Re: [reveal-mode] Hiding short expressions

[Ralf Angeli]

* Stefan (2004-07-02) writes:

>> currently I am trying to make use of reveal-mode for hiding and
>> revealing \footnote{...} expressions in Emacs.  Now the problem is
>> that visible expressions under the control of reveal-mode only get
>> hidden if the cursor moves before the beginning of the line with the
>> expression or past its end.  If you have short expressions within a
>> line it would be nice if the expression became invisible as soon as
>> the cursor moves out of it.
>
>> Are there any reasons why this is not handled like this in reveal.el
>> and would it be possible to change it if there aren't any? 
[...]
> The behavior you seem to want is actually simpler than the current
> behavior (in other words, I first implemented the behavior you want and
> then added code to keep the overlays open even after the cursor moves out
> of the overlay), and it should be easy to change the code such that you can
> choose between different behaviors.

One could add a variable which lets you choose what behavior is used.
But if you wanted to use outline-minor-mode and hiding of footnotes at
the same time in a latex-mode or LaTeX-mode buffer, it would probably
be better to choose the behavior depending on a special attribute of
the overlays.  This could be done e.g. by adding a 'reveal-close
attribute to the 'category property of the overlay:

(put 'some-category 'reveal-close 'on-cursor-out)
(overlay-put ov 'category 'some-category)

Then this gets checked in reveal.el:

--8<---------------cut here---------------start------------->8---
--- /usr/local/share/emacs/21.3.50/lisp/reveal.el       2004-07-02 
22:08:23.000000000 +0200
+++ reveal.el   2004-07-03 12:44:47.000000000 +0200
@@ -116,12 +116,20 @@
      (dolist (ol old-ols)
        (when (and (eq (current-buffer) (overlay-buffer ol))
                  (not (rassq ol reveal-open-spots)))
-        (if (and (>= (point) (save-excursion
-                               (goto-char (overlay-start ol))
-                               (line-beginning-position 1)))
-                 (<= (point) (save-excursion
-                               (goto-char (overlay-end ol))
-                               (line-beginning-position 2))))
+        (if (and (>= (point)
+                     (if (eq (get (overlay-get ol 'category) 'reveal-close)
+                             'on-cursor-out)
+                         (overlay-start ol)
+                       (save-excursion
+                         (goto-char (overlay-start ol))
+                         (line-beginning-position 1))))
+                 (<= (point)
+                     (if (eq (get (overlay-get ol 'category) 'reveal-close)
+                             'on-cursor-out)
+                         (overlay-end ol)
+                       (save-excursion
+                         (goto-char (overlay-end ol))
+                         (line-beginning-position 2)))))
             ;; Still near the overlay: keep it open.
             (push (cons (selected-window) ol) reveal-open-spots)
           ;; Really close it.
--8<---------------cut here---------------end--------------->8---

How does this look like?

I am considering to add some code to AUCTeX in order to support hiding
of LaTeX macros with reveal-mode.  (This hasn't been discussed yet on
the AUCTeX mailing list, though.)  So it would be nice if the above or
something similar could be integrated into Emacs.

-- 
Ralf