Implement `Element.currentCSSZoom` #46925

Ahmad-S792 · 2025-06-18T20:25:32Z

`b762099`

Implement `Element.currentCSSZoom`

https://bugs.webkit.org/show_bug.cgi?id=279881
rdar://136662584

Reviewed by Anne van Kesteren.

This patch implements `currentCSSZoom` as per web specification [1] and
aligns with Gecko / Firefox and Blink / Chrome.

[1] https://drafts.csswg.org/cssom-view/#dom-element-currentcsszoom

This is implemented behind flag while being enabled on 'Safari Technology Preview'.

* Source/WebCore/dom/Element+CSSOMView.idl:
* Source/WebCore/dom/Element.cpp:
(WebCore::Element::currentCSSZoom):
* Source/WebCore/dom/Element.h:
* Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml: Enabled in `preview`
* LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/Element-currentCSSZoom-expected.txt: Progression
* LayoutTests/fast/zooming/currentCSSZoom-body-fixed-regression-test.html:
* LayoutTests/fast/zooming/currentCSSZoom-body-fixed-regression-test-expected.txt:

Canonical link: https://commits.webkit.org/296856@main

d7d1c83

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

annevk

Since this is adding a new feature, could you please add it behind a preference, enabled for preview for now?

webkit-early-warning-system · 2025-06-25T01:38:37Z

EWS run on previous version of this PR (hash e69f85e)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

Source/WebCore/dom/Element.cpp

webkit-early-warning-system · 2025-06-25T21:04:45Z

EWS run on previous version of this PR (hash 1338bae)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

Ahmad-S792 · 2025-06-26T07:57:33Z

@annevk - Can you review this now?

annevk · 2025-06-26T11:52:52Z

Source/WebCore/dom/Element.cpp

@@ -1583,6 +1583,23 @@ int Element::clientHeight()
    return 0;
 }

+double Element::currentCSSZoom()
+{
+    protectedDocument()->updateStyleIfNeeded();


You want

Ref document = this->document() here as you also use document below to get the resolver. But then from that resolver you get a document again? Is that going to be a different document? Seems unlikely.

My interpretation is -> that whenever we come across this 'currentCSSZoom' function, if there is any pending document or anything then just go ahead and update Style and then later apply whatever is below.

That doesn't really answer the question. I don't think obtaining a resolver has any side effects. Updating style obviously does, but that's already done at that point.

@annevk - I updated this to more cleaner version now.

webkit-early-warning-system · 2025-07-01T03:34:58Z

EWS run on current version of this PR (hash d7d1c83)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

annevk

Looks good! Thanks! I think we should create a couple more tests with mixed zoom levels across elements before eventually enabling.

Ahmad-S792 · 2025-07-01T06:50:23Z

Looks good! Thanks! I think we should create a couple more tests with mixed zoom levels across elements before eventually enabling.

Good idea! I would do it over weekend and directly on WPT.

https://bugs.webkit.org/show_bug.cgi?id=279881 rdar://136662584 Reviewed by Anne van Kesteren. This patch implements `currentCSSZoom` as per web specification [1] and aligns with Gecko / Firefox and Blink / Chrome. [1] https://drafts.csswg.org/cssom-view/#dom-element-currentcsszoom This is implemented behind flag while being enabled on 'Safari Technology Preview'. * Source/WebCore/dom/Element+CSSOMView.idl: * Source/WebCore/dom/Element.cpp: (WebCore::Element::currentCSSZoom): * Source/WebCore/dom/Element.h: * Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml: Enabled in `preview` * LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/Element-currentCSSZoom-expected.txt: Progression * LayoutTests/fast/zooming/currentCSSZoom-body-fixed-regression-test.html: * LayoutTests/fast/zooming/currentCSSZoom-body-fixed-regression-test-expected.txt: Canonical link: https://commits.webkit.org/296856@main

webkit-commit-queue · 2025-07-01T07:10:33Z

Committed 296856@main (b762099): https://commits.webkit.org/296856@main

Reviewed commits have been landed. Closing PR #46925 and removing active labels.

Ahmad-S792 requested review from rniwa and cdumez as code owners June 18, 2025 20:25

Ahmad-S792 self-assigned this Jun 18, 2025

Ahmad-S792 added the DOM For bugs specific to XML/HTML DOM elements (including parsing). label Jun 18, 2025

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Ahmad-S792 force-pushed the eng/Implement-Element-currentCSSZoom branch from 6f5929a to f77668a Compare June 18, 2025 21:54

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Ahmad-S792 requested review from smfr and nt1m June 19, 2025 01:18

annevk reviewed Jun 19, 2025

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Ahmad-S792 force-pushed the eng/Implement-Element-currentCSSZoom branch from f77668a to e69f85e Compare June 25, 2025 01:38

annevk reviewed Jun 25, 2025

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Ahmad-S792 force-pushed the eng/Implement-Element-currentCSSZoom branch from e69f85e to 1338bae Compare June 25, 2025 21:04

annevk reviewed Jun 26, 2025

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Ahmad-S792 force-pushed the eng/Implement-Element-currentCSSZoom branch from 1338bae to d7d1c83 Compare July 1, 2025 03:34

annevk approved these changes Jul 1, 2025

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webkit-commit-queue force-pushed the eng/Implement-Element-currentCSSZoom branch from d7d1c83 to b762099 Compare July 1, 2025 07:10

webkit-commit-queue merged commit b762099 into WebKit:main Jul 1, 2025

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