'** Title:  CalcArea
' **Author: Jennifer L. Jessip
'**Created: May 29, 1999
'**Texas A&M University
'
' Description:  Calculates area, perimeter, x centroid value, and y 
'                      centroid value for polygon themes.
' If the View has been projected the calculations are in 
' projected units. Otherwise the calculations are in 'native' map units.
' The script processes the active theme to calculate the items listed above
'
' The script will add the fields Area, Acres and Perimeter to polygon themes
' if they do not exist. If the fields exist, they are deleted and 
' recalculated. Rerun the script if you change the projection of the view.
'
' The factor of 0.0002471 is used by default. Modify as necessary for your
' region.
'
' Requires:  A View with at least one active polygon theme.  You must have 
' write access to the active theme(s).
'
'
' Version: 3.1
'
' Get the view and its projection if any.
'
theView = av.GetActiveDoc
thePrj = theView.GetProjection
if (thePrj.IsNull) then
  hasPrj = false
else
  hasPrj = true
end
'
' Get the active theme. If the first theme is not active, let the user know
' and exit.
'
theActivethemeList = theView.GetActivethemes
if (theActivethemeList.Count = 0) then
  MsgBox.Error("First theme is not active.","")
  Exit
end
'
' Check to see if the first theme is editable
thetheme = theActivethemeList.get(0)
  theFTab = thetheme.GetFTab
  if (theFTab.CanEdit.Not) then
    MsgBox.Info("Cannot edit table for theme:"++thetheme.AsString,"")
  end
  
  '
  ' Make the FTAB editable, and find out which type of feature it is.
  '
  theFTab.SetEditable(TRUE)
  theType = theFTab.FindField("shape").GetType
  if (theType = #FIELD_SHAPEPOLY) then
    '
    ' If it's polygonal check for the existence of the fields "Area" and
    ' Acre and Perimeter. If they do not exist, create them.  Also remove
    ' the extraneous fields created by the Hydrologic Modeling process.
    '
    'AREA
    if(theFtab.FindField("BasinArea") <> nil) then
      theBasinAreaField = theFtab.FindField("BasinArea")
      theFtab.RemoveFields({theBasinAreaField})
    end
    if(theFtab.FindField("Area") = nil) then
      theAreaField = Field.Make("Area",#FIELD_DOUBLE,16,3)
      theFTab.AddFields({theAreaField})
    else
      theBadAreaField = theFtab.FindField("Area")
      theFtab.RemoveFields({theBadAreaField})
      theAreaField = Field.Make("Area",#FIELD_DOUBLE,16,3)
      theFTab.AddFields({theAreaField})
    
    end
    
    'ACRE
    if(theFTab.FindField("Acres") = nil)then
      theAcresField = Field.Make("Acres",#FIELD_DOUBLE,16,3)
      theFTab.AddFields({theAcresField})
    else
      theBadAcreField = theFtab.FindField("Acres")
      theFtab.RemoveFields({theBadAcreField})
      theAcresField = Field.Make("Acres",#FIELD_DOUBLE,16,3)
      theFTab.AddFields({theAcresField})
    end
    
    'PERIMETER
    if (theFtab.FindField("Perimeter") <> nil) then
      theBadPerField = theFtab.Findfield("Perimeter")
      theFtab.RemoveFields({theBadPerField})
    end
    if (theFTab.FindField("Perimeter") = nil) then
      thePerimeterField = Field.Make("Perimeter",#FIELD_DOUBLE,16,3)
      theFTab.AddFields({thePerimeterField})
    else
      theBadPerimeterField = theFtab.FindField("Perimeter")
      theFtab.RemoveFields({theBadPerimeterField})
      thePerimeterField = Field.Make("Perimeter",#FIELD_DOUBLE,16,3)
      theFTab.AddFields({thePerimeterField})      
    end
    
    'XCENTROID
    if(theFtab.FindField("Centroidx") <> nil) then
       theCentroidxField = theFtab.FindField("Centroidx")
       theFtab.RemoveFields({theCentroidxField})
    end
    if(theFtab.FindField("XCentroid") = nil) then
       theXCentroidField = Field.make("XCentroid",#Field_Double,16,8)
       theFtab.AddFields({theXCentroidField})
    else
       theBadXCentroidField = theFtab.FindField("XCentroid")
       theFtab.RemoveFields({theBadXCentroidField})
       theXCentroidField = Field.make("XCentroid",#Field_Double,16,8)
       theFtab.AddFields({theXCentroidField})
    end   
    
    'YCENTROID
    if(theFtab.FindField("Centroidy") <> nil) then
       theCentroidyField = theFtab.FindField("Centroidy")
       theFtab.RemoveFields({theCentroidyField})
    end
    if(theFtab.FindField("YCentroid") = nil) then
       theYCentroidField = Field.make("YCentroid",#Field_Double,16,8)
       theFtab.AddFields({theYCentroidField})
    else
       theBadYCentroidField = theFtab.FindField("YCentroid")
       theFtab.RemoveFields({theBadYCentroidField})
       theYCentroidField = Field.make("YCentroid",#Field_Double,16,8)
       theFtab.AddFields({theYCentroidField})
    end      
    
    'MU_ID
    if (theFtab.FindField("MU_ID") = nil) then
      theNewMUID = Field.Make("MU_ID",#Field_Long,10,0)
      theFtab.AddFields({theNewMUID})
    else   
      theBadMUID = theFtab.FindField("MU_ID")     
      theFtab.RemoveFields({theBadMUID})
      theNewMUID = Field.Make("MU_ID",#Field_Long,10,0)
      theFtab.AddFields({theNewMUID})       
    end
    
          


    
    '
    ' Loop through the FTAB and find the projected area, perimeter, and centroid of each 
    ' shape and set the field values appropriately.
    '
numRecs = theFtab.GetNumRecords    

    For Each rec in 0..(NumRecs - 1)
    
    tShape = theFTab.ReturnValue(theFTab.FindField("shape"),rec)
    theShape = tShape.ReturnProjected(thePrj)
    
      theArea = theShape.ReturnArea
      theAcres = theArea*0.0002471
      thePerimeter = theShape.ReturnLength
      theXCentroid = theShape.ReturnCenter.getX
      theYCentroid = theShape.ReturnCenter.gety
      
      
      theFTab.SetValue(theNewMUID,rec,rec)
      theFTab.SetValue(theAreaField,rec,theArea)
      theFTab.SetValue(theAcresField,rec,theAcres)
      theFTab.SetValue(thePerimeterField,rec,thePerimeter)
      theFTab.SetValue(theXCentroidField,rec,theXCentroid)
      theFTab.SetValue(theYCentroidField,rec,theYCentroid)
    end  

numRecs = theFtab.GetNumRecords

theFtab.SetEditable(False)

  else
    MsgBox.Info("You must use this script on a polygon theme.",
      "View.CalculateAcreage")
    return Nil
  end
  

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