code: function (redraw) {
              var cx, cy;
  
              this._keepCenter = true;
              cx = this._container.clientWidth / 2;
              cy = this._container.clientHeight / 2;
  
              var ix = ((this._image.w * this._zoomLevel) / 2) + (this._image.x * this._zoomLevel) + this._margin;
              var iy = ((this._image.h * this._zoomLevel) / 2) + (this._image.y * this._zoomLevel) + this._margin;
  
              var x = (cx == ix) ? 0 : (cx - ix) / this._zoomLevel;
              var y = (cy == iy) ? 0 : (cy - iy) / this._zoomLevel;
  
              this._image.move({x: x, y: y});
  
              if (redraw === true) {
                  this.redraw();
              }
          }
docs: Center image around the middle point of the drawing area
  @param redraw