' Written by Timothy S. Thomas.
' Programming began 4/9/04.
' Last update was 4/9/04.

' ***********************************************************************
' Modifies my area calc no projection required.ave, to compute the length
' of polylines instead of areas of polygons
' It puts the computed lengths into a dbf file, and joins them to the original
' shapefile.
' ***********************************************************************

' Beginning program
theProject = av.GetProject
theView = av.GetActiveDoc
theTheme = theView.GetActiveThemes.Get(0)
theFTab = theTheme.GetFTab


' **********************************************************
' Establish unique polygon id
' **********************************************************

' This allows the user to pick a field as the basic unit for
' evaluation.
fieldList = theFTab.GetFields.Clone
fieldList.Insert("<Make new unique id field>")
idString = MsgBox.ChoiceAsString(fieldList,"Select ID field",
            "Choose ID field")
if (idString = "<Make new unique id field>") then
  theFTab.SetEditable(True)
  isFld = theFTab.FindField("UniqID")
  if (isFld <> nil) then
    idnew = MsgBox.YesNo("UniqID is already a field.  Do you want to use it?",
                         "Use UniqID?",True)
    if (idnew) then
      idField = isFld
    else
      newName = MsgBox.Input("Name of new ID","New name","NewID")
      idField = Field.Make(newName,#FIELD_LONG,8,0)
      theFTab.AddFields({idField})
      for each rec in theFTab
        theFTab.SetValue(idField,rec,rec+1)
      end
    end
  else
    idField = Field.Make("UniqID",#FIELD_LONG,8,0)
    theFTab.AddFields({idField})
    for each rec in theFTab
      theFTab.SetValue(idField,rec,rec+1)
    end
  end
  theFTab.SetEditable(False)
else
  idField = idString
end
idString = idField.AsString

' A nice way to get a directory name and use it
FTabFN = theFTab.GetSrcName.GetFileName
baseString = FTabFN.GetBaseName
extString = FTabFN.GetExtension
newString = FTabFN.AsString.Substitute(baseString,"")
new2String = baseString.Substitute(extString,"dbf")
theFN = FileDialog.Put(
          (newString + "Length of " + new2String).AsFileName,
          "*.dbf","Data file name")
dataVTab = VTab.MakeNew(theFN,dBase)

newLenString = MsgBox.Input("8 characters or less, no spaces",
                             "Variable name for length field","NewLen")
newidField = idField.Clone
newLenField = Field.Make(newLenString,#Field_Double,16,2)
dataVTab.AddFields({newidField,newLenField})

dataVTab.SetEditable(True)
theFTab.SetEditable(True)
shapeField = theFTab.FindField("Shape")
numRecs = theFTab.GetNumRecords

' Shows message in message bar
av.ShowMsg("Calculating length")

for each r in theFTab
  thePolyline = theFTab.ReturnValue(shapeField,r)
  outrec = dataVTab.AddRecord
  dataVTab.SetValue(newidField,outrec,theFTab.ReturnValue(idField,r))
  dataVTab.SetValue(newLenField,outrec,thePolyline.ReturnLength)
  av.SetStatus(100*(r+1)/numRecs)
end 

' Clears message in message bar
av.ClearMsg

removeList = List.Make
for each d in theProject.GetDocs
  if (d.AsString = newLenString and d.Is(Table)) then
    removeList.Add(d)
  end
end
for each d in removeList
  theProject.RemoveDoc(d)
end
dataTable = Table.Make(dataVTab)
dataTableWin = dataTable.GetWin
dataTableWin.Open
dataTable.SetName(newLenString)
theFTable = theTheme.EditTable

' Join DBF file to FTab
theFTab.Join(idField, dataVTab, newidField)

' Turns off editing
theFTab.SetEditable(false)
dataVTab.SetEditable(false)

dataTableWin.Close

av.PurgeObjects