Modified sunflower

test/codegen/sunflower/sunflower.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library sunflower;
 
 import 'dart:math';
+
+import 'circle.dart';
 import 'dom.dart';
+import 'painter.dart';
 
-const ORANGE = "orange";
 const SEED_RADIUS = 2;
 const SCALE_FACTOR = 4;
-const TAU = PI * 2;
 const MAX_D = 300;
 const centerX = MAX_D / 2;
 const centerY = centerX;
 
-Element querySelector(String selector) => document.querySelector(selector);
-
-final InputElement slider = querySelector("#slider");
+final slider = querySelector("#slider") as InputElement;
 final notes = querySelector("#notes");
 final PHI = (sqrt(5) + 1) / 2;
 int seeds = 0;
-final CanvasRenderingContext2D context =
-    (querySelector("#canvas") as CanvasElement).getContext('2d');
 
 void main() {
   slider.addEventListener('change', (e) => draw());
   draw();
 }
 
 /// Draw the complete figure for the current number of seeds.
 void draw() {
   seeds = int.parse(slider.value);
   context.clearRect(0, 0, MAX_D, MAX_D);
   for (var i = 0; i < seeds; i++) {
     final theta = i * TAU / PHI;
     final r = sqrt(i) * SCALE_FACTOR;
     final x = centerX + r * cos(theta);
     final y = centerY - r * sin(theta);
     new SunflowerSeed(x, y, SEED_RADIUS).draw();
   }
   notes.textContent = "$seeds seeds";
 }
 
 // This example was modified to use classes and mixins.
 class SunflowerSeed extends Circle with CirclePainter {
   SunflowerSeed(num x, num y, num radius, [String color])
   : super(x, y, radius) {
     if (color != null) this.color = color;
   }
 }
 
-abstract class CirclePainter implements Circle {
-  // This demonstrates a field in a mixin.
-  String color = ORANGE;
 
-  /// Draw a small circle representing a seed centered at (x,y).
-  void draw() {
-    context
-      ..beginPath()
-      ..lineWidth = 2
-      ..fillStyle = color
-      ..strokeStyle = color
-      ..arc(x, y, radius, 0, TAU, false)
-      ..fill()
-      ..closePath()
-      ..stroke();
-  }
-}
-
-class Circle {
-  final num x, y, radius;
-
-  Circle(this.x, this.y, this.radius);
-}