Improve <input type=color alpha> performance on macOS

[annevk]

c670903

Improve <input type=color alpha> performance on macOS
https://bugs.webkit.org/show_bug.cgi?id=286803
rdar://143955048

Reviewed by Aditya Keerthi.

Using data: URLs here resulted in annoying flickering when moving the
alpha slider quickly.

Using SVG directly in the shadow tree ran into
https://bugs.webkit.org/show_bug.cgi?id=287472 so therefore we use a
div element with a polygon clip-path. This results in additional render
layers, but websites will likely not have a lot of these controls so
that seems okay.

* LayoutTests/fast/forms/color/color-input-swatch-expected.txt:
* LayoutTests/fast/forms/color/color-input-swatch.html:
* LayoutTests/platform/mac/fast/forms/color/color-input-swatch-expected.txt:
* LayoutTests/platform/mac/fast/forms/color/input-appearance-color-expected.txt:
* Source/WebCore/html/ColorInputType.cpp:
(WebCore::ColorInputType::createShadowSubtree):
(WebCore::ColorInputType::updateColorSwatch):
* Source/WebCore/rendering/RenderTheme.h:
(WebCore::RenderTheme::createColorWellSwatchSubtree):
* Source/WebCore/rendering/mac/RenderThemeMac.h:
* Source/WebCore/rendering/mac/RenderThemeMac.mm:
(WebCore::RenderThemeMac::createColorWellSwatchSubtree):
(WebCore::RenderThemeMac::setColorWellSwatchBackground):

Canonical link: https://commits.webkit.org/290228@main

cebe08f

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
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
🛠 🧪 unsafe-merge	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash af481d7)

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
	✅ 🧪 api-ios	❌ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	❌ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	❌ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[aproskuryakov]

This doesn't look quite right. Maybe you want a shouldBe-like function here to clearly state that empty string is the expectation? Other logged values may benefit from shouldBe, too.

[annevk]

I don't really want to state the expectations as they can differ per platform, as they do here.

[aproskuryakov]

Even this one, empty innerHTML?

That said, color components differing per platform (and I'm sure also per configuration) is only more of a reason to have expectations. Possibly, saying that the numbers should be within a certain range. Currently, you are asking everyone who sees the test fail to investigate for themselves whether the different number means failing or passing, and that's rather hard.

[annevk]

They only differ between macOS and everywhere else at this point. And only macOS has a deeper subtree. Anyone touching the shadow tree for this component would know why this test regressed.

[aproskuryakov]

I hear your explanations, but I still really dislike tests that just dump results, as existing ones that do so are a constant nuisance.

[annevk]

The fast/shadow-dom/color-input-element-shadow-manipulation.html failure on macOS seems like a real problem. Hit testing (at least through document.caretRangeFromPoint()) no longer returns the input element because it now contains SVG in its shadow root. Apparently whenever you'd use SVG in your shadow root you'd be susceptible to this.

[webkit-early-warning-system]

EWS run on current version of this PR (hash cebe08f)

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
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
🛠 🧪 unsafe-merge	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-ews-buildbot]

Safe-Merge-Queue: Build #48499.

[webkit-commit-queue]

Committed 290228@main (c670903): https://commits.webkit.org/290228@main

Reviewed commits have been landed. Closing PR #39814 and removing active labels.