On Thu, Jan 20, 2022 at 11:12 AM John Kitchin <jkitchin@andrew.cmu.edu>
wrote:

> It depends on what the src things look like. You might be able to just
> call ffap or some variant of it. Here is an example of the follow part that
> works for a file and url for me.
>
> #+BEGIN_SRC emacs-lisp
> (org-link-set-parameters
>  "rstack"
>  :follow (lambda (path)
>   (ffap (or (ffap-url-at-point)
>     (ffap-file-at-point)))))
> #+END_SRC
>
> #+RESULTS:
> | :follow | (lambda (path) (ffap (or (ffap-url-at-point)
> (ffap-file-at-point)))) |
>
>
> [[rstack:(("./screenshots/date-20-01-2022-time-10-36-54.png" . fade-out)
> (src2 . fade-in) ("https://google.com" . fade-out))]]
>
>
> This is what I have so far. I'm pretty happy with it; it's quite concise,
and  will fill in default values for the fade in and out instructions.

When I asked my question, I left out an optional second parameter that
these stacking images can take -- a "fragment-index" number. I'm trying to
figure out a way to add that additional info into the link without making
it (a) unnecessarily long, esp for the majority of cases where I won't use
that index; or (b) impossible to read. I guess I could make each list
element a plist instead? Like ((:s ~/image.png :i 4 :f fade-in-then-out))?

Anyway, here's my code:

(defun r-stack-follow (path)
  (let* ((srcs (read path ))
         (completions (-map (lambda (src) (car src)) srcs)  )
         (chosen  (completing-read "Follow link to: " completions)))
    (if (ffap-url-p chosen) (browse-url chosen) (find-file-ace-window
chosen))))
(defun r-stack-export (path desc backend)
  (cond
   ((eq 'html backend)
             (let ((srcs (read path)))
               (format "<div class=\"r-stack\">\n%s</div>\n"
                       (string-join
                        (cl-loop for index from 1
                                 for (src . data-fragment) in srcs
                                 collect
                                 (format "  <img class=\"fragment %s\"
src=\"%s\"/>"
                                         (or data-fragment
                                             (cond
                                              ((eql 1 index) "fade-out")
                                              ((eql  (length srcs) index)
 "fade-in")
                                              (t "fade-in-then-out")))
                                         src))
                        "\n"))))))


(org-link-set-parameters
 "r-stack"
 :follow 'r-stack-follow
 :export 'r-stack-export
 :face '(:foreground "red")
 :help-echo "Click me for a message.")




> 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 Thu, Jan 20, 2022 at 10:21 AM Matt Price <moptop99@gmail.com> wrote:
>
>>
>>
>> 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
>>> @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
>>>>
>>>>