Split layout2.dart into several files

sky/sdk/lib/framework/rendering/render_block.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:sky' as sky;
+import 'render_box.dart';
+import 'render_node.dart';
+
+class BlockParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> { }
+
+class RenderBlock extends RenderBox with ContainerRenderNodeMixin<RenderBox, BlockParentData>,
+                                         RenderBoxContainerDefaultsMixin<RenderBox, BlockParentData> {
+  // lays out RenderBox children in a vertical stack
+  // uses the maximum width provided by the parent
+  // sizes itself to the height of its child stack
+
+  void setParentData(RenderBox child) {
+    if (child.parentData is! BlockParentData)
+      child.parentData = new BlockParentData();
+  }
+
+  // override this to report what dimensions you would have if you
+  // were laid out with the given constraints this can walk the tree
+  // if it must, but it should be as cheap as possible; just get the
+  // dimensions and nothing else (e.g. don't calculate hypothetical
+  // child positions if they're not needed to determine dimensions)
+  sky.Size getIntrinsicDimensions(BoxConstraints constraints) {
+    double height = 0.0;
+    double width = constraints.constrainWidth(constraints.maxWidth);
+    assert(width < double.INFINITY);
+    RenderBox child = firstChild;
+    BoxConstraints innerConstraints = new BoxConstraints(minWidth: width,
+                                                         maxWidth: width);
+    while (child != null) {
+      height += child.getIntrinsicDimensions(innerConstraints).height;
+      assert(child.parentData is BlockParentData);
+      child = child.parentData.nextSibling;
+    }
+
+    return new sky.Size(width, constraints.constrainHeight(height));
+  }
+
+  void performLayout() {
+    assert(constraints is BoxConstraints);
+    double width = constraints.constrainWidth(constraints.maxWidth);
+    double y = 0.0;
+    RenderBox child = firstChild;
+    while (child != null) {
+      child.layout(new BoxConstraints(minWidth: width, maxWidth: width), parentUsesSize: true);
+      assert(child.parentData is BlockParentData);
+      child.parentData.position = new sky.Point(0.0, y);
+      y += child.size.height;
+      child = child.parentData.nextSibling;
+    }
+    size = new sky.Size(width, constraints.constrainHeight(y));
+    assert(size.width < double.INFINITY);
+    assert(size.height < double.INFINITY);
+  }
+
+  void hitTestChildren(HitTestResult result, { sky.Point position }) {
+    defaultHitTestChildren(result, position: position);
+  }
+
+  void paint(RenderNodeDisplayList canvas) {
+    defaultPaint(canvas);
+  }
+
+}
+