' Name:  View.CalculateDistance
'
' Title:  Calculates distances from points in one theme to points in another
'
' Topics:  Analysis
'
' Description: This script will prompt you for two point themes in the 
' active view.  The first is the point theme containing the selected points
' that you wish to calculate the distance FROM. The second is the point theme 
' containing points that you wish to calculate the distance TO.
'
' You will also be prompted for an identifying field in the
' FROM theme.  The value of this field will be used to name to
' distance field in the TO theme.
'
' A distance field will be added to the TO theme for each point 
' selected in the FROM theme.  This distance field will be populated
' with the distance between the selected From point and the To point.
'
' If the view is projected, the distance will be returned in distance units.
'
' Requires:  This script should be attached to a button in the view GUI.  To 
' prepare to use this script:
'
'-    1. Add to your view two point themes.
'-    2. Determine which is to be theFromTheme and which is to be theToTheme.
'-    3. Determine which item is to be the identifying field.  This is most likely
'-       a field that contains a key number or name.
'-    4. Create a selected set of points in theFromTheme, if you like. 
'-    5. Attach this script to a button inthe Veiw GUI, if you like.
'
' Self:  
'
' Returns:  
 

theThemeList = av.GetActiveDoc.GetThemes.Clone
thePrj = av.GetActiveDoc.GetProjection

'  Use these lines to hard-code the input parameters...
'theFromFtab = av.GetProject.FindDoc("View1").FindTheme("FromTheme").GETFTab
'theFromIDField = theFromFtab.FindField("Bnmb")
'theToTheme = av.GetProject.FindDoc("View1").FindTheme("ToTheme")
'theToFtab = theToTheme.GetFTab

'  Use these lines to prompt the user for input parameters...
theFromTheme = (MsgBox.List(theThemeList,"to calculate the distance FROM.","Please select a theme..."))
if (theFromTheme = nil) then exit end 
theFromFtab = theFromTheme.GetFTab
theThemeList.RemoveObj(theFromTheme)   
theToTheme = (MsgBox.List(theThemeList,"to calculate the distance TO.","Please select a theme..."))
if (theToTheme = nil) then exit end  
theToFtab = theToTheme.GetFTab
theFromIDField = MsgBox.ListAsString(theFromFtab.GetFields,"containing the point identifier.","Please select a field...")
  if (theFromIDField = nil) then
    exit
  end  

theFromShapeField = theFromFTab.FindField("Shape")
theToShapeField = theToFtab.FindField("Shape")

theToFtab.SetEditable(true)

for each f in theFromFtab.GetSelection

  theFromIDValue = theFromFtab.ReturnValueString(theFromIDField,f)
  theNewFieldName = "DistTo"+theFromIDValue
  
' If a distance field doesn't exist, add it...
  if (theToFtab.FindField(theNewFieldName) = nil) then
  
'   Choose the field size commensurate with the view's projection.
    if (thePrj.IsNull) then
      theDistanceField = field.make(theNewFieldName,#field_decimal,8,4)
    else
      theDistanceField = field.make(theNewFieldName,#field_decimal,8,2)
    end
      
    theToFtab.addfields({theDistanceField})
' If a distance field does exist, clear it...    
  else
    theToFtab.Calculate("0",theToFtab.FindField(theNewFieldName))
    theDistanceField = theToFTab.FindField(theNewFieldName)  
  end 

' Get the point location you are measuring FROM. 
' If the view is projected, get the the point location in projected units.
  theFromShape = theFromFTab.ReturnValue(theFromShapeField,f)
  if (thePrj.IsNull.Not) then
    theFromShape = theFromShape.ReturnProjected(thePrj)
  end  
  
  for each t in theToFtab
    '  Get the point location you are measuring TO.
    '  Get it in projected units, if the view is projected.
    theToShape = theToFTab.ReturnValue(theToFtab.FindField("Shape"),t)
      if (thePrj.IsNull.Not) then
        theToShape = theToShape.ReturnProjected(thePrj)
      end
      
    ' Calculate the distance between the two points.
    ' Add the value to the output (TO) branch table.    
    theDistance = theFromShape.Distance(theToShape)
    theToFtab.SetValue(theDistanceField,t,theDistance)
  end
  
end   

theToFtab.SetEditable(false)

av.ShowMsg("Distance calculation complete")