[ale] Setting up pseudo-printer

[John Mills]

Dow -

Thanks very much for your note and suggestions.

On Fri, 16 Jan 2004, Dow Hurst wrote:

 [...]
> However, even the lp system can use filters, so a little 
> searching might find a HOWTO on setting a filter that would 
> do what you want.  The Netpbm library is a powerful package 
> for converting image files.  I looked at a tiff2ps package 
> that looked very nice.  I don't have the link for that with me.

> Am I understanding the question correctly?  Which is that 
> you want to print an image?  Gimp will print images 
> fantastically after you set it up for your printer.

I guess my question was too indirect or not well put. I have a short 
script that decodes a text-encoded image file (typically a JPEG) and pipes 
it to 'display' which puts it on my screen. I could use any utility that 
could accept an image format at <stdin>; I just happen to be using 
'display'. This is exactly what I want it to do as though it were a 
printer.

My question is:
 How can I access this script so that 'lpr' will _use_it_ as though it
were a printer. I want to invoke 'lpr -P viewer <file>' on the text file
and just _see_ the image on the screen. No printed copy at all.

I was trying to put my script as a processing filter (a'la _ghostscript_)  
with its text output (and errors) going to /dev/null, and its graphic
output going transparently to the screen. The problem must be analogous to
putting a printer filter on a stream being sent to a remote printer,
except that text output is sent to /dev/null and the image is
transparently redirected to the screen.

Any ideas?

> John Mills wrote:

> > I have a script to pipe through a decoding filter, and uses 'display' to
> > show an image on the screen. For example, I can show an image with:
> >  % cat <encoded_jpeg_file> | /usr/local/bin/viewer_filter
 
> > I'm having some trouble setting this up as a printer, so that I could
> > invoke it with [say]:
> >  % lpr -P viewer <encoded_jpeg_file>

TIA.

 - John Mills
   john.m.mills at alum.mit.edu