Support for alignItems (test incoming)

sky/sdk/lib/framework/rendering/flex.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.
 
 import 'dart:math' as math;
 import 'box.dart';
 import 'object.dart';
 
 class FlexBoxParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> {
   int flex;
 
   void merge(FlexBoxParentData other) {
     if (other.flex != null)
       flex = other.flex;
     super.merge(other);
   }
 
   String toString() => '${super.toString()}; flex=$flex';
 }
 
 enum FlexDirection { horizontal, vertical }
+
 enum FlexJustifyContent {
   flexStart,
   flexEnd,
   center,
   spaceBetween,
   spaceAround,
 }
 
+enum FlexAlignItems {
+  flexStart,
+  flexEnd,
+  center,
+}
+
 typedef double _ChildSizingFunction(RenderBox child, BoxConstraints constraints);
 
 class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, FlexBoxParentData>,
                                         RenderBoxContainerDefaultsMixin<RenderBox, FlexBoxParentData> {
   // lays out RenderBox children using flexible layout
 
   RenderFlex({
     FlexDirection direction: FlexDirection.horizontal,
-    FlexJustifyContent justifyContent: FlexJustifyContent.flexStart
-  }) : _direction = direction, _justifyContent = justifyContent;
+    FlexJustifyContent justifyContent: FlexJustifyContent.flexStart,
+    FlexAlignItems alignItems: FlexAlignItems.center
+  }) : _direction = direction, _justifyContent = justifyContent, _alignItems = alignItems;
 
   FlexDirection _direction;
   FlexDirection get direction => _direction;
   void set direction (FlexDirection value) {
     if (_direction != value) {
       _direction = value;
       markNeedsLayout();
     }
   }
 
   FlexJustifyContent _justifyContent;
   FlexJustifyContent get justifyContent => _justifyContent;
   void set justifyContent (FlexJustifyContent value) {
     if (_justifyContent != value) {
       _justifyContent = value;
       markNeedsLayout();
     }
   }
 
+  FlexAlignItems _alignItems;
+  FlexAlignItems get alignItems => _alignItems;
+  void set alignItems (FlexAlignItems value) {
+    if (_alignItems != value) {
+      _alignItems = value;
+      markNeedsLayout();
+    }
+  }
+
   void setParentData(RenderBox child) {
     if (child.parentData is! FlexBoxParentData)
       child.parentData = new FlexBoxParentData();
   }
 
   double _getIntrinsicSize({ BoxConstraints constraints,
                              FlexDirection sizingDirection,
                              _ChildSizingFunction childSize }) {
     // http://www.w3.org/TR/2015/WD-css-flexbox-1-20150514/#intrinsic-sizes
     if (_direction == sizingDirection) {
@@ skipping 258 matching lines @@
       case FlexDirection.vertical:
         size = constraints.constrain(new Size(crossSize, mainSize));
         crossSize = size.width;
         break;
     }
 
     // Position elements. For now, center the flex items in the cross direction
     double childMainPosition = leadingSpace;
     child = firstChild;
     while (child != null) {
-      double childCrossPosition = crossSize / 2.0 - _getCrossSize(child) / 2.0;
+      double childCrossPosition;
+      switch (_alignItems) {
+        case FlexAlignItems.flexStart:
+          childCrossPosition = 0.0;
+          break;
+        case FlexAlignItems.flexEnd:
+          childCrossPosition = crossSize - _getCrossSize(child);
+          break;
+        case FlexAlignItems.center:
+          childCrossPosition = crossSize / 2.0 - _getCrossSize(child) / 2.0;
+          break;
+      }
       switch (_direction) {
         case FlexDirection.horizontal:
           child.parentData.position = new Point(childMainPosition, childCrossPosition);
           break;
         case FlexDirection.vertical:
           child.parentData.position = new Point(childCrossPosition, childMainPosition);
           break;
       }
       childMainPosition += _getMainSize(child) + betweenSpace;
       child = child.parentData.nextSibling;
     }
   }
 
   void hitTestChildren(HitTestResult result, { Point position }) {
     defaultHitTestChildren(result, position: position);
   }
 
   void paint(RenderObjectDisplayList canvas) {
     defaultPaint(canvas);
   }
 }