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

[Philip Kaludercic <philipk@posteo.net>]

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).

>> An example is my GNU ELPA package Kubed.  In the development version,
>> the manual refers to images which are present on my web server, where I
>> provide HTML versions[1][2] of the manual.  There, the images are
>> displayed properly.  

  Unrelated to this issue, have you considered rendering screenshots as
  SVG files using `x-export-frames'?
                        
                        On the ELPA server[3], OTOH, the images are nowhere
>> to be found, and we instead get just the alt text and caption.  That's
>> expected, but the alt text is shown with no distinctive styling so the
>> result seems quite confusing.
>
> To show images, your HTML version of the manual should reference local
> files, not URLs from your some other server.  And, of course, the
> image files should be part of the package tarball.
>
>> - 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.

[0] https://developer.mozilla.org/en-US/docs/Web/URI/Schemes/data

>> - Provide a IMAGE_LINK_PREFIX value (e.g. pointing to my web server)
>>   that the ELPA server will use while building the HTML manual.
>
> That's definitely not TRT: ELPA packages should be self-contained as
> far as their documentation is concerned.
>
>> - Override the creation of the HTML manual entirely, and have the ELPA
>>   server redirect or link to the version hosted on my web server.
>
> Likewise: there should be no dependency on any server.

I agree.

> Apologies if I misunderstood the problem.

-- 
	Philip Kaludercic on siskin