[Bug-AUCTeX] preview-latex bug with pdflatex

[Matthew H . Plough]

I am able to reproduce the problem that Björn Pedersen reported on
August 29; his original posting is at
http://comments.gmane.org/gmane.emacs.latex.preview.devel/1321 .

The problem is fairly simple.  When pdflatex is used instead of
latex, a pdf containing all of the previews is generated, and pdf2dsc
is run, generating a .dsc file that references the .pdf file.
However, ghostscript only gets run once on that file, so only the
first preview image is extracted.  However, no errors occur.

David Kastrup asked: I don't think so, or there would be more error
messages.  Sorry, this posting appears to have remained unanswered
very long.  I can't reproduce the problem.  Is it still there?



Yes, the problem is still there, but I think I know why it is
happening.  Here are the steps to reproduce (I'm running Aquamacs
Emacs 0.9.6 and a build of AUCTeX and preview-latex from source on
Mac OS X 10.4):

- Fire up Aquamacs Emacs and open a .tex file containing some
equations.  Make sure that regular latex is being used, so a .dvi
is generated and dvips is run.

- Press C-c C-p C-d to generate all previews for the document.
Press C-c C-l (ell) to see compilation results.  Note that ghostscript
gets run a whole lot of times.

- Switch to pdflatex using the configuration options (save for
session and for future use).

- Press C-c C-p C-d again, to generate previews.  Note that all
previews still show up.  Press C-c C-l to see compilation results;
note that ghostscript gets run only once.  David, this is probably
why you couldn't reproduce -- you'll need to do the next steps.

- Kill the buffer -- that way, if you're using desktop, the previews
won't show up when you next open the file.

- Exit Aquamacs Emacs.

- To be extra sure the previews won't show up (I haven't needed to
do this, but it's worth doing), delete all the temporary files that
preview-latex generated.

- Fire up Aquamacs Emacs and open the same .tex file as before.
Make sure that pdflatex will be used.

- Press C-c C-p C-d to generate previews, and press C-c C-l to see
compilation results.  *Note that only the first preview shows up*.

I'm a programmer, but I don't know elisp, so I can't do an in-depth
analysis, but here's what I think is happening.  When the output
is a dvi, dvips gets used, and then a loop runs that extracts each
preview.  However, when the output is a pdf, pdf2dsc gets used, but
then there isn't any loop that extracts the previews.  Thus, only
the first preview gets extracted.

I hope this bug report helps resolve the problem.  It would be
really nice if I could use pdflatex; it cooperates with TeXShop
very well, so I can examine my output with TeXShop (it automatically
reopens the pdf when it's regenerated) while getting nice figure
and equation previews while editing.

Please let me know if more information would be helpful, or if I
can be of further assistance in resolving this issue.

Best regards,
Matt