code: function(bounds, worldBounds) {
          this.featureDx = 0;
          if (worldBounds) {
              var worldWidth = worldBounds.getWidth(),
                  rendererCenterX = (this.extent.left + this.extent.right) / 2,
                  featureCenterX = (bounds.left + bounds.right) / 2,
                  worldsAway = Math.round((featureCenterX - rendererCenterX) / worldWidth);
              this.featureDx = worldsAway * worldWidth;
          }
      }
docs: Method: calculateFeatureDx
  {Number} Calculates the feature offset in x direction. Looking at the
  center of the feature bounds and the renderer extent, we calculate how
  many world widths the two are away from each other. This distance is
  used to shift the feature as close as possible to the center of the
  current enderer extent, which ensures that the feature is visible in the
  current viewport.
  
  Parameters:
  bounds - {<OpenLayers.Bounds>} Bounds of the feature
  worldBounds - {<OpenLayers.Bounds>} Bounds of the world