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AX: VoiceOver does not re-resolve aria-labelledby when referenced element's accessible name is provided by aria-label
https://bugs.webkit.org/show_bug.cgi?id=317597 rdar://180319221 Reviewed by Dominic Mazzoni. When an element references another via aria-labelledby, its accessible name was not recomputed if the referenced element's name changed via aria-label (or alt/title) — only text-content changes propagated. In the isolated tree this left a stale cached name. AXObjectCache::handleTextChanged walks the changed object's ancestors and notifies the objects each one labels (labelForObjects()) so their names get recomputed. That propagation was gated behind `if (isText)`, but aria-label, alt, and title changes reach handleTextChanged with a non-static-text object, so the labelledby referrer was never notified. Hoist the labelForObjects() propagation out of the isText block so it runs for every text/name change. * LayoutTests/accessibility/aria-labelledby-updates-when-aria-label-changes-expected.txt: Added. * LayoutTests/accessibility/aria-labelledby-updates-when-aria-label-changes.html: Added. * Source/WebCore/accessibility/AXObjectCache.cpp: (WebCore::AXObjectCache::handleTextChanged): Canonical link: https://commits.webkit.org/316316@main
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‎LayoutTests/accessibility/aria-labelledby-updates-when-aria-label-changes-expected.txt‎

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This test ensures an aria-labelledby reference recomputes its accessible name when the referenced element's name changes via aria-label, not just via text content.
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PASS: platformValueForW3CName(textSection) === 'Text name'
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PASS: platformValueForW3CName(labelSection) === 'Aria name'
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PASS: platformValueForW3CName(textSection) === 'New text name'
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PASS: platformValueForW3CName(labelSection) === 'New aria name'
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PASS successfullyParsed is true
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TEST COMPLETE
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New text name
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Visual content

‎LayoutTests/accessibility/aria-labelledby-updates-when-aria-label-changes.html‎

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<!DOCTYPE html>
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<html>
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<head>
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<script src="../resources/accessibility-helper.js"></script>
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<script src="../resources/js-test.js"></script>
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</head>
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<body>
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<section id="text-section" aria-labelledby="text-ref">
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<p id="text-ref">Text name</p>
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</section>
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<section id="label-section" aria-labelledby="label-ref">
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<p id="label-ref" role="img" aria-label="Aria name">Visual content</p>
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</section>
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<script>
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var output = "This test ensures an aria-labelledby reference recomputes its accessible name when the referenced element's name changes via aria-label, not just via text content.\n\n";
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if (window.accessibilityController) {
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window.jsTestIsAsync = true;
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var textSection = accessibilityController.accessibleElementById("text-section");
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var labelSection = accessibilityController.accessibleElementById("label-section");
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output += expect("platformValueForW3CName(textSection)", "'Text name'");
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output += expect("platformValueForW3CName(labelSection)", "'Aria name'");
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document.getElementById("text-ref").textContent = "New text name";
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document.getElementById("label-ref").setAttribute("aria-label", "New aria name");
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setTimeout(async function() {
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output += await expectAsync("platformValueForW3CName(textSection)", "'New text name'");
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output += await expectAsync("platformValueForW3CName(labelSection)", "'New aria name'");
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debug(output);
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finishJSTest();
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}, 0);
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}
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</script>
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</body>
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</html>

‎Source/WebCore/accessibility/AXObjectCache.cpp‎

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// Inform this ancestor its textUnderElement-dependent data is now out-of-date.
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postNotification(ancestor.get(), nullptr, AXNotification::TextUnderElementChanged);
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}
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// Any objects this ancestor labeled now also need new AccessibilityText.
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auto labeledObjects = ancestor->labelForObjects();
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for (const auto& labeledObject : labeledObjects)
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postNotification(&downcast<AccessibilityObject>(labeledObject.get()), nullptr, AXNotification::TextChanged);
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}
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// Any objects this ancestor labeled now also need new AccessibilityText. This must run even
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// when |object| is not static text: a name-source change like aria-label, alt, or title on an
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// element referenced via aria-labelledby alters the referrer's accessible name just the same.
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auto labeledObjects = ancestor->labelForObjects();
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for (const auto& labeledObject : labeledObjects)
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postNotification(&downcast<AccessibilityObject>(labeledObject.get()), nullptr, AXNotification::TextChanged);
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}
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postNotification(object, protect(object->document()).get(), AXNotification::TextChanged);

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