_calculatePanForZoomLevel(axis, currZoomLevel) {
    const zoomFactor = currZoomLevel / this._startZoomLevel;
    return this._zoomPoint[axis] - (this._startZoomPoint[axis] - this._startPan[axis]) * zoomFactor;
  }
@private
@param {'x' | 'y'} axis
@param {number} currZoomLevel
@returns {number}