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From: per@chalmers.UUCP (Per Westerlund)
Newsgroups: mod.computers.laser-printers
Subject: dvi2ps, bitmaps and font cacheing
Message-ID: <8609011519.AA06949@chalmers.UUCP>
Date: Mon, 1-Sep-86 23:07:14 EDT
Article-I.D.: chalmers.8609011519.AA06949
Posted: Mon Sep  1 23:07:14 1986
Date-Received: Tue, 2-Sep-86 20:46:25 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 60
Approved: laser-lovers@washington.arpa

We recently got our LaserWriterPlus, and is using it for Tex/LaTeX on
SUN-2s, running 2.0.  The driver is dvi2ps on a recent UNIX-TeX tape
from Washington, the one where the gf-format is not yet supported.

We have run into some problems with this driver. (Actually it is not a
driver, just a translator.)

- For the fun of it I tried to print a document called "A Guide to
  TeX for the Troff User", by Mike Urban. (It was on the tape.)

  There is no way I can make the LaserWrite print the first page of
  Appendix B, Font Samples. It contains among other examples the word
  "BIG", in font 'aminch'. The bitmap is just to big, around 25 kbyte
  for the three letters.

- During normal work, mostly 10pt type, two or three different
  fonts, I usually get from 5 to 25 pages before the LaserWrite
  quits with the message "VMerror: Offending command......."


Some questions:

- The big bitmaps can be much more compactly represented,
  cf. *gf <-> *pxl. Would it not be possible to send a
  PostScript program that builds the bitmap, prints the
  character and then releases the memory used by the bitmap?
  Alternatively, there could be a similar interpreter in the
  prolog, and a compact description could be sent instead.

  Maybe big characters can be represented as outline fonts; it
  should be possible to trace the border pixels of a big
  traditional letter bitmap and make a path out of it. This
  does not work for patterned bitmaps of course.

- What is beeing done on font-cacheing?

  If big bitmaps can be more compactly represented, it should
  almost always be possible to print any single page.

  If then the conservative approach was used, and all of the
  used memory is reclaimed between pages, unlimited stretches
  of pages could be printed.

  Is there something in between? Reclaim some of the memory,
  and use it for new bitmaps.


Even if this has not been done, it would be nice to hear of
work in progress, or ideas that it might be possible to
pursue.

			Per Westerlund perw@holtec.UUCP

Excuse any abuse of the English (American?) language, my
Swedish is much better.

[[Editor's note: If you are doing work on this, please cc me as well
as perw as I am currently gearing up to do some work on this for the
Unix TeX distribution copy.  My address is furuta@mimsy.umd.edu.
Thanks.				--Rick ]]