Selection based on a polygon...

[Bill MacDonald]

Hi,

 

I'm trying to query map features by drawing a polygon on the map and am
having nothing but trouble with this.

 

Here is a sample of the code I'm using:  

 

Dim sLayerName As String = "Points"

      Dim layerObj As MgLayer

      layerObj = map.GetLayers().GetItem(sLayerName)

 

      Dim featureResId As MgResourceIdentifier

      featureResId = New
MgResourceIdentifier(layerObj.GetFeatureSourceId())

 

      Dim featureGeometryName As String

      featureGeometryName = layerObj.GetFeatureGeometryName()

 

      Dim sClassName As String

      sClassName = layerObj.GetFeatureClassName()

 

      Dim queryOptions As New MgFeatureQueryOptions()

 

        Dim sFilter As String = ""

        queryOptions.SetFilter(sFilter)

 

        Dim wktRW As New MgWktReaderWriter()

 

        Dim geom As MgGeometry

        Dim sPolygon As String

        sPolygon = "POLYGON XY (("

 

        While i < dCoords.Length

            sPolygon = sPolygon & dCoords(0, 0) & " " & dCoords(0, 1) &
", "

            i = i + 1

        End While

 

        If Right(sPolygon, 2) = ", " Then sPolygon = Left(sPolygon,
Len(sPolygon) - 2)

 

        sPolygon = sPolygon & "))"

 

        geom = wktRW.Read(sPolygon)

        queryOptions.SetSpatialFilter(featureGeometryName, geom,
MgFeatureSpatialOperations.Inside)

 

        Dim featureReader As MgFeatureReader

        featureReader = featureService.SelectFeatures(featureResId,
sClassName, queryOptions)

 

        ' Process each item in the MgFeatureReader, displaying the owner
name And address

        While featureReader.ReadNext()

            Dim val As String

            val = featureReader.GetString("NAME") & ", " &
featureReader.GetString("RPROPAD")

 

            Response.Write(val & "<br />")

        End While

 

 

I think I may have problems with the creation of the POLYGON but I'm
sure there are other things I am missing.

Any help would be greatly appreciated

 

Thanks

 

Billy

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