Basic line charts

packages/playfair/lib/playfair.dart

@@ -4,5 +4,10 @@
 
 library playfair;
 
-import 'dart:math' as math;
+import 'dart:sky' as sky;
 
+import 'package:sky/widgets/framework.dart';
+import 'package:sky/rendering/box.dart';
+import 'package:sky/rendering/object.dart';
+
+part 'src/base.dart';

packages/playfair/lib/src/base.dart

@@ -0,0 +1,96 @@
+// 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.
+
+part of playfair;
+
+class ChartData {
+  const ChartData({ this.startX, this.endX, this.startY, this.endY, this.dataSet });
+  final double startX;
+  final double endX;
+  final double startY;
+  final double endY;
+  final List<sky.Point> dataSet;
+}
+
+class Chart extends LeafRenderObjectWrapper {
+  Chart({ Key key, this.data }) : super(key: key);
+
+  final ChartData data;
+
+  RenderChart createNode() => new RenderChart(data: data);
+  RenderChart get root => super.root;
+
+  void syncRenderObject(Widget old) {
+    super.syncRenderObject(old);
+    root.data = data;
+  }
+}
+
+class RenderChart extends RenderConstrainedBox {
+
+  RenderChart({
+    ChartData data
+  }) : _painter = new ChartPainter(data),
+       super(child: null, additionalConstraints: BoxConstraints.expand);
+
+  final ChartPainter _painter;
+
+  ChartData get data => _painter.data;
+  void set data (ChartData value) {
+    assert(value != null);
+    if (value == _painter.data)
+      return;
+    _painter.data = value;
+    markNeedsPaint();
+  }
+
+  void paint(PaintingCanvas canvas, Offset offset) {
+    assert(size.width != null);
+    assert(size.height != null);
+    _painter.paint(canvas, offset & size);
+    super.paint(canvas, offset);
+  }
+}
+
+class ChartPainter {
+  ChartPainter(this.data);
+
+  ChartData data;
+
+  Point _convertPointToRectSpace(sky.Point point, Rect rect) {
+    double x = rect.left + ((point.x - data.startX) / (data.endX - data.startX)) * rect.width;
+    double y = rect.bottom - ((point.y - data.startY) / (data.endY - data.startY)) * rect.height;
+    return new Point(x, y);
+  }
+
+  void _paintChart(sky.Canvas canvas, Rect rect) {
+    Paint paint = new Paint()
+      ..strokeWidth = 2.0
+      ..color = const Color(0xFF000000);
+    List<sky.Point> dataSet = data.dataSet;
+    assert(dataSet != null);
+    assert(dataSet.length > 0);
+    Path path = new Path();
+    Point start = _convertPointToRectSpace(data.dataSet[0], rect);
+    path.moveTo(start.x, start.y);
+    for(sky.Point point in data.dataSet) {
+      Point current = _convertPointToRectSpace(point, rect);
+      canvas.drawCircle(current, 3.0, paint);
+      path.lineTo(current.x, current.y);
+    }
+    paint.setStyle(sky.PaintingStyle.stroke);
+    canvas.drawPath(path, paint);
+  }
+
+  void _paintScale(sky.Canvas canvas, Rect rect) {
+    Paint paint = new Paint()..color = const Color(0xFF000000);
+    canvas.drawText("${data.startY}", rect.bottomRight, paint);
+    canvas.drawText("${data.endY}", rect.topRight, paint);
+  }
+
+  void paint(sky.Canvas canvas, Rect rect) {
+    _paintChart(canvas, rect);
+    _paintScale(canvas, rect);
+  }
+}

packages/playfair/test/playfair_test.dart

@@ -1,12 +1,13 @@
-// Copyright (c) 2015 The Chromium Authors. All rights reserved.
+// 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.
 
 library playfair.test;
 
-import 'package:test/test.dart';
+// import 'package:test/test.dart';
 
-import 'package:playfair/playfair.dart';
+// import 'package:playfair/playfair.dart';
 
 void main() {
+  // TODO(jackson): Tests
 }