getViewport({
    scale,
    rotation = this.rotate,
    offsetX = 0,
    offsetY = 0,
    dontFlip = false,
  } = {}) {
    return new PageViewport({
      viewBox: this.view,
      userUnit: this.userUnit,
      scale,
      rotation,
      offsetX,
      offsetY,
      dontFlip,
    });
  }
@param {GetViewportParameters} params - Viewport parameters.
@returns {PageViewport} Contains 'width' and 'height' properties
  along with transforms required for rendering.