code: function computePathBox(path) {
              var points = [];
              if (arguments.length === 1) {
                  points = path;
              }
              else {
                  for (var i = 0, l = arguments.length; i < l; i++) {
                      Array.prototype.splice.apply(points, [points.length, 0].concat(arguments[i]));
                  }
              }
              return computeBoundingBox(points);
          }
docs: 计算曲线点边界
  
  @private
  @param {Array} path path对象, 支持多个path
  @return {Object} {x, y, width, height}