bug#49344: shr: Add support for "data-src" attribute in <img> nodes

bug#49344: shr: Add support for "data-src" attribute in <img> nodes

[杨英超]

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Dear maintainers:

I found eww fails to show card-images which is described in the following
web page:

https://www.geeksforgeeks.org/why-card-images-use-data-src-not-src-for-image-in-bootstrap-4/

For example, if you open following page with eww & firefox, you will notice
the differences:   http://www.interdb.jp/pg/pgsql05.html

I modified shr.el a little bit to support "data-src" attribute, so eww can
display card-images properly.

 Hope it helps.

Regards
yc

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From bb7537f18af348e27169fdb4675279a6ac936f91 Mon Sep 17 00:00:00 2001
From: yangyingchao <yangyingchao@icloud.com>
Date: Fri, 2 Jul 2021 11:46:12 +0800
Subject: [PATCH] Add support for "data-src" attribute in <img> tag.

* lisp/net/shr.el (shr--preferred-image) (shr-tag-img): support
  "data-src"  attribute
---
 lisp/net/shr.el | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lisp/net/shr.el b/lisp/net/shr.el
index 873f0457e3..cc2007b2a4 100644
--- a/lisp/net/shr.el
+++ b/lisp/net/shr.el
@@ -1661,7 +1661,8 @@ shr-tag-img
   (when (or url
 	    (and dom
 		 (or (> (length (dom-attr dom 'src)) 0)
-                     (> (length (dom-attr dom 'srcset)) 0))))
+                     (> (length (dom-attr dom 'srcset)) 0)
+                     (> (length (dom-attr dom 'data-src)) 0))))
     (when (> (current-column) 0)
       (insert "\n"))
     (let ((alt (dom-attr dom 'alt))
@@ -1793,7 +1794,7 @@ shr--preferred-image
                   (> (cadr (car srcset)) frame-width))
         (setq candidate (caar srcset))
         (pop srcset)))
-    (or candidate (dom-attr dom 'src))))
+    (or candidate (dom-attr dom 'src) (dom-attr dom 'data-src))))
 
 (defun shr-string-number (string)
   (if (null string)
-- 
2.31.1

bug#49344: shr: Add support for "data-src" attribute in <img> nodes

[Phil Sainty]

On 2021-07-03 12:56, 杨英超 wrote:
> https://www.geeksforgeeks.org/why-card-images-use-data-src-not-src-for-image-in-bootstrap-4/

The meaning of any 'data-*' attribute is 100% application-defined.
I don't think that any web browsers should be assuming that a
'data-src' attribute is actually a 'src' attribute (that's not
any kind of standard AFAIK), nor implement workarounds for specific
web sites that are not generating sane HTML.

The initial markup should have a proper 'src' attribute.  If the
site wants the initial state to be different in the presence of
Javascript, then it should be using Javascript to modify the
initial state accordingly, following a progressive-enhancement
approach.

As eww doesn't support Javascript, this particular case is only
one of many things which won't work when the site developers
make bad assumptions about Javascript.  I would expect your
example to fail in any web browser where JS was disabled or
not supported.

E.g. for me, using Firefox, the site looks very similar in
Firefox and eww because I use the uMatrix extension to only
permit Javascript to run on sites where I have explicitly
allowed it.  (Actually, the site looks *better* in eww, because
their code blocks in Firefox are barely readable on account
of the appallingly poor contrast between background and text.)

This is simply bad web design, and I don't think that's eww's
problem to solve.


-Phil

bug#49344: shr: Add support for "data-src" attribute in <img> nodes

[Lars Ingebrigtsen]

Phil Sainty <psainty@orcon.net.nz> writes:

> This is simply bad web design, and I don't think that's eww's
> problem to solve.

Indeed, so I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#49344: shr: Add support for "data-src" attribute in <img> nodes

[杨英超]

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At your wish, although I don't agree. I have my own fork I can play with.

Lars Ingebrigtsen <larsi@gnus.org> 于2021年7月4日周日 下午9:55写道：

> Phil Sainty <psainty@orcon.net.nz> writes:
>
> > This is simply bad web design, and I don't think that's eww's
> > problem to solve.
>
> Indeed, so I'm closing this bug report.
>
> --
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no
>

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