From what I can tell, this shipped in Firefox a few days ago, and
should be in 127: https://bugzilla.mozilla.org/show_bug.cgi?id=1281158#c26
LGTM1
On 5/13/24 4:15 PM, 'Daniel Clark' via blink-dev wrote:
/> Gecko: No signal
(https://bugzilla.mozilla.org/show_bug.cgi?id=1281158//)/
/> It's hard to parse the sentiment in that bug, but it doesn't seem
negative at least :) I don't know if it's worth filing a position request/
Since I last looked at this bug, Gecko has actually started
implementing the feature:
https://hg.mozilla.org/mozilla-central/rev/df46563babe2. Based on this
comment
<https://hg.mozilla.org/mozilla-central/rev/df46563babe2#l13.37>
they’re also excluding counter(), so they’ll match the behavior I’m
proposing to ship here. Looking at
https://bugzilla.mozilla.org/show_bug.cgi?id=1896047 the work isn’t
quite finished yet. So based on these updates I think it’s fair to say
that the Gecko position is actually “In Development” rather than “No
Signal”.
/> I believe this is behind the CSSContentMultiArgAltText flag, right? /
That’s right.
-- Dan
*From:*Vladimir Levin <vmp...@chromium.org>
*Sent:* Monday, May 13, 2024 11:44 AM
*To:* Daniel Clark <dan...@microsoft.com>
*Cc:* blink-dev@chromium.org
*Subject:* Re: [blink-dev] Intent to Ship: Multi-argument alt text in
CSS Generated Content
On Mon, May 13, 2024 at 2:23 PM 'Daniel Clark' via blink-dev
<blink-dev@chromium.org> wrote:
*Contact emails*
dan...@microsoft.com
*Explainer*
None
*Specification*
https://drafts.csswg.org/css-content-3/#valdef-content---string--counter--attrand
https://drafts.csswg.org/css-content-3/#alt
<https://drafts.csswg.org/css-content-3/#alt>
*Summary*
The CSS content property allows developers to specify alternative
text for accessibility with the following syntax:
.has-before-content::before { content: url("cat.jpg") / "A cute
cat"; }
This functionality, where the alt text is given by a single
string, is already supported in Chromium
(https://chromestatus.com/feature/4550056227110912). However, the
spec allows the alt text to be given by an arbitrary number of
elements, which in addition to strings can be attr() functions or
counters.
For example:
.has-before-content::before { content: url("cat.jpg") / "A cute "
attr(data-animal); }
This Intent tracks the expansion of the Chromium implementation to
support an arbitrary number of arguments as well as attr()
functions in addition to strings.
Note that this Intent to Ship does **not** include the addition of
counter support. This turns out to add significant complexity
since counters are normally evaluated as part of layout tree
computation and the alt text being evaluated does not participate
in the layout tree. The existing WebKit implementation of this
feature does not support counters
<https://github.com/WebKit/WebKit/blob/c1c858cf081e67326c44328c12ab5ddb53a8799b/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp#L3675>,
so by shipping what’s proposed here Chromium will align with WebKit.
*Blink component*
Blink>Accessibility
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EAccessibility>
*TAG review*
https://github.com/w3ctag/design-reviews/issues/351
*TAG review status*
Issues Addressed
*Risks*
*Interoperability and Compatibility*
The new syntax will fail to parse in browser where it’s not
supported, so until browser support is widespread, developers
should include a preceding fallback line to specify the content:
.has-before-content::before {
content: url("cat.jpg"); /* Used if the following line doesn't
parse */
content: url("cat.jpg") / "A cute " attr(data-animal);
}
This compat risk is not really new given the feature’s current
state of partial support.
The lack of counter support in this implementation means there
will still be a gap between what we’re planning to ship here and
the spec. However since Chromium already ships a partial
implementation, and the updated implementation supports more of
the spec and puts us into alignment with WebKit, shipping this
puts things in a strictly better position.
/Gecko/: No signal
(https://bugzilla.mozilla.org/show_bug.cgi?id=1281158)
It's hard to parse the sentiment in that bug, but it doesn't seem
negative at least :) I don't know if it's worth filing a position request
/WebKit/: Shipped/Shipping
(https://github.com/WebKit/WebKit/pull/22185)
/Web developers/: There have been several blog posts ([1]
<https://www.sitelint.com/blog/alternative-text-for-css-generated-content>,
[2]
<https://adrianroselli.com/2020/10/alternative-text-for-css-generated-content.html>,
[3]
<https://www.stefanjudis.com/today-i-learned/css-content-accepts-alternative-text/#edits-part-1-%E2%80%93-define-the-alternative-text-in-html-or-custom-properties>,
[4]
<https://johnkavanagh.co.uk/articles/alternative-text-in-the-css-content-property/>)
and a StackOverflow answer
<https://stackoverflow.com/questions/5943223/put-title-alt-attributes-into-css-after-content-image>written
about the feature, with positive sentiment.
/Other signals/: This functionality is tested as part of the
Interop2024 Accessibility focus area. Specifically,
https://wpt.fyi/results/accname/name/comp_name_from_content.html?label=master&label=experimental&aligned&view=interop&q=label%3Ainterop-2024-accessibility
<https://wpt.fyi/results/accname/name/comp_name_from_content.html?label=master&label=experimental&aligned&view=interop&q=label%3Ainterop-2024-accessibility>sub-tests
"(button|heading|link) name from fallback content mixing attr()
and strings with ::before and ::after"
*WebView application risks*
/Does this intent deprecate or change behavior of existing APIs,
such that it has potentially high risk for Android WebView-based
applications?/
No
*Debuggability*
The accessible text can be viewed in the accessibility tree via
chrome://accessibility. DevTools allows this part of the content
property to be edited in the Style pane.
*Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?*
Yes
*Is this feature fully tested by **web-platform-tests*
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>*?*
https://wpt.fyi/results/css/css-content/parsing/content-valid.html
https://wpt.fyi/results/accname/name/comp_name_from_content.html(sub-tests
"(button|heading|link) name from fallback content mixing attr()
and strings with ::before and ::after")
*Flag name on chrome://flags*
None
*Finch feature name*
None
I believe this is behind the CSSContentMultiArgAltText flag, right?
*Non-finch justification*
None
*Requires code in //chrome?*
False
*Availability expectation*
Already implemented in WebKit. Mozilla bug is
https://bugzilla.mozilla.org/show_bug.cgi?id=1281158.
*Estimated milestones*
127
*Anticipated spec changes*
None
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5168344402755584
*Links to previous Intent discussions*
Intent to prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/MW4PR00MB1455CC35408799CAF44F732CC5162%40MW4PR00MB1455.namprd00.prod.outlook.com
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