Make the checkbox in settings control the radio buttons in the drawer, to demonstrate how to link state in different places in an app.

R=jackson@google.com

Review URL: https://codereview.chromium.org/1197333002.

examples/stocks2/lib/stock_app.dart

@@ -13,22 +13,45 @@ import 'package:sky/widgets/widget.dart';
 import 'stock_data.dart';
 import 'stock_home.dart';
 import 'stock_settings.dart';
+import 'stock_types.dart';
 
 class StocksApp extends App {
 
+  NavigationState _navigationState;
   StocksApp() {
     _navigationState = new NavigationState([
       new Route(
         name: '/', 
-        builder: (navigator, route) => new StockHome(navigator, route, _stocks)
+        builder: (navigator, route) => new StockHome(navigator, _stocks, stockMode, modeUpdater)
       ),
       new Route(
         name: '/settings',
-        builder: (navigator, route) => new StockSettings(navigator)
+        builder: (navigator, route) => new StockSettings(navigator, stockMode, settingsUpdater)
       ),
     ]);
   }
 
+  void onBack() {
+    setState(() {
+      _navigationState.pop();
+    });
+    // TODO(jackson): Need a way to invoke default back behavior here
+  }
+
+  StockMode stockMode = StockMode.optimistic;
+  void modeUpdater(StockMode value) {
+    setState(() {
+      stockMode = value;
+    });
+  }
+  void settingsUpdater({StockMode mode}) {
+    setState(() {
+      if (mode != null)
+        stockMode = mode;
+    });
+  }
+
+  final List<Stock> _stocks = [];
   void didMount() {
     super.didMount();
     new StockDataFetcher((StockData data) {
@@ -38,16 +61,6 @@ class StocksApp extends App {
     });
   }
 
-  final List<Stock> _stocks = [];
-  NavigationState _navigationState;
-
-  void onBack() {
-    setState(() {
-      _navigationState.pop();
-    });
-    // TODO(jackson): Need a way to invoke default back behavior here
-  }
-
   Widget build() {
     return new Theme(
       data: new ThemeData.light(

examples/stocks2/lib/stock_home.dart

@@ -23,25 +23,30 @@ import 'package:sky/widgets/widget.dart';
 import 'stock_data.dart';
 import 'stock_list.dart';
 import 'stock_menu.dart';
+import 'stock_types.dart';
 
-enum StockMode { optimistic, pessimistic }
+typedef void ModeUpdater(StockMode mode);
 
 class StockHome extends Component {
 
-  StockHome(this.navigator, RouteBase route, this.stocks) : super(stateful: true) {
+  StockHome(this.navigator, this.stocks, this.stockMode, this.modeUpdater) : super(stateful: true) {
     // if (debug)
     //   new Timer(new Duration(seconds: 1), dumpState);
     _drawerController = new DrawerController(_handleDrawerStatusChanged);
   }
 
+  Navigator navigator;
+  List<Stock> stocks;
+  StockMode stockMode;
+  ModeUpdater modeUpdater;
+
   void syncFields(StockHome source) {
     navigator = source.navigator;
     stocks = source.stocks;
+    stockMode = source.stockMode;
+    modeUpdater = source.modeUpdater;
   }
 
-  Navigator navigator;
-  List<Stock> stocks;
-
   bool _isSearching = false;
   String _searchQuery;
 
@@ -102,11 +107,12 @@ class StockHome extends Component {
     });
   }
 
-  StockMode _stockMode = StockMode.optimistic;
   void _handleStockModeChange(StockMode value) {
     setState(() {
-      _stockMode = value;
+      stockMode = value;
     });
+    if (modeUpdater != null)
+      modeUpdater(value);
   }
 
   Drawer buildDrawer() {
@@ -127,14 +133,14 @@ class StockHome extends Component {
           onPressed: () => _handleStockModeChange(StockMode.optimistic),
           children: [
             new Flexible(child: new Text('Optimistic')),
-            new Radio(value: StockMode.optimistic, groupValue: _stockMode, onChanged: _handleStockModeChange)
+            new Radio(value: StockMode.optimistic, groupValue: stockMode, onChanged: _handleStockModeChange)
           ]),
         new MenuItem(
           icon: 'action/thumb_down',
           onPressed: () => _handleStockModeChange(StockMode.pessimistic),
           children: [
             new Flexible(child: new Text('Pessimistic')),
-            new Radio(value: StockMode.pessimistic, groupValue: _stockMode, onChanged: _handleStockModeChange)
+            new Radio(value: StockMode.pessimistic, groupValue: stockMode, onChanged: _handleStockModeChange)
           ]),
         new MenuDivider(),
         new MenuItem(

examples/stocks2/lib/stock_settings.dart

@@ -12,24 +12,43 @@ import 'package:sky/widgets/scaffold.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 
+import 'stock_types.dart';
+
+typedef void SettingsUpdater({StockMode mode});
+
 class StockSettings extends Component {
 
-  StockSettings(this._navigator);
+  StockSettings(this.navigator, this.stockMode, this.updater) : super(stateful: true);
 
-  Navigator _navigator;
+  Navigator navigator;
+  StockMode stockMode;
+  SettingsUpdater updater;
 
-  bool _awesome = false;
-  void _handleAwesomeChanged(bool value) {
+  void syncFields(StockSettings source) {
+    navigator = source.navigator;
+    stockMode = source.stockMode;
+    updater = source.updater;
+  }
+
+  void _handleStockModeChanged(bool value) {
     setState(() {
-      _awesome = value;
+      stockMode = value ? StockMode.optimistic : StockMode.pessimistic;
     });
+    sendUpdates();
+  }
+
+  void sendUpdates() {
+    if (updater != null)
+      updater(
+        mode: stockMode
+      );
   }
 
   Widget buildToolBar() {
     return new ToolBar(
       left: new IconButton(
         icon: 'navigation/arrow_back_white',
-        onPressed: _navigator.pop),
+        onPressed: navigator.pop),
       center: new Text('Settings', style: Theme.of(this).text.title)
     );
   }
@@ -41,10 +60,10 @@ class StockSettings extends Component {
       child: new Block([
         new MenuItem(
           icon: 'action/thumb_up',
-          onPressed: () => _handleAwesomeChanged(!_awesome),
+          onPressed: () => _handleStockModeChanged(stockMode == StockMode.optimistic ? false : true),
           children: [
             new Flexible(child: new Text('Everything is awesome')),
-            new Checkbox(value: _awesome, onChanged: _handleAwesomeChanged)
+            new Checkbox(value: stockMode == StockMode.optimistic, onChanged: _handleStockModeChanged)
           ]
         ),
       ])

examples/stocks2/lib/stock_types.dart

@@ -0,0 +1 @@
+enum StockMode { optimistic, pessimistic }