Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: d166513e8cf28fb3cc4e03f03a078d562ac084c4
https://github.com/WebKit/WebKit/commit/d166513e8cf28fb3cc4e03f03a078d562ac084c4
Author: Ahmad Saleem <[email protected]>
Date: 2026-05-25 (Mon, 25 May 2026)
Changed paths:
A LayoutTests/http/tests/preload/picture-source-loading-lazy-expected.txt
A LayoutTests/http/tests/preload/picture-source-loading-lazy.html
M
LayoutTests/imported/w3c/web-platform-tests/html/syntax/speculative-parsing/generated/page-load/picture-source-no-img.tentative-expected.txt
M Source/WebCore/html/parser/HTMLPreloadScanner.cpp
M Source/WebCore/html/parser/HTMLPreloadScanner.h
Log Message:
-----------
<picture> <source> candidates are speculatively preloaded even when the inner
<img> has loading="lazy"
https://bugs.webkit.org/show_bug.cgi?id=315466
rdar://177833110
Reviewed by Chris Dumez.
This patch aligns WebKit with Gecko / Firefox and Blink / Chromium.
The preload scanner emits a fetch for a matched <source> inside a
<picture> as soon as it is selected, without consulting the inner
<img>'s loading attribute. Because <source> appears before <img> in
source order, the lazy-load short-circuit in
StartTagScanner::createPreloadRequest never sees loading="lazy", and
alternative-format / srcset candidates for off-screen lazy images are
fetched up front — then fetched again when the image approaches the
viewport.
Defer the matched <source> preload in per-<picture> state instead of
emitting it immediately. Flush it when the inner <img> is seen and is
not loading="lazy"; drop it if the <img> is lazy or if the <picture>
closes without an <img>. Also read the <img>'s loading attribute even
when a sibling <source> already matched (the previous code bailed out
on alreadyMatchedSource before reaching it).
*
LayoutTests/imported/w3c/web-platform-tests/html/syntax/speculative-parsing/generated/page-load/picture-source-no-img.tentative-expected.txt:
Progression
* Source/WebCore/html/parser/HTMLPreloadScanner.cpp:
(WebCore::TokenPreloadScanner::StartTagScanner::processAttributes):
(WebCore::TokenPreloadScanner::StartTagScanner::isLazyloadingImage const):
(WebCore::TokenPreloadScanner::StartTagScanner::processAttribute):
(WebCore::TokenPreloadScanner::scan):
* Source/WebCore/html/parser/HTMLPreloadScanner.h:
* LayoutTests/http/tests/preload/picture-source-loading-lazy-expected.txt
* LayoutTests/http/tests/preload/picture-source-loading-lazy.html:
Canonical link: https://commits.webkit.org/313833@main
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