Make RenderParagraph mutable, and make it fit the new RenderNode protocols

sky/examples/raw/simple_render_tree.dart

Index: sky/examples/raw/simple_render_tree.dart
diff --git a/sky/examples/raw/simple_render_tree.dart b/sky/examples/raw/simple_render_tree.dart
new file mode 100644
index 0000000000000000000000000000000000000000..58d4e934e2ec0c3e1126e82eb1da8dda96a32865
--- /dev/null
+++ b/sky/examples/raw/simple_render_tree.dart
@@ -0,0 +1,87 @@
+// 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:sky' as sky;
+import 'package:sky/framework/app.dart';
+import 'package:sky/framework/layout2.dart';
+
+class RenderSolidColor extends RenderDecoratedBox {
+  final sky.Size desiredSize;
+  final int backgroundColor;
+
+  RenderSolidColor(int backgroundColor, { this.desiredSize: const sky.Size.infinite() })
+      : backgroundColor = backgroundColor,
+        super(decoration: new BoxDecoration(backgroundColor: backgroundColor)) {
+  }
+
+  BoxDimensions getIntrinsicDimensions(BoxConstraints constraints) {
+    return new BoxDimensions.withConstraints(constraints,
+                                             width: desiredSize.width,
+                                             height: desiredSize.height);
+  }
+
+  void performLayout() {
+    size = constraints.constrain(desiredSize);
+  }
+
+  void handlePointer(sky.PointerEvent event) {
+    if (event.type == 'pointerdown')
+      decoration = new BoxDecoration(backgroundColor: 0xFFFF0000);
+    else if (event.type == 'pointerup')
+      decoration = new BoxDecoration(backgroundColor: backgroundColor);
+  }
+}
+
+AppView app;
+
+void main() {
+  RenderFlex flexRoot = new RenderFlex(direction: FlexDirection.Vertical);
+
+  RenderNode root = new RenderDecoratedBox(
+    decoration: new BoxDecoration(backgroundColor: 0xFF000000),
+    child: flexRoot
+  );
+
+  void addFlexChildSolidColor(RenderFlex parent, int backgroundColor, { int flex: 0 }) {
+    RenderNode child = new RenderSolidColor(backgroundColor);
+    parent.add(child);
+    child.parentData.flex = flex;
+  }
+
+  // Yellow bar at top
+  addFlexChildSolidColor(flexRoot, 0xFFFFFF00, flex: 1);
+
+  // Turquoise box
+  flexRoot.add(new RenderSolidColor(0x7700FFFF, desiredSize: new sky.Size(100.0, 100.0)));
+
+  // Green and cyan render block with padding
+  var renderBlock = new RenderBlock();
+
+  renderBlock.add(new RenderSolidColor(0xFF00FF00, desiredSize: new sky.Size(100.0, 50.0)));
+  renderBlock.add(new RenderSolidColor(0x7700FFFF, desiredSize: new sky.Size(50.0, 100.0)));
+
+  var renderDecoratedBlock = new RenderDecoratedBox(
+    decoration: new BoxDecoration(backgroundColor: 0xFFFFFFFF),
+    child: renderBlock
+  );
+
+  flexRoot.add(new RenderPadding(const EdgeDims(10.0, 10.0, 10.0, 10.0), renderDecoratedBlock));
+
+  var row = new RenderFlex(direction: FlexDirection.Horizontal);
+
+  // Purple and blue cells
+  addFlexChildSolidColor(row, 0x77FF00FF, flex: 1);
+  addFlexChildSolidColor(row, 0xFF0000FF, flex: 2);
+
+  var decoratedRow = new RenderDecoratedBox(
+    decoration: new BoxDecoration(backgroundColor: 0xFF333333),
+    child: row
+  );
+
+  flexRoot.add(decoratedRow);
+  decoratedRow.parentData.flex = 3;
+
+  app = new AppView(root);
+
+}