Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 3ebfc2b3a2576dff38122413858c423034309fbb
https://github.com/WebKit/WebKit/commit/3ebfc2b3a2576dff38122413858c423034309fbb
Author: Tyler Wilcock <tyle...@apple.com>
Date: 2025-04-21 (Mon, 21 Apr 2025)
Changed paths:
A LayoutTests/accessibility/mac/orphaned-text-in-button-expected.txt
A LayoutTests/accessibility/mac/orphaned-text-in-button.html
M Source/WebCore/accessibility/AccessibilityListBoxOption.h
M Source/WebCore/accessibility/AccessibilityNodeObject.cpp
M Source/WebCore/accessibility/AccessibilityRenderObject.cpp
Log Message:
-----------
AX: After ENABLE(INCLUDE_IGNORED_IN_CORE_AX_TREE), descendants of
!canHaveChildren() objects can become orphaned, causing various incorrect AT
behaviors
https://bugs.webkit.org/show_bug.cgi?id=291762
rdar://149563180
Reviewed by Joshua Hoffman.
After ENABLE(INCLUDE_IGNORED_IN_CORE_AX_TREE), each object in the isolated tree
should have the same parentObject() as
its main-thread equivalent. We did do this correctly, at least as far as
storing the right AXIsolatedObject::m_parentID.
However, the isolated tree is a copy of the main-thread tree, and
Accessibility{Node,Render}Object::addChildren() exited
early for any object that !canHaveChildren(). This meant that when we created
the isolated tree, we never create isolated
objects for these descendants, and thus when we go to look up the object stored
in a descendants m_parentID, we fail
to get anything.
Orphaned objects (those who return nil for NSAccessibilityParentAttribute)
cause VoiceOver to fail to create its own
internal element for that object, in turn causing lots of wrong behaviors. The
issue that motivated this was navigating
by character inside a button's text, and no bounding box was being drawn.
Fix this by allowing !canHaveChildren() objects to insert children. We already
consider descendants of !canHaveChildren
objects to be ignored, so inserting children for !canHaveChildren objects
allows us to have a full and complete accessibility
tree while maintaining the correct AT-facing behavior (because we ignore these
descendants).
This change exposed one existing bug that caused this:
ASSERT(isTableComponent(child) || isTableComponent(*this) ||
child.parentObject() == this);
to fire in AccessibilityObject::insertChild. This was caught by
imported/w3c/web-platform-tests/accname/name/comp_name_from_content.html
only because this test happened to use ::before on a button element, which now
adds children. But this issue has been
around ever since
https://github.com/WebKit/WebKit/commit/6a44b38c10d068df677abf94c3f1d96e75fefb7a
landed, as that changed
AccessibilityRenderObject::addChildren to add ::before and ::after as children
without making the analagous change to
AccessibilityRenderObject::parentObject to force ::before and ::after to
consider their generating element to be their parent.
This same ASSERT was hit for AccessibilityListBoxOption, which have an unusal
DOM structure. Fix this by overriding
addChildren for this subclass to do nothing, matching the behavior before this
commit and preventing the ASSERT.
* LayoutTests/accessibility/mac/orphaned-text-in-button-expected.txt: Added.
* LayoutTests/accessibility/mac/orphaned-text-in-button.html: Added.
* Source/WebCore/accessibility/AccessibilityListBoxOption.h:
* Source/WebCore/accessibility/AccessibilityNodeObject.cpp:
(WebCore::AccessibilityNodeObject::addChildren):
* Source/WebCore/accessibility/AccessibilityRenderObject.cpp:
(WebCore::AccessibilityRenderObject::parentObject const):
(WebCore::AccessibilityRenderObject::addChildren):
Canonical link: https://commits.webkit.org/293929@main
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