bug#73425: 31.0.50; Support images in HTML versions of ELPA package manuals

[Eli Zaretskii <eliz@gnu.org>]

> From: Philip Kaludercic <philipk@posteo.net>
> Cc: Eshel Yaron <me@eshelyaron.com>,  73425@debbugs.gnu.org
> Date: Sun, 22 Sep 2024 18:03:26 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Cc: Philip Kaludercic <philipk@posteo.net>
> >> Date: Sun, 22 Sep 2024 18:06:16 +0200
> >> From:  Eshel Yaron via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >> 
> >> I'm opening this feature request following a discussion with Philip
> >> elsewhere: Texinfo manual can include images, but AFAIK (and please
> >> correct me if I'm wrong here) there's currently no way for ELPA packages
> >> to include images in their manuals and have these images appear also in
> >> the HTML version of the manual that the ELPA server builds and serves.
> >
> > Why "no way"?  If the image files are present at their filenames as
> > mentioned by the HTML version of the documentation, they will be shown
> > by the browser.
> 
> The issue is that when generating the HTML documentation for
> elpa.gnu.org, we don't copy out any files, but just generate the HTML
> version of the manual.
> 
> What we need is some kind of an indication in the package specification,
> what files should be copied out for the manual to access, as otherwise
> the images would only be hidden in the package tarball, that a web
> browser cannot access (AFAIK).

"Copied" where and why?  Aren't the HTML docs generated in the
package's tree, like the Info docs?

> >> - Include images in the package repository, somehow indicate in the
> >>   package specification that the manual refers to these images, and have
> >>   the ELPA server keep the images around in a predictable location, so I
> >>   can link to it from the manual.
> >
> > I don't understand why this would be needed.  Simply include the image
> > files with the package, and the rest should "just work", AFAIU.
> 
> Do you know if TeXinfo has an option to inline images?  If the
> "makeinfo" command could somehow generate data: urls when exporting
> images, then this could be very easily solved.

This is already supported, for a long time, both in Info and HTML
formats (and in other formats as well; see the node "Image Syntax" in
the Texinfo manual.