Enable accessible name of a control to include multiple <label> elements.

third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp

 /*
  * Copyright (C) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 32 matching lines @@
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLMeterElement.h"
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLSelectElement.h"
 #include "core/html/HTMLTableCaptionElement.h"
 #include "core/html/HTMLTableCellElement.h"
 #include "core/html/HTMLTableElement.h"
 #include "core/html/HTMLTableRowElement.h"
 #include "core/html/HTMLTableSectionElement.h"
 #include "core/html/HTMLTextAreaElement.h"
+#include "core/html/LabelsNodeList.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/html/shadow/MediaControlElements.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/LayoutObject.h"
 #include "core/svg/SVGElement.h"
 #include "modules/accessibility/AXObjectCacheImpl.h"
 #include "platform/UserGestureIndicator.h"
 #include "platform/text/PlatformLocale.h"
 #include "wtf/text/StringBuilder.h"
 
@@ skipping 573 matching lines @@
         return false;
 
     // An SVG root is focusable by default, but it's probably not interactive, so don't
     // include it. It can still be made accessible by giving it an ARIA role.
     if (roleValue() == SVGRootRole)
         return false;
 
     return true;
 }
 
-HTMLLabelElement* AXNodeObject::labelForElement(const Element* element) const
-{
-    if (!element->isHTMLElement() || !toHTMLElement(element)->isLabelable())
-        return 0;
-
-    const AtomicString& id = element->getIdAttribute();
-    if (!id.isEmpty()) {
-        if (HTMLLabelElement* labelFor = element->treeScope().labelElementForId(id))
-            return labelFor;
-    }
-
-    HTMLLabelElement* labelWrappedElement = Traversal<HTMLLabelElement>::firstAncestor(*element);
-    if (labelWrappedElement && labelWrappedElement->control() == toLabelableElement(element))
-        return labelWrappedElement;
-
-    return 0;
-}
-
 AXObject* AXNodeObject::menuButtonForMenu() const
 {
     Element* menuItem = menuItemElementForMenu();
 
     if (menuItem) {
         // ARIA just has generic menu items. AppKit needs to know if this is a top level items like MenuBarButton or MenuBarItem
         AXObject* menuItemAX = axObjectCache().getOrCreate(menuItem);
         if (menuItemAX && menuItemAX->isMenuButton())
             return menuItemAX;
     }
@@ skipping 933 matching lines @@
         if (nameSources) {
             foundTextAlternative = true;
             nameSources->last().text = textAlternative;
         } else {
             return textAlternative;
         }
     }
 
     nameFrom = AXNameFromUninitialized;
 
-    if (foundTextAlternative) {
+    if (nameSources && foundTextAlternative) {
         for (size_t i = 0; i < nameSources->size(); ++i) {
             if (!(*nameSources)[i].text.isNull() && !(*nameSources)[i].superseded) {
                 NameSource& nameSource = (*nameSources)[i];
                 nameFrom = nameSource.type;
                 if (!nameSource.relatedObjects.isEmpty())
                     *relatedObjects = nameSource.relatedObjects;
                 return nameSource.text;
             }
         }
     }
@@ skipping 73 matching lines @@
     // Step 2C from: http://www.w3.org/TR/accname-aam-1.1
     const AtomicString& ariaLabel = getAttribute(aria_labelAttr);
     if (!ariaLabel.isEmpty())
         return false;
 
     // Based on http://rawgit.com/w3c/aria/master/html-aam/html-aam.html#accessible-name-and-description-calculation
     // 5.1/5.5 Text inputs, Other labelable Elements
     HTMLElement* htmlElement = nullptr;
     if (getNode()->isHTMLElement())
         htmlElement = toHTMLElement(getNode());
-    if (htmlElement && htmlElement->isLabelable()) {
-        HTMLLabelElement* label = labelForElement(htmlElement);
-        if (label)
+    if (htmlElement && isLabelableElement(htmlElement)) {
+        if (toLabelableElement(htmlElement)->labels() && toLabelableElement(htmlElement)->labels()->length() > 0)
             return true;
     }
 
     return false;
 }
 
 LayoutRect AXNodeObject::elementRect() const
 {
     // First check if it has a custom rect, for example if this element is tied to a canvas path.
     if (!m_explicitElementRect.isEmpty())
@@ skipping 446 matching lines @@
 
     const HTMLInputElement* inputElement = nullptr;
     if (isHTMLInputElement(getNode()))
         inputElement = toHTMLInputElement(getNode());
 
     // 5.1/5.5 Text inputs, Other labelable Elements
     // If you change this logic, update AXNodeObject::nameFromLabelElement, too.
     HTMLElement* htmlElement = nullptr;
     if (getNode()->isHTMLElement())
         htmlElement = toHTMLElement(getNode());
+
     if (htmlElement && htmlElement->isLabelable()) {
-        // label
         nameFrom = AXNameFromRelatedElement;
         if (nameSources) {
             nameSources->append(NameSource(*foundTextAlternative));
             nameSources->last().type = nameFrom;
             nameSources->last().nativeSource = AXTextFromNativeHTMLLabel;
         }
-        HTMLLabelElement* label = labelForElement(htmlElement);
-        if (label) {
-            AXObject* labelAXObject = axObjectCache().getOrCreate(label);
-            // Avoid an infinite loop for label wrapped
-            if (labelAXObject && !visited.contains(labelAXObject)) {
-                textAlternative = recursiveTextAlternative(*labelAXObject, false, visited);
 
-                if (relatedObjects) {
-                    localRelatedObjects.append(new NameSourceRelatedObject(labelAXObject, textAlternative));
-                    *relatedObjects = localRelatedObjects;
-                    localRelatedObjects.clear();
-                }
+        LabelsNodeList* labels = toLabelableElement(htmlElement)->labels();
+        if (labels && labels->length() > 0) {
+            StringBuilder accumulatedText;
+            for (unsigned labelIndex = 0; labelIndex < labels->length(); ++labelIndex) {
+                Element* label = labels->item(labelIndex);
+                AXObject* labelAXObject = axObjectCache().getOrCreate(label);
+                // Avoid an infinite loop for label wrapped
+                if (labelAXObject && !visited.contains(labelAXObject)) {
+                    *foundTextAlternative = true;
+                    String result = recursiveTextAlternative(*labelAXObject, false, visited);
+                    if (!result.isEmpty()) {
+                        if (!accumulatedText.isEmpty())
+                            accumulatedText.append(" ");
+                        accumulatedText.append(result);
+                    }
 
-                if (nameSources) {
-                    NameSource& source = nameSources->last();
-                    source.relatedObjects = *relatedObjects;
-                    source.text = textAlternative;
-                    if (label->getAttribute(forAttr) == htmlElement->getIdAttribute())
-                        source.nativeSource = AXTextFromNativeHTMLLabelFor;
-                    else
-                        source.nativeSource = AXTextFromNativeHTMLLabelWrapped;
-                    *foundTextAlternative = true;
-                } else {
-                    return textAlternative;
+                    if (relatedObjects) {

[aboxhall, 2016/05/16 17:19:01]

Now that I've had a closer look, this is weird. Setting `*relatedObjects =
localRelatedObjects` should only happen once, not once per loop.

I'm wondering if we should split this out into a separate method, and combine it
somehow with the aria-labelledby logic, since it seems like they are closely
related. The main difference seems to be that this checks
`visited.contains(axObject)` here, whereas the aria-labelledby logic checks it
during the recursive step
(https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...).

[dmazzoni, 2016/06/01 19:53:23]

OK, ready for another look. I had this call AXObject::textFromElements
just like textFromAriaLabelledby does, so now they share most of the
same logic.

+                        localRelatedObjects.append(new NameSourceRelatedObject(labelAXObject, result));
+                        *relatedObjects = localRelatedObjects;
+                    }
+
+                    if (nameSources) {
+                        NameSource& source = nameSources->last();
+                        source.relatedObjects = *relatedObjects;
+                        source.text = textAlternative;
+                        if (label->getAttribute(forAttr) == htmlElement->getIdAttribute())
+                            source.nativeSource = AXTextFromNativeHTMLLabelFor;
+                        else
+                            source.nativeSource = AXTextFromNativeHTMLLabelWrapped;
+                    }
                 }
             }
+
+            if (relatedObjects)
+                localRelatedObjects.clear();
+
+            textAlternative = accumulatedText.toString();
+            if (!nameSources && *foundTextAlternative)
+                return textAlternative;
         }
     }
 
     // 5.2 input type="button", input type="submit" and input type="reset"
     if (inputElement && inputElement->isTextButton()) {
         // value attribue
         nameFrom = AXNameFromValue;
         if (nameSources) {
             nameSources->append(NameSource(*foundTextAlternative, valueAttr));
             nameSources->last().type = nameFrom;
@@ skipping 568 matching lines @@
     return placeholder;
 }
 
 DEFINE_TRACE(AXNodeObject)
 {
     visitor->trace(m_node);
     AXObject::trace(visitor);
 }
 
 } // namespace blink