Roll Observatory packages and add a roll script

charted/lib/svg/shapes/line.dart

-//
-// Copyright 2014 Google Inc. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-//
-
-part of charted.svg.shapes;
-
-/// Function to convert a list of points to path.
-typedef String LineInterpolator(Iterable<math.Point> points, int tension);
-
-///
-/// [SvgLine] provides a data-driven way to create path descriptions
-/// that can be used to draw lines.
-///
-class SvgLine implements SvgShape {
-  static const LINE_INTERPOLATOR_LINEAR = 'linear';
-
-  static final LINE_INTERPOLATORS = {
-    LINE_INTERPOLATOR_LINEAR: _linear
-  };
-
-  /// Callback to access/convert datum to x coordinate value.
-  final SelectionValueAccessor<num> xValueAccessor;
-
-  /// Callback to access/convert datum to y coordinate value.
-  final SelectionValueAccessor<num> yValueAccessor;
-
-  /// Callback that is used to determine if a value is considered valid.
-  /// If [isDefined] returns false at any time, the value isn't part
-  /// of the line - the line would be split.
-  final SelectionCallback<bool> isDefined;
-
-  /// Interpolator that is used for creating the path.
-  final LineInterpolator interpolator;
-
-  /// Tension of the line, as used by a few interpolators.
-  final int tension;
-
-  SvgLine({
-      this.xValueAccessor: defaultDataToX,
-      this.yValueAccessor: defaultDataToY,
-      this.isDefined: defaultIsDefined,
-      this.tension: 0,
-      String interpolate: LINE_INTERPOLATOR_LINEAR })
-      : interpolator = LINE_INTERPOLATORS[interpolate] {
-    assert(interpolator != null);
-  }
-
-  /// Generates path for drawing a line based in the selected [interpolator]
-  @override
-  String path(data, int index, Element e) {
-    assert(data is Iterable);
-    var segments = new StringBuffer(),
-        points = [];
-    for (int i = 0, len = data.length; i < len; ++i) {
-      final d = data.elementAt(i);
-      if (isDefined(d, i, e)) {
-        points.add(new math.Point(xValueAccessor(d, i), yValueAccessor(d, i)));
-      } else if (points.isNotEmpty){
-        segments.write('M${interpolator(points, tension)}');
-        points.clear();
-      }
-    }
-    if (points.isNotEmpty) {
-      segments.write('M${interpolator(points, tension)}');
-    }
-    return segments.toString();
-  }
-
-  /// Default implementation of [xValueAccessor].
-  /// Returns the first element if [d] is an iterable, otherwise returns [d].
-  static num defaultDataToX(d, i) => d is Iterable ? d.first : d;
-
-  /// Default implementation of [yValueAccessor].
-  /// Returns the second element if [d] is an iterable, otherwise returns [d].
-  static num defaultDataToY(d, i) => d is Iterable ? d.elementAt(1) : d;
-
-  /// Default implementation of [isDefined].
-  /// Returns true for all non-null values of [d].
-  static bool defaultIsDefined(d, i, e) => d != null;
-
-  /// Linear interpolator.
-  static String _linear(Iterable points, _) =>
-      points.map((pt) => '${pt.x},${pt.y}').join('L');
-}