Support for background images on cards, style demo home

sky/sdk/lib/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 'package:vector_math/vector_math.dart';
 
 import '../base/debug.dart';
@@ skipping 945 matching lines @@
 
   RenderDecoratedBox({
     BoxDecoration decoration,
     RenderBox child
   }) : _painter = new BoxPainter(decoration), super(child);
 
   BoxPainter _painter;
   BoxDecoration get decoration => _painter.decoration;
   void set decoration (BoxDecoration value) {
     assert(value != null);
+    if (value.backgroundImage != null) {
+      if (_painter.decoration.backgroundImage != null)
+        _painter.decoration.backgroundImage.removeChangeListener(markNeedsPaint);

[abarth-chromium, 2015/06/26 23:35:59]

Don't we need to removeChangeListener even if value.backgroundImage == null (for
example, if _painter.decoration.backgroundImage is non-null)?

[jackson, 2015/06/29 16:53:25]

We do, thanks

+      value.backgroundImage.addChangeListener(markNeedsPaint);
+    }
     if (value == _painter.decoration)
       return;
     _painter.decoration = value;
     markNeedsPaint();
   }
 
   void paint(RenderCanvas canvas) {
     assert(size.width != null);
     assert(size.height != null);
     _painter.paint(canvas, new Rect.fromSize(size));
@@ skipping 275 matching lines @@
 
   void defaultPaint(RenderCanvas canvas) {
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is ParentDataType);
       canvas.paintChild(child, child.parentData.position);
       child = child.parentData.nextSibling;
     }
   }
 }