Bug 204937 – Support for resolving highlight pseudo element style

• Component: CSS
• Status: RESOLVED FIXED

[Antti Koivisto]

::highlight(foo)

[Antti Koivisto]

Created attachment 384996 [details]
patch

[Simon Fraser (smfr)]

Comment on attachment 384996 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=384996&action=review

> LayoutTests/ChangeLog:9
> +        * highlight/highlight-pseudo-element-style-expected.txt: Added.
> +        * highlight/highlight-pseudo-element-style.html: Added.

OK for now but the tests should really all be web platform tests.

> LayoutTests/highlight/highlight-pseudo-element-style.html:7
> +::highlight(green-range) { color: green }
> +span::highlight(blue-range) { color: blue }

Would be good to test a style that ::highlight sets but span::highlight does not.

> Source/WebCore/ChangeLog:25
> +        * css/SelectorChecker.h:
> +        * css/parser/CSSSelectorParser.cpp:
> +        (WebCore::CSSSelectorParser::consumePseudo):
> +        * rendering/style/RenderStyle.h:
> +        * style/ElementRuleCollector.cpp:
> +        (WebCore::Style::ElementRuleCollector::ruleMatches):
> +        * style/ElementRuleCollector.h:
> +        (WebCore::Style::PseudoElementRequest::PseudoElementRequest):
> +
> +        Add the requested highlight name.

How does code discover the names of all the applicable highlights for a given element?

[Antti Koivisto]

> How does code discover the names of all the applicable highlights for a
> given element?

The spec connects styles with

CSS.highlights.set("example-highlight", highlightRangeGroup);

and then you would query for "example-highlight" for all elements within the range. As far as I see there is no need to ever enumerate highlight names.

[Antti Koivisto]

Created attachment 385026 [details]
patch

[WebKit Commit Bot]

Comment on attachment 385026 [details]
patch

Clearing flags on attachment: 385026

Committed r253210: <https://trac.webkit.org/changeset/253210>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/57705431>

[Simon Fraser (smfr)]

(In reply to Antti Koivisto from comment #3)
> > How does code discover the names of all the applicable highlights for a
> > given element?
> 
> The spec connects styles with
> 
> CSS.highlights.set("example-highlight", highlightRangeGroup);
> 
> and then you would query for "example-highlight" for all elements within the
> range. As far as I see there is no need to ever enumerate highlight names.

I meant how does our text painting code find the list of highlights that may apply to an element?

[Antti Koivisto]

> I meant how does our text painting code find the list of highlights that may
> apply to an element?

Details depend on how you are representing ranges in the rendering side and who is caching styles, but basically

1) look up which highlight ranges containing the element being painted
2) with the range/element pairs look up the styles (via getUncachedPseudoStyle)
3) cache the style somewhere (maybe in the range itself, maybe extension of getCachedPseudoStyle).

This is a sort of combination how marker and first-line painting currently works.

[Antti Koivisto]

It would be nice to generalize the existing concepts on rendering side rather than writing yet another separate thing.