code: function (data, callback, start, end) {
          start == null && (start = 0);
          end == null && (end = data.count());
  
          var axesMap = this._axesMap;
          var dimensions = this.dimensions;
          var dataDimensions = [];
          var axisModels = [];
  
          zrUtil.each(dimensions, function (axisDim) {
              dataDimensions.push(data.mapDimension(axisDim));
              axisModels.push(axesMap.get(axisDim).model);
          });
  
          var hasActiveSet = this.hasAxisBrushed();
  
          for (var dataIndex = start; dataIndex < end; dataIndex++) {
              var activeState;
  
              if (!hasActiveSet) {
                  activeState = 'normal';
              }
              else {
                  activeState = 'active';
                  var values = data.getValues(dataDimensions, dataIndex);
                  for (var j = 0, lenj = dimensions.length; j < lenj; j++) {
                      var state = axisModels[j].getActiveState(values[j]);
  
                      if (state === 'inactive') {
                          activeState = 'inactive';
                          break;
                      }
                  }
              }
  
              callback(activeState, dataIndex);
          }
      }
docs: Travel data for one time, get activeState of each data item.
  @param {module:echarts/data/List} data
  @param {Functio} cb param: {string} activeState 'active' or 'inactive' or 'normal'
  {number} dataIndex
  @param {number} [start=0] the start dataIndex that travel from.
  @param {number} [end=data.count()] the next dataIndex of the last dataIndex will be travel.