[Effen] basic layout container class for custom layout

sky/framework/fn.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 library fn;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:sky' as sky;
 import 'reflect.dart' as reflect;
@@ skipping 565 matching lines @@
     Style style,
     String inlineStyle
   }) : super(
     key: key,
     children: children,
     style: style,
     inlineStyle: inlineStyle
   );
 }
 
+abstract class LayoutContainer extends Container {
+
+  LayoutContainer({
+    Object key,
+    List<UINode> children,
+    Style style,
+    String inlineStyle
+  }) : super(
+    key: key,
+    children: children,
+    style: style,
+    inlineStyle: inlineStyle
+  );
+
+  sky.Node _createNode() {
+    var result = super._createNode();
+    result.setLayoutManager(() => layout(_root));
+    return result;
+  }
+
+  void _syncNode(SkyNodeWrapper old) {
+    super._syncNode(old);
+    _root.setNeedsLayout();
+  }
+
+  void layout(sky.Element skyNode);
+  // set skyNode.width if you have an opinion about your width
+  // for each skyNode.getChildElements()[i]:
+  //   set .width
+  //   call .layout()
+  //   set .x, .y
+  //   set .width if you want to force a width
+  //   set .height if you want to force a height
+  // set skyNode.height
+
+}
+
 class Image extends SkyElementWrapper {
 
   String get _tagName => 'img';
 
   static final Image _emptyImage = new Image();
 
   SkyNodeWrapper get _emptyNode => _emptyImage;
 
   final String src;
   final int width;
@@ skipping 285 matching lines @@
 
 abstract class App extends Component {
   sky.Node _host;
 
   App() : super(stateful: true) {
     _host = sky.document.createElement('div');
     sky.document.appendChild(_host);
     _scheduleComponentForRender(this);
   }
 }