Re: Suggestion / feature request

[Carlos Aguilar <carlos.aguilar@unilim.fr>]

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Le 19/04/2012 16:17, Tassilo Horn a écrit :
> Carlos Aguilar<carlos.aguilar@unilim.fr>  writes:
>
> Hi Carlos,
>
>> I often use doc-view mode with medium to large pdf/ps/dvi files, when
>> writing/modifying latex documents.
> Yes, frequently changing documents are clearly not the prime use-case
> for doc-view, exactly because of the reasons you mention.  Do you use
> AUCTeX for writing your documents?  If yes, then preview-latex might be
> exactly what you need.
>
> ,----[ (info "(preview-latex)Top") ]
> |    preview-latex is a package embedding preview fragments into Emacs
> | source buffers under the AUCTeX editing environment for LaTeX.  It uses
> | `preview.sty' for the extraction of certain environments (most notably
> | displayed formulas).  Other applications of this style file are
> | possible and exist.
> `----
>
Ummm I suppose I am a bit of a maniac I really feel unconfortable if I 
don't have the real pdf in front of me and can go back and forward to 
check the global aspect of the document  ...
>> I wondered if it would be possible to keep a set of signatures of the
>> pdf/ps/dvi pages processed so that those that are unchanged are not
>> reconverted to (already existing) bitmap images.
> Um, I have no idea how to do that.  Doc-view only knows the PNG images
> generated from the original document, and you can't compare those with
> pages in the document.
>
> Well, it also has the old document's contents in the current buffer and
> the updated document is on the file system, so in theory it could also
> compare the documents.  But I have no clue how to do that.  Googling
> around, I've found http://www.qtrac.eu/comparepdf.html, but I'm not sure
> if it does the trick.  (Oh, and of course if the comparison of the docs
> is not significantly cheaper than a reconversion, there's no sense in
> doing so. ;-))
Of course it must be MUCH cheaper.

I have tried to use pdftk burst (which splits almost instantaneously a 
pdf file in a set of files with one page each) with two closely 
different versions of a large pdf. The idea was : if the pdf for each 
file is exactly the same when pages are unchanged just a checksum will 
do the test (and be very significantly cheaper than a reconversion).

The resulting pdf files are close for each page but different. Maybe 
there is a workaround with pdftk or directly with gs ... but before 
doing that the question is :
Would you change doc-view if it is possible to find a (simple enough) 
way to obtain the functionality I am talking about ? Or do you believe 
this is uninteresting/dangerous/outofscope ?

cheers,

Carlos


> Bye,
> Tassilo

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