code: function getSplinePath(points, isInCircle, constaint) {
      var data = [];
      var first = points[0];
      var prePoint = null;
      if (points.length <= 2) {
        return PathUtil.getLinePath(points, isInCircle);
      }
      Util.each(points, function (point) {
        if (!prePoint || !(prePoint.x === point.x && prePoint.y === point.y)) {
          data.push(point.x);
          data.push(point.y);
          prePoint = point;
        }
      });
      constaint = constaint || [// 范围
      [0, 0], [1, 1]];
      var splinePath = Spline.catmullRom2bezier(data, isInCircle, constaint);
      splinePath.unshift(['M', first.x, first.y]);
      return splinePath;
    }
docs: get spline： 限定了范围的平滑线