Refactor fn2.dart, since it breached our 1000-line threshold.

sky/sdk/lib/framework/components2/checkbox.dart

Index: sky/sdk/lib/framework/components2/checkbox.dart
diff --git a/sky/sdk/lib/framework/components2/checkbox.dart b/sky/sdk/lib/framework/components2/checkbox.dart
deleted file mode 100644
index 36fd278dbdbe9bfe133dc2d80b550616bc1a35c7..0000000000000000000000000000000000000000
--- a/sky/sdk/lib/framework/components2/checkbox.dart
+++ /dev/null
@@ -1,72 +0,0 @@
-// 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 'package:sky/framework/theme2/colors.dart' as colors;
-
-import 'dart:sky' as sky;
-import '../fn2.dart';
-import '../rendering/box.dart';
-import '../rendering/object.dart';
-import 'button_base.dart';
-
-typedef void ValueChanged(value);
-
-class Checkbox extends ButtonBase {
-
-  Checkbox({ Object key, this.onChanged, this.checked }) : super(key: key);
-
-  bool checked;
-  ValueChanged onChanged;
-
-  void syncFields(Checkbox source) {
-    checked = source.checked;
-    onChanged = source.onChanged;
-    super.syncFields(source);
-  }
-
-  void _handleClick(sky.Event e) {
-    onChanged(!checked);
-  }
-
-  UINode buildContent() {
-    // TODO(jackson): This should change colors with the theme
-    sky.Color color = highlight ? colors.Purple[500] : const sky.Color(0x8A000000);
-    const double kEdgeSize = 20.0;
-    const double kEdgeRadius = 1.0;
-    return new EventListenerNode(
-      new Container(
-        margin: const EdgeDims.symmetric(horizontal: 5.0),
-        width: kEdgeSize + 2.0,
-        height: kEdgeSize + 2.0,
-        child: new CustomPaint(
-          callback: (sky.Canvas canvas, Size size) {
-
-            sky.Paint paint = new sky.Paint()..color = color
-                                             ..strokeWidth = 2.0;
-
-            // Draw the outer rrect
-            paint.setStyle(checked ? sky.PaintingStyle.strokeAndFill : sky.PaintingStyle.stroke);
-            sky.Rect rect = new sky.Rect.fromLTRB(0.0, 0.0, kEdgeSize, kEdgeSize);
-            sky.RRect rrect = new sky.RRect()..setRectXY(rect, kEdgeRadius, kEdgeRadius);
-            canvas.drawRRect(rrect, paint);
-
-            // Draw the inner check
-            if (checked) {
-              // TODO(jackson): Use the theme color
-              paint.color = const sky.Color(0xFFFFFFFF);
-              paint.setStyle(sky.PaintingStyle.stroke);
-              sky.Path path = new sky.Path();
-              path.moveTo(kEdgeSize * 0.2, kEdgeSize * 0.5);
-              path.lineTo(kEdgeSize * 0.4, kEdgeSize * 0.7);
-              path.lineTo(kEdgeSize * 0.8, kEdgeSize * 0.3);
-              canvas.drawPath(path, paint);
-            }
-          }
-        )
-      ),
-      onGestureTap: _handleClick
-    );
-  }
-
-}