Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!batcomputer!rpi!plato.rdrc.rpi.edu!jvmiller
From: jvmiller@plato.rdrc.rpi.edu (Jim Miller)
Newsgroups: comp.sys.amiga
Subject: PLT:, HPGL, DumpRastPort()
Keywords: PLT:, HPGL, DumpRastPort, CAD, handler
Message-ID: <5375@rpi.edu>
Date: 8 Jun 89 21:00:42 GMT
Sender: usenet@rpi.edu
Distribution: usa
Lines: 45


My co-author (Richard Champeaux) and I have been writing a file-handler
that accepts HPGL (pen plotter) commands and dumps a rasterimage to a dot-
matrix printer.  Since most CAD packages will only perform screen dumps
to a dot-matrix printer, hardcopy output quality is usually pretty poor.
These same CAD packages will usually produce output for a HP pen plotter.
By redirecting the HPGL output from these CAD packages to PLT: high quality
hardcopies can be generated.  PLT: inquires from preferences your desired
resolution and takes advantage of the printer's capabilites by mapping
the plotter's coordinate system onto the printer's coordinate system.
It assumes that the printer is using 8.5" x 11" paper.  Most of the 
HPGL primitives have been implemented.  I have yet to find a CAD package that
uses the commands I haven't implemented (the only command no implemented that
would be useful is  the rotate command [allows portrait plots]).

PLT: divides the printer's page into smaller rasters that it plots separately
then dumps to the printer.  This prevents the handler from grabbing all of 
the computer's memory.  We then use the printer driver's dump_rast_port
command (I don't recall the exact name) to dump each raster to the printer.
We have tested the handler on a Okidata-292 dot-matrix printer and
it works great (sorry no color support as of yet).

My problem arises when using a LaserJet printer.  Apparently the dump_rast_port
routine send a reset as its first packet.  This reset causes the LaserJet
to eject a page.  This is very unsatisfactory when the raster section is only 
50 lines tall.  My question is:

	Is it possible to inhibit the dump_rast_port routine from 
	sending the reset packet at the start of each dump (or from the
	dumps after the first one)?


Also, if anyone is interested in testing this handler then let me know how
to get it to you.  I would like to see (hear?) how it performs on other
printers (I only have access to the Okidata-292 and LaserJet Series II).

This was our solution to the inadequate CAD hardcopy routines, plus it
gaves us a HPGL interpretor.

I hope someone has an answer to my question so I can move onto
emulating more commands (like fills, arcs, etc.).


Jim Miller
Rich Champeaux