Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 6371c7a9813368cba21d606cb2a3209d064144c1
https://github.com/WebKit/WebKit/commit/6371c7a9813368cba21d606cb2a3209d064144c1
Author: Dominic Mazzoni <[email protected]>
Date: 2026-07-20 (Mon, 20 Jul 2026)
Changed paths:
M
LayoutTests/accessibility/mac/index-for-zero-offset-text-marker-expected.txt
M LayoutTests/accessibility/mac/index-for-zero-offset-text-marker.html
A LayoutTests/accessibility/mac/text-marker-index-round-trip-expected.txt
A
LayoutTests/accessibility/mac/text-marker-index-round-trip-list-expected.txt
A LayoutTests/accessibility/mac/text-marker-index-round-trip-list.html
A
LayoutTests/accessibility/mac/text-marker-index-round-trip-nested-blocks-expected.txt
A
LayoutTests/accessibility/mac/text-marker-index-round-trip-nested-blocks.html
A
LayoutTests/accessibility/mac/text-marker-index-round-trip-table-expected.txt
A LayoutTests/accessibility/mac/text-marker-index-round-trip-table.html
A LayoutTests/accessibility/mac/text-marker-index-round-trip.html
A LayoutTests/resources/ax-text-marker-helper.js
M Source/WebCore/accessibility/AXTextMarker.cpp
Log Message:
-----------
AX: AXTextMarkerForIndex and AXIndexForTextMarker don't round-trip in the
isolated tree
https://bugs.webkit.org/show_bug.cgi?id=319672
rdar://182515917
Reviewed by Tyler Wilcock and Andres Gonzalez.
AXIndexForTextMarker and AXTextMarkerForIndex are documented inverses
-- VoiceOver converts a text marker to a document-relative index and
back -- but in the isolated-tree text path the two directions were
implemented by separate traversals that counted positions differently:
- AXTextMarkerRange::toString (the string) walks findObjectWithRuns and emits a
newline
"don't repeat a newline" rule).
- offsetFromRoot (AXIndexForTextMarker) walked nextInPreOrder and counted
newlines with
an emitsNewline() bool that added at most 1, never accounting for
DoubleNewline.
- nextMarkerFromOffset (AXTextMarkerForIndex) walked findMarker and counted
every step.
Because these three disagree, converting a marker to an index and back
drifted, and the drift accumulated with each list, table, nested block
wrapper, <br>, and paragraph break, so selecting content further down
a page (e.g. Wikipedia) was increasingly wrong.
Make offsetFromRoot and nextMarkerFromOffset inverses by construction
by driving both from a single shared forward walk
(forEachRunObjectForward) that mirrors AXTextMarkerRange:: toString's
iteration and newline emission. The index of a marker is defined as
the number of characters before it in that walk; nextMarkerFromOffset
walks the same way until it has consumed that many characters. Image
alt text is intentionally excluded, so the index space is independent
of it. The round-trip is now exact for every real (run-position)
marker -- which is what VoiceOver round-trips -- while positions
inside an emitted newline gap, which have no marker of their own, snap
to an adjacent boundary (bounded and non-accumulating).
Tests: accessibility/mac/text-marker-index-round-trip-list.html
accessibility/mac/text-marker-index-round-trip-nested-blocks.html
accessibility/mac/text-marker-index-round-trip-table.html
accessibility/mac/text-marker-index-round-trip.html
* LayoutTests/accessibility/mac/index-for-zero-offset-text-marker-expected.txt:
* LayoutTests/accessibility/mac/index-for-zero-offset-text-marker.html:
* LayoutTests/accessibility/mac/text-marker-index-round-trip-expected.txt:
Added.
* LayoutTests/accessibility/mac/text-marker-index-round-trip-list-expected.txt:
Added.
* LayoutTests/accessibility/mac/text-marker-index-round-trip-list.html: Added.
*
LayoutTests/accessibility/mac/text-marker-index-round-trip-nested-blocks-expected.txt:
Added.
*
LayoutTests/accessibility/mac/text-marker-index-round-trip-nested-blocks.html:
Added.
*
LayoutTests/accessibility/mac/text-marker-index-round-trip-table-expected.txt:
Added.
* LayoutTests/accessibility/mac/text-marker-index-round-trip-table.html: Added.
* LayoutTests/accessibility/mac/text-marker-index-round-trip.html: Added.
* LayoutTests/resources/ax-text-marker-helper.js: Added.
(checkRoundTripAllTextMarkerIndicesWithinContainer):
* Source/WebCore/accessibility/AXTextMarker.cpp:
(WebCore::runEndsWithNewline):
(WebCore::emittedNewlineLength):
(WebCore::forEachRunObjectForward):
(WebCore::AXTextMarker::offsetFromRoot const):
(WebCore::AXTextMarker::nextMarkerFromOffset const):
Canonical link: https://commits.webkit.org/317545@main
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