Use Point, Size, and Rect in layout2.dart

sky/examples/raw/sector-layout.dart

Index: sky/examples/raw/sector-layout.dart
diff --git a/sky/examples/raw/sector-layout.dart b/sky/examples/raw/sector-layout.dart
index 3b6d388edf96a9d4819d3d89489904e424d960de..2e7483996e30bc6c4b31bd245a5ed103db837f4a 100644
--- a/sky/examples/raw/sector-layout.dart
+++ b/sky/examples/raw/sector-layout.dart
@@ -264,7 +264,7 @@ class RenderSectorRing extends RenderSectorWithChildren {
     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;
     }
   }
@@ -384,7 +384,7 @@ class RenderSectorSlice extends RenderSectorWithChildren {
     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;
     }
   }
@@ -463,10 +463,12 @@ class RenderBoxToRenderSectorAdapter extends RenderBox {
   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