ArcGis 创建Annotation注记要素类、添加注记要素 并加载到Activeview AO C#

AO中一般有两种方式存储图面注记元素，一种使用TextElement，它是文档级的元素，编辑后要通过文档（mxd）保存；另一种是使用Annotation要素类，它是一个独立的要素类（featureclass），需要存储到地理数据库中。使用Annotation featureclass 的方式更灵活、更强大，至于如何灵活，如何强大，待你用到便自知。

1、创建一个标准的Annotation要素类（StandardAnnotationClass）

    public AnnotationMark(IFeatureClass outPolygonFc,string mdbPath,int referenceScale)
         {
             string annotationName = "Annotation";
             IWorkspaceFactory workspaceFactory = new AccessWorkspaceFactoryClass();
             IFeatureWorkspace featureWorkspace = workspaceFactory.OpenFromFile(mdbPath, ) as IFeatureWorkspace;
             IGeoDataset geoDataset = outPolygonFc as IGeoDataset;
             ISpatialReference spatialReference = geoDataset.SpatialReference;
             Utils.UserWorkspace.FeatureWorkspace.TryDeleteFeatureClass(annotationName, featureWorkspace);
             featureClass = Utils.UserWorkspace.FeatureWorkspace.CreateStandardAnnotationClass(featureWorkspace, null,annotationName, spatialReference, referenceScale, esriUnits.esriMeters, null);
         }

下面是一个摘自Esri官网的代码段，可以使用它创建StandardAnnotationClass。

值得注意的是：
featureDataset根据数据库是否有数据集（dataset）而定，可以是null;
referenceScale是注记的参考比例，注记元素会以此为基准，放大或缩小，一般建议设置为出图比例尺，这样所设置的字号即出图字号。
configKeyword=""

  public static IFeatureClass CreateStandardAnnotationClass(IFeatureWorkspace featureWorkspace, IFeatureDataset featureDataset, String className,
 ISpatialReference spatialReference, int referenceScale, esriUnits referenceScaleUnits, String configKeyword)
         {
             // Create an annotation class and provide it with a name.
             ILabelEngineLayerProperties labelEngineLayerProperties = new
                 LabelEngineLayerPropertiesClass();
             IAnnotateLayerProperties annotateLayerProperties = (IAnnotateLayerProperties)
                 labelEngineLayerProperties;
             annotateLayerProperties.Class = "Annotation";

             // Get the symbol from the annotation class. Make any changes to its properties
             // here.
             ITextSymbol annotationTextSymbol = labelEngineLayerProperties.Symbol;
             ISymbol annotationSymbol = (ISymbol)annotationTextSymbol;

             // Create a symbol collection and add the default symbol from the
             // annotation class to the collection. Assign the resulting symbol ID
             // to the annotation class.
             ISymbolCollection symbolCollection = new SymbolCollectionClass();
             ISymbolCollection2 symbolCollection2 = (ISymbolCollection2)symbolCollection;
             ISymbolIdentifier2 symbolIdentifier2 = null;
             symbolCollection2.AddSymbol(annotationSymbol, "Annotation", out
                 symbolIdentifier2);
             labelEngineLayerProperties.SymbolID = symbolIdentifier2.ID;

             // Add the annotation class to a collection.
             IAnnotateLayerPropertiesCollection annotateLayerPropsCollection = new
                 AnnotateLayerPropertiesCollectionClass();
             annotateLayerPropsCollection.Add(annotateLayerProperties);

             // Create a graphics layer scale object.
             IGraphicsLayerScale graphicsLayerScale = new GraphicsLayerScaleClass();
             graphicsLayerScale.ReferenceScale = referenceScale;
             graphicsLayerScale.Units = referenceScaleUnits;

             // Create the overposter properties for the standard label engine.
             IOverposterProperties overposterProperties = new BasicOverposterPropertiesClass();

             // Instantiate a class description object.
             IObjectClassDescription ocDescription = new
                 AnnotationFeatureClassDescriptionClass();
             IFeatureClassDescription fcDescription = (IFeatureClassDescription)ocDescription;

             // Get the shape field from the class description's required fields.
             IFields requiredFields = ocDescription.RequiredFields;
             int shapeFieldIndex = requiredFields.FindField(fcDescription.ShapeFieldName);
             IField shapeField = requiredFields.get_Field(shapeFieldIndex);
             IGeometryDef geometryDef = shapeField.GeometryDef;
             IGeometryDefEdit geometryDefEdit = (IGeometryDefEdit)geometryDef;
             geometryDefEdit.SpatialReference_2 = spatialReference;

             // Create the annotation layer factory.
             IAnnotationLayerFactory annotationLayerFactory = new FDOGraphicsLayerFactoryClass();

             // Create the annotation feature class and an annotation layer for it.
             IAnnotationLayer annotationLayer = annotationLayerFactory.CreateAnnotationLayer
                 (featureWorkspace, featureDataset, className, geometryDef, null,
                 annotateLayerPropsCollection, graphicsLayerScale, symbolCollection, false,
                 false, false, true, overposterProperties, configKeyword);

             // Get the feature class from the feature layer.
             IFeatureLayer featureLayer = (IFeatureLayer)annotationLayer;
             IFeatureClass featureClass = featureLayer.FeatureClass;

             return featureClass;
         }

2、创建Annotation要素（Annotation feature）

上面开始在AnnotationMark类的构造函数中创建了Annotation要素类featureClass，下面是创建Annotation 要素 feature的代码。

博主竟没有在墙内网络上找到相关的实现方案，只得爬墙去攒了这片代码，它主要是使用了ISymbolCollectionElement接口设置了Feature的各种属性。此外，网络上还有使用IFormattedTextSymbol接口的方案，博主并未测试，有需要可以戳下面链接：

Why do these annotations appear stacked/overlapping?（再羡国外论坛生态）

值得注意的是：
IGeometry pointGeometry 这个几何对象应该是一个IPoint;
esriTextHorizontalAlignment 与 esriTextVerticalAlignment指示这个point在Annotation元素（一个面Polygon）的哪个位置，借此确定放置位置。
ISymbolCollectionElement或者IFormattedTextSymbol还有更多的属性可以设置（本文不做补充），这些属性便是该要素记录各字段的值。

  public void CreateAnnotationFeature(IGeometry pointGeometry,string text,string fontName,double fontSize,esriTextHorizontalAlignment horizontalAlignment,
             esriTextVerticalAlignment verticalAlignment)
         {
             IFeature feature = featureClass.CreateFeature();

             ISymbolCollectionElement symbolCollectionElement = new TextElementClass();
             symbolCollectionElement.FontName = fontName;
             symbolCollectionElement.Size = fontSize;
             symbolCollectionElement.Text = text;
             symbolCollectionElement.HorizontalAlignment = horizontalAlignment;
             symbolCollectionElement.VerticalAlignment = verticalAlignment;
             symbolCollectionElement.Geometry = pointGeometry;

             IElement element = symbolCollectionElement as IElement;
             IAnnotationFeature2 annotationFeature2 = feature as IAnnotationFeature2;
             annotationFeature2.Annotation =element;
             annotationFeature2.Status = esriAnnotationStatus.esriAnnoStatusPlaced;
             feature.Store();
         }

3、要素类添加为图层

不啰嗦，上代码：

           IWorkspaceFactory workspaceFactory = new AccessWorkspaceFactoryClass();
             IFeatureWorkspace featureWorkspace = workspaceFactory.OpenFromFile(mdbPath, ) as IFeatureWorkspace;
             IAnnotationLayerFactory annotationLayerFactory = new FDOGraphicsLayerFactoryClass();
             IAnnotationLayer annotationLayer = annotationLayerFactory.OpenAnnotationLayer(featureWorkspace, null, "Annotation");
             ILayer layer_Annotation = annotationLayer as ILayer;
             layer_Annotation.Name = tfh + "_Annotation";