ArcEngine標注和注記

轉自原文 ArcEngine標注和注記

標注和注記是ArcEngine中提供的兩種使用文字信息標注地圖要素的方式.其中標注是作為圖層的屬性存在的,可以動態創建,注記作為地理要素被存儲.需要注意的是Shp文件不支持注記.  繪制標注的方式有兩種.讓我們先看第一種:

  1.使用TextElment繪制標注.

這種方法的原理就是把屬性表中的某個屬性創建TextElment對象,然后使用IGraphicsContainer 的AddElement方法添加標注.實例代碼:

        //使用TextElment繪制標注, fieldName為要繪制的屬性
        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 = "宋體",
                Size = 5
            } as IFontDisp;
            

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

            IGraphicsContainer pGraContainer = axMapControl.Map as IGraphicsContainer;

            //遍歷要標注的要素
            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);//要標注的字段的索引
            IEnvelope pEnv = null;
            ITextElement pTextElment = null;
            IElement pEle = null;
            while (pFeature != null)
            {
                //使用地理對象的中心作為標注的位置
                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;
                //添加標注
                pGraContainer.AddElement(pEle, 0);
                pFeature = pFeatCur.NextFeature();
            }
            (axMapControl.Map as IActiveView).PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, axMapControl.Extent);
        }

2.使用ArcEngine中的標注對象口.LabelEngineLayerProperties來標注要素

IGeoFeatureLayer中的AnnotationProperties是一個包含LabelEngineLayerProperties對象的標注集合.而 LabelEngineLayerProperties實現了:

     IAnnotateProperties,  //
 IAnnotateLayerProperties, //可以控制標注的顯示比例尺,過濾條件等
 ILabelEngineLayerProperties, 
 IAnnotateLayerTransformationProperties //控制標注的參考比例尺,單位,標注邊界和縮放比率等

等幾個主要的接口.LabelEngineLayerProperties可以操作標注要素的多個屬性和行為,如設置文本的標注位置,標注尺寸,設置腳本,文字符號等.該類實現了大量操作標注的屬性和方法,對於復雜的標注非常有用,而TextElment適合簡單的標注. ILabelEngineLayerProperties2是LabelEngineLayerPropertiesClass 的主接口.他的Expression和IsExpressionSimple用法如下:

        IsExpressionSimple=true,Expression為簡單表達式,其形式為: "["+屬性字段名+"]"+其他,

        IsExpressionSimple=true=false,Expression為復雜表達式,其內容也為一個字符串,但是一個完整的VBScript or JScript 函數或者表達式.

 ExpressionParser屬性是一個Expression解析器,它支持更復雜的JS和Vbs代碼.

 //添加標注,比TextElment功能更強大
        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 = "宋體",
                Bold = true
            } as IFontDisp;

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

            //用來控制標注和要素的相對位置關系
            ILineLabelPosition pLineLpos = new LineLabelPositionClass()
            {
                Parallel = false,  //修改標注的屬性
                Perpendicular = true,
                InLine = true
            };
            //用來控制標注沖突
            ILineLabelPlacementPriorities pLinePlace = new LineLabelPlacementPrioritiesClass()
            {
                AboveStart = 5, //讓above 和start的優先級為5
                BelowAfter = 4
            };
            //用來實現對ILineLabelPosition 和 ILineLabelPlacementPriorities以及更高級屬性的控制
            IBasicOverposterLayerProperties pBOLP = new BasicOverposterLayerPropertiesClass()
            {
                FeatureType = esriBasicOverposterFeatureType.esriOverposterPolygon,
                LineLabelPlacementPriorities = pLinePlace,
                LineLabelPosition = pLineLpos
            };

            //創建標注對象
            ILabelEngineLayerProperties pLableEngine = new LabelEngineLayerPropertiesClass()
            {
                Symbol = pTextSymbol,
                BasicOverposterLayerProperties = pBOLP,
                IsExpressionSimple = true,
                Expression = "["+fieldName+"]"
            };

            //設置標注的參考比例尺
            IAnnotateLayerTransformationProperties pAnnoLyrPros = pLableEngine as IAnnotateLayerTransformationProperties;
            pAnnoLyrPros.ReferenceScale = 2500000;

            //設置標注可見的最大最小比例尺
            IAnnotateLayerProperties pAnnoPros = pLableEngine as IAnnotateLayerProperties;
            pAnnoPros.AnnotationMaximumScale = 2500000;
            pAnnoPros.AnnotationMinimumScale = 25000000;
            //pAnnoPros.WhereClause屬性  設置過濾條件

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