[Pkg-cups-devel] Bug#508275: Option to always force even number of pages output per document

[martin f krafft]

also sprach Roger Leigh <rleigh at codelibre.net> [2008.12.09.1727 +0100]:
> I agree this would be useful.  I do, however, have a simple
> workaround:
> 
> Print the even pages first, then the odd pages.  This way,
> you won't have any printed pages left in the paper tray
> whether or not you have an odd or even number of pages in the
> job, and it will likely (printer-dependent) have all the
> pages in the correct orientation ready to staple/bind.

I really doubt this would work. Let's do the game using three
documents with 3/4/5 pages:

Desired output:

  doc A: 1/2 3
  doc B: 1/2 3/4
  doc C: 1/2 3/4 5

linearising all 12 pages and printing the even pages will yield:

  A2 B1 B3 C1 C3 C5

now reversing the pages and printing the odd pages in reversed order
(as required for manual duplexing):

  C5 C3 C1 B3 B1 A2
  C4 C2 B4 B2 A3 A1

Even if I hadn't used reverse:

  A2 B1 B3 C1 C3 C5
  A1 A3 B2 B4 C2 C4

C1/B4 and B1/A4 are pages from separate documents, which end up on
the same sheet. I don't want this, which I may not have expressed
entirely.

If lp always ensured that there'd be an even number printed, you'd
get (using 0 for an empty page:

  A1 A3 B1 B3 C1 C3 C5

which, after reversing and all that jazz would yield:

  C5 C3 C1 B3 B1 A3 A1
  C0 C4 C2 B4 B2 A0 A2

Basically, those fake empty pages make sure that all odd pages in
a concatenated collection also correspond to pages that are
odd-numbered in the individual documents themselves.

Does it make sense now?

-- 
 .''`.   martin f. krafft <madduck at d.o>      Related projects:
: :'  :  proud Debian developer               http://debiansystem.info
`. `'`   http://people.debian.org/~madduck    http://vcs-pkg.org
  `-  Debian - when you have better things to do than fixing systems
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