Barcode Plugin Development: Difference between revisions

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{{Discussion Index}} [[Category:Development]][[Category:EN]]
{{Discussion Index}} [[Category:Development]][[Category:EN]]
The [http://documentation.scribus.net/index.php/Barcode_Generator barcode plugin] does not currently provide all of the functionality that is available in the underlying library, [http://bwipp.terryburton.co.uk 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.
This page is intended to provide a collaboration point to coordinate improvements to the [http://documentation.scribus.net/index.php/Barcode_Generator barcode plugin] which is based on [http://bwipp.terryburton.co.uk Barcode Writer in Pure PostScript] (BWIPP). Please extend, debate and discuss as appropriate.


==Simple tasks==
The BWIPP wiki provides [https://github.com/bwipp/postscriptbarcode/wiki/Developing-a-Frontend-to-BWIPP some recommendations for frontends].


* 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 [http://bwipp.terryburton.co.uk/#download here].
==Scribus tasks==
* Hexify the data and options string input from Scribus to BWIPP to prevent PostScript injection by means of unescaped ")" or otherwise. See this discussion [https://bitbucket.org/whosaysni/elaphe/issue/18/make-codestring-optionstring-hexilified here].
* Add an advanced checkbox that allows the user to directly provide the options string to the library for advanced users who follow the [https://github.com/bwipp/postscriptbarcode/wiki BWIPP reference].
* Locking the aspect ratio of the imported object could be advantageous.


==Moderate tasks==
* Create a new type of Scribus Barcode Item:
** The input is currently a vector item that can be ungrouped. Ungrouping makes little sense because it typically changes the relationship between the barcode elements, spoiling the meaning of the barcode.
** The imported object should initially have a fixed aspect ratio. Only occasionally does it make sense to re-scale the imported image since nominal symbol sizes are standardised.
** Ideally, double-clicking on such an item would bring up the barcode dialogue (not the Group Tab of the PP), so that a user can change the data, and the barcode drawing would be updated after clicking an "Update" button. For this, Scribus must store the value behind the created barcode: codeEdit, optionsEdit, lnColor, bgColor, txtColor (Checkbox states unnecessary as encoded in optionsEdit).


* 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 [http://www.terryburton.co.uk/barcodewriter/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.
* Allow the barcode plugin to be driven from ScripterNG.
* Allow the barcode plugin to be driven from ScripterNG.
==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==
==Collaborative tasks==
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The following tasks require some degree of coordination between Scribus and [[User:Terryburton|Terry Burton]], the author of BWIPP.
The following tasks require some degree of coordination between Scribus and [[User:Terryburton|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.
* 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 with new format by simply replacing the barcode.ps file. [IN PROGRESS UPSTREAM - https://github.com/bwipp/postscriptbarcode/tree/master/libs]
* Create a new type of Scribus Item (a vector item that cannot be ungrouped) that also stores the value behind the created barcode (e.g. a URL). Ideally, double-clicking on such an item would bring up the barcode dialogue (not the Group Tab of the PP), so that a user can change the data, and the barcode drawing would be updated after clicking an "Update" button. This would, obviously, require some extensions to the Scribus core, as well as changes to the file format.
* Mentor a GSOC student on this barcode plugin.

Latest revision as of 11:02, 18 September 2023

This article is part of the Ongoing Discussions series.
Installation • Usability • MacOS • Fonts • Other

This page is intended to provide a collaboration point to coordinate improvements to the barcode plugin which is based on Barcode Writer in Pure PostScript (BWIPP). Please extend, debate and discuss as appropriate.

The BWIPP wiki provides some recommendations for frontends.

Scribus tasks

  • Create a new type of Scribus Barcode Item:
    • The input is currently a vector item that can be ungrouped. Ungrouping makes little sense because it typically changes the relationship between the barcode elements, spoiling the meaning of the barcode.
    • The imported object should initially have a fixed aspect ratio. Only occasionally does it make sense to re-scale the imported image since nominal symbol sizes are standardised.
    • Ideally, double-clicking on such an item would bring up the barcode dialogue (not the Group Tab of the PP), so that a user can change the data, and the barcode drawing would be updated after clicking an "Update" button. For this, Scribus must store the value behind the created barcode: codeEdit, optionsEdit, lnColor, bgColor, txtColor (Checkbox states unnecessary as encoded in optionsEdit).
  • Allow the barcode plugin to be driven from ScripterNG.

Collaborative tasks

The following tasks require some degree of 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 with new format by simply replacing the barcode.ps file. [IN PROGRESS UPSTREAM - https://github.com/bwipp/postscriptbarcode/tree/master/libs]
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