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);
+        LabelsNodeList* labels = toLabelableElement(htmlElement)->labels();
+        if (labels && labels->length() > 0) {
+            nameFrom = AXNameFromRelatedElement;

[aboxhall, 2016/05/13 20:19:16]

This needs to be set outside this if block, as before. Perhaps it'd be less
confusing if we renamed this variable "potentialNameFrom"?

Also, need to create and append the NameSource here regardless of whether a
label is found, for the same reason. Have a look at how it's done for
aria-labelledby for how to handle multiple relatedObjects.

[dmazzoni, 2016/05/13 22:22:42]

OK, done. I was thinking it was okay to skip it if there weren't any label
elements, but we want to show the full possible name calculation either way.

I also moved *foundTextAlternative = true up so that it only sets it to true if
at least one label is actually found, just to be safe.

+            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)) {
+                    String result = recursiveTextAlternative(*labelAXObject, false, visited);
+                    if (!result.isEmpty()) {
+                        if (!accumulatedText.isEmpty())
+                            accumulatedText.append(" ");
+                        accumulatedText.append(result);
+                    }
 
-                if (relatedObjects) {
-                    localRelatedObjects.append(new NameSourceRelatedObject(labelAXObject, textAlternative));
-                    *relatedObjects = localRelatedObjects;
-                    localRelatedObjects.clear();
-                }
+                    if (relatedObjects) {
+                        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;
-                    *foundTextAlternative = true;
-                } else {
-                    return textAlternative;
+                    if (nameSources) {
+                        nameSources->append(NameSource(*foundTextAlternative));
+                        NameSource& source = nameSources->last();
+                        source.type = nameFrom;
+                        source.nativeSource = AXTextFromNativeHTMLLabel;
+                        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();
+            *foundTextAlternative = true;
+
+            if (!nameSources)
+                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