On Wed, Jan 19, 2022 at 12:18 PM John Kitchin <jkitchin@andrew.cmu.edu> wrote:
I am not sure this is quite what you are looking for. You could use a macro like this. 



{{{r-stack(((src1 . fade-out) (src2 . fade-in) (src3 . fade-out)))}}}

* code :noexport:

#+macro: r-stack (eval (r-stack $1))

#+BEGIN_SRC emacs-lisp
(defun r-stack (src-alist)
  "SRC-alist will be a string containing a list of (src . data-fragment)
src is a url or filename
data-fragment

Returns a string for export."  
  (let ((src (read src-alist)))
    (format "#+BEGIN_EXPORT html
<div class=\"r-stack\">
%s      
</div>
,#+END_EXPORT"
   (string-join
    (cl-loop for (src . data-fragment) in src
     collect
     (format "  <img data-fragment=\"%s\" src=\"%s\"/>"
     data-fragment src))
    "\n"))))


(r-stack "((src1 . fade-out) (src2 . fade-in) (src3 . fade-out))")
#+END_SRC

#+RESULTS:
: #+BEGIN_EXPORT html
: <div class="r-stack">
:   <img data-fragment="fade-out" src="src1"/>
:   <img data-fragment="fade-in" src="src2"/>
:   <img data-fragment="fade-out" src="src3"/>      
: </div>
: #+END_EXPORT

You could also make a link do that.

Huh.  This wasn't at all what I was thinking but it may be a much better way than I'd htought of. 

A link seems like it would be a great solution, especially if I could figure out how to get the :follow function to open an individual ~src~ path. Would you use "looking-at" to get the right candidate, or can you think of a way to get completion candidates for a function that opens the file? I'm looking at your eamples in https://kitchingroup.cheme.cmu.edu/blog/2016/11/04/New-link-features-in-org-9 but can't quite follow the code.

Thank so mjch for this really interesting solution.

John

-----------------------------------
Professor John Kitchin (he/him/his)
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803


On Wed, Jan 19, 2022 at 9:42 AM Matt Price <moptop99@gmail.com> wrote:
I am trying ot figure out if I can create a simplified syntax for a particular special block in a derived HTML exporter. 

I'm trying to produce HTML like this:

<div class="r-stack>
  <img data-fragment="fade-out" src="...."/>
  <img data-fragment="fade-in" src="..."/>
</div>


The derived backend (org-re-reveal) already has an 
#+ATTR_REVEAL that an make the data-fragment attributes, so it's not hard to produce
 the desired outpu:

#+begin_r-stack
#+ATTR_REVEAL: :frag appear
[[imglink1]]
#+ATTR_REVEAL: :frag appear
[[imglink2]]
#+end_r-stack


However, I'd really like to add a less verbose syntax, like this:

#+begin_r-stack :frag (appear appear)
[[imglink1]]
[[imglink2]]
#+end_r-stack

My question is: will the exporter preserve information from these header-like arguments, and is 
there a mechanism I can use in a custom ~special-block-function~ to make use of htem?

Thanks for your help as always!

Matt