Material light and dark themes for Sky widgets

sky/sdk/lib/widgets/switch.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 'package:sky/theme/colors.dart' as colors;
 import 'package:sky/theme/shadows.dart';
 
 import '../painting/shadows.dart';
 import '../rendering/box.dart';
 import 'basic.dart';
+import 'theme.dart';
 import 'toggleable.dart';
 export 'toggleable.dart' show ValueChanged;
 
-// TODO(jackson): This should change colors with the theme
-sky.Color _kThumbOnColor = colors.Purple[500];
 const sky.Color _kThumbOffColor = const sky.Color(0xFFFAFAFA);
-sky.Color _kTrackOnColor = new sky.Color(_kThumbOnColor.value & (0x80 << 24));
 const sky.Color _kTrackOffColor = const sky.Color(0x42000000);
 const double _kSwitchWidth = 35.0;
 const double _kThumbRadius = 10.0;
 const double _kSwitchHeight = _kThumbRadius * 2.0;
 const double _kTrackHeight = 14.0;
 const double _kTrackRadius = _kTrackHeight / 2.0;
 const double _kTrackWidth = _kSwitchWidth - (_kThumbRadius - _kTrackRadius) * 2.0;
 
 class Switch extends Toggleable {
   // TODO(jackson): Hit-test the switch so that it can respond to both taps and swipe gestures
 
   Switch({
     String key,
     bool value,
     ValueChanged onChanged
   }) : super(key: key, value: value, onChanged: onChanged);
 
   Size get size => const Size(_kSwitchWidth + 2.0, _kSwitchHeight + 2.0);
 
   void customPaintCallback(sky.Canvas canvas, Size size) {
-    sky.Color thumbColor = value ? _kThumbOnColor : _kThumbOffColor;
-    sky.Color trackColor = value ? _kTrackOnColor : _kTrackOffColor;
+    sky.Color thumbColor = _kThumbOffColor;
+    sky.Color trackColor = _kTrackOffColor;
+    if (value) {
+      thumbColor = Theme.of(this).primary[500];
+      trackColor = new sky.Color(thumbColor.value & 0x80FFFFFF);
+    }
 
     // Draw the track rrect
     sky.Paint paint = new sky.Paint()..color = trackColor;
     paint.setStyle(sky.PaintingStyle.fill);
     sky.Rect rect = new sky.Rect.fromLTRB(
       0.0,
       _kSwitchHeight / 2.0 - _kTrackHeight / 2.0,
       _kTrackWidth,
       _kSwitchHeight / 2.0 + _kTrackHeight / 2.0
     );
     sky.RRect rrect = new sky.RRect()..setRectXY(rect, _kTrackRadius, _kTrackRadius);
     canvas.drawRRect(rrect, paint);
 
     // Draw the raised thumb with a shadow
     paint.color = thumbColor;
     var builder = new ShadowDrawLooperBuilder();
     for (BoxShadow boxShadow in shadows[1])
       builder.addShadow(boxShadow.offset, boxShadow.color, boxShadow.blur);
     paint.setDrawLooper(builder.build());
 
     // The thumb contracts slightly during the animation
     double inset = 2.0 - (toggleAnimation.value - 0.5).abs() * 2.0;
     Point thumbPos = new Point(
       _kTrackRadius + toggleAnimation.value * (_kTrackWidth - _kTrackRadius * 2),
       _kSwitchHeight / 2.0
     );
     canvas.drawCircle(thumbPos.x, thumbPos.y, _kThumbRadius - inset, paint);
   }
 }