HowTo Perform the spatial selection 'Share a line segment with' using ArcObjects

HowTo  Perform the spatial selection 'Share a line segment with' using ArcObjects

Article ID:	26528
Software:	ArcGIS - ArcEditor 8.1, 8.1.2, 8.2, 8.3 ArcGIS - ArcInfo 8.1, 8.1.2, 8.2, 8.3 ArcGIS - ArcView 8.1, 8.1.2, 8.2, 8.3
Platforms:	Windows NT 4.0, 2000, XP

Summary


Instructions provided illustrate how to duplicate the functionality of ArcMap's spatial selection 'share a line segment with' through ArcObjects code.

 

Procedure


Start ArcMap.

Open the Visual Basic Editor. -show me-

In the Project Explorer window, expand Project.mxt and select ArcMap Objects > ThisDocument. Right-click and select View Code.-show me- 


 Code in the Project's ThisDocument code module will only run in the current map document. If you want to store the code in all map documents open the Normal.mxt ThisDocument code module.

 

Copy/Paste the following code into the code module. 

Option Explicit

 
Public Sub SelectPolyAsSharesSegementWith()

 
Dim pMxDoc As IMxDocument

Set pMxDoc = ThisDocument

Dim pMap As IMap

Set pMap = pMxDoc.FocusMap

 
' Union all of the search features into one geometry and strip off

' it's boundary for use in the search. Since we are only interested

' in shared segments, not areas, the boundary is all that is needed.

 
' Get search layer

Dim pPolygonLyr As IFeatureLayer

Set pPolygonLyr = pMap.Layer(1)

Dim pLFeatClass As IFeatureClass

Set pLFeatClass = pPolygonLyr.FeatureClass

 
' Loop through the polygons, simplify them and then

' add them to a Geometry Bag.

Dim pFeatureCursor As IFeatureCursor

Set pFeatureCursor = pLFeatClass.Search(Nothing, True)

Dim pFeature As IFeature

Set pFeature = pFeatureCursor.NextFeature

Dim pGeometryCollection As IGeometryCollection

Set pGeometryCollection = New GeometryBag

Dim pTopologicalOperator2 As ITopologicalOperator2

 
Do While Not pFeature Is Nothing

Set pTopologicalOperator2 = pFeature.ShapeCopy

pTopologicalOperator2.IsKnownSimple = False

pTopologicalOperator2.Simplify

pGeometryCollection.AddGeometry pTopologicalOperator2

Set pFeature = pFeatureCursor.NextFeature

Loop

 
' Union all the polygons

Dim pTopologicalOperator1 As ITopologicalOperator2

Set pTopologicalOperator1 = New Polygon

pTopologicalOperator1.ConstructUnion pGeometryCollection

 
' Construct the boundary of the unioned polygons

Dim pTopologicalOperator3 As ITopologicalOperator2

Set pTopologicalOperator3 = New Polyline

Set pTopologicalOperator3 = pTopologicalOperator1.Boundary

 
' Use the boundary to find the candidate features

 
' Get the target FeatureClass

Dim pFeatureLayer As IFeatureLayer

Set pFeatureLayer = pMap.Layer(0)

Dim pFeatureClass As IFeatureClass

Set pFeatureClass = pFeatureLayer.FeatureClass

 
' Set up a scratch workspace to use for the selection

Dim pScratchWorkspace As IWorkspace

Dim pScratchWorkspaceFactory As IScratchWorkspaceFactory

Set pScratchWorkspaceFactory = New ScratchWorkspaceFactory

Set pScratchWorkspace = pScratchWorkspaceFactory.DefaultScratchWorkspace

 
' Setup the spatial filter

Dim pSpatialFilter As ISpatialFilter

Set pSpatialFilter = New SpatialFilter

With pSpatialFilter

Set .Geometry = pTopologicalOperator3

.GeometryField = "SHAPE"

.SpatialRel = esriSpatialRelIntersects

End With

 
' Perform the search and create a selection set

Dim pTempSelection As ISelectionSet

Set pTempSelection = pFeatureClass.Select(pSpatialFilter, esriSelectionTypeIDSet, esriSelectionOptionNormal, pScratchWorkspace)

 
' Loop through the features and check to see if they share a segment

' with the search geometry. If they don't, remove them from the selection

' set.

 
' Create a feature cursor to allow us the examine the candidate features

Dim pTempFeatCur As IFeatureCursor

pTempSelection.Search Nothing, True, pTempFeatCur

 
Dim iOIDList(1) As Long

Dim iOIDListCount As Long

iOIDListCount = 1

Dim pGeometry As IPolyline

Dim pTempFeat As IFeature

 
' Fetch the first feature

Set pTempFeat = pTempFeatCur.NextFeature

Dim pTempPolyline As IPolyline

 
' Check for the one dimentional intersection of the geometries.

' If there is no intersection the returned geometry will be empty. If

' it is, remove it from the selection set.

 
Dim pTopologicalOperator4 As ITopologicalOperator2

Set pTopologicalOperator4 = New Polygon

 
Do

iOIDList(0) = pTempFeat.OID

 
Set pTopologicalOperator4 = pTempFeat.ShapeCopy

 
pTopologicalOperator4.IsKnownSimple = False

pTopologicalOperator4.Simplify

 
Set pTempPolyline = pTopologicalOperator4.Boundary

 
Set pGeometry = pTopologicalOperator3.Intersect(pTempPolyline, esriGeometry1Dimension)

If pGeometry.IsEmpty Then

pTempSelection.RemoveList iOIDListCount, iOIDList(0)

End If

 
Set pTempFeat = pTempFeatCur.NextFeature

Loop Until pTempFeat Is Nothing

 
' Set the feature selection

Dim pFeatureSelection As IFeatureSelection

Set pFeatureSelection = pFeatureLayer

Set pFeatureSelection.SelectionSet = pTempSelection

 
' Display the selected features.

Dim pdoc As IMxDocument

Set pdoc = ThisDocument

pdoc.ActiveView.Refresh

 End Sub

 

Close the Visual Basic Editor.

Run the code. -show me-

 

Created: 4/1/2004
Last Modified: 7/1/2008

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Comments


By Anonymous - 07/20/2005 7:47 AM

Hello, The sample code to select polygons that share a segment with the selected polygon did not work for me. Although I tested it in 9.1, no library is explicitly defined so I don't think this is the problem. http://support.esri.com/index.cfm?fa=knowledgebase.techarticles.articleShow&d=26528 Sincerely, Valentina