如何用接口控制线标注时的位置是以页面上下为准还是以线左右为准

            IGeoFeatureLayer pGeoFeatureLayer = pFeatureLayer as IGeoFeatureLayer;

            pGeoFeatureLayer.DisplayAnnotation = true;//允许标注 



            IFeatureClass pFeatureClass;

            pFeatureClass = pGeoFeatureLayer.FeatureClass;



            //矢量图层标注信息设置 

            IAnnotateLayerPropertiesCollection pAnnotateLayerPropertiesCollection;

            pAnnotateLayerPropertiesCollection = pGeoFeatureLayer.AnnotationProperties;

            pAnnotateLayerPropertiesCollection.Clear();



            //定义一个矢量图层动态标注显示 

            IAnnotateLayerProperties pAnnotateLayerProperties;



            //定义控制线标注的相对位置 

            ILineLabelPosition pLineLabelPosition;



            //控制线标注的属性设置 

            ILineLabelPlacementPriorities pLineLabelPlacementPriorities;

            IBasicOverposterLayerProperties pBasicOverposterLayerProperties;

            ILabelEngineLayerProperties pLabelEngineLayerProperties;



            pLineLabelPosition = new LineLabelPositionClass();

            pLineLabelPosition.Parallel = true;

            pLineLabelPosition.Perpendicular = false;



            //设置相对位置

            pLineLabelPosition.Left = true;

            pLineLabelPosition.Above = false;



            pLineLabelPlacementPriorities = new LineLabelPlacementPrioritiesClass();

            pBasicOverposterLayerProperties = new BasicOverposterLayerPropertiesClass();

            pBasicOverposterLayerProperties.FeatureType = esriBasicOverposterFeatureType.esriOverposterPolyline;

            pBasicOverposterLayerProperties.LineLabelPlacementPriorities = pLineLabelPlacementPriorities;

            pBasicOverposterLayerProperties.LineLabelPosition = pLineLabelPosition;



            pLabelEngineLayerProperties = new LabelEngineLayerPropertiesClass();

            pLabelEngineLayerProperties.BasicOverposterLayerProperties = pBasicOverposterLayerProperties;

            pLabelEngineLayerProperties.Symbol.Size = 10;//字体大小 

            pLabelEngineLayerProperties.Expression = [ + fieldname + ];//标注字段 



            pAnnotateLayerProperties = pLabelEngineLayerProperties as IAnnotateLayerProperties;

            pAnnotateLayerPropertiesCollection.Add(pAnnotateLayerProperties);