Simplify Scaffold

Rather than using a custom render object, we can just use a Stack.

examples/address_book/lib/main.dart

@@ -81,7 +81,7 @@ class AddressBookHome extends StatelessComponent {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(context),
+      toolBar: buildToolBar(context),
       body: buildBody(context),
       floatingActionButton: buildFloatingActionButton(context)
     );

examples/demo_launcher/lib/main.dart

@@ -192,7 +192,7 @@ final ThemeData _theme = new ThemeData(
 class DemoHome extends StatelessComponent {
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: new ToolBar(center: new Text('Sky Demos')),
+      toolBar: new ToolBar(center: new Text('Sky Demos')),
       body: new Material(
         type: MaterialType.canvas,
         child: new DemoList()

examples/fitness/lib/feed.dart

@@ -219,7 +219,7 @@ class FeedFragmentState extends State<FeedFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildBody(),
       snackBar: new Placeholder(key: _snackBarPlaceholderKey),
       floatingActionButton: buildFloatingActionButton()

examples/fitness/lib/meal.dart

@@ -105,7 +105,7 @@ class MealFragmentState extends State<MealFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildBody()
     );
   }

examples/fitness/lib/measurement.dart

@@ -200,7 +200,7 @@ class MeasurementFragmentState extends State<MeasurementFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildBody(context),
       snackBar: new Placeholder(key: _snackBarPlaceholderKey)
     );

examples/fitness/lib/settings.dart

@@ -122,7 +122,7 @@ class SettingsFragmentState extends State<SettingsFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildSettingsPane(context)
     );
   }

examples/mine_digger/lib/main.dart

@@ -182,7 +182,7 @@ class MineDiggerState extends State<MineDigger> {
     return new Title(
       title: 'Mine Digger',
       child: new Scaffold(
-        toolbar: buildToolBar(context),
+        toolBar: buildToolBar(context),
         body: new Container(
           child: new Center(child: board),
           decoration: new BoxDecoration(backgroundColor: Colors.grey[50])

examples/stocks/lib/stock_home.dart

@@ -237,7 +237,7 @@ class StockHomeState extends State<StockHome> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: _isSearching ? buildSearchBar() : buildToolBar(),
+      toolBar: _isSearching ? buildSearchBar() : buildToolBar(),
       body: buildTabNavigator(),
       snackBar: new Placeholder(key: _snackBarPlaceholderKey),
       floatingActionButton: buildFloatingActionButton()

examples/stocks/lib/stock_settings.dart

@@ -119,7 +119,7 @@ class StockSettingsState extends State<StockSettings> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(context),
+      toolBar: buildToolBar(context),
       body: buildSettingsPane(context)
     );
   }

examples/stocks/lib/stock_symbol_viewer.dart

@@ -25,7 +25,7 @@ class StockSymbolViewerState extends State<StockSymbolViewer> {
     TextStyle headings = Theme.of(context).text.body2;
 
     return new Scaffold(
-      toolbar: new ToolBar(
+      toolBar: new ToolBar(
         left: new IconButton(
           icon: 'navigation/arrow_back',
           onPressed: config.navigator.pop

examples/widgets/card_collection.dart

@@ -342,7 +342,7 @@ class CardCollectionState extends State<CardCollection> {
     }
 
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: body
     );
   }

examples/widgets/date_picker.dart

@@ -34,7 +34,7 @@ class DatePickerDemoState extends State<DatePickerDemo> {
       ),
       child: new Stack([
         new Scaffold(
-          toolbar: new ToolBar(center: new Text("Date Picker")),
+          toolBar: new ToolBar(center: new Text("Date Picker")),
           body: new Material(
             child: new Row(
               [new Text(_dateTime.toString())],

examples/widgets/drag_and_drop.dart

@@ -101,7 +101,7 @@ class DragAndDropApp extends StatefulComponent {
 class DragAndDropAppState extends State<DragAndDropApp> {
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: new ToolBar(
+      toolBar: new ToolBar(
         center: new Text('Drag and Drop Flutter Demo')
       ),
       body: new Material(

examples/widgets/ensure_visible.dart

@@ -89,7 +89,7 @@ class EnsureVisibleApp extends App {
         child: new Title(
           title: 'Cards',
           child: new Scaffold(
-            toolbar: new ToolBar(center: new Text('Tap a Card')),
+            toolBar: new ToolBar(center: new Text('Tap a Card')),
             body: cardCollection
           )
         )

examples/widgets/overlay_geometry.dart

@@ -138,7 +138,7 @@ class OverlayGeometryAppState extends State<OverlayGeometryApp> {
   Widget build(BuildContext context) {
     List<Widget> layers = <Widget>[
       new Scaffold(
-        toolbar: new ToolBar(center: new Text('Tap a Card')),
+        toolBar: new ToolBar(center: new Text('Tap a Card')),
         body: new Container(
           padding: const EdgeDims.symmetric(vertical: 12.0, horizontal: 8.0),
           decoration: new BoxDecoration(backgroundColor: Theme.of(context).primarySwatch[50]),

examples/widgets/pageable_list.dart

@@ -149,7 +149,7 @@ class PageableListAppState extends State<PageableListApp> {
     return new IconTheme(
       data: const IconThemeData(color: IconThemeColor.white),
       child: new Scaffold(
-        toolbar: buildToolBar(),
+        toolBar: buildToolBar(),
         body: buildBody(context)
       )
     );

examples/widgets/progress_indicator.dart

@@ -103,7 +103,7 @@ class ProgressIndicatorAppState extends State<ProgressIndicatorApp> {
         child: new Title(
           title: 'Progress Indicators',
           child: new Scaffold(
-            toolbar: new ToolBar(center: new Text('Progress Indicators')),
+            toolBar: new ToolBar(center: new Text('Progress Indicators')),
             body: new DefaultTextStyle(
               style: Theme.of(context).text.title,
               child: body

examples/widgets/scale.dart

@@ -59,7 +59,7 @@ class ScaleAppState extends State<ScaleApp> {
     return new Theme(
       data: new ThemeData.dark(),
       child: new Scaffold(
-        toolbar: new ToolBar(
+        toolBar: new ToolBar(
             center: new Text('Scale Demo')),
         body: new Material(
           type: MaterialType.canvas,

examples/widgets/sector.dart

@@ -124,7 +124,7 @@ class SectorApp extends App {
       child: new Title(
         title: 'Sector Layout',
         child: new Scaffold(
-          toolbar: new ToolBar(
+          toolBar: new ToolBar(
             center: new Text('Sector Layout in a Widget Tree')
           ),
           body: buildBody()

examples/widgets/styled_text.dart

@@ -106,7 +106,7 @@ HAL: This mission is too important for me to allow you to jeopardize it.''';
           color: Colors.grey[50],
           child: interactiveBody
         ),
-        toolbar: new ToolBar(
+        toolBar: new ToolBar(
           center: new Text('Hal and Dave')
         )
       )

examples/widgets/tabs.dart

@@ -131,7 +131,7 @@ class TabbedNavigatorAppState extends State<TabbedNavigatorApp> {
     );
 
     return new Scaffold(
-      toolbar: toolbar,
+      toolBar: toolbar,
       body: tabNavigator
     );
   }

packages/flutter/lib/src/material/constants.dart

@@ -14,6 +14,7 @@ const double kStatusBarHeight = 50.0;
 // Mobile Portrait: 56dp
 // Tablet/Desktop: 64dp
 const double kToolBarHeight = 56.0;
+const double kSnackBarHeight = 52.0;
 
 const double kMaterialDrawerHeight = 140.0;
 const double kScrollbarSize = 10.0;

packages/flutter/lib/src/widgets/scaffold.dart

@@ -6,247 +6,88 @@ import 'dart:sky' as sky;
 
 import 'package:sky/material.dart';
 import 'package:sky/rendering.dart';
+import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
 
-// Slots are painted in this order and hit tested in reverse of this order
-enum _ScaffoldSlots {
-  body,
-  statusBar,
-  toolbar,
-  snackBar,
-  floatingActionButton,
-  drawer
-}
-
-class _RenderScaffold extends RenderBox {
-
-  _RenderScaffold({
-    RenderBox body,
-    RenderBox statusBar,
-    RenderBox toolbar,
-    RenderBox snackBar,
-    RenderBox floatingActionButton,
-    RenderBox drawer
-  }) {
-    this[_ScaffoldSlots.body] = body;
-    this[_ScaffoldSlots.statusBar] = statusBar;
-    this[_ScaffoldSlots.toolbar] = toolbar;
-    this[_ScaffoldSlots.snackBar] = snackBar;
-    this[_ScaffoldSlots.floatingActionButton] = floatingActionButton;
-    this[_ScaffoldSlots.drawer] = drawer;
-  }
-
-  Map<_ScaffoldSlots, RenderBox> _slots = new Map<_ScaffoldSlots, RenderBox>();
-  RenderBox operator[] (_ScaffoldSlots slot) => _slots[slot];
-  void operator[]= (_ScaffoldSlots slot, RenderBox value) {
-    RenderBox old = _slots[slot];
-    if (old == value)
-      return;
-    if (old != null)
-      dropChild(old);
-    if (value == null) {
-      _slots.remove(slot);
-    } else {
-      _slots[slot] = value;
-      adoptChild(value);
-    }
-    markNeedsLayout();
-  }
-
-  void attachChildren() {
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      RenderBox box = _slots[slot];
-      if (box != null)
-        box.attach();
-    }
-  }
-
-  void detachChildren() {
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      RenderBox box = _slots[slot];
-      if (box != null)
-        box.detach();
-    }
-  }
-
-  void visitChildren(RenderObjectVisitor visitor) {
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      RenderBox box = _slots[slot];
-      if (box != null)
-        visitor(box);
-    }
-  }
-
-  _ScaffoldSlots remove(RenderBox child) {
-    assert(child != null);
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      if (_slots[slot] == child) {
-        this[slot] = null;
-        return slot;
-      }
-    }
-    return null;
-  }
-
-  bool get sizedByParent => true;
-  void performResize() {
-    size = constraints.biggest;
-    assert(!size.isInfinite);
-  }
-
-  // TODO(eseidel): These change based on device size!
-  // http://www.google.com/design/spec/layout/metrics-keylines.html#metrics-keylines-keylines-spacing
-  static const kButtonX = 16.0; // left from right edge of body
-  static const kButtonY = 16.0; // up from bottom edge of body
-
-  void performLayout() {
-    double bodyHeight = size.height;
-    double bodyPosition = 0.0;
-    double fabOffset = 0.0;
-    if (_slots[_ScaffoldSlots.statusBar] != null) {
-      RenderBox statusBar = _slots[_ScaffoldSlots.statusBar];
-      statusBar.layout(new BoxConstraints.tight(new Size(size.width, kStatusBarHeight)));
-      assert(statusBar.parentData is BoxParentData);
-      statusBar.parentData.position = new Point(0.0, size.height - kStatusBarHeight);
-      bodyHeight -= kStatusBarHeight;
-    }
-    if (_slots[_ScaffoldSlots.toolbar] != null) {
-      RenderBox toolbar = _slots[_ScaffoldSlots.toolbar];
-      double toolbarHeight = kToolBarHeight + sky.view.paddingTop;
-      toolbar.layout(new BoxConstraints.tight(new Size(size.width, toolbarHeight)));
-      assert(toolbar.parentData is BoxParentData);
-      toolbar.parentData.position = Point.origin;
-      bodyPosition += toolbarHeight;
-      bodyHeight -= toolbarHeight;
-    }
-    if (_slots[_ScaffoldSlots.body] != null) {
-      RenderBox body = _slots[_ScaffoldSlots.body];
-      body.layout(new BoxConstraints.tight(new Size(size.width, bodyHeight)));
-      assert(body.parentData is BoxParentData);
-      body.parentData.position = new Point(0.0, bodyPosition);
-    }
-    if (_slots[_ScaffoldSlots.snackBar] != null) {
-      RenderBox snackBar = _slots[_ScaffoldSlots.snackBar];
-      // TODO(jackson): On tablet/desktop, minWidth = 288, maxWidth = 568
-      snackBar.layout(
-        new BoxConstraints(minWidth: size.width, maxWidth: size.width, minHeight: 0.0, maxHeight: bodyHeight),
-        parentUsesSize: true
-      );
-      assert(snackBar.parentData is BoxParentData);
-      snackBar.parentData.position = new Point(0.0, bodyPosition + bodyHeight - snackBar.size.height);
-      fabOffset += snackBar.size.height;
-    }
-    if (_slots[_ScaffoldSlots.floatingActionButton] != null) {
-      RenderBox floatingActionButton = _slots[_ScaffoldSlots.floatingActionButton];
-      Size area = new Size(size.width - kButtonX, size.height - kButtonY);
-      floatingActionButton.layout(new BoxConstraints.loose(area), parentUsesSize: true);
-      assert(floatingActionButton.parentData is BoxParentData);
-      floatingActionButton.parentData.position = (area - floatingActionButton.size).toPoint() + new Offset(0.0, -fabOffset);
-    }
-    if (_slots[_ScaffoldSlots.drawer] != null) {
-      RenderBox drawer = _slots[_ScaffoldSlots.drawer];
-      drawer.layout(new BoxConstraints(minWidth: 0.0, maxWidth: size.width, minHeight: size.height, maxHeight: size.height));
-      assert(drawer.parentData is BoxParentData);
-      drawer.parentData.position = Point.origin;
-    }
-  }
-
-  void paint(PaintingContext context, Offset offset) {
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      RenderBox box = _slots[slot];
-      if (box != null) {
-        assert(box.parentData is BoxParentData);
-        context.paintChild(box, box.parentData.position + offset);
-      }
-    }
-  }
-
-  void hitTestChildren(HitTestResult result, { Point position }) {
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values.reversed) {
-      RenderBox box = _slots[slot];
-      if (box != null) {
-        assert(box.parentData is BoxParentData);
-        if (box.hitTest(result, position: (position - box.parentData.position).toPoint()))
-          return;
-      }
-    }
-  }
-
-  String debugDescribeChildren(String prefix) {
-    return _slots.keys.map((slot) => '${prefix}${slot}: ${_slots[slot].toStringDeep(prefix)}').join();
-  }
-}
-
-class Scaffold extends RenderObjectWidget {
+class Scaffold extends StatelessComponent {
   Scaffold({
     Key key,
-    Widget body,
-    Widget statusBar,
-    Widget toolbar,
-    Widget snackBar,
-    Widget floatingActionButton,
-    Widget drawer
-  }) : super(key: key) {
-    _children[_ScaffoldSlots.body] = body;
-    _children[_ScaffoldSlots.statusBar] = statusBar;
-    _children[_ScaffoldSlots.toolbar] = toolbar;
-    _children[_ScaffoldSlots.snackBar] = snackBar;
-    _children[_ScaffoldSlots.floatingActionButton] = floatingActionButton;
-    _children[_ScaffoldSlots.drawer] = drawer;
-  }
-
-  final Map<_ScaffoldSlots, Widget> _children = new Map<_ScaffoldSlots, Widget>();
-
-  _RenderScaffold createRenderObject() => new _RenderScaffold();
-
-  _ScaffoldElement createElement() => new _ScaffoldElement(this);
-}
-
-class _ScaffoldElement extends RenderObjectElement<Scaffold> {
-  _ScaffoldElement(Scaffold widget) : super(widget);
-
-  Map<_ScaffoldSlots, Element> _children;
-
-  _RenderScaffold get renderObject => super.renderObject;
-
-  void visitChildren(ElementVisitor visitor) {
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      Element element = _children[slot];
-      if (element != null)
-        visitor(element);
-    }
-  }
-
-  void mount(Element parent, dynamic newSlot) {
-    super.mount(parent, newSlot);
-    _children = new Map<_ScaffoldSlots, Element>();
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      Element newChild = widget._children[slot]?.createElement();
-      _children[slot] = newChild;
-      newChild?.mount(this, slot);
-    }
-  }
-
-  void update(Scaffold newWidget) {
-    super.update(newWidget);
-    assert(widget == newWidget);
-    for (_ScaffoldSlots slot in _ScaffoldSlots.values) {
-      _children[slot] = updateChild(_children[slot], widget._children[slot], slot);
-      assert((_children[slot] == null) == (widget._children[slot] == null));
-    }
+    this.body,
+    this.statusBar,
+    this.toolBar,
+    this.snackBar,
+    this.floatingActionButton
+  }) : super(key: key);
+
+  final Widget body;
+  final Widget statusBar;
+  final Widget toolBar;
+  final Widget snackBar;
+  final Widget floatingActionButton;
+
+  Widget build(BuildContext context) {
+    double toolBarHeight = 0.0;
+    if (toolBar != null)
+      toolBarHeight = kToolBarHeight + sky.view.paddingTop;
+
+    double statusBarHeight = 0.0;
+    if (statusBar != null)
+      statusBarHeight = kStatusBarHeight;
+
+    List<Widget> children = <Widget>[];
+
+    if (body != null) {
+      children.add(new Positioned(
+        top: toolBarHeight, right: 0.0, bottom: statusBarHeight, left: 0.0,
+        child: body
+      ));
+    }
+
+    if (statusBar != null) {
+      children.add(new Positioned(
+        right: 0.0, bottom: 0.0, left: 0.0,
+        child: new SizedBox(
+          height: statusBarHeight,
+          child: statusBar
+        )
+      ));
+    }
+
+    if (toolBar != null) {
+      children.add(new Positioned(
+        top: 0.0, right: 0.0, left: 0.0,
+        child: new SizedBox(
+          height: toolBarHeight,
+          child: toolBar
+        )
+      ));
+    }
+
+    if (snackBar != null || floatingActionButton != null) {
+      List<Widget> floatingChildren = <Widget>[];
+
+      if (floatingActionButton != null) {
+        floatingChildren.add(new Padding(
+          // TODO(eseidel): These change based on device size!
+          padding: const EdgeDims.only(right: 16.0, bottom: 16.0),
+          child: floatingActionButton
+        ));
       }
 
-  void insertChildRenderObject(RenderObject child, _ScaffoldSlots slot) {
-    renderObject[slot] = child;
+      // TODO(jackson): On tablet/desktop, minWidth = 288, maxWidth = 568
+      if (snackBar != null) {
+        floatingChildren.add(new ConstrainedBox(
+          constraints: const BoxConstraints(maxHeight: kSnackBarHeight),
+          child: snackBar
+        ));
       }
 
-  void moveChildRenderObject(RenderObject child, dynamic slot) {
-    removeChildRenderObject(child);
-    insertChildRenderObject(child, slot);
+      children.add(new Positioned(
+        right: 0.0, bottom: statusBarHeight, left: 0.0,
+        child: new Column(floatingChildren, alignItems: FlexAlignItems.end)
+      ));
     }
 
-  void removeChildRenderObject(RenderObject child) {
-    assert(renderObject == child.parent);
-    renderObject.remove(child);
+    return new Stack(children);
   }
 }

packages/flutter/lib/src/widgets/snack_bar.dart

@@ -15,7 +15,6 @@ import 'package:sky/src/widgets/placeholder.dart';
 import 'package:sky/src/widgets/theme.dart';
 import 'package:sky/src/widgets/transitions.dart';
 
-const double _kSnackHeight = 52.0;
 const double _kSideMargins = 24.0;
 const double _kVerticalPadding = 14.0;
 const Color _kSnackBackground = const Color(0xFF323232);
@@ -72,14 +71,14 @@ class SnackBar extends StatelessComponent {
       performance: performance,
       height: new AnimatedValue<double>(
         0.0,
-        end: _kSnackHeight,
+        end: kSnackBarHeight,
         curve: easeIn,
         reverseCurve: easeOut
       ),
       child: new ClipRect(
         child: new OverflowBox(
-          minHeight: _kSnackHeight,
-          maxHeight: _kSnackHeight,
+          minHeight: kSnackBarHeight,
+          maxHeight: kSnackBarHeight,
           child: new Material(
             level: 2,
             color: _kSnackBackground,