Extend Sky's RenderFlex with intrinsic sizes and compute cross-size height

sky/sdk/lib/framework/rendering/box.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 'dart:sky' as sky;
 import 'dart:typed_data';
 import 'object.dart';
 import '../painting/shadows.dart';
 import 'package:vector_math/vector_math.dart';
@@ skipping 538 matching lines @@
 
   Size _requestedSize;
   Size get requestedSize => _requestedSize;
   void set requestedSize (Size value) {
     if (value == _requestedSize)
       return;
     _requestedSize = value;
     markNeedsLayout();
   }
 
-  void performLayout() {
+  Size _sizeForConstraints(BoxConstraints innerConstraints) {
     // If there's no image, we can't size ourselves automatically
     if (_image == null) {
       double width = requestedSize.width == null ? 0.0 : requestedSize.width;
       double height = requestedSize.height == null ? 0.0 : requestedSize.height;
-      size = constraints.constrain(new Size(width, height));
-      return;
+      return constraints.constrain(new Size(width, height));
     }
 
     // If neither height nor width are specified, use inherent image dimensions
     // If only one dimension is specified, adjust the other dimension to
     // maintain the aspect ratio
     if (requestedSize.width == null) {
       if (requestedSize.height == null) {
-        size = constraints.constrain(new Size(_image.width.toDouble(), _image.height.toDouble()));
+        return constraints.constrain(new Size(_image.width.toDouble(), _image.height.toDouble()));
       } else {
         double width = requestedSize.height * _image.width / _image.height;
-        size = constraints.constrain(new Size(width, requestedSize.height));
+        return constraints.constrain(new Size(width, requestedSize.height));
       }
     } else if (requestedSize.height == null) {
       double height = requestedSize.width * _image.height / _image.width;
-      size = constraints.constrain(new Size(requestedSize.width, height));
+      return constraints.constrain(new Size(requestedSize.width, height));
     } else {
-      size = constraints.constrain(requestedSize);
+      return constraints.constrain(requestedSize);
     }
   }
 
+  double getMinIntrinsicWidth(BoxConstraints constraints) {
+    if (requestedSize.width == null && requestedSize.height == null)
+      return constraints.constrainWidth(0.0);
+    return _sizeForConstraints(constraints).width;
+  }
+
+  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+    return _sizeForConstraints(constraints).width;
+  }
+
+  double getMinIntrinsicHeight(BoxConstraints constraints) {
+    if (requestedSize.width == null && requestedSize.height == null)
+      return constraints.constrainHeight(0.0);
+    return _sizeForConstraints(constraints).height;
+  }
+
+  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+    return _sizeForConstraints(constraints).height;
+  }
+
+  void performLayout() {
+    size = _sizeForConstraints(constraints);
+  }
+
   void paint(RenderObjectDisplayList canvas) {
     if (_image == null) return;
     bool needsScale = size.width != _image.width || size.height != _image.height;
     if (needsScale) {
       double widthScale = size.width / _image.width;
       double heightScale = size.height / _image.height;
       canvas.save();
       canvas.scale(widthScale, heightScale);
     }
     Paint paint = new Paint();
@@ skipping 194 matching lines @@
     }
 
     return _cachedBackgroundPaint;
   }
 
   void paint(RenderObjectDisplayList canvas) {
     assert(size.width != null);
     assert(size.height != null);
 
     if (_decoration.backgroundColor != null || _decoration.boxShadow != null ||
-        _deocration.gradient != null) {
+        _decoration.gradient != null) {
       Rect rect = new Rect.fromLTRB(0.0, 0.0, size.width, size.height);
       if (_decoration.borderRadius == null)
         canvas.drawRect(rect, _backgroundPaint);
       else
         canvas.drawRRect(new sky.RRect()..setRectXY(rect, _decoration.borderRadius, _decoration.borderRadius), _backgroundPaint);
     }
 
     if (_decoration.border != null) {
       assert(_decoration.borderRadius == null); // TODO(abarth): Implement borders with border radius.
 
@@ skipping 278 matching lines @@
 
   void defaultPaint(RenderObjectDisplayList canvas) {
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is ParentDataType);
       canvas.paintChild(child, child.parentData.position);
       child = child.parentData.nextSibling;
     }
   }
 }