Re: Suggestion / feature request

[Tassilo Horn <tassilo@member.fsf.org>]

Carlos Aguilar <carlos.aguilar@unilim.fr> writes:

Hi Carlos,

> time (mkdir file1_burst; cd file1_burst; pdftk ../file1.pdf burst; cd ..
> mkdir file2_burst; cd file2_burst; pdftk ../file2.pdf burst
> for I in pg*; do echo $I; diff -a $I ../file1_burst/$I|grep -v 
> 'BaseFont\|FontName\|Creator\|Info\|...c...\|\-\-\-\|..c..'; done
> cd .. ; rm -Rf file1_burst; rm -Rf file2_burst)
>
> pg_0085.pdf
> < x?T?n?0
>          ??W?(5CQ??^
> < 0000059304 00000 n
>> 0000059305 00000 n
> < 0000059402 00000 n
> < 0000059466 00000 n
> < 0000059513 00000 n
>> 0000059403 00000 n
>> 0000059467 00000 n
>> 0000059514 00000 n
> < 59672
>> 59673
> pg_0086.pdf
>
> real    0m7.009s
> user    0m6.160s
> sys    0m0.210s
>
> This can probably be optimized much. The only page for which there is
> a difference is the one with a change. Doc-view reconversion needs in
> the same computer 20 seconds.

Hm, seven seconds is not so super-fast compared to a complete
reconversion taking 20 seconds.  And if you edit one of the first pages
in the TeX doc, it takes additional 7 seconds to find out that you have
to reconvert almost everything, anyway.

Especially consider that you are most probably viewing page 85 when you
change it in the TeX document and recompile.  Then, if doc-view would
use such a diff-command it'll take 7 seconds for it to know that it
needs to reconvert only page 85.  The current doc-view behavior is to
start the reconversion immediately *with the current page first*.  So
right now, you'll see your changes on the current page almoust
instantly.

The many temporary files are a bit problematic, too...

Another problem is that while we can somehow expect that most (at least
GNU/Linux) machines have GhostScript installed, but that's probably not
the case for pdftk.

But in general, if there was some command that given to PDF files
quickly tells me the pages that differ, I'd try to make use of it in
doc-view, of course, as an optional feature.  But "quickly" means
something around one second for a 100 pages doc.

Bye,
Tassilo