ArcEngine 水平分子式标注
在ArcMap中，实现水平分子式标注的方法是在Label Expression中选中Advanced，输入如下VBA代码：
Function FindLabel ( [FieldName1] , [FieldName2] )
FindLabel = [FieldName1] &chr(13)&"———————————"&chr(13)& [FieldName2]
End Function
或者：
Function FindLabel ( [FieldName1] , [FieldName2] )
FindLabel = "<und>"&" "&[FieldName1] &" "&"</und>"& vbcrlf &[FieldName2]
End Function
注释：方法一中 chr(13)表示换行，间隔线表示分母线，&为VBScript连接字符，分母线的长短用间隔数表示，
也就是 字段1，换行，分母线，换行，字段2
方法二中 <und> </und>表示下划线，vbclf表示换行，分母线的长短用空格数表示，
也就是 加下划线的字段1，换行，字段2
最后，分子和分母与分母线的间隔，可通过(TextSymbol)Symbol—>(Symbol Selector)Propertie—>(Editor)Formatting Text中的Leading调节。
在ArcEngine中，实现代码如下所示：
IGeoFeatureLayer geoFeatureLayer = featureLayer as IGeoFeatureLayer;
ITextSymbol textSymbol = new ESRI.ArcGIS.Display.TextSymbol();
if (featureLayer.FeatureClass.ShapeType == esriGeometryType.esriGeometryPolygon)
{
continue;
}
else if (featureLayer.FeatureClass.ShapeType == esriGeometryType.esriGeometryPolyline)
{
textSymbol.Color = ((geoFeatureLayer.Renderer as ISimpleRenderer).Symbol as ILineSymbol).Color;
}
else if (featureLayer.FeatureClass.ShapeType == esriGeometryType.esriGeometryPoint)
{
textSymbol.Color = ((geoFeatureLayer.Renderer as ISimpleRenderer).Symbol as IMarkerSymbol).Color;
}
textSymbol.HorizontalAlignment = esriTextHorizontalAlignment.esriTHACenter;
ILabelEngineLayerProperties2 pLelp = new LabelEngineLayerPropertiesClass();
pLelp.IsExpressionSimple = false;
pLelp.Symbol = textSymbol;
IAnnotationExpressionEngine AnnExpEng = new AnnotationVBScriptEngineClass();
pLelp.ExpressionParser = AnnExpEng;
//方法一
//pLelp.Expression = "Function FindLabel (" + "[编号]" + ", " + "[编号备注]" + ") \n " +
// " FindLabel = " + "[编号]" + "&chr(13)" +"&\"——————————\""+ "&chr(13)" + "&[编号备注]" + "\n End Function";
//方法二
pLelp.Expression = "Function FindLabel (" + "[编号]" + ", " + "[编号备注]" + ") \n " +
" FindLabel = " + "\"<und>\"" + "&\" \"" + "&[编号]" + "&\" \"" + "&\"</und>\"" + " &vbcrlf " + "&[编号备注]" + "\n End Function";
IBasicOverposterLayerProperties pBasicOverposterLayerProperties = pLelp.BasicOverposterLayerProperties;
pBasicOverposterLayerProperties.NumLabelsOption = esriBasicNumLabelsOption.esriOneLabelPerShape;
//水平标注
ILineLabelPosition linelabelPosition;
linelabelPosition = new LineLabelPositionClass();
linelabelPosition.Horizontal = true;
linelabelPosition.Above = false;
linelabelPosition.Parallel = false;
linelabelPosition.Perpendicular = false;
linelabelPosition.InLine = true;
linelabelPosition.Below = false;
linelabelPosition.OnTop = true;
pBasicOverposterLayerProperties.LineLabelPosition = linelabelPosition;
pLelp.BasicOverposterLayerProperties = pBasicOverposterLayerProperties;
pBasicOverposterLayerProperties.LabelWeight = esriBasicOverposterWeight.esriHighWeight;
IAnnotateLayerProperties alps = (IAnnotateLayerProperties)pLelp;
alps.DisplayAnnotation = true;
alps.FeatureLayer = geoFeatureLayer;
alps.LabelWhichFeatures = esriLabelWhichFeatures.esriAllFeatures;
geoFeatureLayer.AnnotationProperties.Clear();
geoFeatureLayer.AnnotationProperties.Add(alps);
geoFeatureLayer.DisplayAnnotation = true;
System.Runtime.InteropServices.Marshal.ReleaseComObject(textSymbol);