Factor BoxPainter out of RenderDecoratedBox

sky/sdk/lib/framework/rendering/box.dart

Index: sky/sdk/lib/framework/rendering/box.dart
diff --git a/sky/sdk/lib/framework/rendering/box.dart b/sky/sdk/lib/framework/rendering/box.dart
index e1a4545cd9561fbc003ab278db0ea5659b11345b..efbef3d22a0389e8513ed24e912b12e8e30c1590 100644
--- a/sky/sdk/lib/framework/rendering/box.dart
+++ b/sky/sdk/lib/framework/rendering/box.dart
@@ -6,10 +6,12 @@ import 'dart:math' as math;
 import 'dart:sky' as sky;
 import 'dart:typed_data';
 import 'object.dart';
-import '../painting/shadows.dart';
+import '../painting/box_painter.dart';
 import 'package:vector_math/vector_math.dart';
 import 'package:sky/framework/net/image_cache.dart' as image_cache;
 
+export '../painting/box_painter.dart';
+
 // GENERIC BOX RENDERING
 // Anything that has a concept of x, y, width, height is going to derive from this
 
@@ -686,262 +688,31 @@ class RenderImage extends RenderBox {
   String debugDescribeSettings(String prefix) => '${super.debugDescribeSettings(prefix)}${prefix}url: ${src}\n${prefix}dimensions: ${requestedSize}\n';
 }
 
-class BorderSide {
-  const BorderSide({
-    this.color: const Color(0xFF000000),
-    this.width: 1.0
-  });
-  final Color color;
-  final double width;
-
-  static const none = const BorderSide(width: 0.0);
-
-  int get hashCode {
-    int value = 373;
-    value = 37 * value * color.hashCode;
-    value = 37 * value * width.hashCode;
-    return value;
-  }
-  String toString() => 'BorderSide($color, $width)';
-}
-
-class Border {
-  const Border({
-    this.top: BorderSide.none,
-    this.right: BorderSide.none,
-    this.bottom: BorderSide.none,
-    this.left: BorderSide.none
-  });
-
-  const Border.all(BorderSide side) :
-    top = side,
-    right = side,
-    bottom = side,
-    left = side;
-
-  final BorderSide top;
-  final BorderSide right;
-  final BorderSide bottom;
-  final BorderSide left;
-
-  int get hashCode {
-    int value = 373;
-    value = 37 * value * top.hashCode;
-    value = 37 * value * right.hashCode;
-    value = 37 * value * bottom.hashCode;
-    value = 37 * value * left.hashCode;
-    return value;
-  }
-  String toString() => 'Border($top, $right, $bottom, $left)';
-}
-
-class BoxShadow {
-  const BoxShadow({
-    this.color,
-    this.offset,
-    this.blur
-  });
-
-  final Color color;
-  final Size offset;
-  final double blur;
-
-  String toString() => 'BoxShadow($color, $offset, $blur)';
-}
-
-abstract class Gradient {
-  sky.Shader createShader();
-}
-
-class LinearGradient extends Gradient {
-  LinearGradient({
-    this.endPoints,
-    this.colors,
-    this.colorStops,
-    this.tileMode: sky.TileMode.clamp
-  });
-
-  String toString() =>
-      'LinearGradient($endPoints, $colors, $colorStops, $tileMode)';
-
-  sky.Shader createShader() {
-    return new sky.Gradient.Linear(this.endPoints, this.colors, this.colorStops,
-                                   this.tileMode);
-  }
-
-  final List<Point> endPoints;
-  final List<Color> colors;
-  final List<double> colorStops;
-  final sky.TileMode tileMode;
-}
-
-class RadialGradient extends Gradient {
-  RadialGradient({
-    this.center,
-    this.radius,
-    this.colors,
-    this.colorStops,
-    this.tileMode: sky.TileMode.clamp
-  });
-
-  String toString() =>
-      'RadialGradient($center, $radius, $colors, $colorStops, $tileMode)';
-
-  sky.Shader createShader() {
-    return new sky.Gradient.Radial(this.center, this.radius, this.colors,
-                                   this.colorStops, this.tileMode);
-  }
-
-  final Point center;
-  final double radius;
-  final List<Color> colors;
-  final List<double> colorStops;
-  final sky.TileMode tileMode;
-}
-
-// This must be immutable, because we won't notice when it changes
-class BoxDecoration {
-  const BoxDecoration({
-    this.backgroundColor,
-    this.border,
-    this.borderRadius,
-    this.boxShadow,
-    this.gradient
-  });
-
-  final Color backgroundColor;
-  final double borderRadius;
-  final Border border;
-  final List<BoxShadow> boxShadow;
-  final Gradient gradient;
-
-  String toString([String prefix = '']) {
-    List<String> result = [];
-    if (backgroundColor != null)
-      result.add('${prefix}backgroundColor: $backgroundColor');
-    if (border != null)
-      result.add('${prefix}border: $border');
-    if (borderRadius != null)
-      result.add('${prefix}borderRadius: $borderRadius');
-    if (boxShadow != null)
-      result.add('${prefix}boxShadow: ${boxShadow.map((shadow) => shadow.toString())}');
-    if (gradient != null)
-      result.add('${prefix}gradient: $gradient');
-    if (result.isEmpty)
-      return '${prefix}<no decorations specified>';
-    return result.join('\n');
-  }
-}
-
 class RenderDecoratedBox extends RenderProxyBox {
 
   RenderDecoratedBox({
     BoxDecoration decoration,
     RenderBox child
-  }) : _decoration = decoration, super(child) {
-    assert(_decoration != null);
-  }
+  }) : _painter = new BoxPainter(decoration), super(child);
 
-  BoxDecoration _decoration;
-  BoxDecoration get decoration => _decoration;
+  BoxPainter _painter;
+  BoxDecoration get decoration => _painter.decoration;
   void set decoration (BoxDecoration value) {
     assert(value != null);
-    if (value == _decoration)
+    if (value == _painter.decoration)
       return;
-    _decoration = value;
-    _cachedBackgroundPaint = null;
+    _painter.decoration = value;
     markNeedsPaint();
   }
 
-  Paint _cachedBackgroundPaint;
-  Paint get _backgroundPaint {
-    if (_cachedBackgroundPaint == null) {
-      Paint paint = new Paint();
-
-      if (_decoration.backgroundColor != null)
-        paint.color = _decoration.backgroundColor;
-
-      if (_decoration.boxShadow != null) {
-        var builder = new ShadowDrawLooperBuilder();
-        for (BoxShadow boxShadow in _decoration.boxShadow)
-          builder.addShadow(boxShadow.offset, boxShadow.color, boxShadow.blur);
-        paint.setDrawLooper(builder.build());
-      }
-
-      if (_decoration.gradient != null)
-        paint.setShader(_decoration.gradient.createShader());
-
-      _cachedBackgroundPaint = paint;
-    }
-
-    return _cachedBackgroundPaint;
-  }
-
   void paint(RenderObjectDisplayList canvas) {
     assert(size.width != null);
     assert(size.height != null);
-
-    if (_decoration.backgroundColor != null || _decoration.boxShadow != null ||
-        _decoration.gradient != null) {
-      Rect rect = new Rect.fromLTRB(0.0, 0.0, size.width, size.height);
-      if (_decoration.borderRadius == null)
-        canvas.drawRect(rect, _backgroundPaint);
-      else
-        canvas.drawRRect(new sky.RRect()..setRectXY(rect, _decoration.borderRadius, _decoration.borderRadius), _backgroundPaint);
-    }
-
-    if (_decoration.border != null) {
-      assert(_decoration.borderRadius == null); // TODO(abarth): Implement borders with border radius.
-
-      assert(_decoration.border.top != null);
-      assert(_decoration.border.right != null);
-      assert(_decoration.border.bottom != null);
-      assert(_decoration.border.left != null);
-
-      Paint paint = new Paint();
-      Path path;
-
-      paint.color = _decoration.border.top.color;
-      path = new Path();
-      path.moveTo(0.0,0.0);
-      path.lineTo(_decoration.border.left.width, _decoration.border.top.width);
-      path.lineTo(size.width - _decoration.border.right.width, _decoration.border.top.width);
-      path.lineTo(size.width, 0.0);
-      path.close();
-      canvas.drawPath(path, paint);
-
-      paint.color = _decoration.border.right.color;
-      path = new Path();
-      path.moveTo(size.width, 0.0);
-      path.lineTo(size.width - _decoration.border.right.width, _decoration.border.top.width);
-      path.lineTo(size.width - _decoration.border.right.width, size.height - _decoration.border.bottom.width);
-      path.lineTo(size.width, size.height);
-      path.close();
-      canvas.drawPath(path, paint);
-
-      paint.color = _decoration.border.bottom.color;
-      path = new Path();
-      path.moveTo(size.width, size.height);
-      path.lineTo(size.width - _decoration.border.right.width, size.height - _decoration.border.bottom.width);
-      path.lineTo(_decoration.border.left.width, size.height - _decoration.border.bottom.width);
-      path.lineTo(0.0, size.height);
-      path.close();
-      canvas.drawPath(path, paint);
-
-      paint.color = _decoration.border.left.color;
-      path = new Path();
-      path.moveTo(0.0, size.height);
-      path.lineTo(_decoration.border.left.width, size.height - _decoration.border.bottom.width);
-      path.lineTo(_decoration.border.left.width, _decoration.border.top.width);
-      path.lineTo(0.0,0.0);
-      path.close();
-      canvas.drawPath(path, paint);
-    }
-
+    _painter.paint(canvas, new Rect.fromSize(size));
     super.paint(canvas);
   }
 
-  String debugDescribeSettings(String prefix) => '${super.debugDescribeSettings(prefix)}${prefix}decoration:\n${decoration.toString(prefix + "  ")}\n';
+  String debugDescribeSettings(String prefix) => '${super.debugDescribeSettings(prefix)}${prefix}decoration:\n${_painter.decoration.toString(prefix + "  ")}\n';
 }
 
 class RenderTransform extends RenderProxyBox {