Implement measurement using futures

client/layout/GridLayout.dart

 // Copyright (c) 2011, 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
@@ skipping 67 matching lines @@
       rowSizing = _GridTrackParser.parseTrackSizing(
           view.customStyle['grid-row-sizing']),
 
       columnSizing = _GridTrackParser.parseTrackSizing(
           view.customStyle['grid-column-sizing']) {
 
     _rowTracks = rows != null ? rows.tracks : new List<GridTrack>();
     _columnTracks = columns != null ? columns.tracks : new List<GridTrack>();
   }
 
+
   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.
   /** The main entry point for layout computation. */
-  bool measureLayout(int width, int height) {
-    _gridWidth = width;
-    _gridHeight = height;
+  void measureLayout(Future<Size> size, Completer<bool> changed) {
+    _ensureAllTracks();
+    window.requestLayoutFrame(() {
+      _gridWidth = size.value.width;
+      _gridHeight = size.value.height;
 
-    _ensureAllTracks();
-
-    if (_rowTracks.length < 1 || _columnTracks.length < 1) {
-      return false; // nothing to do
-    }
-
-    _measureTracks();
-    _setBoundsOfChildren();
-    return true;
+      if (_rowTracks.length > 0 && _columnTracks.length > 0) {
+        _measureTracks();
+        _setBoundsOfChildren();
+        if (changed != null) {
+          changed.complete(true);
+        }
+      }
+    });
   }
 
   /**
    * 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 296 matching lines @@
   void _ensureAllTracks() {
     final items = CollectionUtils.map(view.childViews, (view) => view.layout);
 
     for (final child in items) {
       if (child.layoutParams == null) {
         final p = new GridLayoutParams(child.view, this);
         _ensureTrack(_rowTracks, rowSizing, p.row, p.rowSpan);
         _ensureTrack(_columnTracks, columnSizing, p.column, p.columnSpan);
         child.layoutParams = p;
       }
+      child.cacheExistingBrowserLayout();
     }
   }
 
   /**
    * Given the track sizes that were computed, position children in the grid.
    */
   void _setBoundsOfChildren() {
     final items = CollectionUtils.map(view.childViews, (view) => view.layout);
 
     for (final item in items) {
@@ skipping 70 matching lines @@
     }
     return result;
   }
 
   int _getSpanCount(ViewLayout item) {
     GridLayoutParams childLayout = item.layoutParams;
     return (_dimension == Dimension.WIDTH ?
         childLayout.columnSpan : childLayout.rowSpan);
   }
 }