bug#36475: [PATCH] Handle 'abbr' and 'acronym' tags in shr.el

[Basil L. Contovounesios]

severity 36475 wishlist
quit

Nicholas Drozd <nicholasdrozd@gmail.com> writes:

> I came across some `abbr` tags in the wild: check out the first
> paragraph of http://mindprod.com/jgloss/unmainobfuscation.html. EWW
> doesn't handle those, so here is a patch for that.
>
> My understanding is that there is also an `acronym` tag which has been
> deprecated in favor of `abbr`. I figured we might as well cover that
> one too just in case.

+1.

> I picked the `diary` face for abbreviations, but that choice didn't
> have a lot of thought put into it. Whoever commits can choose
> something else.

Indeed I don't think the 'diary' face is a very good fit.  Not only is
it undefined unless calendar.el is loaded, but it also has a quite
jarring red/yellow foreground by default, and bears no relation to
abbreviations.

The major browsers use a dotted underline, and text in Emacs that has a
'help-echo' property is usually fontified with a face inheriting from
'link' (outside of the mode line, images, and buttons, of course).

So my suggestion is to provide a new face inheriting from either
'shr-link', 'link', or 'underline'.  Personally, I would also add
':underline (:style wave)', as it reminds me of the dotted underline in
external browsers:

(defface shr-abbreviation
  '((t :inherit underline :underline (:style wave)))
  "Face for <abbr> elements.")

Thoughts?  Lars?

> Let's try to get this merged <abbr title="as soon as possible">ASAP</abbr>.
>
> From a720473ad1001d3a72f9b3f3155f5488726cabde Mon Sep 17 00:00:00 2001
> From: Nick Drozd <nicholasdrozd@gmail.com>
> Date: Mon, 1 Jul 2019 23:46:10 -0500
> Subject: [PATCH] Handle 'abbr' and 'acronym' tags in shr.el
>
> * lisp/net/shr.el: Add 'abbr' and 'acronym' tag handling.

Nit: I think this should list the new functions, as per usual:

* lisp/net/shr.el (shr-tag-abbr, shr-tag-acronym): New functions
handling 'abbr' and 'acronym' tags, respectively.

> * etc/NEWS: Announce change in shr behavrior.
> ---
>  etc/NEWS        |  3 +++
>  lisp/net/shr.el | 15 +++++++++++++++
>  2 files changed, 18 insertions(+)
>
> diff --git a/etc/NEWS b/etc/NEWS
> index abbece374a..464dae2454 100644
> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -989,6 +989,9 @@ This attribute is meant to tell screen readers to ignore 
> a tag.
>  ---
>  *** The <code ...> tag is now handled.
>  
> +---
> +*** The <abbr ...> and <acronym ...> tags are now handled.
> +

I suggest announcing all new tags (i.e. including <code>) in a single
NEWS entry.

>  ** Htmlfontify
>  
>  *** The functions 'hfy-color', 'hfy-color-vals' and
> diff --git a/lisp/net/shr.el b/lisp/net/shr.el
> index 7fdb3212d4..3af3db637a 100644
> --- a/lisp/net/shr.el
> +++ b/lisp/net/shr.el
> @@ -1470,6 +1470,21 @@ shr-tag-a
>      (when url
>        (shr-urlify (or shr-start start) (shr-expand-url url) title))))
>  
> +(defun shr-tag-abbr (dom)
> +  (let ((title (dom-attr dom 'title))
> +     (start (point)))
> +    (shr-generic dom)
> +    (shr-add-font start (point) 'diary)
> +    (add-text-properties
> +     start (point)
> +     (list
> +      'help-echo title
> +      'mouse-face 'highlight))))

According to Mozilla[1], the 'title' attribute is optional, so perhaps
we should avoid this fontification if the attribute is missing, which is
what Firefox and Chromium seem do.

[1]: https://developer.mozilla.org/en/docs/Web/HTML/Element/abbr

Apart from these minor comments, LGTM.

Thanks,

-- 
Basil