fixForZoom(fn) {
      return (p) => this.fixForZoomWrapper(p, fn);
    }
Wrap point operations to convert zoomed coords from screen to image and back
Good for event handlers, receiving screen coords, but working with image coords
Accepts both [x, y] and {x, y} points; preserves this format
@param {PointFn} fn wrapped function do some math with image coords
@return {PointFn} outer function do some math with screen coords