Settings menu item in stock2 doesn't work

The underlying problem is that we lacked a RenderObjectWrapper for the
RenderView, which meant we couldn't handle changing the RenderObject that was
the root of the RenderView. This CL introduces a RenderViewWrapper and uses it
in a new AppContainer widget root. This change allows us to make App a
non-magical Component that is inserted into the AppContainer in the newly
introduced runApp function.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1184823006.

examples/game/main.dart

@@ -23,7 +23,7 @@ void main() {
 
 void allLoaded(ImageMap loader) {
   _loader = loader;
-  new GameDemoApp();
+  runApp(new GameDemoApp());
 }
 
 class GameDemoApp extends App {

examples/stocks2/lib/stock_app.dart

@@ -12,8 +12,6 @@ import 'stock_settings.dart';
 
 class StocksApp extends App {
 
-  StocksApp({ RenderView renderViewOverride }) : super(renderViewOverride: renderViewOverride);
-
   NavigationState _navState = new NavigationState([
     new Route(name: '/', builder: (navigator) => new StockHome(navigator)),
     new Route(name: '/settings', builder: (navigator) => new StockSettings(navigator)),
@@ -37,7 +35,7 @@ class StocksApp extends App {
 
 void main() {
   print("starting stocks app!");
-  App app = new StocksApp();
+  runApp(new StocksApp());
   WidgetAppView.appView.onFrame = () {
     // uncomment this for debugging:
     // WidgetAppView.appView.debugDumpRenderTree();

examples/widgets/container.dart

@@ -51,5 +51,5 @@ class ContainerApp extends App {
 }
 
 void main() {
-  new ContainerApp();
+  runApp(new ContainerApp());
 }

examples/widgets/hello_widgets.dart

@@ -11,5 +11,5 @@ class HelloWorldApp extends App {
 }
 
 void main() {
-  new HelloWorldApp();
+  runApp(new HelloWorldApp());
 }

examples/widgets/navigation.dart

@@ -73,5 +73,5 @@ class NavigationExampleApp extends App {
 }
 
 void main() {
-  App app = new NavigationExampleApp();
+  runApp(new NavigationExampleApp());
 }

examples/widgets/sector.dart

@@ -137,7 +137,7 @@ class SectorApp extends App {
 }
 
 void main() {
-  App app = new SectorApp();
+  runApp(new SectorApp());
   WidgetAppView.appView.onFrame = () {
     // uncomment this for debugging:
     // WidgetAppView.appView.debugDumpRenderTree();

home.dart

@@ -79,5 +79,5 @@ class SkyHome extends App {
 }
 
 void main() {
-  new SkyHome();
+  runApp(new SkyHome());
 }

sdk/lib/app/view.dart

@@ -42,6 +42,7 @@ class AppView {
   static AppView _app; // used to enforce that we're a singleton
 
   RenderView _renderView;
+  RenderView get renderView => _renderView;
 
   ViewConstraints get _viewConstraints =>
       new ViewConstraints(width: sky.view.width, height: sky.view.height);

sdk/lib/widgets/basic.dart

@@ -15,7 +15,7 @@ import 'widget.dart';
 export '../rendering/box.dart' show BoxConstraints, BoxDecoration, Border, BorderSide, EdgeDims;
 export '../rendering/flex.dart' show FlexDirection, FlexJustifyContent, FlexAlignItems;
 export '../rendering/object.dart' show Point, Size, Rect, Color, Paint, Path;
-export 'widget.dart' show Widget, Component, App, Listener, ParentDataNode;
+export 'widget.dart' show Widget, Component, App, runApp, Listener, ParentDataNode;
 
 
 // PAINTING NODES

sdk/lib/widgets/widget.dart

@@ -23,7 +23,7 @@ abstract class Widget {
 
   Widget({ String key }) {
     _key = key != null ? key : runtimeType.toString();
-    assert(this is AbstractWidgetRoot || _inRenderDirtyComponents); // you should not build the UI tree ahead of time, build it only during build()
+    assert(this is AbstractWidgetRoot || this is App || _inRenderDirtyComponents); // you should not build the UI tree ahead of time, build it only during build()
   }
 
   String _key;
@@ -474,7 +474,10 @@ abstract class RenderObjectWrapper extends Widget {
   static RenderObjectWrapper _getMounted(RenderObject node) => _nodeMap[node];
 
   void _sync(Widget old, dynamic slot) {
-    assert(parent != null);
+    // TODO(abarth): We should split RenderObjectWrapper into two pieces so that
+    //               RenderViewObject doesn't need to inherit all this code it
+    //               doesn't need.
+    assert(parent != null || this is RenderViewWrapper);
     if (old == null) {
       _root = createNode();
       var ancestor = findAncestor(RenderObjectWrapper);
@@ -767,10 +770,14 @@ class WidgetAppView extends AppView {
 
 }
 
+abstract class App extends Component {
+  // Override this to handle back button behavior in your app
+  void onBack() { }
+}
+
 abstract class AbstractWidgetRoot extends Component {
 
-  AbstractWidgetRoot({ RenderView renderViewOverride }) : super(stateful: true) {
-    WidgetAppView.initWidgetAppView(renderViewOverride: renderViewOverride);
+  AbstractWidgetRoot() : super(stateful: true) {
     _mounted = true;
     _scheduleComponentForRender(this);
   }
@@ -789,27 +796,24 @@ abstract class AbstractWidgetRoot extends Component {
 
 }
 
-abstract class App extends AbstractWidgetRoot {
+class RenderViewWrapper extends OneChildRenderObjectWrapper {
+  RenderViewWrapper({ String key, Widget child }) : super(key: key, child: child);
 
-  App({ RenderView renderViewOverride }) : super(renderViewOverride: renderViewOverride);
+  RenderView get root => super.root;
+  RenderView createNode() => WidgetAppView._appView.renderView;
+}
 
-  void _buildIfDirty() {
-    super._buildIfDirty();
+class AppContainer extends AbstractWidgetRoot {
+  AppContainer(this.app);
 
-    if (root.parent == null) {
-      // we haven't attached it yet
-      WidgetAppView._appView.root = root;
-      WidgetAppView._appView.eventListeners.add((event) {
-        if (event.type == "back")
-          onBack();
-      });
-    }
-    assert(root.parent is RenderView);
-  }
+  final App app;
 
-  // Override this to handle back button behavior in your app
-  void onBack() { }
+  Widget build() => new RenderViewWrapper(child: app);
+}
 
+void runApp(App app, { RenderView renderViewOverride }) {
+  WidgetAppView.initWidgetAppView(renderViewOverride: renderViewOverride);
+  new AppContainer(app);
 }
 
 typedef Widget Builder();

tests/framework/stocks.dart

@@ -18,7 +18,7 @@ void main() {
   TestRenderView testRenderView = new TestRenderView();
 
   test("launching stock app", () {
-    new StocksApp(renderViewOverride: testRenderView);
+    runApp(new StocksApp(), renderViewOverride: testRenderView);
     new Future.microtask(testRenderView.checkFrame);
   });
 }

tests/resources/display_list.dart

@@ -160,10 +160,7 @@ class TestRenderView extends RenderView {
 }
 
 class TestApp extends App {
-  TestApp({
-    this.builder,
-    RenderView renderViewOverride
-  }) : super(renderViewOverride: renderViewOverride);
+  TestApp({ this.builder });
 
   Function builder;
 
@@ -176,7 +173,7 @@ class WidgetTester {
   TestRenderView renderView = new TestRenderView();
 
   Future test(Function builder) {
-    new TestApp(renderViewOverride: renderView, builder: builder);
+    runApp(new TestApp(builder: builder), renderViewOverride: renderView);
     return new Future.microtask(renderView.checkFrame);
   }