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List:       gimp-print-devel
Subject:    Re: [Gimp-print-devel] Printer Driver for Generic Text
From:       Johannes Meixner <jsmeix () suse ! de>
Date:       2013-03-22 8:55:41
Message-ID: alpine.LNX.2.00.1303220909020.22828 () nelson ! suse ! de
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Hello,

(The spelling is Gutenprint - not guttenprint.)

On Mar 21 09:25 Tony Schenk wrote (excerpt):
> ... Mac OS X drivers that would support a text only printer.
> Our current embossers can be connected to the Mac by USB,
> USB to Parallel adapter or via an Ethernet network.
> The drive requirement of the embossers is very simple
> as they accept ASCII characters that have been defined
> to create the 64 braille characters along with standard
> control characters such as CR, LF and FF.
> It is not necessary to be able to format and print from
> every Mac application as braille requires the use of a
> translation software package such as DBT from Duxbury
> Systems to format the text properly.

I only know about Linux but because Mac OS X is based on BSD Unix
and because Mac OS X and Linux use CUPS as printing system,
the following generic information might help you:

In the CUPS printing system the conversion of the original data that
should be printed (like PDF or JPEG) into printer specific data
(like PostScript or PCL) is done by several so called "filters".

In the CUPS printing system the final printer specific data is sent
to the printer device via one so called "backend".

See "The Filter (includes the Driver)" versus "The Backends" in
http://en.opensuse.org/SDB:CUPS_in_a_Nutshell

If no conversion of the original data into printer specific data
is needed, no filters are needed which means the original data can
be sent as is in so called "raw" mode directly by the backend to
the printer device, see "raw" at
http://en.opensuse.org/SDB:CUPS_in_a_Nutshell

In your case this could mean (if I understand it correctly)
that the translation software package such as DBT produces
the final data for your braille embosser so that you only
need a CUPS backend to send the final data to the embosser.

CUPS provides ready-made backends for various kind of
connection types, in particular for USB and Ethernet,
see "The Backends" in
http://en.opensuse.org/SDB:CUPS_in_a_Nutshell

What you should try out on a Mac OS X system is:

- Somehow make final data for your braille embosser (you may
   even use Windows to make it and copy a file with that final
   data onto the Mac OS X system).

- Set up a "raw" print queue on the Mac OS X system.

- Submit the final data for your braille embosser to that raw
   print queue on the Mac OS X system.

In contrast if the translation software package such as DBT
does not produce final data for your braille embosser
but only format the text properly but without conversion
into the right ASCII characters that have been defined
to create the 64 braille characters along with standard
control characters such as CR LF and FF, then you need
to implement matching conversion software on your own.

This conversion software is what one could call the "driver"
for your braille embosser.

What such a conversion software would have to do is to take
its input (the formatted text from DBT), convert it, and
output the right ASCII characters plus control characters
for your braille embosser at stdout, see
http://en.opensuse.org/SDB:Using_Your_Own_Filters_to_Print_with_CUPS
how this can be done for CUPS under Linux. In particular see the
section "Printing Plain Text in Printer-Specific Encoding"
and therein note the "System V style interface script"
which might be the right way how to do it in your case.

If you made the converter as System V style interface script
you would set up a print queue with that System V style
interface script on the Mac OS X system.

When formatted text from DBT is submitted to that print queue,
CUPS would run your System V style interface script and what
it outputs is sent by the CUPS backend to the braille embosser.

For CUPS on a Mac OS X system it should be in principle the same as
for CUPS under Linux. But I don't have Mac OS X specific knowledge
how to add own filters (i.e. drivers) to CUPS under Mac OS X.

Summary:
If I understand it correctly, you do not need a Gutenprint
raster data driver (or any other kind of raster data driver).
You may need a converter (System V style interface script)
for "Printing Plain Text in Printer-Specific Encoding"
or you may not need any converter/filter/driver at all.


Kind Regards
Johannes Meixner
-- 
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