Create ex11-7

ch11/ex11-7

@@ -0,0 +1,140 @@
+# Adding Page Navigation with Routes (Declarative)
+
+```dart
+import 'package:flutter/material.dart';
+
+void main() => runApp(const MyApp());
+
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Code Sample for Navigator',
+      // MaterialApp contains our top-level Navigator
+      initialRoute: '/signup',
+      routes: <String, WidgetBuilder>{
+        '/': (BuildContext context) => const HomePage(),
+        '/signup': (BuildContext context) => const SignUpPage(),
+      },
+    );
+  }
+}
+
+class HomePage extends StatelessWidget {
+  const HomePage({super.key});
+  @override
+  Widget build(BuildContext context) {
+    return DefaultTextStyle(
+      style: Theme.of(context).textTheme.headline4!,
+      child: Container(
+        color: Colors.white,
+        alignment: Alignment.center,
+        child: const Text('Home Page'),
+      ),
+    );
+  }
+}
+
+class SignUpPage extends StatelessWidget {
+  const SignUpPage({super.key});
+  @override
+  Widget build(BuildContext context) {
+    // SignUpPage builds its own Navigator, which ends up being a nested
+    // Navigator in our app.
+    return Navigator(
+      initialRoute: 'signup/personal_info',
+      onGenerateRoute: (RouteSettings settings) {
+        WidgetBuilder builder;
+        switch (settings.name) {
+          case 'signup/personal_info':
+            // Assume CollectPersonalInfoPage collects personal info and then
+            // navigates to 'signup/choose_credentials'.
+            builder = (BuildContext context) => const CollectPersonalInfoPage();
+            break;
+          case 'signup/choose_credentials':
+            // Assume ChooseCredentialsPage collects new credentials and then
+            // invokes 'onSignupComplete()'.
+            builder = (BuildContext _) => ChooseCredentialsPage(
+                  onSignupComplete: () {
+                    // Referencing Navigator.of(context) from here refers to the
+                    // top-level Navigator because SignUpPage is above the
+                    // nested Navigator that it created. Therefore, this pop()
+                    // will pop the entire "sign-up" journey and return to the
+                    // "" route, AKA HomePage.
+                    Navigator.of(context).pop();
+                  },
+                );
+            break;
+          default:
+            throw Exception('Invalid route: ${settings.name}');
+        }
+        return MaterialPageRoute<void>(builder: builder, settings: settings);
+      },
+    );
+  }
+}
+
+class ChooseCredentialsPage extends StatelessWidget {
+  const ChooseCredentialsPage({
+    super.key,
+    required this.onSignupComplete,
+  });
+  final VoidCallback onSignupComplete;
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: onSignupComplete,
+      child: DefaultTextStyle(
+        style: Theme.of(context).textTheme.headline4!,
+        child: Container(
+          color: Colors.pinkAccent,
+          alignment: Alignment.center,
+          child: const Text('Choose Credentials Page'),
+        ),
+      ),
+    );
+  }
+}
+
+class CollectPersonalInfoPage extends StatelessWidget {
+  const CollectPersonalInfoPage({super.key});
+  @override
+  Widget build(BuildContext context) {
+    return DefaultTextStyle(
+      style: Theme.of(context).textTheme.headline4!,
+      child: Container(
+        color: Colors.white,
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            const Text(
+              "Name: Max, Address: Fury Road",
+              style: TextStyle(fontSize: 20, color: Colors.black87),
+            ),
+            const SizedBox(height: 10.0),
+            GestureDetector(
+              onTap: () {
+                // This moves from the personal info page to the credentials page,
+                // replacing this page with that one.
+                Navigator.of(context)
+                    .pushReplacementNamed('signup/choose_credentials');
+              },
+              child: const SizedBox(
+                child: Text(
+                  'Link: Page',
+                  style: TextStyle(
+                      fontSize: 20,
+                      color: Colors.blue,
+                      decoration: TextDecoration.underline),
+                ),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+```