GetUnionRange in open office basic calc spreadsheet

'Implying Range 1 > Range 2
Function getUnionRange(Byval range1, Byval range2)
Dim rg1Addr, rg2Addr
 rg1Addr = range1.getRangeAddress()
 rg2Addr = range2.getRangeAddress()

 rg1Addr.StartRow = rg1Addr.StartRow
 rg1Addr.EndRow =   rg2Addr.EndRow
 rg1Addr.StartColumn = rg1Addr.StartColumn
 rg1Addr.EndColumn =  rg2Addr.EndColumn

 getUnionRange = getRangeByAddress(range1.getSpreadsheet(),rg1Addr)

End Function

'pass a spreadsheet-document, sheet or range  together with a c.s.s.table.CellRangeAddress
'return empty if oAddr out of bounds or wrong obj
Function getRangeByAddress(obj, oAddr as com.sun.star.table.CellRangeAddress)
on error goto nullErr:
Dim oSheet
   If obj.supportsService("com.sun.star.sheet.SpreadsheetDocument") then
      REM use the sheet specified by given address
      oSheet = obj.getSheets.getByIndex(oAddr.Sheet)
   else
      REM use given object (range/sheet) as parent range
      oSheet = obj
   endif
   getRangeByAddress = oSheet.getCellRangeByPosition(oAddr.StartColumn,oAddr.StartRow,oAddr.EndColumn,oAddr.EndRow)
exit function
nullErr:
   getRangeByAddress = Null
End Function