ArcEngine标注和注记(-)

       标注和注记是ArcEngine中提供的两种使用文字信息标注地图要素的方式.其中标注是作为图层的属性存在的,可以动态创建,注记作为地理要素被存储.需要注意的是Shp文件不支持注记.  绘制标注的方式有两种.让我们先看第一种:

    1.使用TextElment绘制标注.

    这种方法的原理就是把属性表中的某个属性创建TextElment对象,然后使用IGraphicsContainer 的AddElement方法添加标注.实例代码:

        //使用TextElment绘制标注, fieldName为要绘制的属性
        public static void AddLable(AxMapControl axMapControl, ILayer layer, string fieldName)
        {
            IRgbColor pColor = new RgbColorClass()
            {
                Red = 255,
                Blue = 0,
                Green = 0
            };
            IFontDisp pFont = new StdFont()
            {
                Name = "宋体",
                Size = 5
            } as IFontDisp;
            

            ITextSymbol pTextSymbol = new TextSymbolClass()
            {
                Color = pColor,
                Font = pFont,
                Size = 11
            };

            IGraphicsContainer pGraContainer = axMapControl.Map as IGraphicsContainer;

            //遍历要标注的要素
            IFeatureLayer pFeaLayer = layer as IFeatureLayer;
            IFeatureClass pFeaClass = pFeaLayer.FeatureClass;
            IFeatureCursor pFeatCur = pFeaClass.Search(null, false);
            IFeature pFeature = pFeatCur.NextFeature();
            int index = pFeature.Fields.FindField(fieldName);//要标注的字段的索引
            IEnvelope pEnv = null;
            ITextElement pTextElment = null;
            IElement pEle = null;
            while (pFeature != null)
            {
                //使用地理对象的中心作为标注的位置
                pEnv = pFeature.Extent;
                IPoint pPoint = new PointClass();
                pPoint.PutCoords(pEnv.XMin + pEnv.Width * 0.5, pEnv.YMin + pEnv.Height * 0.5);

                pTextElment = new TextElementClass()
                {
                    Symbol = pTextSymbol,
                    ScaleText = true,
                    Text = pFeature.get_Value(index).To\String()
                };
                pEle = pTextElment as IElement;
                pEle.Geometry = pPoint;
                //添加标注
                pGraContainer.AddElement(pEle, 0);
                pFeature = pFeatCur.NextFeature();
            }
            (axMapControl.Map as IActiveView).PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, axMapControl.Extent);
        }

　　   2.使用ArcEngine中的标注对象口.LabelEngineLayerProperties来标注要素

        IGeoFeatureLayer中的AnnotationProperties是一个包含LabelEngineLayerProperties对象的标注集合.而 LabelEngineLayerProperties实现了:

     IAnnotateProperties,  //
     IAnnotateLayerProperties, //可以控制标注的显示比例尺,过滤条件等
     ILabelEngineLayerProperties, 
     IAnnotateLayerTransformationProperties //控制标注的参考比例尺,单位,标注边界和缩放比率等

等几个主要的接口.LabelEngineLayerProperties可以操作标注要素的多个属性和行为,如设置文本的标注位置,标注尺寸,设置脚本,文字符号等.该类实现了大量操作标注的属性和方法,对于复杂的标注非常有用,而TextElment适合简单的标注. ILabelEngineLayerProperties2是LabelEngineLayerPropertiesClass 的主接口.他的Expression和IsExpressionSimple用法如下:

        IsExpressionSimple=true,Expression为简单表达式,其形式为: "["+属性字段名+"]"+其他,

        IsExpressionSimple=true=false,Expression为复杂表达式,其内容也为一个字符串,但是一个完整的VBScript or JScript 函数或者表达式.

 ExpressionParser属性是一个Expression解析器,它支持更复杂的JS和Vbs代码.

  

        //添加标注,比TextElment功能更强大
        public static void AddAnnotate(ILayer layer,string fieldName)
        {
            IGeoFeatureLayer pGeoLayer = layer as IGeoFeatureLayer;
            IAnnotateLayerPropertiesCollection IPALPColl = pGeoLayer.AnnotationProperties;
            IPALPColl.Clear();

            IRgbColor pColor = GetColor(255, 0, 0, 255);
            IFontDisp pFont = new StdFont()
            {
                Name = "宋体",
                Bold = true
            } as IFontDisp;

            ITextSymbol pTextSymbol = new TextSymbolClass()
            {
                Color = pColor,
                Font = pFont,
                Size = 12
            };

            //用来控制标注和要素的相对位置关系
            ILineLabelPosition pLineLpos = new LineLabelPositionClass()
            {
                Parallel = false,  //修改标注的属性
                Perpendicular = true,
                InLine = true
            };
            //用来控制标注冲突
            ILineLabelPlacementPriorities pLinePlace = new LineLabelPlacementPrioritiesClass()
            {
                AboveStart = 5, //让above 和start的优先级为5
                BelowAfter = 4
            };
            //用来实现对ILineLabelPosition 和 ILineLabelPlacementPriorities以及更高级属性的控制
            IBasicOverposterLayerProperties pBOLP = new BasicOverposterLayerPropertiesClass()
            {
                FeatureType = esriBasicOverposterFeatureType.esriOverposterPolygon,
                LineLabelPlacementPriorities = pLinePlace,
                LineLabelPosition = pLineLpos
            };

            //创建标注对象
            ILabelEngineLayerProperties pLableEngine = new LabelEngineLayerPropertiesClass()
            {
                Symbol = pTextSymbol,
                BasicOverposterLayerProperties = pBOLP,
                IsExpressionSimple = true,
                Expression = "["+fieldName+"]"
            };

            //设置标注的参考比例尺
            IAnnotateLayerTransformationProperties pAnnoLyrPros = pLableEngine as IAnnotateLayerTransformationProperties;
            pAnnoLyrPros.ReferenceScale = 2500000;

            //设置标注可见的最大最小比例尺
            IAnnotateLayerProperties pAnnoPros = pLableEngine as IAnnotateLayerProperties;
            pAnnoPros.AnnotationMaximumScale = 2500000;
            pAnnoPros.AnnotationMinimumScale = 25000000;
            //pAnnoPros.WhereClause属性  设置过滤条件

            IPALPColl.Add(pAnnoPros);
            pGeoLayer.DisplayAnnotation = true;
        }