[State Restoration] Material Dialogs, Cupertino Dialogs, CupertinoTab…

…Scaffold/TabView, CupertinoTextFields (#409)

* Cupertino alert, text field and tab bar demo state restoration

* Make one material dialog restorable

* Finish up state restoration for material dialogs

* Action sheet state restoration, rootNavigator feedback

lib/demos/cupertino/cupertino_tab_bar_demo.dart

@@ -38,6 +38,7 @@ class CupertinoTabBarDemo extends StatelessWidget {
     return DefaultTextStyle(
       style: CupertinoTheme.of(context).textTheme.textStyle,
       child: CupertinoTabScaffold(
+        restorationId: 'cupertino_tab_scaffold',
         tabBar: CupertinoTabBar(
           items: [
             for (final tabInfo in _tabInfo)
@@ -49,6 +50,7 @@ class CupertinoTabBarDemo extends StatelessWidget {
         ),
         tabBuilder: (context, index) {
           return CupertinoTabView(
+            restorationScopeId: 'cupertino_tab_view_$index',
             builder: (context) => _CupertinoDemoTab(
               title: _tabInfo[index].title,
               icon: _tabInfo[index].icon,

lib/demos/cupertino/cupertino_text_field_demo.dart

@@ -20,11 +20,13 @@ class CupertinoTextFieldDemo extends StatelessWidget {
       ),
       child: SafeArea(
         child: ListView(
+          restorationId: 'text_field_demo_list_view',
           padding: const EdgeInsets.all(16),
           children: [
             Padding(
               padding: const EdgeInsets.symmetric(vertical: 8),
               child: CupertinoTextField(
+                restorationId: 'email_address_text_field',
                 placeholder: localizations.demoTextFieldEmail,
                 keyboardType: TextInputType.emailAddress,
                 clearButtonMode: OverlayVisibilityMode.editing,
@@ -34,13 +36,15 @@ class CupertinoTextFieldDemo extends StatelessWidget {
             Padding(
               padding: const EdgeInsets.symmetric(vertical: 8),
               child: CupertinoTextField(
+                restorationId: 'login_password_text_field',
                 placeholder: localizations.rallyLoginPassword,
                 clearButtonMode: OverlayVisibilityMode.editing,
                 obscureText: true,
                 autocorrect: false,
               ),
             ),
             CupertinoTextField(
+              restorationId: 'pin_number_text_field',
               prefix: const Icon(
                 CupertinoIcons.padlock_solid,
                 size: 28,

lib/demos/material/dialog_demo.dart

@@ -10,13 +10,79 @@ import 'package:flutter_gen/gen_l10n/gallery_localizations.dart';
 
 // BEGIN dialogDemo
 
-class DialogDemo extends StatelessWidget {
+class DialogDemo extends StatefulWidget {
   DialogDemo({Key key, @required this.type}) : super(key: key);
 
   final DialogDemoType type;
 
+  @override
+  _DialogDemoState createState() => _DialogDemoState();
+}
+
+class _DialogDemoState extends State<DialogDemo> with RestorationMixin {
+  RestorableRouteFuture<String> _alertDialogRoute;
+  RestorableRouteFuture<String> _alertDialogWithTitleRoute;
+  RestorableRouteFuture<String> _simpleDialogRoute;
+
+  @override
+  String get restorationId => 'dialog_demo';
+
+  @override
+  void restoreState(RestorationBucket oldBucket, bool initialRestore) {
+    registerForRestoration(
+      _alertDialogRoute,
+      'alert_demo_dialog_route',
+    );
+    registerForRestoration(
+      _alertDialogWithTitleRoute,
+      'alert_demo_with_title_dialog_route',
+    );
+    registerForRestoration(
+      _simpleDialogRoute,
+      'simple_dialog_route',
+    );
+  }
+
+  // Displays the popped String value in a snackbar.
+  void _showInSnackBar(String value) {
+    // The value passed to Navigator.pop() or null.
+    if (value != null) {
+      ScaffoldMessenger.of(context).hideCurrentSnackBar();
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(
+            GalleryLocalizations.of(context).dialogSelectedOption(value),
+          ),
+        ),
+      );
+    }
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    _alertDialogRoute = RestorableRouteFuture<String>(
+      onPresent: (navigator, arguments) {
+        return navigator.restorablePush(_alertDialogDemoRoute);
+      },
+      onComplete: _showInSnackBar,
+    );
+    _alertDialogWithTitleRoute = RestorableRouteFuture<String>(
+      onPresent: (navigator, arguments) {
+        return navigator.restorablePush(_alertDialogWithTitleDemoRoute);
+      },
+      onComplete: _showInSnackBar,
+    );
+    _simpleDialogRoute = RestorableRouteFuture<String>(
+      onPresent: (navigator, arguments) {
+        return navigator.restorablePush(_simpleDialogDemoRoute);
+      },
+      onComplete: _showInSnackBar,
+    );
+  }
+
   String _title(BuildContext context) {
-    switch (type) {
+    switch (widget.type) {
       case DialogDemoType.alert:
         return GalleryLocalizations.of(context).demoAlertDialogTitle;
       case DialogDemoType.alertTitle:
@@ -29,101 +95,111 @@ class DialogDemo extends StatelessWidget {
     return '';
   }
 
-  Future<void> _showDemoDialog<T>({BuildContext context, Widget child}) async {
-    child = ApplyTextOptions(
-      child: Theme(
-        data: Theme.of(context),
-        child: child,
-      ),
-    );
-    final value = await showDialog<T>(
-      context: context,
-      builder: (context) => child,
-    );
-    // The value passed to Navigator.pop() or null.
-    if (value != null && value is String) {
-      ScaffoldMessenger.of(context).hideCurrentSnackBar();
-      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
-        content:
-            Text(GalleryLocalizations.of(context).dialogSelectedOption(value)),
-      ));
-    }
-  }
-
-  void _showAlertDialog(BuildContext context) {
+  static Route<String> _alertDialogDemoRoute(
+    BuildContext context,
+    Object arguments,
+  ) {
     final theme = Theme.of(context);
     final dialogTextStyle = theme.textTheme.subtitle1
         .copyWith(color: theme.textTheme.caption.color);
-    _showDemoDialog<String>(
+
+    return DialogRoute<String>(
       context: context,
-      child: AlertDialog(
-        content: Text(
-          GalleryLocalizations.of(context).dialogDiscardTitle,
-          style: dialogTextStyle,
+      builder: (context) => ApplyTextOptions(
+        child: AlertDialog(
+          content: Text(
+            GalleryLocalizations.of(context).dialogDiscardTitle,
+            style: dialogTextStyle,
+          ),
+          actions: [
+            _DialogButton(text: GalleryLocalizations.of(context).dialogCancel),
+            _DialogButton(text: GalleryLocalizations.of(context).dialogDiscard),
+          ],
         ),
-        actions: [
-          _DialogButton(text: GalleryLocalizations.of(context).dialogCancel),
-          _DialogButton(text: GalleryLocalizations.of(context).dialogDiscard),
-        ],
       ),
     );
   }
 
-  void _showAlertDialogWithTitle(BuildContext context) {
+  static Route<String> _alertDialogWithTitleDemoRoute(
+    BuildContext context,
+    Object arguments,
+  ) {
     final theme = Theme.of(context);
     final dialogTextStyle = theme.textTheme.subtitle1
         .copyWith(color: theme.textTheme.caption.color);
-    _showDemoDialog<String>(
+
+    return DialogRoute<String>(
       context: context,
-      child: AlertDialog(
-        title: Text(GalleryLocalizations.of(context).dialogLocationTitle),
-        content: Text(
-          GalleryLocalizations.of(context).dialogLocationDescription,
-          style: dialogTextStyle,
+      builder: (context) => ApplyTextOptions(
+        child: AlertDialog(
+          title: Text(GalleryLocalizations.of(context).dialogLocationTitle),
+          content: Text(
+            GalleryLocalizations.of(context).dialogLocationDescription,
+            style: dialogTextStyle,
+          ),
+          actions: [
+            _DialogButton(
+                text: GalleryLocalizations.of(context).dialogDisagree),
+            _DialogButton(text: GalleryLocalizations.of(context).dialogAgree),
+          ],
         ),
-        actions: [
-          _DialogButton(text: GalleryLocalizations.of(context).dialogDisagree),
-          _DialogButton(text: GalleryLocalizations.of(context).dialogAgree),
-        ],
       ),
     );
   }
 
-  void _showSimpleDialog(BuildContext context) {
+  static Route<String> _simpleDialogDemoRoute(
+    BuildContext context,
+    Object arguments,
+  ) {
     final theme = Theme.of(context);
-    _showDemoDialog<String>(
+
+    return DialogRoute<String>(
       context: context,
-      child: SimpleDialog(
-        title: Text(GalleryLocalizations.of(context).dialogSetBackup),
-        children: [
-          _DialogDemoItem(
-            icon: Icons.account_circle,
-            color: theme.colorScheme.primary,
-            text: 'username@gmail.com',
-          ),
-          _DialogDemoItem(
-            icon: Icons.account_circle,
-            color: theme.colorScheme.secondary,
-            text: 'user02@gmail.com',
-          ),
-          _DialogDemoItem(
-            icon: Icons.add_circle,
-            text: GalleryLocalizations.of(context).dialogAddAccount,
-            color: theme.disabledColor,
-          ),
-        ],
+      builder: (context) => ApplyTextOptions(
+        child: SimpleDialog(
+          title: Text(GalleryLocalizations.of(context).dialogSetBackup),
+          children: [
+            _DialogDemoItem(
+              icon: Icons.account_circle,
+              color: theme.colorScheme.primary,
+              text: 'username@gmail.com',
+            ),
+            _DialogDemoItem(
+              icon: Icons.account_circle,
+              color: theme.colorScheme.secondary,
+              text: 'user02@gmail.com',
+            ),
+            _DialogDemoItem(
+              icon: Icons.add_circle,
+              text: GalleryLocalizations.of(context).dialogAddAccount,
+              color: theme.disabledColor,
+            ),
+          ],
+        ),
       ),
     );
   }
 
+  static Route<void> _fullscreenDialogRoute(
+    BuildContext context,
+    Object arguments,
+  ) {
+    return MaterialPageRoute<void>(
+      builder: (context) => _FullScreenDialogDemo(),
+      fullscreenDialog: true,
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     return Navigator(
       // Adding [ValueKey] to make sure that the widget gets rebuilt when
       // changing type.
-      key: ValueKey(type),
+      key: ValueKey(widget.type),
+      restorationScopeId: 'navigator',
       onGenerateRoute: (settings) {
         return _NoAnimationMaterialPageRoute<void>(
+          settings: settings,
           builder: (context) => Scaffold(
             appBar: AppBar(
               automaticallyImplyLeading: false,
@@ -133,24 +209,19 @@ class DialogDemo extends StatelessWidget {
               child: ElevatedButton(
                 child: Text(GalleryLocalizations.of(context).dialogShow),
                 onPressed: () {
-                  switch (type) {
+                  switch (widget.type) {
                     case DialogDemoType.alert:
-                      _showAlertDialog(context);
+                      _alertDialogRoute.present();
                       break;
                     case DialogDemoType.alertTitle:
-                      _showAlertDialogWithTitle(context);
+                      _alertDialogWithTitleRoute.present();
                       break;
                     case DialogDemoType.simple:
-                      _showSimpleDialog(context);
+                      _simpleDialogRoute.present();
                       break;
                     case DialogDemoType.fullscreen:
-                      Navigator.push<void>(
-                        context,
-                        MaterialPageRoute(
-                          builder: (context) => _FullScreenDialogDemo(),
-                          fullscreenDialog: true,
-                        ),
-                      );
+                      Navigator.restorablePush<void>(
+                          context, _fullscreenDialogRoute);
                       break;
                   }
                 },
@@ -171,14 +242,19 @@ class _NoAnimationMaterialPageRoute<T> extends MaterialPageRoute<T> {
     bool maintainState = true,
     bool fullscreenDialog = false,
   }) : super(
-            builder: builder,
-            maintainState: maintainState,
-            settings: settings,
-            fullscreenDialog: fullscreenDialog);
+          builder: builder,
+          maintainState: maintainState,
+          settings: settings,
+          fullscreenDialog: fullscreenDialog,
+        );
 
   @override
-  Widget buildTransitions(BuildContext context, Animation<double> animation,
-      Animation<double> secondaryAnimation, Widget child) {
+  Widget buildTransitions(
+    BuildContext context,
+    Animation<double> animation,
+    Animation<double> secondaryAnimation,
+    Widget child,
+  ) {
     return child;
   }
 }
@@ -193,7 +269,7 @@ class _DialogButton extends StatelessWidget {
     return TextButton(
       child: Text(text),
       onPressed: () {
-        Navigator.of(context, rootNavigator: true).pop(text);
+        Navigator.of(context).pop(text);
       },
     );
   }
@@ -215,7 +291,7 @@ class _DialogDemoItem extends StatelessWidget {
   Widget build(BuildContext context) {
     return SimpleDialogOption(
       onPressed: () {
-        Navigator.of(context, rootNavigator: true).pop(text);
+        Navigator.of(context).pop(text);
       },
       child: Row(
         mainAxisAlignment: MainAxisAlignment.start,