handleDraggerDrag_(event) {
    if (this.dragging_) {
      const deltaX = event.clientX - this.startX_;
      const deltaY = event.clientY - this.startY_;
      const relativePosition = this.getRelativePosition_(deltaX, deltaY);
      this.currentResolution_ =
        this.getResolutionForPosition_(relativePosition);
      this.getMap().getView().setResolution(this.currentResolution_);
    }
  }
Handle dragger drag events.

@param {PointerEvent} event The drag event.
@private