var geometryParam = new SuperMap.REST.GetFeaturesByGeometryParameters({
    datasetNames: datasetNames,
    geometry: region,
    attributeFilter: attributeFilter,
    toIndex:-1,
    spatialQueryMode: SuperMap.REST.SpatialQueryMode.INTERSECT
});
var getFeaturesByGeometryService =
    new SuperMap.REST.GetFeaturesByGeometryService(dataUrl, {
        eventListeners: {
            "processCompleted": callback,
            "processFailed": function (data) {
            }
        }
    });

通过多边形查询线数据服务,返回的结果是完整的线段。我如何获得多边形内的线段?