docs: function (shouldNotCenter) {
              var state = this.state,
                  zoomState = state.zoomState,
                  ratio = zoomState.zoom / zoomState.prevZoom,
                  newScrollLeft, newScrollTop;
  
              // update scroll position
              newScrollLeft = state.scrollLeft * ratio;
              newScrollTop = state.scrollTop * ratio;
  
              // zoom to center
              if (shouldNotCenter !== true) {
                  newScrollTop += state.viewportDimensions.offsetHeight * (ratio - 1) / 2;
                  newScrollLeft += state.viewportDimensions.offsetWidth * (ratio - 1) / 2;
              }
  
              // scroll!
              this.scrollToOffset(newScrollLeft, newScrollTop);
          }