Use Point, Size, and Rect in layout2.dart

sky/examples/raw/sector-layout.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:sky/framework/app.dart';
 import 'package:sky/framework/layout2.dart';
 
 const double kTwoPi = 2 * math.PI;
@@ skipping 246 matching lines @@
   }
 
   // paint origin is 0,0 of our circle
   // each sector then knows how to paint itself at its location
   void paint(RenderNodeDisplayList canvas) {
     // TODO(ianh): avoid code duplication
     super.paint(canvas);
     RenderSector child = firstChild;
     while (child != null) {
       assert(child.parentData is SectorChildListParentData);
-      canvas.paintChild(child, 0.0, 0.0);
+      canvas.paintChild(child, new sky.Point());

[Hixie, 2015/05/28 18:45:22]

I don't like the way this looks. It's not obvious that it's a zero point.
Maybe try sky.Point.ZERO and have that be a getter that returns a new 0,0 ?

       child = child.parentData.nextSibling;
     }
   }
 
 }
 
 class RenderSectorSlice extends RenderSectorWithChildren {
   // lays out RenderSector children in a stack
 
   RenderSectorSlice({
@@ skipping 99 matching lines @@
   }
 
   // paint origin is 0,0 of our circle
   // each sector then knows how to paint itself at its location
   void paint(RenderNodeDisplayList canvas) {
     // TODO(ianh): avoid code duplication
     super.paint(canvas);
     RenderSector child = firstChild;
     while (child != null) {
       assert(child.parentData is SectorChildListParentData);
-      canvas.paintChild(child, 0.0, 0.0);
+      canvas.paintChild(child, new sky.Point());
       child = child.parentData.nextSibling;
     }
   }
 
 }
 
 class RenderBoxToRenderSectorAdapter extends RenderBox {
 
   RenderBoxToRenderSectorAdapter({ double innerRadius: 0.0, RenderSector child }) :
     _innerRadius = innerRadius {
@@ skipping 58 matching lines @@
     layoutDone();
   }
 
   double width;
   double height;
 
   // paint origin is 0,0 of our circle
   void paint(RenderNodeDisplayList canvas) {
     super.paint(canvas);
     if (child != null)
-      canvas.paintChild(child, width/2.0, height/2.0);
+      canvas.paintChild(child, new sky.Point(width/2.0, height/2.0));

[Hixie, 2015/05/28 18:45:22]

We could replace width/height with a Rect and then use thatRect.center here.

   }
 
-  bool hitTest(HitTestResult result, { double x, double y }) {
+  bool hitTest(HitTestResult result, { sky.Point position }) {
+    double x = position.x;
+    double y = position.y;
     if (child == null)
       return false;
     // translate to our origin
     x -= width/2.0;
     y -= height/2.0;
     // convert to radius/theta
     double radius = math.sqrt(x*x+y*y);
     double theta = (math.atan2(x, -y) - math.PI/2.0) % kTwoPi;
     if (radius < innerRadius)
       return false;
@@ skipping 46 matching lines @@
   rootCircle.add(new RenderSolidColor(0xFF0000FF, desiredDeltaTheta: kTwoPi * 0.4));
   var stack = new RenderSectorSlice(padding: 2.0);
   stack.add(new RenderSolidColor(0xFFFFFF00, desiredDeltaRadius: 20.0));
   stack.add(new RenderSolidColor(0xFFFF9000, desiredDeltaRadius: 20.0));
   stack.add(new RenderSolidColor(0xFF00FF00));
   rootCircle.add(stack);
 
   var root = new RenderBoxToRenderSectorAdapter(innerRadius: 50.0, child: rootCircle);
   app = new AppView(root);
 }