[printing-discuss] Re: [printing-driver] proposal of what features the communication to a printer driver should support

Robert L Krawitz rlk at alum.mit.edu
Sun Dec 2 06:51:03 PST 2001


(BTW, there's a good chance that this posting won't make it to the
Sourceforge lists.  Right now I seem to be unable to actually post to
lists on Sourceforge, which as you can imagine is causing me much
grief wrt gimp-print.)

   From: "Mark Hamzy" <hamzy at us.ibm.com>
   Date: Fri, 30 Nov 2001 11:24:27 -0600

   Device management
   -----------------

    - Query a device's programmatic language description. (PCL,
      ESC/P2, PS, HG/GL) NOTE:  This can allow spoolers to move jobs
      between similar print queues.

I think the issue of compatible print queues needs to be completely
separate from the issue of the general language description.  Indeed,
for modern printers (beyond Postscript and perhaps PCL), it isn't
clear to me that the high level language description is even very
useful except for organization within a driver.

For my second point, while all Epson Stylus printers use "ESCP/2
Raster", the dialects are mutually not entirely comprehensible.  While
a file for the e. g. Stylus Photo 870 can be sent to an 890, the
converse may not be true.  Certainly a raw file for the 870 cannot be
sent to a Stylus C80, so for all external intents and purposes they
speak a different language.

What happens within the driver is another matter, of course; from an
implementation standpoint, they share a lot.  From a higher level
standpoint they don't share much at all.

But even if we're not talking about a raw file (and I seriously hope
we're not; those things are just too big!), I think we should take a
higher level look at what constitutes a "similar print queue" from the
user's perspective.  Suppose I have three printers:

  Epson Stylus Photo 780
  Canon S800
  Epson Stylus C80

Suppose the 780 is down, but there are some (non-raw) files queued for
it.  Which printer should they be diverted to?  It isn't clear.  Most
likely I would want to divert it to the S800 (which is a very high
quality, 6-color photo printer), not to the C80.  The reasoning -- and
this cannot be captured by knowing anything about the familial
resemblance -- is that the C80 is a fast 4-color printer, so if I'm
printing to the 780 I'm probably printing a smaller graphic with more
demanding quality requirements.



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