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.

John

-----------------------------------
Professor John Kitchin (he/him/his)
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu



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
>
>