update () {
    const { elem } = this
    if (getRotationAngle(elem)) {
      this.matrix = getMatrix(elem)
      this.imatrix = this.matrix.inverse()
    } else {
      this.matrix = null
      this.imatrix = null
    }

    this.eachSeg(function (i) {
      this.item = elem.pathSegList.getItem(i)
      this.update()
    })

    return this
  }
Update position of all points.
@returns {Path}