Example showing alternate async measurement solution

client/layout/GridLayout.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Implements a grid-based layout system based on:
  * [http://dev.w3.org/csswg/css3-grid-align/]
  *
  * This layout is designed to support animations and work on browsers that
  * don't support grid natively. As such, we implement it on top of absolute
  * positioning.
@@ skipping 76 matching lines @@
 
   int get currentWidth() => _gridWidth;
   int get currentHeight() => _gridHeight;
 
   void cacheExistingBrowserLayout() {
     // We don't need to do anything as we don't rely on the _cachedViewRect
     // when the grid layout is used.
   }
 
   // TODO(jacobr): cleanup this method so that it returns a Future
   // rather than taking a Completer as an argument.

[arv (Not doing code reviews), 2012/01/17 20:25:00]

Update TODO

[Jacob, 2012/01/21 03:01:25]

Done.

   /** The main entry point for layout computation. */
-  void measureLayout(Future<Size> size, Completer<bool> changed) {
+  bool measureLayout(int width, int height) {
+    assert(window.inMeasurementFrame);
     _ensureAllTracks();
-    window.requestLayoutFrame(() {
-      _gridWidth = size.value.width;
-      _gridHeight = size.value.height;
+    _gridWidth = width;
+    _gridHeight = height;
 
-      if (_rowTracks.length > 0 && _columnTracks.length > 0) {
-        _measureTracks();
-        _setBoundsOfChildren();
-        if (changed != null) {
-          changed.complete(true);
-        }
-      }
-    });
+    if (_rowTracks.length > 0 && _columnTracks.length > 0) {
+      _measureTracks();
+      _setBoundsOfChildren();
+      return true;
+    }
+    return false;
   }
 
   /**
    * The top level measurement function.
    * [http://dev.w3.org/csswg/css3-grid-align/#calculating-size-of-grid-tracks]
    */
   void _measureTracks() {
     // Resolve logical width, then height. Width comes first so we can use
     // the width when determining the content-sized height.
     try {
@@ skipping 387 matching lines @@
     }
     return result;
   }
 
   int _getSpanCount(ViewLayout item) {
     GridLayoutParams childLayout = item.layoutParams;
     return (_dimension == Dimension.WIDTH ?
         childLayout.columnSpan : childLayout.rowSpan);
   }
 }