Barcode Plugin Development

This article is part of the Ongoing Discussions series.

Installation • Usability • MacOS • Fonts • Other

The barcode plugin does not currently provide all of the functionality that is available in the underlying library, Barcode Writer in Pure PostScript (BWIPP).

This page is intended to provide a collaboration point to coordinate improvements to the barcode plugin. Please extend, debate and discuss as appropriate.

Simple tasks

• Switch from the monolithic flavour of BWIPP to the monolithic-package flavour which is functionally equivalent, more suited to distribution and DSC-conforming. Has been tested by replacing the existing barcode.ps and works as expected. Description of the available flavours here.
• Hexify the data and options string input from Scribus to BWIPP to prevent PostScript injection by means of unescaped ")" or otherwise. See this discussion here.
• Add an advanced checkbox that allows the user to directly provide the options string to the library for advanced users who follow the BWIPP reference.

Moderate tasks

• Add support for the remaining barcode symbologies that are supported by BWIPP:
  • Point of Sale: ISMN, ISSN
  • GS1 DataBar: GS1 DataBar Omnidirectional, GS1 DataBar Stacked, GS1 DataBar Stacked Omnidirectional, GS1 DataBar Truncated, GS1 DataBar Limited, GS1 DataBar Expanded, GS1 DataBar Expanded Stacked
  • Supply Chain: SSCC-18, EAN-14, GS1 DataMatrix
  • Common 2D symbols: Data Matrix, Aztec Code, PDF417, MicroPDF417
  • Common 1D symbols: Code 39 Full ASCII, Code 93, Code 93 Full ASCII
  • Postal symbols: USPS PLANET, USPS Intelligent Mail, USPS FIM, Royal TNT Post, Japan Post, Australia Post, Deutsche Post Identcode, Deutsche Post Leitcode, MaxiCode
  • Pharmaceutical symbols: Pharmacode, Two-track Pharmacode, Code 32, Pharmazentralnummer
  • Less-used 2D symbols: Codablock F, Code 16K, Code 49, Code One
  • Less-used 1D symbols: Code 11, Codabar, Telepen, Channel Code, PosiCode, BC412
  • GS1 Composite symbols: EAN-13 Composite, EAN-8 Composite, UPC-A Composite, UPC-E Composite, GS1 DataBar Omnidirectional Composite, GS1 DataBar Stacked Composite, GS1 DataBar Stacked Omnidirectional Composite, GS1 DataBar Truncated Composite, GS1 DataBar Limited Composite, GS1 DataBar Expanded Composite, GS1 DataBar Expanded Stacked Composite, GS1-128 Composite
  • HIBC symbols: HIBC Codablock F, HIBC Code 128, HIBC Code 39, HIBC Data Matrix, HIBC PDF417, HIBC MicroPDF417, HIBC QR Code
• To make the presentation of the list of barcode formats manageable we should sort the list of barcodes in the same/similar way as the web-based generator here.
• Use the BWIPP error reporting mechanism to provide specific error messages to users so that they can understand why a given input is invalid. For example, the following PS procedure can be used to invoke barcode.ps and on error will halt with the descriptive text of the error (e.g. "BWIPP ERROR: EAN-13 must be 12 or 13 digits") written to STDERR which Scribus can display in the GUI:

 %!PS
 errordict begin
 /handleerror {
   $error begin
   errorname dup length string cvs 0 6 getinterval (bwipp.) eq {
     (%stderr) (w) file
     dup (\nBWIPP ERROR: ) writestring
     dup errorname dup length string cvs writestring
     dup ( ) writestring
     dup errorinfo dup length string cvs writestring
     dup (\n) writestring
     dup flushfile end quit
   } if
   end //handleerror exec
 } bind def
 end
 % If necessary, set up anything specific to the environment here.
 (barcode.ps) run

• Allow the location of the barcode.ps file to be configured by the user so that non-admins users can provide a local version and distributions that deprecate bundled libraries can provide a separately packaged version. One way to do this is to provide a configuration dialog with PATH_TO_BWIPP=USER|DEFAULT.
  • Use the user supplied path if PATH_TO_BWIPP=USER.
  • Apply the following search order if PATH_TO_BWIPP=DEFAULT:
    • ~/.scribus/plugins/barcode.ps (user replacement)
    • [%APP_INSTALL_DIR%]/share/scribus/plugins/barcode.ps (bundled version)
    • /usr/share/postscriptbarcode/barcode.ps (Fedora's postscriptbarcode package)
    • /usr/share/libpostscriptbarcode/barcode.ps (Debian's libpostscriptbarcode package)
  • In either case, if barcode.ps is not found, prompt the user by showing the dialog with PATH_TO_BWIPP=USER pre-selected.

Harder tasks

• Support new barcode formats automatically by scanning the barcode.ps metadata for BEGIN/END ENCODER blocks.
• Extract descriptions, example data and example options from the barcode.ps metadata by scanning for DESC, EXAM and EXOP stanzas within BEGIN/ENCODER ENCODER blocks.

Example barcode.ps metadata for an encoder:

 % --BEGIN ENCODER ean8--
 % --REQUIRES preamble raiseerror renlinear ean5 ean2--
 % --DESC: EAN-8
 % --EXAM: 02345673
 % --EXOP: includetext guardwhitespace
 % --RNDR: renlinear
 ... PostScript resource definition here ...
 % --END ENCODER ean8--

Collaborative tasks

The following require close coordination between Scribus and Terry Burton the author of BWIPP.

• Extend the barcode.ps metadata to describe the options that are available for each encoder so that any frontends such as the Scribus plugin can be light on compiled in data and enhanced by simply replacing the barcode.ps file.