code: function (graphicModel, api) {
          var elOptions = graphicModel.option.elements;
          var rootGroup = this.group;
          var elMap = this._elMap;
  
          // Bottom-up tranvese all elements (consider ec resize) to locate elements.
          for (var i = elOptions.length - 1; i >= 0; i--) {
              var elOption = elOptions[i];
              var el = elMap.get(elOption.id);
  
              if (!el) {
                  continue;
              }
  
              var parentEl = el.parent;
              var containerInfo = parentEl === rootGroup
                  ? {
                      width: api.getWidth(),
                      height: api.getHeight()
                  }
                  : { // Like 'position:absolut' in css, default 0.
                      width: parentEl.__ecGraphicWidth || 0,
                      height: parentEl.__ecGraphicHeight || 0
                  };
  
              layoutUtil.positionElement(
                  el, elOption, containerInfo, null,
                  {hv: elOption.hv, boundingMode: elOption.bounding}
              );
          }
      }
docs: Locate graphic elements.
  
  @private
  @param {Object} graphicModel graphic model
  @param {module:echarts/ExtensionAPI} api extension API