AX: textUnderElement for hidden elements targeted by aria-labelledby …

…should expose all subtree text, not just the direct target of aria-labelledby

https://bugs.webkit.org/show_bug.cgi?id=271918
rdar://problem/125634439

Reviewed by Chris Fleizach.

https://w3c.github.io/accname/#comp_labelledby

> The result of LabelledBy Recursion in combination with Hidden Not Referenced means that user agents MUST include all
> nodes in the subtree as part of the accessible name or accessible description, when the node referenced by aria-labelledby
> or aria-describedby is hidden.

Prior to this patch, we correctly exposed the text of the children directly underneath DOM hidden nodes targeted by
aria-labelledby, but not grandchildren or deeper, which is what the spec requires.

This allows us to pass 7 more WPT subtests.

This patch also renames AccessibilityTextUnderElementMode to TextUnderElementMode, as the former is very long and implicit
considering the type is defined in the Accessibility namespace.

* LayoutTests/imported/w3c/web-platform-tests/accname/name/comp_label-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/accname/name/comp_labelledby_hidden_nodes-expected.txt:
* LayoutTests/platform/gtk/imported/w3c/web-platform-tests/accname/name/comp_label-expected.txt:
* Source/WebCore/accessibility/AXCoreObject.h:
(WebCore::TextUnderElementMode::TextUnderElementMode):
(WebCore::AccessibilityTextUnderElementMode::AccessibilityTextUnderElementMode): Deleted.
* Source/WebCore/accessibility/AXLogger.cpp:
(WebCore::operator<<):
* Source/WebCore/accessibility/AccessibilityMathMLElement.cpp:
(WebCore::AccessibilityMathMLElement::textUnderElement const):
* Source/WebCore/accessibility/AccessibilityMathMLElement.h:
* Source/WebCore/accessibility/AccessibilityNodeObject.cpp:
(WebCore::AccessibilityNodeObject::visibleText const):
(WebCore::shouldUseAccessibilityObjectInnerText):
(WebCore::AccessibilityNodeObject::textUnderElement const):
(WebCore::AccessibilityNodeObject::title const):
(WebCore::accessibleNameForNode):
* Source/WebCore/accessibility/AccessibilityNodeObject.h:
* Source/WebCore/accessibility/AccessibilityObject.h:
* Source/WebCore/accessibility/AccessibilityRenderObject.cpp:
(WebCore::AccessibilityRenderObject::textUnderElement const):
(WebCore::AccessibilityRenderObject::shouldGetTextFromNode const):
* Source/WebCore/accessibility/AccessibilityRenderObject.h:
* Source/WebCore/accessibility/atspi/AccessibilityObjectTextAtspi.cpp:
(WebCore::AccessibilityObjectAtspi::text const):
(WebCore::AccessibilityObject::getLengthForTextRange const):
* Source/WebCore/accessibility/isolatedtree/AXIsolatedObject.cpp:
(WebCore::AXIsolatedObject::textUnderElement const):
* Source/WebCore/accessibility/isolatedtree/AXIsolatedObject.h:

Canonical link: https://commits.webkit.org/276864@main

LayoutTests/imported/w3c/web-platform-tests/accname/name/comp_label-expected.txt

@@ -250,12 +250,7 @@ FAIL aria-label undefined on img w/o alt assert_equals: <img aria-label="undefin
 FAIL aria-label undefined on img w/ empty alt assert_equals: <img alt="" aria-label="undefined" data-expectedlabel="" data-testname="aria-label undefined on img w/ empty alt" class="ex"> expected "" but got "undefined"
 FAIL aria-label undefined on img w/o alt but w/ title assert_equals: <img aria-label="undefined" data-expectedlabel="title" data-testname="aria-label undefined on img w/o alt but w/ title" class="ex"> expected "title" but got "undefined"
 FAIL aria-label undefined on img w/ empty alt but w/ title assert_equals: <img alt="" aria-label="undefined" data-expectedlabel="title" data-testname="aria-label undefined on img w/ empty alt but w/ title" class="ex"> expected "title" but got "undefined"
-FAIL button's hidden referenced name (display:none) supercedes aria-label assert_equals: <button aria-labelledby="span1" aria-label="foo" data-expectedlabel="label" data-testname="button's hidden referenced name (display:none) supercedes aria-label" class="ex">
-  <span id="span1" style="display:none;">
-    <span id="span2" style="display:none;">label</span>
-  </span>
-x
-</button> expected "label" but got "foo"
+PASS button's hidden referenced name (display:none) supercedes aria-label
 PASS button's hidden referenced name (visibility:hidden) supercedes aria-label
 FAIL button's hidden referenced name (visibility:hidden) with hidden aria-labelledby traversal falls back to aria-label assert_equals: <button aria-labelledby="span4" aria-label="foo" data-expectedlabel="foo" data-testname="button's hidden referenced name (visibility:hidden) with hidden aria-labelledby traversal falls back to aria-label" class="ex">
   <span id="span4">

LayoutTests/imported/w3c/web-platform-tests/accname/name/comp_labelledby_hidden_nodes-expected.txt

@@ -22,16 +22,16 @@ PASS button with aria-labelledby using span without display:none (with nested di
 PASS button with aria-labelledby using display:none hidden span (with nested sibling spans)
 PASS button with aria-labelledby using span without display:none (with nested display:none sibling spans)
 PASS button with aria-labelledby using span with display:none (with nested display:inline sibling spans)
-FAIL button with aria-labelledby using visibility:hidden span (with nested span) assert_equals: <button aria-labelledby="b11" data-expectedlabel="foo bar" data-testname="button with aria-labelledby using visibility:hidden span (with nested span)" class="ex">x</button> expected "foo bar" but got "foo"
-FAIL button with aria-labelledby using visibility:hidden span (with nested spans, depth 2) assert_equals: <button aria-labelledby="b21" data-expectedlabel="foo bar baz" data-testname="button with aria-labelledby using visibility:hidden span (with nested spans, depth 2)" class="ex">x</button> expected "foo bar baz" but got "foo"
+PASS button with aria-labelledby using visibility:hidden span (with nested span)
+PASS button with aria-labelledby using visibility:hidden span (with nested spans, depth 2)
 PASS button with aria-labelledby using span without visibility:hidden (with nested visibility:hidden spans, depth 2)
-FAIL button with aria-labelledby using visibility:hidden hidden span (with nested sibling spans) assert_equals: <button aria-labelledby="b41" data-expectedlabel="foo bar baz" data-testname="button with aria-labelledby using visibility:hidden hidden span (with nested sibling spans)" class="ex">x</button> expected "foo bar baz" but got "foo"
+PASS button with aria-labelledby using visibility:hidden hidden span (with nested sibling spans)
 PASS button with aria-labelledby using span without visibility:hidden (with nested visibility:hidden sibling spans)
 PASS button with aria-labelledby using span with visibility:hidden (with nested visibility:visible sibling spans)
-FAIL button with aria-labelledby using visibility:collapse span (with nested span) assert_equals: <button aria-labelledby="c11" data-expectedlabel="foo bar" data-testname="button with aria-labelledby using visibility:collapse span (with nested span)" class="ex">x</button> expected "foo bar" but got "foo"
-FAIL button with aria-labelledby using visibility:collapse span (with nested spans, depth 2) assert_equals: <button aria-labelledby="c21" data-expectedlabel="foo bar baz" data-testname="button with aria-labelledby using visibility:collapse span (with nested spans, depth 2)" class="ex">x</button> expected "foo bar baz" but got "foo"
+PASS button with aria-labelledby using visibility:collapse span (with nested span)
+PASS button with aria-labelledby using visibility:collapse span (with nested spans, depth 2)
 PASS button with aria-labelledby using span without visibility:collapse (with nested visibility:visible spans, depth 2)
-FAIL button with aria-labelledby using visibility:collapse span (with nested sibling spans) assert_equals: <button aria-labelledby="c41" data-expectedlabel="foo bar baz" data-testname="button with aria-labelledby using visibility:collapse span (with nested sibling spans)" class="ex">x</button> expected "foo bar baz" but got "foo"
+PASS button with aria-labelledby using visibility:collapse span (with nested sibling spans)
 PASS button with aria-labelledby using span without visibility:collapse (with nested visibility:collapse sibling spans)
 PASS button with aria-labelledby using span with visibility:collapse (with nested visible sibling spans)
 PASS button with aria-labelledby using aria-hidden span (with nested span)

LayoutTests/platform/gtk/imported/w3c/web-platform-tests/accname/name/comp_label-expected.txt

@@ -250,12 +250,7 @@ FAIL aria-label undefined on img w/o alt assert_equals: <img aria-label="undefin
 FAIL aria-label undefined on img w/ empty alt assert_equals: <img alt="" aria-label="undefined" data-expectedlabel="" data-testname="aria-label undefined on img w/ empty alt" class="ex"> expected "" but got "undefined"
 FAIL aria-label undefined on img w/o alt but w/ title assert_equals: <img aria-label="undefined" data-expectedlabel="title" data-testname="aria-label undefined on img w/o alt but w/ title" class="ex"> expected "title" but got "undefined"
 FAIL aria-label undefined on img w/ empty alt but w/ title assert_equals: <img alt="" aria-label="undefined" data-expectedlabel="title" data-testname="aria-label undefined on img w/ empty alt but w/ title" class="ex"> expected "title" but got "undefined"
-FAIL button's hidden referenced name (display:none) supercedes aria-label assert_equals: <button aria-labelledby="span1" aria-label="foo" data-expectedlabel="label" data-testname="button's hidden referenced name (display:none) supercedes aria-label" class="ex">
-  <span id="span1" style="display:none;">
-    <span id="span2" style="display:none;">label</span>
-  </span>
-x
-</button> expected "label" but got "foo"
+PASS button's hidden referenced name (display:none) supercedes aria-label
 PASS button's hidden referenced name (visibility:hidden) supercedes aria-label
 FAIL button's hidden referenced name (visibility:hidden) with hidden aria-labelledby traversal falls back to aria-label assert_equals: <button aria-labelledby="span4" aria-label="foo" data-expectedlabel="foo" data-testname="button's hidden referenced name (visibility:hidden) with hidden aria-labelledby traversal falls back to aria-label" class="ex">
   <span id="span4">

Source/WebCore/accessibility/AXCoreObject.h

@@ -727,21 +727,22 @@ enum class AccessibilityOrientation {
     Undefined,
 };
 
-struct AccessibilityTextUnderElementMode {
-    enum ChildrenInclusion {
-        TextUnderElementModeSkipIgnoredChildren,
-        TextUnderElementModeIncludeAllChildren,
-        TextUnderElementModeIncludeNameFromContentsChildren, // This corresponds to ARIA concept: nameFrom
+struct TextUnderElementMode {
+    enum class Children : uint8_t {
+        SkipIgnoredChildren,
+        IncludeAllChildren,
+        IncludeNameFromContentsChildren, // This corresponds to ARIA concept: nameFrom
     };
 
-    ChildrenInclusion childrenInclusion;
+    Children childrenInclusion;
     bool includeFocusableContent;
+    bool considerHiddenState { true };
     Node* ignoredChildNode;
 
-    AccessibilityTextUnderElementMode(ChildrenInclusion c = TextUnderElementModeSkipIgnoredChildren, bool i = false, Node* ignored = nullptr)
-        : childrenInclusion(c)
-        , includeFocusableContent(i)
-        , ignoredChildNode(ignored)
+    TextUnderElementMode(Children childrenInclusion = Children::SkipIgnoredChildren, bool includeFocusable = false, Node* ignoredChild = nullptr)
+        : childrenInclusion(childrenInclusion)
+        , includeFocusableContent(includeFocusable)
+        , ignoredChildNode(ignoredChild)
     { }
 };
 
@@ -1140,7 +1141,7 @@ class AXCoreObject : public ThreadSafeRefCountedAndCanMakeThreadSafeWeakPtr<AXCo
 
     // Methods for determining accessibility text.
     virtual String stringValue() const = 0;
-    virtual String textUnderElement(AccessibilityTextUnderElementMode = AccessibilityTextUnderElementMode()) const = 0;
+    virtual String textUnderElement(TextUnderElementMode = TextUnderElementMode()) const = 0;
     virtual String text() const = 0;
     virtual unsigned textLength() const = 0;
 #if PLATFORM(COCOA)
@@ -1725,5 +1726,6 @@ WTF::TextStream& operator<<(WTF::TextStream&, const AXCoreObject&);
 WTF::TextStream& operator<<(WTF::TextStream&, AccessibilityText);
 WTF::TextStream& operator<<(WTF::TextStream&, AccessibilityTextSource);
 WTF::TextStream& operator<<(WTF::TextStream&, AXRelationType);
+WTF::TextStream& operator<<(WTF::TextStream&, const TextUnderElementMode&);
 
 } // namespace WebCore

Source/WebCore/accessibility/AXLogger.cpp

@@ -540,6 +540,33 @@ TextStream& operator<<(TextStream& stream, AXRelationType relationType)
     return stream;
 }
 
+TextStream& operator<<(WTF::TextStream& stream, const TextUnderElementMode& mode)
+{
+    String childrenInclusion;
+    switch (mode.childrenInclusion) {
+    case TextUnderElementMode::Children::SkipIgnoredChildren:
+        childrenInclusion = "SkipIgnoredChildren"_s;
+        break;
+    case TextUnderElementMode::Children::IncludeAllChildren:
+        childrenInclusion = "IncludeAllChildren"_s;
+        break;
+    case TextUnderElementMode::Children::IncludeNameFromContentsChildren:
+        childrenInclusion = "IncludeNameFromContentsChildren"_s;
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+        break;
+    }
+
+    stream << childrenInclusion << ", includeFocusableContent: " << mode.includeFocusableContent;
+    // Only log the non-default value of false to avoid noise.
+    if (!mode.considerHiddenState)
+        stream << ", considerHiddenState: 0";
+    if (mode.ignoredChildNode)
+        stream << ", ignoredChildNode: " << mode.ignoredChildNode;
+    return stream;
+}
+
 TextStream& operator<<(TextStream& stream, AXObjectCache::AXNotification notification)
 {
     switch (notification) {

Source/WebCore/accessibility/AccessibilityMathMLElement.cpp

@@ -66,7 +66,7 @@ AccessibilityRole AccessibilityMathMLElement::determineAccessibilityRole()
     return AccessibilityRole::MathElement;
 }
 
-String AccessibilityMathMLElement::textUnderElement(AccessibilityTextUnderElementMode mode) const
+String AccessibilityMathMLElement::textUnderElement(TextUnderElementMode mode) const
 {
     if (m_isAnonymousOperator) {
         UChar operatorChar = downcast<RenderMathMLOperator>(*m_renderer).textContent();

Source/WebCore/accessibility/AccessibilityMathMLElement.h

@@ -49,7 +49,7 @@ class AccessibilityMathMLElement : public AccessibilityRenderObject {
 
 private:
     AccessibilityRole determineAccessibilityRole() final;
-    String textUnderElement(AccessibilityTextUnderElementMode = AccessibilityTextUnderElementMode()) const override;
+    String textUnderElement(TextUnderElementMode = TextUnderElementMode()) const override;
     String stringValue() const override;
     bool isIgnoredElementWithinMathTree() const final;
 

Source/WebCore/accessibility/AccessibilityNodeObject.cpp

@@ -1925,7 +1925,7 @@ void AccessibilityNodeObject::visibleText(Vector<AccessibilityText>& textOrder)
         return;
 
     if (dependsOnTextUnderElement()) {
-        AccessibilityTextUnderElementMode mode;
+        TextUnderElementMode mode;
 
         // Headings often include links as direct children. Those links need to be included in text under element.
         if (isHeading())
@@ -2191,10 +2191,10 @@ void AccessibilityNodeObject::setIsExpanded(bool expand)
 
 // When building the textUnderElement for an object, determine whether or not
 // we should include the inner text of this given descendant object or skip it.
-static bool shouldUseAccessibilityObjectInnerText(AccessibilityObject* obj, AccessibilityTextUnderElementMode mode)
+static bool shouldUseAccessibilityObjectInnerText(AccessibilityObject* obj, TextUnderElementMode mode)
 {
     // Do not use any heuristic if we are explicitly asking to include all the children.
-    if (mode.childrenInclusion == AccessibilityTextUnderElementMode::TextUnderElementModeIncludeAllChildren)
+    if (mode.childrenInclusion == TextUnderElementMode::Children::IncludeAllChildren)
         return true;
 
     // Consider this hypothetical example:
@@ -2215,7 +2215,7 @@ static bool shouldUseAccessibilityObjectInnerText(AccessibilityObject* obj, Acce
     // containers with lots of children.
 
     // ARIA states that certain elements are not allowed to expose their children content for name calculation.
-    if (mode.childrenInclusion == AccessibilityTextUnderElementMode::TextUnderElementModeIncludeNameFromContentsChildren
+    if (mode.childrenInclusion == TextUnderElementMode::Children::IncludeNameFromContentsChildren
         && !obj->accessibleNameDerivesFromContent())
         return false;
 
@@ -2259,7 +2259,7 @@ static void appendNameToStringBuilder(StringBuilder& builder, String&& text)
     builder.append(WTFMove(text));
 }
 
-String AccessibilityNodeObject::textUnderElement(AccessibilityTextUnderElementMode mode) const
+String AccessibilityNodeObject::textUnderElement(TextUnderElementMode mode) const
 {
     Node* node = this->node();
     if (RefPtr text = dynamicDowncast<Text>(node))
@@ -2272,17 +2272,25 @@ String AccessibilityNodeObject::textUnderElement(AccessibilityTextUnderElementMo
     // The Accname specification states that if the current node is hidden, and not directly
     // referenced by aria-labelledby or aria-describedby, and is not a host language text
     // alternative, the empty string should be returned.
-    if (isDOMHidden() && !isAriaVisible && !is<HTMLLabelElement>(node) && (node && !ancestorsOfType<HTMLCanvasElement>(*node).first())) {
+    if (mode.considerHiddenState && isDOMHidden() && !isAriaVisible && !is<HTMLLabelElement>(node) && (node && !ancestorsOfType<HTMLCanvasElement>(*node).first())) {
         if (labelForObjects().isEmpty() && descriptionForObjects().isEmpty())
             return { };
+
+        // This object is a hidden label or description for another object, so ignore hidden states for our
+        // subtree text under element traversals too (https://w3c.github.io/accname/#comp_labelledby).
+        //
+        // "The result of LabelledBy Recursion in combination with Hidden Not Referenced means that user
+        // agents MUST include all nodes in the subtree as part of the accessible name or accessible
+        // description, when the node referenced by aria-labelledby or aria-describedby is hidden."
+        mode.considerHiddenState = false;
     }
 
     StringBuilder builder;
     for (RefPtr child = firstChild(); child; child = child->nextSibling()) {
         if (mode.ignoredChildNode && child->node() == mode.ignoredChildNode)
             continue;
 
-        bool shouldDeriveNameFromAuthor = (mode.childrenInclusion == AccessibilityTextUnderElementMode::TextUnderElementModeIncludeNameFromContentsChildren && !child->accessibleNameDerivesFromContent());
+        bool shouldDeriveNameFromAuthor = (mode.childrenInclusion == TextUnderElementMode::Children::IncludeNameFromContentsChildren && !child->accessibleNameDerivesFromContent());
         if (shouldDeriveNameFromAuthor) {
             appendNameToStringBuilder(builder, accessibleNameForNode(child->node()));
             continue;
@@ -2372,7 +2380,7 @@ String AccessibilityNodeObject::title() const
     if (isLink())
         return textUnderElement();
     if (isHeading())
-        return textUnderElement(AccessibilityTextUnderElementMode(AccessibilityTextUnderElementMode::TextUnderElementModeSkipIgnoredChildren, true));
+        return textUnderElement(TextUnderElementMode(TextUnderElementMode::Children::SkipIgnoredChildren, true));
 
     return { };
 }
@@ -2556,7 +2564,7 @@ static String accessibleNameForNode(Node* node, Node* labelledbyNode)
     String text;
     if (axObject) {
         if (axObject->accessibleNameDerivesFromContent())
-            text = axObject->textUnderElement(AccessibilityTextUnderElementMode(AccessibilityTextUnderElementMode::TextUnderElementModeIncludeNameFromContentsChildren, true, labelledbyNode));
+            text = axObject->textUnderElement(TextUnderElementMode(TextUnderElementMode::Children::IncludeNameFromContentsChildren, true, labelledbyNode));
     } else
         text = (element ? element->innerText() : node->textContent()).simplifyWhiteSpace(isUnicodeWhitespace);
 

Source/WebCore/accessibility/AccessibilityNodeObject.h

@@ -105,7 +105,7 @@ class AccessibilityNodeObject : public AccessibilityObject {
 
     URL url() const override;
     unsigned hierarchicalLevel() const override;
-    String textUnderElement(AccessibilityTextUnderElementMode = AccessibilityTextUnderElementMode()) const override;
+    String textUnderElement(TextUnderElementMode = TextUnderElementMode()) const override;
     String accessibilityDescriptionForChildren() const;
     String description() const override;
     String helpText() const override;

Source/WebCore/accessibility/AccessibilityObject.h

@@ -385,7 +385,7 @@ class AccessibilityObject : public AXCoreObject, public CanMakeWeakPtr<Accessibi
     bool isARIAStaticText() const { return ariaRoleAttribute() == AccessibilityRole::StaticText; }
     String stringValue() const override { return { }; }
     bool dependsOnTextUnderElement() const;
-    String textUnderElement(AccessibilityTextUnderElementMode = AccessibilityTextUnderElementMode()) const override { return { }; }
+    String textUnderElement(TextUnderElementMode = TextUnderElementMode()) const override { return { }; }
     String text() const override { return { }; }
     unsigned textLength() const final;
 #if ENABLE(AX_THREAD_TEXT_APIS)

Source/WebCore/accessibility/AccessibilityRenderObject.cpp

@@ -663,7 +663,7 @@ String AccessibilityRenderObject::helpText() const
     return { };
 }
 
-String AccessibilityRenderObject::textUnderElement(AccessibilityTextUnderElementMode mode) const
+String AccessibilityRenderObject::textUnderElement(TextUnderElementMode mode) const
 {
     if (!m_renderer)
         return AccessibilityNodeObject::textUnderElement(mode);
@@ -680,7 +680,7 @@ String AccessibilityRenderObject::textUnderElement(AccessibilityTextUnderElement
 
     // We use a text iterator for text objects AND for those cases where we are
     // explicitly asking for the full text under a given element.
-    if (is<RenderText>(*m_renderer) || mode.childrenInclusion == AccessibilityTextUnderElementMode::TextUnderElementModeIncludeAllChildren) {
+    if (is<RenderText>(*m_renderer) || mode.childrenInclusion == TextUnderElementMode::Children::IncludeAllChildren) {
         // If possible, use a text iterator to get the text, so that whitespace
         // is handled consistently.
         Document* nodeDocument = nullptr;
@@ -728,7 +728,7 @@ String AccessibilityRenderObject::textUnderElement(AccessibilityTextUnderElement
     return AccessibilityNodeObject::textUnderElement(mode);
 }
 
-bool AccessibilityRenderObject::shouldGetTextFromNode(AccessibilityTextUnderElementMode mode) const
+bool AccessibilityRenderObject::shouldGetTextFromNode(TextUnderElementMode mode) const
 {
     if (!m_renderer)
         return true;
@@ -737,7 +737,7 @@ bool AccessibilityRenderObject::shouldGetTextFromNode(AccessibilityTextUnderElem
     // the child nodes to define positions. CSS tables and their anonymous descendants lack
     // children with nodes.
     if (m_renderer->isAnonymous() && m_renderer->isTablePart())
-        return mode.childrenInclusion == AccessibilityTextUnderElementMode::TextUnderElementModeIncludeAllChildren;
+        return mode.childrenInclusion == TextUnderElementMode::Children::IncludeAllChildren;
 
     // AccessibilityRenderObject::textUnderElement() calls rangeOfContents() to create the text
     // range. rangeOfContents() does not include CSS-generated content.