Writing a DXF Interface Program
Writing a DXF Interface Program
Writing a DXF File
The following example is a simple Visual Basic 6 program that reads a DXF file and extracts specific codes and values from a given object in a given section.
' ReadDXF extracts specified code/value pairs from a DXF file.
' This function requires four string parameters, a valid DXF
' file name, a DXF section name, the name of an object in that
' section, and a comma delimited list of codes.
'
Function ReadDXF( _
ByVal dxfFile As String, ByVal strSection As String, _
ByVal strObject As String, ByVal strCodeList As String)
Dim tmpCode, lastObj As String
Open dxfFile For Input As #1
' Get the first code/value pair
codes = ReadCodes
' Loop through the whole file until the "EOF" line
While codes(1) <> "EOF"
' If the group code is '0' and the value is 'SECTION' ..
If codes(0) = "0" And codes(1) = "SECTION" Then
' This must be a new section, so get the next
' code/value pair.
codes = ReadCodes()
' If this section is the right one ..
If codes(1) = strSection Then
' Get the next code/value pair and ..
codes = ReadCodes
' Loop through this section until the 'ENDSEC'
While codes(1) <> "ENDSEC"
' While in a section, all '0' codes indicate
' an object. If you find a '0' store the
' object name for future use.
If codes(0) = "0" Then lastObj = codes(1)
' If this object is one you're interested in
If lastObj = strObject Then
' Surround the code with commas
tmpCode = "," & codes(0) & ","
' If this code is in the list of codes ..
If InStr(strCodeList, tmpCode) Then
' Append the return value.
ReadDXF = ReadDXF & _
codes(0) & "=" & codes(1) & vbCrLf
End If
End If
' Read another code/value pair
codes = ReadCodes
Wend
End If
Else
codes = ReadCodes
End If
Wend
Close #1
End Function
' ReadCodes reads two lines from an open file and returns a two item
' array, a group code and its value. As long as a DXF file is read
' two lines at a time, all should be fine. However, to make your
' code more reliable, you should add some additional error and
' other checking.
'
Function ReadCodes() As Variant
Dim codeStr, valStr As String
Line Input #1, codeStr
Line Input #1, valStr
' Trim the leading and trailing space from the code
ReadCodes = Array(Trim(codeStr), valStr)
End Function