorSupport> {
+  static const TAG = 'NavigatorSupport';
+  GlobalKey<NavigatorState> navigatorKey = GlobalKey();
+
+  NavigatorState _parentNavigator;
+
+  NavigatorState get parent =>  _parentNavigator;
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    if (_parentNavigator != Navigator.of(context)) {
+      _parentNavigator = Navigator.of(context);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return WillPopScope(
+        child: Navigator(
+          pages: widget.pages,
+          key: navigatorKey,
+          onGenerateRoute: widget.onGenerateRoute,
+          initialRoute: widget.initialRoute,
+          transitionDelegate: widget.transitionDelegate,
+          observers: [],
+          onGenerateInitialRoutes: widget.onGenerateInitialRoutes,
+          onPopPage: widget.onPopPage,
+          onUnknownRoute: widget.onUnknownRoute,
+        ),
+        onWillPop: () async {
+          if (navigatorKey.currentState.canPop()) {
+            navigatorKey.currentState.pop();
+            return false;
+          } else {
+            return true;
+          }
+        },
+    );
+  }
+}
+
+