[haiku-development] Re: GSoC Project - Continue the CUPS port
- From: "Ithamar R. Adema" <ithamar.adema@xxxxxxxxxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Tue, 06 Apr 2010 01:34:45 +0200
[sorry, pressed enter to soon previously]
Hi,
Ionut Cristian Paraschiv wrote:
If there is someone who knows what is yet to be implemented at this
project, please give me some information. I've looked through the
sources, but I haven't figured out this yet.
Thank you!
CUPS is mostly working, I guess most of the basic functionality should
compile and run cleanly. Besides the sources already pointed out in this
thread, there's a patch at HaikuPorts[1] and there's the GPL source
code[2] from ZETA (a previously commercial BeOS distribution).
However, CUPS basically only implements general printer driver
management, not the actual printer support. A lot of the functionality
in CUPS is already supported by our current print_server & transport add
ons. The interesting parts (taking a closer look at the ZETA
implementation) is in foomatic[3], which is a database of printer
descriptions (it uses an XML database converted to PPD[4] files) for
describing the supported printers and their features.
The real interesting part, and what ZETA used CUPS/foomatic for, is the
actual printer drivers. Most of them use Ghostscript[5] backends to
convert Postscript to the output format used by the printer. This gets
Haiku the real printer supported that is normally expected when people
talk about the CUPS port.
I was involved in earlier goes at porting CUPS to Haiku, and the
implementation for ZETA. I've got a bunch of patches on my local
development tree of Haiku that improves our current printing
infrastructure. These should be committed around BeGeistert (next weekend).
My personal opinion is that CUPS might be a bit too much. I'd rather
find a good way to create a printer driver that uses either Ghostscript
or the Ghostscript backends to create the output stream, and then
utilize our current transport add ons for actually sending the data to
the printer.
So, the first step would be to determine which printing functionality we
actually want to have out of CUPS, and it'll probably turn out to be
easier to expand our current print_server to implement this. Then use
the foomatic XML database to come up with a good format to store printer
feature sets (my current idea is to either use PPD files, and add
attributes to them for quick lookup), and use Ghostscript backends for
the actual printing through a special printer driver.
Besides all this there is a certain amount of cleanup to do in the
current printing architecture, as there's a whole lot of shared code
floating about at different places in the Haiku source tree that should,
IMNSHO should be integrated into the print_server. A discussion on this,
especially wether or not we want to keep R5 backwards compatibility on
printer driver/transport add on level would be appropriate (dropping
that would make it possible to have a much cleaner addon structure for
the print_server, making all this much easier).
I was planning to discuss a lot of this @ BeGeistert, but an earlier
discussion on the list wouldn't hurt either I guess...
HTH,
Ithamar.
[1] http://ports.haiku-files.org/wiki/net-print/cups
[2] http://www.zeta-os.com/cms/download.php?view.19
[3]
http://www.linuxfoundation.org/collaborate/workgroups/openprinting/database/foomatic
[4] http://en.wikipedia.org/wiki/PostScript_Printer_Description
[5] http://pages.cs.wisc.edu/~ghost/
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