bug#37881: 27.0.50; Changing font size in Info-mode messes up formatting of body text

bug#37881: 27.0.50; Changing font size in Info-mode messes up formatting of body text

[Stefan Kangas]

When I browse Info in "emacs -Q", the default formatting gets messed
up when I change the font size using C-x C-+.  I end up with text that
looks visually more like this:

The following functions are responsible for installing
 the user’s
customization settings for variables and faces, respec
tively.  When the
user invokes ‘Save for future sessions’ in the Customi
ze interface, that

It would be nice if we could reflow the text as the font size changes.

Best regards,
Stefan Kangas

bug#37881: 27.0.50; Changing font size in Info-mode messes up formatting of body text

[Eli Zaretskii]

tags 37881 wontfix
close 37881
thanks

> From: Stefan Kangas <stefan@marxist.se>
> Date: Wed, 23 Oct 2019 03:47:03 +0200
> 
> When I browse Info in "emacs -Q", the default formatting gets messed
> up when I change the font size using C-x C-+.  I end up with text that
> looks visually more like this:
> 
> The following functions are responsible for installing
>  the user’s
> customization settings for variables and faces, respec
> tively.  When the
> user invokes ‘Save for future sessions’ in the Customi
> ze interface, that
> 
> It would be nice if we could reflow the text as the font size changes.

Thanks for suggesting this feature.

I don't think we should try doing anything like that in the Emacs Info
reader.  The Info reader is meant to display Texinfo documents
formatted as Info files.  Info files are formatted by 'makeinfo', not
by the reader, and that formatting includes filling and justification,
and produces files with hard newlines, already "flowed" to the static
dimensions of the page that 'makeinfo' imagines.  Attempt to reflow
these formatted files is bound to produce sub-optimal results, because
formatting loses information.

As just a random example, the original Texinfo sources include
commands such as @w{..} (which requests that its argument not be
broken between lines).  This command disappears without a trace from
the Info output, after having done its job, so if you reflow the text,
you might well violate that restriction, and the result will be
confusing for the readers.

Similarly, the @* command forces a line break, but the produced
newline won't tell you that it is different from any other newline in
the Info file, so the reflowed text may well lack a line break there.

And there are other commands with similar effects, which cannot be
deduced by looking at the Info output.

So such a feature, even if implemented, will never work in a
satisfactory manner, because the Info format was simply not designed
to support such browsers.

The right way to have dynamically reflowed documentation text is to
use something similar to HTML in conjunction with shr.el, and enhanced
with Texinfo features (like index-search) not generally supported in
HTML.  By a coincidence (or maybe something else), such a project is
being slowly developed as part of the Texinfo package, you can find
the relevant discussions on the bug-texinfo mailing list.  When this
feature is part of Texinfo, we will have to think about implementing a
corresponding browser for manuals thus formatted.

So I'm going to close this bug as wontfix; hopefully, you understand
my rationale, and agree with it.

Thanks.

bug#37881: 27.0.50; Changing font size in Info-mode messes up formatting of body text

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

> Thanks for suggesting this feature.

Thanks for taking the time to write up an insightful reply.

> The right way to have dynamically reflowed documentation text is to
> use something similar to HTML in conjunction with shr.el, and enhanced
> with Texinfo features (like index-search) not generally supported in
> HTML.  By a coincidence (or maybe something else), such a project is
> being slowly developed as part of the Texinfo package, you can find
> the relevant discussions on the bug-texinfo mailing list.  When this
> feature is part of Texinfo, we will have to think about implementing a
> corresponding browser for manuals thus formatted.

That does indeed sound very interesting.

> So I'm going to close this bug as wontfix; hopefully, you understand
> my rationale, and agree with it.

Yes, I agree.

I would have suggested that we perhaps could tell texinfo to reflow
the page for us to the correct number of columns, but I think waiting
for the above new feature sounds much better.  Since that's in the
pipeline, there is no point in wasting time implementing anything else
right now.

Thanks again,
Stefan Kangas

bug#37881: 27.0.50; Changing font size in Info-mode messes up formatting of body text

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Wed, 23 Oct 2019 22:27:39 +0200
> Cc: 37881@debbugs.gnu.org
> 
> I would have suggested that we perhaps could tell texinfo to reflow
> the page for us to the correct number of columns

That would mean to run makeinfo every time you want to read a manual,
something that takes several seconds: an annoying delay, I think.