bug#32348: 27.0.50; EWW/SHR: Please add support for hiding DOM nodes with aria-hidden=true

[T.V Raman]

Noam Postavsky <npostavs@gmail.com> writes:

Yes, please go ahead and push to Master.
Re the comment about including in eww's readable, it gets rid of the
zillion "share with" links on sites like the BBc. 
> "T.V Raman" <raman@google.com> writes:
>
>> Another place to leverage aria-hidden might be in EWW's "readable"
>> command. Note that in general those nodes are shown on screen but are
>> useless for the most part -- and usually inoperable under EWW. As an
>> example, articles from the BBC for instance use these nodes to add
>> buttons for "share via messenger" etc.
>
> Unless the "readable" command is actually giving bad results for
> real-world pages (is it?), I wouldn't start complicating the heuristic
> with more checks.  It doesn't even check for display:none at the moment.
>
> I've updated my previous patch with some more documentation, so that
> someone who doesn't know anything about "aria-hidden" (e.g., me, before
> this thread) could have some chance of figuring out what it's good for.
> I'll push to master in a few days.
>
> From ead5619e844fced271866349fd34990641bf75c6 Mon Sep 17 00:00:00 2001
> From: Noam Postavsky <npostavs@gmail.com>
> Date: Tue, 7 Aug 2018 20:40:56 -0400
> Subject: [PATCH v2] Optionally skip rendering of tags with aria-hidden
>  (Bug#32348)
>
> * lisp/net/shr.el (shr-discard-aria-hidden): New option.
> (shr-descend): Suppress aria-hidden=true tags if it's set.
> * doc/misc/eww.texi (Advanced): Document shr-discard-aria-hidden.
> * etc/NEWS: Announce it.
>
> fixup! shr: Allow skipping tags with aria-hidden (Bug#32348)
> ---
>  doc/misc/eww.texi | 10 ++++++++++
>  etc/NEWS          |  3 +++
>  lisp/net/shr.el   | 12 +++++++++++-
>  3 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/doc/misc/eww.texi b/doc/misc/eww.texi
> index 43adc2eda0..bd5aef6a8a 100644
> --- a/doc/misc/eww.texi
> +++ b/doc/misc/eww.texi
> @@ -262,6 +262,16 @@ Advanced
>  variables @code{shr-color-visible-distance-min} and
>  @code{shr-color-visible-luminance-min} to get a better contrast.
>  
> +@vindex shr-discard-aria-hidden
> +@cindex aria-hidden
> +  The HTML attribute @code{aria-hidden} is meant to tell screen
> +readers to ignore a tag's contents.  You can customize the variable
> +@code{shr-discard-aria-hidden} to tell @code{shr} to ignore such tags.
> +This can be useful when using a screen reader on the output of
> +@code{shr} (e.g., on EWW buffer text).  Or even when not using a
> +screen reader, since web authors often put this tag on non-essential
> +decorative content.
> +
>  @cindex Desktop Support
>  @cindex Saving Sessions
>    In addition to maintaining the history at run-time, EWW will also
> diff --git a/etc/NEWS b/etc/NEWS
> index 60951dfac0..d2e111fd60 100644
> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -396,6 +396,9 @@ and its value has been changed to Duck Duck Go.
>  'shr-selected-link' face to give the user feedback that the command
>  has been executed.
>  
> ++++
> +*** New option 'shr-discard-aria-hidden'.
> +
>  ** Htmlfontify
>  
>  *** The functions 'hfy-color', 'hfy-color-vals' and
> diff --git a/lisp/net/shr.el b/lisp/net/shr.el
> index edea7cb297..0fbaf6f211 100644
> --- a/lisp/net/shr.el
> +++ b/lisp/net/shr.el
> @@ -68,6 +68,14 @@ shr-use-fonts
>    :group 'shr
>    :type 'boolean)
>  
> +(defcustom shr-discard-aria-hidden nil
> +  "If non-nil, don't render tags with `aria-hidden=\"true\"'.
> +This attribute is meant to tell screen readers to ignore the
> +tag's content."
> +  :version "27.1"
> +  :group 'shr
> +  :type 'boolean)
> +
>  (defcustom shr-use-colors t
>    "If non-nil, respect color specifications in the HTML."
>    :version "26.1"
> @@ -509,7 +517,9 @@ shr-descend
>                                       shr-stylesheet))
>         (setq style nil)))
>        ;; If we have a display:none, then just ignore this part of the DOM.
> -      (unless (equal (cdr (assq 'display shr-stylesheet)) "none")
> +      (unless (or (equal (cdr (assq 'display shr-stylesheet)) "none")
> +                  (and shr-discard-aria-hidden
> +                       (equal (dom-attr dom 'aria-hidden) "true")))
>          ;; We don't use shr-indirect-call here, since shr-descend is
>          ;; the central bit of shr.el, and should be as fast as
>          ;; possible.  Having one more level of indirection with its

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