转自原文 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; }