Roll Observatory packages and add a roll script

charted/lib/svg/shapes/arc.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;
-
-///
-/// [SvgArc] provides a data-driven way to create path descriptions
-/// that can be used to draw arcs - like those used in pie-charts.
-///
-class SvgArc implements SvgShape {
-  static const _OFFSET = -HALF_PI;
-  static const _MAX = TAU - EPSILON;
-
-  /// [innerRadiusCallback] is called to get inner radius of the arc.
-  /// As with other callbacks, [innerRadiusCallback] is passed data, index
-  /// and element in the context.
-  final SelectionCallback<num> innerRadiusCallback;
-
-  /// [outerRadiusCallback] is called to get outer radius of the arc.
-  /// As with other callbacks, [outerRadiusCallback] is passed data, index
-  /// and element in the context.
-  final SelectionCallback<num> outerRadiusCallback;
-
-  /// [startAngleCallback] is called to get the start angle of the arc.
-  /// As with other callbacks, [startAngleCallback] is passed data, index
-  /// and element in the context.
-  final SelectionCallback<num> startAngleCallback;
-
-  /// [endAngleCallback] is called to get the start angle of the arc.
-  /// As with other callbacks, [endAngleCallback] is passed data, index
-  /// and element in the context.
-  final SelectionCallback<num> endAngleCallback;
-
-  SvgArc({
-      this.innerRadiusCallback : defaultInnerRadiusCallback,
-      this.outerRadiusCallback: defaultOuterRadiusCallback,
-      this.startAngleCallback: defaultStartAngleCallback,
-      this.endAngleCallback: defaultEndAngleCallback
-  });
-
-  String path(d, int i, Element e) {
-    var ir = innerRadiusCallback(d, i, e),
-        or = outerRadiusCallback(d, i, e),
-        start = startAngleCallback(d, i, e) + _OFFSET,
-        end = endAngleCallback(d, i, e) + _OFFSET,
-        sa = math.min(start, end),
-        ea = math.max(start, end),
-        delta = ea - sa;
-
-    if (delta > _MAX) {
-      return ir > 0
-          ? "M0,$or" "A$or,$or 0 1,1 0,-$or" "A$or,$or 0 1,1 0,$or"
-            "M0,$ir" "A$ir,$ir 0 1,0 0,-$ir" "A$ir,$ir 0 1,0 0,$ir" "Z"
-          : "M0,$or" "A$or,$or 0 1,1 0,-$or" "A$or,$or 0 1,1 0,$or" "Z";
-    }
-
-    var ss = math.sin(sa),
-        se = math.sin(ea),
-        cs = math.cos(sa),
-        ce = math.cos(ea),
-        df = delta < PI ? 0 : 1;
-
-    return ir > 0
-        ? "M${or * cs},${or * ss}" "A$or,$or 0 $df,1 ${or * ce},${or * se}"
-          "L${ir * ce},${ir * se}" "A$ir,$ir 0 $df,0 ${ir * cs},${ir * ss}"
-          "Z"
-        : "M${or * cs},${or * ss}" "A$or,$or 0 $df,1 ${or * ce},${or * se}"
-          "L0,0" "Z";
-  }
-
-  List centroid(d, int i, Element e) {
-    var r = (innerRadiusCallback(d, i, e) + outerRadiusCallback(d, i, e)) / 2,
-        a = (startAngleCallback(d, i, e) + endAngleCallback(d, i, e)) / 2 -
-            math.PI / 2;
-    return [math.cos(a) * r, math.sin(a) * r];
-  }
-
-  /// Default [innerRadiusCallback] returns data.innerRadius
-  static num defaultInnerRadiusCallback(d, i, e) =>
-      d is! SvgArcData || d.innerRadius == null ? 0 : d.innerRadius;
-
-  /// Default [outerRadiusCallback] returns data.outerRadius
-  static num defaultOuterRadiusCallback(d, i, e) =>
-      d is! SvgArcData || d.outerRadius == null ? 0 : d.outerRadius;
-
-  /// Default [startAngleCallback] returns data.startAngle
-  static num defaultStartAngleCallback(d, i, e) =>
-      d is! SvgArcData || d.startAngle == null ? 0 : d.startAngle;
-
-  /// Default [endAngleCallback] that returns data.endAngle
-  static num defaultEndAngleCallback(d, i, e) =>
-      d is! SvgArcData || d.endAngle == null ? 0 : d.endAngle;
-}
-
-/// Value type for SvgArc as used by default property accessors in SvgArc
-class SvgArcData {
-  dynamic data;
-  num value;
-  num innerRadius;
-  num outerRadius;
-  num startAngle;
-  num endAngle;
-
-  SvgArcData(this.data, this.value,
-      this.startAngle, this.endAngle, [
-      this.innerRadius = 0, this.outerRadius = 100 ]);
-}
-
-
-/// Returns the interpolator between two [SvgArcData] [a] and [b].
-///
-/// The interpolator will interpolate the older innerRadius and outerRadius with
-/// newer ones, as well as older startAngle and endAngle with newer ones.
-Interpolator interpolateSvgArcData(SvgArcData a, SvgArcData b) {
-  var ast = a.startAngle,
-      aen = a.endAngle,
-      ai = a.innerRadius,
-      ao = a.outerRadius,
-      bst = b.startAngle - ast,
-      ben = b.endAngle - aen,
-      bi = b.innerRadius - ai,
-      bo = b.outerRadius - ao;
-
-  return (t) => new SvgArcData(b.data, b.value,
-    (ast + bst * t), (aen + ben * t), (ai + bi * t), (ao + bo * t));
-}