>
> - Carsten
>
> On Nov 16, 2009, at 1:07 AM, Eric Schulte wrote:
>
>> Hi,
>>
>> The attached patch changes the latex fragment image generation so that
>> it saves images into files named by the sha1 hash of the latex source
>> code.  By checking for the existence of image files before image
>> generation the regeneration of identical images is avoided.
>>
>> In practice I find that this greatly speeds up export to html and the
>> `org-preview-latex-fragment' command.
>>
>> Cheers -- Eric
>>
>> From 13e1c48fa6cac43b0c87ca0fbc8e349f7a9fa864 Mon Sep 17 00:00:00 2001
>> From: Eric Schulte <schulte.eric@gmail.com>
>> Date: Sun, 15 Nov 2009 17:00:09 -0700
>> Subject: [PATCH] latex fragment images cached using sha1 hash keys
>>
>>  Latex fragment images are now saved in files named by the sha1 hash
>>  of the latex text used to create the image.  By checking if files
>>  exist before images generation the regeneration of identical latex
>>  images is avoided.
>> ---
>> lisp/ChangeLog |    6 ++++++
>> lisp/org.el    |   18 +++++++-----------
>> 2 files changed, 13 insertions(+), 11 deletions(-)
>>
>> diff --git a/lisp/ChangeLog b/lisp/ChangeLog
>> index 339f248..f18755c 100755
>> --- a/lisp/ChangeLog
>> +++ b/lisp/ChangeLog
>> @@ -1,3 +1,9 @@
>> +2009-11-16  Eric Schulte  <schulte.eric@gmail.com>
>> +
>> +	* org.el (org-format-latex): Latex images are now saved to files
>> +	named by the sha1 hash of the latex source text avoiding
>> +	regeneration of identical images.
>> +
>> 2009-11-15  Carsten Dominik  <carsten.dominik@gmail.com>
>>
>> 	* org-wl.el (org-wl-store-link): Handle the case that
>> diff --git a/lisp/org.el b/lisp/org.el
>> index bf6573b..46348fc 100644
>> --- a/lisp/org.el
>> +++ b/lisp/org.el
>> @@ -14550,15 +14550,9 @@ Some of the options can be changed using
>> the variable
>> 	 (opt org-format-latex-options)
>> 	 (matchers (plist-get opt :matchers))
>> 	 (re-list org-latex-regexps)
>> -	 (cnt 0) txt link beg end re e checkdir
>> +	 (cnt 0) txt hash link beg end re e checkdir
>> 	 executables-checked
>> 	 m n block linkfile movefile ov)
>> -    ;; Check if there are old images files with this prefix, and
>> remove them
>> -    (when (file-directory-p todir)
>> -      (mapc 'delete-file
>> -	    (directory-files
>> -	     todir 'full
>> -	     (concat (regexp-quote prefixnodir) "_[0-9]+\\.png$"))))
>>     ;; Check the different regular expressions
>>     (while (setq e (pop re-list))
>>       (setq m (car e) re (nth 1 e) n (nth 2 e)
>> @@ -14576,9 +14570,10 @@ Some of the options can be changed using
>> the variable
>> 	    (setq txt (match-string n)
>> 		  beg (match-beginning n) end (match-end n)
>> 		  cnt (1+ cnt)
>> -		  linkfile (format "%s_%04d.png" prefix cnt)
>> -		  movefile (format "%s_%04d.png" absprefix cnt)
>> 		  link (concat block "[[file:" linkfile "]]" block))
>> +            (setq hash (sha1 txt)
>> +		  linkfile (format "%s_%s.png" prefix hash)
>> +		  movefile (format "%s_%s.png" absprefix hash))
>> 	    (if msg (message msg cnt))
>> 	    (goto-char beg)
>> 	    (unless checkdir ; make sure the directory exists
>> @@ -14592,8 +14587,9 @@ Some of the options can be changed using the
>> variable
>> 	       "dvipng" "needed to convert LaTeX fragments to images")
>> 	      (setq executables-checked t))
>>
>> -	    (org-create-formula-image
>> -	     txt movefile opt forbuffer)
>> +            (unless (file-exists-p movefile)
>> +              (org-create-formula-image
>> +               txt movefile opt forbuffer))
>> 	    (if overlays
>> 		(progn
>> 		  (mapc (lambda (o)
>> --
>> 1.6.4.73.gc144
>>
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>
> - Carsten