bug#60692: 29.0.60; current-indentation wrong without outline ellipsis

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 60692@debbugs.gnu.org
> Date: Tue, 10 Jan 2023 19:54:11 +0200
> 
> > If you've read the discussion of bug#56837, then I explained there why
> > this is how it is.  In a nutshell, indentation is regarded as
> > display-related aspect, so asking about indentation of invisible text
> > makes no sense.
> 
> But when an ellipsis is used, current-indentation
> works correctly in invisible text.

Because the ellipsis replaces the invisible text, and
current-indentation accounts for the ellipsis.  When the ellipsis
isn't present, there's nothing to account for.

In any case, if you want to know the indentation disregarding
invisible property, current-indentation is not what you want.

> 
> >>   (setq-local outline-level
> >>               (lambda ()
> >>                 "`outline-level' function for Python mode."
> >>                 (1+ (/ (current-indentation) python-indent-offset))))
> >>
> >>   (setq-local outline-level (lambda () (1+ (/ (current-indentation)
> >>                                          ruby-indent-level))))
> >>
> >> But this fails when users want to remove an ellipsis.
> >
> > I'm surprised the indentation is used for this purpose when it is
> > known that text will be sometimes hidden.  May I suggest to use text
> > properties for this purpose?
> 
> I don't understand how text properties could be used to get
> the indentation.

Before you hide anything, analyze the indentation and assign to each
outline level the value of the property that equals the level.  Then
you can know the level of any piece of text just by accessing the
property value.