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bug#21710: 25.0.50; self-insert-command before a folded outline inserts
From: |
Eli Zaretskii |
Subject: |
bug#21710: 25.0.50; self-insert-command before a folded outline inserts after the outline |
Date: |
Wed, 21 Oct 2015 20:02:33 +0300 |
> From: Oleh Krehel <ohwoeowho@gmail.com>
> Cc: 21710@debbugs.gnu.org
> Date: Wed, 21 Oct 2015 15:05:16 +0200
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> > The reason for this is that on all header lines but the last inserting
> > the first 't' makes it invisible.
>
> This isn't a good behavior. `self-insert-command' should not put text
> into an invisible region.
It doesn't. It inserts the character at point. The problem is that
the inserted character becomes invisible because the overlay becomes
applicable to it.
> "C-e" should complement this behavior, starting from:
>
> * |foo...
> * bar...
>
> pressing "C-e" should result in:
>
> * foo|...
> * bar...
If that's what you want, you need to program that into the mode. The
default effect of C-e is to put point one character before the newline
on the same visible line, which is _after_ the invisible text. IOW,
this is not a bug, but perhaps a missing feature.
> And from the state above, pressing "C-d" should result in:
> (user-error "Overlay read-only"), instead of deleting hidden characters.
Once again, you need to program that. By default, C-d just deletes
the character at point.
> > Then point adjustment kicks in, and moves point out of the
> > invisible region, so the second 't' is inserted at the end of the
> > sub-level text.
>
> Can you point me to a place where I can read up on this point
> adjustment?
Some minimal Lisp-level documentation is in "(elisp) Adjusting Point.
For the gory details, see the function adjust_point_for_property in
keyboard.c.
> I'd like to help in fixing this bug, if it's not too complicated.
It's not a bug in point adjustment, strictly speaking: that part does
its job as intended. The problem is with the fact that the inserted
character becomes invisible.
> So far, I'm looking at this code:
>
> (defun outline-flag-region (from to flag)
> "Hide or show lines from FROM to TO, according to FLAG.
> If FLAG is nil then text is shown, while if FLAG is t the text is hidden."
> (remove-overlays from to 'invisible 'outline)
> (when flag
> ;; We use `front-advance' here because the invisible text begins at the
> ;; very end of the heading, before the newline, so text inserted at FROM
> ;; belongs to the heading rather than to the entry.
> (let ((o (make-overlay from to nil 'front-advance)))
> (overlay-put o 'evaporate t)
> (overlay-put o 'invisible 'outline)
> (overlay-put o 'isearch-open-invisible
> (or outline-isearch-open-invisible-function
> 'outline-isearch-open-invisible))))
> ;; Seems only used by lazy-lock. I.e. obsolete.
> (run-hooks 'outline-view-change-hook))
>
> The comment about `front-advance' implies that what I proposed above was
> the intended behavior, which is broken currently.
Then why does it work correctly on the last heading?