Bug 170762 – Updating class name of a shadow host does not update the style applied by descendants of :host()

• Component: CSS
• Status: RESOLVED FIXED

[Ryosuke Niwa]

https://trac.webkit.org/changeset/202227 fixed the case where :host rule applies to itself,
but not any rules that apply styles to its descendants.

[Ryosuke Niwa]

See http://jsbin.com/masaxeq/edit?html,output

[Radar WebKit Bug Importer]

<rdar://problem/31572668>

[vpusher]

Experiencing the same issue with my custom element (game-card) but with an attribute selector:

:host([unrevealed]) #flipper

> We can see the rule appear and match in the dev tools (transform: rotateY...), but the styles are not really applied to the #flipper element (the card should rotate on the Y axis, like it was flipped).

You can inspect it there: https://www.webcomponents.org/element/vpusher/game-card

> Click on the card to toggle the 'unrevealed' attribute on the host, then check the #flipper styles.

The thing is, if you uncheck, then check the rule in the dev tools, it applies properly.

Hope I helped.

[Ryosuke Niwa]

*** Bug 169706 has been marked as a duplicate of this bug. ***

[Antti Koivisto]

Created attachment 309710 [details]
patch

[Ryosuke Niwa]

Comment on attachment 309710 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=309710&action=review

> Source/WebCore/css/RuleSet.cpp:208
> +    return leftmostSelector->match() == CSSSelector::PseudoClass && leftmostSelector->pseudoClassType() ==CSSSelector::PseudoClassHost;

Nit: Need a space after the second ==.

> Source/WebCore/css/RuleSet.h:218
> +    bool m_hasHostPseudoClassRulesMatchingInShadowTree { false };

You might wanna put this next to another boolean for better packing not that it matters much.

> LayoutTests/fast/shadow-dom/css-scoping-host-class-and-attribute-mutation.html:108
> +test("#host4", "#shadow4", (host) => {
> +   host.setAttribute('id','green');
> +});

Could you also add a variant for modifying ID/class/attribute of a node inside the shadow tree?

[Antti Koivisto]

Created attachment 309889 [details]
patch

[WebKit Commit Bot]

Comment on attachment 309889 [details]
patch

Clearing flags on attachment: 309889

Committed r216761: <http://trac.webkit.org/changeset/216761>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

_legacyUndefinedCheck: true