Give RenderObject a useful toString().

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 'package:vector_math/vector_math.dart';
 import 'package:sky/framework/net/image_cache.dart' as image_cache;
@@ skipping 91 matching lines @@
     value = 37 * value + maxWidth.hashCode;
     value = 37 * value + minHeight.hashCode;
     value = 37 * value + maxHeight.hashCode;
     return value;
   }
   String toString() => "BoxConstraints($minWidth<=w<$maxWidth, $minHeight<=h<$maxHeight)";
 }
 
 class BoxParentData extends ParentData {
   sky.Point position = new sky.Point(0.0, 0.0);
+  String toString() => 'position=$position';
 }
 
 abstract class RenderBox extends RenderObject {
 
   void setParentData(RenderObject child) {
     if (child.parentData is! BoxParentData)
       child.parentData = new BoxParentData();
   }
 
   // override this to report what dimensions you would have if you
@@ skipping 84 matching lines @@
 
   sky.Size getIntrinsicDimensions(BoxConstraints constraints) {
     return constraints.constrain(_desiredSize);
   }
 
   void performLayout() {
     size = constraints.constrain(_desiredSize);
     if (child != null)
       child.layout(new BoxConstraints.tight(size));
   }
+
+  String debugDescribeSettings(String prefix) => '${prefix}desiredSize: ${desiredSize}';
 }
 
 class RenderClip extends RenderProxyBox {
   RenderClip({ RenderBox child }) : super(child);
 
   void paint(RenderObjectDisplayList canvas) {
     if (child != null) {
       canvas.save();
       canvas.clipRect(new sky.Rect.fromSize(size));
       child.paint(canvas);
@@ skipping 52 matching lines @@
     if (child != null) {
       assert(child.parentData is BoxParentData);
       sky.Rect childBounds = new sky.Rect.fromPointAndSize(child.parentData.position, child.size);
       if (childBounds.contains(position)) {
         child.hitTest(result, position: new sky.Point(position.x - child.parentData.position.x,
                                                       position.y - child.parentData.position.y));
       }
     }
   }
 
+  String debugDescribeSettings(String prefix) => '${prefix}padding: ${padding}';
 }
 
 class RenderImage extends RenderBox {
 
   RenderImage(String url, sky.Size dimensions) {
     requestedSize = dimensions;
     src = url;
   }
 
   sky.Image _image;
@@ skipping 54 matching lines @@
       double widthScale = size.width / _image.width;
       double heightScale = size.height / _image.height;
       canvas.save();
       canvas.scale(widthScale, heightScale);
     }
     sky.Paint paint = new sky.Paint();
     canvas.drawImage(_image, 0.0, 0.0, paint);
     if (needsScale)
       canvas.restore();
   }
+
+  String debugDescribeSettings(String prefix) => '${prefix}url: ${src}\n${prefix}dimensions: ${requestedSize}';
 }
 
 class BorderSide {
   const BorderSide({
     this.color: const sky.Color(0xFF000000),
     this.width: 1.0
   });
   final sky.Color color;
   final double width;
 
@@ skipping 38 matching lines @@
 
 // This must be immutable, because we won't notice when it changes
 class BoxDecoration {
   const BoxDecoration({
     this.backgroundColor,
     this.border
   });
 
   final sky.Color backgroundColor;
   final Border border;
+
+  String toString([String prefix = '']) {
+    List<String> result = [];
+    if (backgroundColor != null)
+      result.add('${prefix}backgroundColor: $backgroundColor');
+    if (border != null)
+      result.add('${prefix}border: $border');
+    if (result.isEmpty)
+      return '${prefix}<no decorations specified>';
+    return result.join('\n');
+  }
 }
 
 class RenderDecoratedBox extends RenderProxyBox {
 
   RenderDecoratedBox({
     BoxDecoration decoration,
     RenderBox child
   }) : _decoration = decoration, super(child) {
     assert(_decoration != null);
   }
@@ skipping 58 matching lines @@
       path.moveTo(0.0, size.height);
       path.lineTo(_decoration.border.left.width, size.height - _decoration.border.bottom.width);
       path.lineTo(_decoration.border.left.width, _decoration.border.top.width);
       path.lineTo(0.0,0.0);
       path.close();
       canvas.drawPath(path, paint);
     }
 
     super.paint(canvas);
   }
+
+  String debugDescribeSettings(String prefix) => '${prefix}decoration:\n${decoration.toString(prefix + "  ")}';
 }
 
 class RenderTransform extends RenderProxyBox {
   RenderTransform({
     Matrix4 transform,
     RenderBox child
   }) : super(child) {
     assert(transform != null);
     this.transform = transform;
   }
@@ skipping 175 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;
     }
   }
 }