GNU bug report logs - #76494
[PATCH] Highlight fill-column-indicator when current line is longer than `fill-column'

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: [PATCH] Highlight fill-column-indicator when current line is longer
 than `fill-column'
Date: Sat, 22 Feb 2025 22:21:02 -0600

[Message part 1 (text/plain, inline)]

Tags: patch

This patch allow warn to user if current line exceeds
display-fill-column-indicator-column.

When current line exceeds display-fill-column-indicator-column ...
                                           |
(print "......................................")
                                           |
... fill-column indicator face will change ^
temporarily to a noticeable face to warn the user that the current
column is getting too long.

I also wanted to do the same for indicator character but I couldn't find
a way to implement it.

(I hope this feature has been understood)

[0001-Highlight-fill-column-indicator-when-current-line-is.patch (text/patch, attachment)]

[Message part 3 (text/plain, inline)]

-- 
                                                   - E.G via GNU Emacs.

Message #8 received at 76494 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Elijah Gabe Pérez <eg642616 <at> gmail.com>
Cc: 76494 <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Sun, 23 Feb 2025 08:14:56 +0200

> From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
> Date: Sat, 22 Feb 2025 22:21:02 -0600
> 
> This patch allow warn to user if current line exceeds
> display-fill-column-indicator-column.

Thanks.

> When current line exceeds display-fill-column-indicator-column ...
>                                            |
> (print "......................................")
>                                            |
> ... fill-column indicator face will change ^
> temporarily to a noticeable face to warn the user that the current
> column is getting too long.

I see your change adds a post-command-hook, but when and how is that
hook removed?

> I also wanted to do the same for indicator character but I couldn't find
> a way to implement it.

What do you mean by "indicator character"?

> +(defcustom display-fill-column-indicator-warning nil
> +  "Highlight fill-column-indicator when cursor is above `fill-column'.
> +Non-nil means highlight fill-column-indicator when cursor is
> +above `fill-column'."
> +  :type 'boolean)

This lacks a :version tag.

Also, what do you mean by "cursor is above `fill-column'"?  The
"above" part confuses me.

> +(defface display-fill-column-indicator-warning-face
> +  '((t :inherit error :stipple nil))
> +  "Face used to highlight fill-column-indicator when the line is too long.")

This should also have a :version tag.  And fill-column-indicator
should be quoted, so that help command produce a cross-reference from
it.

Message #11 received at 76494 <at> debbugs.gnu.org (full text, mbox):

From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 76494 <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Sun, 23 Feb 2025 01:11:43 -0600

[Message part 1 (text/plain, inline)]

Eli Zaretskii <eliz <at> gnu.org> writes:

> I see your change adds a post-command-hook, but when and how is that
> hook removed?

The hook is removed when display-fill-column-indicator-mode is turn-off,
i forgot to remove the hook in the submitted patch, I've fixed it.

>> I also wanted to do the same for indicator character but I couldn't find
>> a way to implement it.
>
> What do you mean by "indicator character"?

i meant `display-fill-column-indicator-character', I wanted to
allow changing its character to a custom one.

example: use this `┃' character (or one chosen by the user)
instead default `│' when changing the fill-column-indicator face.

>> +(defcustom display-fill-column-indicator-warning nil
>> +  "Highlight fill-column-indicator when cursor is above `fill-column'.
>> +Non-nil means highlight fill-column-indicator when cursor is
>> +above `fill-column'."
>> +  :type 'boolean)
>
> This lacks a :version tag.
>
> Also, what do you mean by "cursor is above `fill-column'"?  The
> "above" part confuses me.

I updated the patch to clarify this part.

[0001-Highlight-fill-column-indicator-when-current-line-is.patch (text/x-patch, attachment)]

[Message part 3 (text/plain, inline)]

-- 
                                                   - E.G via GNU Emacs.

Message #14 received at 76494 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Elijah Gabe Pérez <eg642616 <at> gmail.com>
Cc: 76494 <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Sun, 23 Feb 2025 09:59:06 +0200

> From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
> Cc: 76494 <at> debbugs.gnu.org
> Date: Sun, 23 Feb 2025 01:11:43 -0600
> 
> Eli Zaretskii <eliz <at> gnu.org> writes:
> 
> >> I also wanted to do the same for indicator character but I couldn't find
> >> a way to implement it.
> >
> > What do you mean by "indicator character"?
> 
> i meant `display-fill-column-indicator-character', I wanted to
> allow changing its character to a custom one.
> 
> example: use this `┃' character (or one chosen by the user)
> instead default `│' when changing the fill-column-indicator face.

The character is the same for all the screen lines, so if you change
it, that affects all the lines.

Message #17 received at 76494 <at> debbugs.gnu.org (full text, mbox):

From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 76494 <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Sun, 23 Feb 2025 19:15:07 -0600

Eli Zaretskii <eliz <at> gnu.org> writes:

> The character is the same for all the screen lines, so if you change
> it, that affects all the lines.

Not if you use setq-local which prevents this problem,
such as this code:

(add-hook 'display-fill-column-indicator-mode-hook
   (lambda ()
       (add-hook
        'post-command-hook
        (lambda ()
          (if (> (save-excursion (end-of-line) (current-column))
                 fill-column)
              (progn
                (setq-local
                 display-fill-column-indicator-character 9475)
                (face-remap-set-base 'fill-column-indicator
                                     (list :inherit 'error :stipple nil
                                           :box nil :strike-through nil
                                           :overline nil :underline nil)))
            (setq-local
             display-fill-column-indicator-character 9474)
            (face-remap-reset-base 'fill-column-indicator)))
        nil t)))

I couldn't find a way to implement it without it looking terrifying,
so I think I'll just settle with the highlight.

-- 
                                                   - E.G via GNU Emacs.

Message #20 received at 76494 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Elijah Gabe Pérez <eg642616 <at> gmail.com>
Cc: 76494 <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Mon, 24 Feb 2025 14:31:39 +0200

> From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
> Cc: 76494 <at> debbugs.gnu.org
> Date: Sun, 23 Feb 2025 19:15:07 -0600
> 
> Eli Zaretskii <eliz <at> gnu.org> writes:
> 
> > The character is the same for all the screen lines, so if you change
> > it, that affects all the lines.
> 
> Not if you use setq-local which prevents this problem,
> such as this code:

There might be some misunderstanding: using setq-local makes the
character local to a buffer, whereas I thought you wanted to use a
special character only for the lines that exceed the fill-column?
When I use your code, then whenever I'm on a line that is too long,
_all_ the fill-column indicators in the window change into the U+2503
character shown in red, not just the indicator of that single line.

Did I misunderstand what you are trying to accomplish?

Message #25 received at 76494 <at> debbugs.gnu.org (full text, mbox):

From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 76494 <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Mon, 24 Feb 2025 21:32:29 -0600

Eli Zaretskii <eliz <at> gnu.org> writes:

> There might be some misunderstanding: using setq-local makes the
> character local to a buffer, whereas I thought you wanted to use a
> special character only for the lines that exceed the fill-column?

Even if I wanted to, that wouldn't be possible because of the way
display-fill-column-indicator is designed.

> When I use your code, then whenever I'm on a line that is too long,
> _all_ the fill-column indicators in the window change into the U+2503
> character shown in red, not just the indicator of that single line.

Yeah, that's correct, affects the entire indicator.


something like this:

                                           │
                                           │
                                           │
(print "..|........................")      │
          ^ (cursor)                       │
(print "---")                              │
                                           │
                                 indicator ^

                                           ┃
                                           ┃
                                           ┃
(print "...............|........................")
                       ^ (cursor)          ┃
(print "---")                              ┃
                                           ┃
                                 indicator ^

                                           │
                                           │
                                           │
(print ".......................................")
                                           │
(print "---")|                             │
             ^ (cursor)                    │
                                 indicator ^

-- 
                                                   - E.G via GNU Emacs.

Message #30 received at 76494-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Elijah Gabe Pérez <eg642616 <at> gmail.com>
Cc: 76494-done <at> debbugs.gnu.org
Subject: Re: bug#76494: [PATCH] Highlight fill-column-indicator when current
 line is longer than `fill-column'
Date: Sun, 09 Mar 2025 11:21:40 +0200

> From: Elijah Gabe Pérez <eg642616 <at> gmail.com>
> Cc: 76494 <at> debbugs.gnu.org
> Date: Sun, 23 Feb 2025 01:11:43 -0600
> 
> Eli Zaretskii <eliz <at> gnu.org> writes:
> 
> > I see your change adds a post-command-hook, but when and how is that
> > hook removed?
> 
> The hook is removed when display-fill-column-indicator-mode is turn-off,
> i forgot to remove the hook in the submitted patch, I've fixed it.
> 
> >> I also wanted to do the same for indicator character but I couldn't find
> >> a way to implement it.
> >
> > What do you mean by "indicator character"?
> 
> i meant `display-fill-column-indicator-character', I wanted to
> allow changing its character to a custom one.
> 
> example: use this `┃' character (or one chosen by the user)
> instead default `│' when changing the fill-column-indicator face.
> 
> >> +(defcustom display-fill-column-indicator-warning nil
> >> +  "Highlight fill-column-indicator when cursor is above `fill-column'.
> >> +Non-nil means highlight fill-column-indicator when cursor is
> >> +above `fill-column'."
> >> +  :type 'boolean)
> >
> > This lacks a :version tag.
> >
> > Also, what do you mean by "cursor is above `fill-column'"?  The
> > "above" part confuses me.
> 
> I updated the patch to clarify this part.

Thanks, installed on the master branch, and closing the bug.

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