[Qt-interest] Need help printing

[Konrad Rosenbaum]

On Sunday 26 July 2009, Scott Aron Bloom wrote:
> But my customer is saying, that the PCL6X driver wont work without a
> syntax error, but the old PCL5 works, but its prints at about 2-3 pages
> per minute in comparision to the 20-30 ppm that other tools can put out.
>
>
>
> Any ideas?  Any gotchas I should look for?

What platform is this? Windoze, CUPS?

If it is CUPS - I had a bit of fun a while back debugging the path of a 
document through it...

It has a habit of being slow for some file formats.

CUPS (like the old lp/lpr based system) is a filter-chain setup: it 
understands a variety of formats and then makes sure they are converted 
until they hit a printer native format. Depending on the printer driver the 
formats that are considered native can be PS, PDF, PCL, etc.pp.

Qt outputs PDF (which is the IPP/CUPS default format since a few versions, 
before that it used to be PS). Depending on your printer setup that PDF is 
either converted to PCL directly or filtered through pdftops first. The 
latter has a few gotchas - there is a CUPS implementation of that filter, 
but some Linux distributions (eg. Debian/etch) replace it with the upstream 
pdftops and introduce a few problems (like faulty page sizing or printing 
delays) along the way.

In order to find out what went wrong:

*print to a PDF file and then print this file with lpr - see if it makes a 
difference (yes: it's Qts fault, no: it's CUPS' fault)

*convert the PDF to PS and print (faster: something is wrong with pdftops, 
still slow: it gets complicated here)

*if you don't have it yet, you need to read a lot about CUPS format filters 
and debug the path of the document through the filters (there is a verbose 
setting for CUPS that at least lets you see what filters are started in the 
logs - apart from lots of junk you weren't interested in)


	Konrad
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