[cups] Cups 1.7.5: Paper tray/feeder not free for printer

[Johannes Meixner]

Hello,

On Mar 15 17:59 Rolf-Werner Eilert wrote (excerpt):
> When I have to print a letter on the firm's paper + need a copy for me,
> I put a piece of paper in the manual feeder, then say "print 2 copies".
> The printer sees there is paper in the feeder and prefers that.
> Once it is gone, the printer takes the paper from the tray to print my copy.
>
> In other words: The printer decides about the paper source.

The printer only decides about the paper source
provided nothing in the printing data the printer gets
enforces the printer to use a particular paper source.

> In Cups, there has always been "Tray 1" as default.

That contradicts that "the printer decides about the
paper source".
Either the printer decides or it gets told what to do.
In the latter case something outside of the printer decides
and tells the printer via the printing data what to do.

It does not happen in CUPS itself what paper source is used.
It is not CUPS itself that actually makes printer specific things.

There are various filtering programs (unless you print in 'raw' mode)
together with printer driver software (unless you have a real
PostScript printer) that make printer specific things by converting
the original print job data (from the application) into
printer specific data.

Accordingly also each particular application could make a difference
depending on what particular print job data a particular application
creates.
For an example how the final printing result may depend on what
particular print job data a particular application had created
have a look at the "Example: LibreOffice 'landscape printing'" in
https://en.opensuse.org/SDB:Landscape_Printing


> Now I am on a new system with Cups 1.7.5, and all of the sudden
> the printer cannot decide for himself anymore, i. e. whatever
> I choose, it insists on paper from that source.

I guess on your old system you had the traditional
PostScript-centric workflow ("workflow" means how the various
filtering programs plus printer driver software behave)
in particular when on your old system you used CUPS <= 1.5.4.

With newer CUPS there was a change away from the traditional
PostScript-centric workflow to the new PDF workflow, cf.
"Common printing data formats" at
https://en.opensuse.org/Concepts_printing


In general regarding "How to Report a Printing Issue" see
https://en.opensuse.org/SDB:How_to_Report_a_Printing_Issue
which also povides some initial basic tests how you could
diagnose the cause of your particular printing issue,
in particular how to "Get what the application submits to CUPS".

To inspect the final printing data that is sent to the printer
see "A backend that sends its input into a file for debugging" at
https://en.opensuse.org/SDB:Using_Your_Own_Backends_to_Print_with_CUPS


Kind Regards
Johannes Meixner
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