合并要素--how to use "ConstructUnion"

合并要素--how to use "ConstructUnion"

 

 参考：http://forums.esri.com/Thread.asp?c=93&f=1170&t=80838

 

 The following VBA macro creates a graphic element that is the union of all selected polygons in the map. The union is constructed using a geometry bag.

 

 

Sub UnionFeatures()



Dim pMxDoc As IMxDocument



Dim pEnumFeature As IEnumFeature



Dim pFeature As IFeature



Dim pGeoBag As IGeometryBag



Dim pGeoCollection As IGeometryCollection



Dim pTopoOp As ITopologicalOperator2



Dim pPolygon As IPolygon



Dim pPolygonElement As IPolygonElement



Dim pElement As IElement



Dim pGC As IGraphicsContainer







Set pMxDoc = ThisDocument



Set pEnumFeature = pMxDoc.FocusMap.FeatureSelection



pEnumFeature.Reset



Set pGeoBag = New GeometryBag



Set pGeoCollection = pGeoBag







Set pFeature = pEnumFeature.Next



Do While Not pFeature Is Nothing



If pFeature.Shape.GeometryType = esriGeometryPolygon Then



Set pTopoOp = pFeature.ShapeCopy



pTopoOp.IsKnownSimple = False



pTopoOp.Simplify



pGeoCollection.AddGeometry pTopoOp



End If







Set pFeature = pEnumFeature.Next



Loop







Set pTopoOp = New Polygon



pTopoOp.ConstructUnion pGeoBag



Set pPolygon = pTopoOp



Set pGC = pMxDoc.FocusMap



Set pPolygonElement = New PolygonElement



Set pElement = pPolygonElement



pElement.Geometry = pPolygon



pGC.AddElement pElement, 0



pMxDoc.ActiveView.Refresh



End Sub