[hpoj-devel] Re: HP OJ Development

[<pa...@rc...>]

James Klicman wrote:
> I've been keeping an eye on the hpoj project hoping that scanning would
> appear one day for the OfficeJet 700 series.
> 
> I was wondering if you could give me a few pointers to get me started on
> implementing scanning support, I'm seriously contemplating digging into
> it now. I am a proficient programmer and have an OfficeJet 710 that I'm
> tire of using through VMWare. :-)

Hi, James.  I'm sorry I haven't yet gotten around to that.  It's been on my
TODO list for a long time, but currently I'm bogged down in rewriting the
low-level I/O drivers.  Ultimately I intend to write a new SANE backend that
unifies all of the different OfficeJet scanning methods (SCL/raw, SCL/MFPDTF,
PML/MFPDTF, and PML/MFPDTF-fax-receive) over parallel, USB, and JetDirect
connections.  That's probably beyond the scope you want to deal with to get
your 710 scanning, so you can certainly take a stab at writing something to
get just that class (PML/MFPDTF) working if you'd like.  It shouldn't be too
hard to extend "hpo scan" to extract the image data from the packetized data
stream and save it to a .pnm file.  I have a little bit of documentation that
might be helpful on this, but the only stipulation is that you can't
redistribute it verbatim, according to the person at HP who originally
provided it.

One problem I can think of that you might run into is that the current I/O
drivers (which I'm trying to replace) don't deal well with multiple channels
open on the peripheral at the same time, which is the case when using the PML
channel to set up and start the scan and the scan channel to receive the data.

It would be preferable to discuss this on the hpoj-devel mailing list, since
that's what it's for.  :-)  In any case, thanks for your interest in helping
out with development.

David