[css-anchor-position] Computed value of position-area
#11828
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The CSS Working Group just discussed
The full IRC log of that discussion<bkardell> TabAtkins: the position-area property has a number of syntaxes - it has two that are exactly equivalent<TabAtkins> start start and `block-start inline-start` <bkardell> elika said they should be equivalent, tab doesn'thavean opinion <bkardell> TabAtkins: which of the pair it should go to elika? opinion? <fantasai> astearns: Should it be the shortest serialization or the most explicit one? <bkardell> kiet: I opened this - It comes up because I am implementing and some of the tests are mismatched because webkit serializes one way, chrome another - if we have one way it's easier to write tests <bkardell> florian: make it short if we can <bkardell> TabAtkins: if it is already the case that multiple browsers do this, but just disagreeonwhich I would agree and say lets just use start start <bkardell> Proposed resolution: block-start and inline-start will serialize to start start and they will compute to start start <bkardell> kiet: this also applies to self block start...? <bkardell> TabAtkins: yes <TabAtkins> proposed: block/inline-start-end (and the self-* variants) compute to start/end or self-start/end <bkardell> resolved <bkardell> resolved: block/inline-start-end (and the self-* variants) compute to start/end or self-start/end <bkardell> RESOLVED: block/inline-start-end (and the self-* variants) compute to start/end or self-start/end <bkardell> !!!! |
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…sition-area rdar://146814606 https://bugs.webkit.org/show_bug.cgi?id=289589 Reviewed by Antti Koivisto. This commit implements swapping due to a try-tactic [1] for position-area. This is done at style building time; BuilderConverter::convertPositionArea will flip position-area as specified by the position-try fallback. This is needed instead of flipping position-area at layout time, because position-area should compute to the flipped value. There are some remaining test failures in try-tactic-position-area.html; these has to do with how position-area should be computed. The test expects the computed value of position-area to use axis-ambiguous keywords, when the specified value also uses those keywords (e.g: 'start end' computes to 'start end'). However, WebKit currently computes to their axis-unambiguous equivalent (e.g: 'start end' computes to 'block-start block-end'). This issue is tracked in [2]. [1]: https://drafts.csswg.org/css-anchor-position-1/#swap-due-to-a-try-tactic [2]: w3c/csswg-drafts#11828 * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/anchor-scroll-position-try-013-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/anchor-scroll-position-try-014-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/last-successful-basic-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/last-successful-change-fallbacks-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/last-successful-iframe-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/last-successful-intermediate-ignored-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/position-area-in-position-try-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-anchor-position/try-tactic-position-area-expected.txt: * Source/WebCore/rendering/style/PositionArea.cpp: (WebCore::operator<<): - Implemented operator<<(TextStream ts, PositionArea{Axis,Track,Self}) operator<<(TextStream ts, PositionAreaSpan) will use these functions instead. - operator<< that takes references were changed to take values. * Source/WebCore/rendering/style/PositionArea.h: (WebCore::oppositePositionAreaAxis): - See below. * Source/WebCore/style/StyleBuilderConverter.h: (WebCore::Style::flipPositionAreaByLogicalAxis): - Added function to flip position-area by a logical axis (block/inline). (WebCore::Style::mirrorPositionAreaAcrossDiagonal): - Added function to flip position-area according to flip-start. (WebCore::Style::BuilderConverter::convertPositionArea): - Added code to flip position-area according to the fallback try tactic, if specified. (WebCore::Style::BuilderConverter::convertPositionTryFallbacks): - Tightened parsing a bit by rejecting the CSS value if duplicate tactics are found. (WebCore::Style::positionAreaOppositeAxis): Deleted. - Renamed to oppositePositionAreaAxis, and moved to PositionArea.h Canonical link: https://commits.webkit.org/293219@main
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The
position-areasyntax has multiple syntaxes in order to accommodate different relationships to the writing mode, but it also has two syntaxes which are exactly equivalent: thestart startsyntax and theblock-start inline-startsyntax.Should these two compute to each other? I think it would make sense to do so.
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