' **********************************************************
' UnionAll.AVE
'
' Unions all polygons of the theme.
'
' Written by Tim Thomas on 12/10/01.
'
' Used ideas from the following:
' Find Gaps and Overlaps
' Author: David M. Theobald, davet@nrel.colostate.edu
' Date: August 1999
' ************************************************************

theView = av.GetActiveDoc
theActiveTheme = theView.GetActiveThemes.Get(0)
theFTab = theActiveTheme.GetFTab
theshapeFld = theFTab.FindField ( "Shape" )

' ************************************************************
' Make new shapefile
' ************************************************************

FTabFN = theFTab.GetSrcName.GetFileName
baseString = FTabFN.GetBaseName
extString = FTabFN.GetExtension
newString = FTabFN.AsString.Substitute(baseString,"")
new2String = baseString.Substitute(extString,"shp")
newFTabFN = FileDialog.Put(
          (newString + "Union " + new2String).AsFileName,
          "*.shp","Union shapefile name")
newFTab = FTab.MakeNew(newFTabFN,Polygon) 
newShapeField = newFTab.FindField("Shape")
idField = Field.Make ("UnionID", #FIELD_BYTE, 2, 0)
newFTab.AddFields ( { idField } )

' Union all polygons
theUnion = theFTab.ReturnValue ( theshapeFld, 0 )
for each rec in theFTab
  thePoly = theFTab.ReturnValue ( theshapeFld, rec )
  theUnion = thePoly.ReturnUnion(theUnion)
end

rec = newFTab.AddRecord
newFTab.SetValue ( newShapeField, rec, theUnion )
newFTab.SetValue ( idField, rec, 1)
newFTab.SetEditable ( FALSE )
newFTheme = FTheme.Make ( newFTab )
theView.AddTheme ( newFTheme )