_onScaling(fEvent) {
      const selectedCorner = fEvent.transform.corner;
      const pointer = this.canvas.getPointer(fEvent.e);
      const settings = this._calcScalingSizeFromPointer(pointer, selectedCorner);

      // On scaling cropzone,
      // change real width and height and fix scaleFactor to 1
      this.scale(1).set(settings);

      this.canvasEventTrigger[events.OBJECT_SCALED](this);
    }
onScaling event listener
@param {{e: MouseEvent}} fEvent - Fabric event
@private