[DevTools] Accessibility: Show siblings and children of selected node

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/accessibility/InspectorAccessibilityAgent.h"
 
 #include "core/HTMLNames.h"
 #include "core/dom/AXObjectCache.h"
 #include "core/dom/DOMNodeIds.h"
 #include "core/dom/Element.h"
@@ skipping 20 matching lines @@
 using protocol::Accessibility::AXRelatedNode;
 using protocol::Accessibility::AXRelationshipAttributes;
 using protocol::Accessibility::AXValue;
 using protocol::Accessibility::AXWidgetAttributes;
 using protocol::Accessibility::AXWidgetStates;
 
 using namespace HTMLNames;
 
 namespace {
 
+static const double kIDForInspectedNodeWithNoAXNode = 0;
+
 void fillLiveRegionProperties(AXObject& axObject,
                               protocol::Array<AXProperty>& properties) {
   if (!axObject.liveRegionRoot())
     return;
 
   properties.addItem(
       createProperty(AXLiveRegionAttributesEnum::Live,
                      createValue(axObject.containerLiveRegionStatus(),
                                  AXValueTypeEnum::Token)));
   properties.addItem(
@@ skipping 315 matching lines @@
   std::unique_ptr<AXValue> roleNameValue;
   if (!roleName.isNull()) {
     roleNameValue = createValue(roleName, AXValueTypeEnum::Role);
   } else {
     roleNameValue = createValue(AXObject::internalRoleName(role),
                                 AXValueTypeEnum::InternalRole);
   }
   return roleNameValue;
 }
 
+bool isAncestorOf(AXObject* possibleAncestor, AXObject* descendant) {
+  if (!possibleAncestor || !descendant)
+    return false;
+
+  AXObject* ancestor = descendant;
+  while (ancestor) {
+    if (ancestor == possibleAncestor)
+      return true;
+    ancestor = ancestor->parentObject();
+  }
+  return false;
+}
+
 }  // namespace
 
 InspectorAccessibilityAgent::InspectorAccessibilityAgent(
     Page* page,
     InspectorDOMAgent* domAgent)
     : m_page(page), m_domAgent(domAgent) {}
 
-void InspectorAccessibilityAgent::getAXNodeChain(
+void InspectorAccessibilityAgent::getPartialAXTree(
     ErrorString* errorString,
     int domNodeId,
-    bool fetchAncestors,
-    std::unique_ptr<protocol::Array<protocol::Accessibility::AXNode>>* nodes) {
+    std::unique_ptr<protocol::Array<AXNode>>* nodes) {
   if (!m_domAgent->enabled()) {
     *errorString = "DOM agent must be enabled";
     return;
   }
   Node* domNode = m_domAgent->assertNode(errorString, domNodeId);
   if (!domNode)
     return;
 
   Document& document = domNode->document();
   document.updateStyleAndLayoutIgnorePendingStylesheets();
   DocumentLifecycle::DisallowTransitionScope disallowTransition(
       document.lifecycle());
   LocalFrame* localFrame = document.frame();
   if (!localFrame) {
     *errorString = "Frame is detached.";
     return;
   }
   std::unique_ptr<ScopedAXObjectCache> scopedCache =
       ScopedAXObjectCache::create(document);
   AXObjectCacheImpl* cache = toAXObjectCacheImpl(scopedCache->get());
 
   AXObject* inspectedAXObject = cache->getOrCreate(domNode);
   *nodes = protocol::Array<protocol::Accessibility::AXNode>::create();
   if (!inspectedAXObject || inspectedAXObject->accessibilityIsIgnored()) {
-    (*nodes)->addItem(buildObjectForIgnoredNode(domNode, inspectedAXObject));
+    (*nodes)->addItem(
+        buildObjectForIgnoredNode(domNode, inspectedAXObject, *nodes, *cache));
   } else {
-    (*nodes)->addItem(buildProtocolAXObject(*inspectedAXObject));
+    (*nodes)->addItem(buildProtocolAXObject(*inspectedAXObject,
+                                            inspectedAXObject, *nodes, *cache));
   }
 
-  if (fetchAncestors && inspectedAXObject) {
-    AXObject* parent = inspectedAXObject->parentObjectUnignored();
-    while (parent) {
-      (*nodes)->addItem(buildProtocolAXObject(*parent));
-      parent = parent->parentObjectUnignored();
-    }
+  if (!inspectedAXObject)
+    return;
+
+  AXObject* parent = inspectedAXObject->parentObjectUnignored();
+  if (!parent)
+    return;
+
+  addAncestors(*parent, inspectedAXObject, *nodes, *cache);
+}
+
+void InspectorAccessibilityAgent::addAncestors(
+    AXObject& firstAncestor,
+    AXObject* inspectedAXObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  AXObject* ancestor = &firstAncestor;
+  while (ancestor) {
+    nodes->addItem(
+        buildProtocolAXObject(*ancestor, inspectedAXObject, nodes, cache));
+    ancestor = ancestor->parentObjectUnignored();
   }
 }
 
 std::unique_ptr<AXNode> InspectorAccessibilityAgent::buildObjectForIgnoredNode(
     Node* domNode,
-    AXObject* axObject) const {
+    AXObject* axObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
   AXObject::IgnoredReasons ignoredReasons;
 
-  AXID axID = 0;
+  AXID axID = kIDForInspectedNodeWithNoAXNode;
   if (axObject)
     axID = axObject->axObjectID();
   std::unique_ptr<AXNode> ignoredNodeObject =
       AXNode::create().setNodeId(String::number(axID)).setIgnored(true).build();
   if (axObject) {
     axObject->computeAccessibilityIsIgnored(&ignoredReasons);
-    axID = axObject->axObjectID();
-    AccessibilityRole role = axObject->roleValue();
+    AccessibilityRole role = AccessibilityRole::IgnoredRole;
     ignoredNodeObject->setRole(createRoleNameValue(role));
+
+    populateRelatives(*axObject, axObject, *(ignoredNodeObject.get()), nodes,
+                      cache);
   } else if (domNode && !domNode->layoutObject()) {
+    populateDOMNodeRelatives(*domNode, *(ignoredNodeObject.get()), nodes,
+                             cache);
     ignoredReasons.append(IgnoredReason(AXNotRendered));
   }
 
+  if (domNode)
+    ignoredNodeObject->setDomNodeId(DOMNodeIds::idForNode(domNode));
+
   std::unique_ptr<protocol::Array<AXProperty>> ignoredReasonProperties =
       protocol::Array<AXProperty>::create();
   for (size_t i = 0; i < ignoredReasons.size(); i++)
     ignoredReasonProperties->addItem(createProperty(ignoredReasons[i]));
   ignoredNodeObject->setIgnoredReasons(std::move(ignoredReasonProperties));
 
   return ignoredNodeObject;
 }
 
+void InspectorAccessibilityAgent::populateDOMNodeRelatives(
+    Node& inspectedDOMNode,
+    AXNode& nodeObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  // Walk up parents until an AXObject can be found.
+  Node* parentNode = FlatTreeTraversal::parent(inspectedDOMNode);
+  AXObject* parentAXObject = cache.getOrCreate(parentNode);
+  while (!parentAXObject) {
+    parentNode = FlatTreeTraversal::parent(inspectedDOMNode);
+    parentAXObject = cache.getOrCreate(parentNode);
+  };
+  if (parentAXObject) {
+    if (parentAXObject->accessibilityIsIgnored())
+      parentAXObject = parentAXObject->parentObjectUnignored();
+    // Populate parent, ancestors and siblings.
+    nodeObject.setParentId(String::number(parentAXObject->axObjectID()));
+    std::unique_ptr<AXNode> parentNodeObject =
+        buildProtocolAXObject(*parentAXObject, nullptr, nodes, cache);
+    std::unique_ptr<protocol::Array<AXNodeId>> siblingIds =
+        protocol::Array<AXNodeId>::create();
+    findDOMNodeChildren(siblingIds, *parentNode, inspectedDOMNode, nodes,
+                        cache);
+    parentNodeObject->setChildIds(std::move(siblingIds));
+    nodes->addItem(std::move(parentNodeObject));
+
+    AXObject* grandparentAXObject = parentAXObject->parentObjectUnignored();
+    if (grandparentAXObject)
+      addAncestors(*grandparentAXObject, nullptr, nodes, cache);
+  }
+
+  // Then populate children.
+  std::unique_ptr<protocol::Array<AXNodeId>> childIds =
+      protocol::Array<AXNodeId>::create();
+  findDOMNodeChildren(childIds, inspectedDOMNode, inspectedDOMNode, nodes,
+                      cache);
+}
+
+void InspectorAccessibilityAgent::findDOMNodeChildren(
+    std::unique_ptr<protocol::Array<AXNodeId>>& childIds,
+    Node& parentNode,
+    Node& inspectedDOMNode,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  NodeList* childNodes = parentNode.childNodes();
+  for (size_t i = 0; i < childNodes->length(); ++i) {
+    Node* childNode = childNodes->item(i);
+    if (childNode == &inspectedDOMNode) {
+      childIds->addItem(String::number(kIDForInspectedNodeWithNoAXNode));
+      continue;
+    }
+    AXObject* childAXObject = cache.getOrCreate(childNode);
+    if (childAXObject && !childAXObject->accessibilityIsIgnored()) {
+      addChild(childIds, *childAXObject, nullptr, nodes, cache);
+      continue;
+    }
+
+    if (!childAXObject ||
+        childNode->isShadowIncludingInclusiveAncestorOf(&inspectedDOMNode)) {
+      // If the inspected node may be a descendant of this node, keep walking
+      // recursively until we find its actual siblings.
+      findDOMNodeChildren(childIds, *childNode, inspectedDOMNode, nodes, cache);
+      continue;
+    }
+
+    // Otherwise, just add the un-ignored children.
+    const AXObject::AXObjectVector& indirectChildren =
+        childAXObject->children();
+    for (unsigned i = 0; i < indirectChildren.size(); ++i)
+      addChild(childIds, *(indirectChildren[i]), nullptr, nodes, cache);
+  }
+}
+
 std::unique_ptr<AXNode> InspectorAccessibilityAgent::buildProtocolAXObject(
-    AXObject& axObject) const {
+    AXObject& axObject,
+    AXObject* inspectedAXObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
   AccessibilityRole role = axObject.roleValue();
   std::unique_ptr<AXNode> nodeObject =
       AXNode::create()
           .setNodeId(String::number(axObject.axObjectID()))
           .setIgnored(false)
           .build();
   nodeObject->setRole(createRoleNameValue(role));
 
   std::unique_ptr<protocol::Array<AXProperty>> properties =
       protocol::Array<AXProperty>::create();
@@ skipping 23 matching lines @@
         }
       }
       name->setSources(std::move(nameSourceProperties));
     }
     nodeObject->setProperties(std::move(properties));
     nodeObject->setName(std::move(name));
   } else {
     nodeObject->setProperties(std::move(properties));
   }
 
-  fillCoreProperties(axObject, *(nodeObject.get()));
+  fillCoreProperties(axObject, inspectedAXObject, *(nodeObject.get()), nodes,
+                     cache);
   return nodeObject;
 }
 
-void InspectorAccessibilityAgent::fillCoreProperties(AXObject& axObject,
-                                                     AXNode& nodeObject) const {
+void InspectorAccessibilityAgent::fillCoreProperties(
+    AXObject& axObject,
+    AXObject* inspectedAXObject,
+    AXNode& nodeObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
   AXNameFrom nameFrom;
   AXObject::AXObjectVector nameObjects;
   axObject.name(nameFrom, &nameObjects);
 
   AXDescriptionFrom descriptionFrom;
   AXObject::AXObjectVector descriptionObjects;
   String description =
       axObject.description(nameFrom, descriptionFrom, &descriptionObjects);
   if (!description.isEmpty()) {
     nodeObject.setDescription(
         createValue(description, AXValueTypeEnum::ComputedString));
   }
   // Value.
   if (axObject.supportsRangeValue()) {
     nodeObject.setValue(createValue(axObject.valueForRange()));
   } else {
     String stringValue = axObject.stringValue();
     if (!stringValue.isEmpty())
       nodeObject.setValue(createValue(stringValue));
   }
+
+  populateRelatives(axObject, inspectedAXObject, nodeObject, nodes, cache);
+
+  Node* node = axObject.getNode();
+  if (node)
+    nodeObject.setDomNodeId(DOMNodeIds::idForNode(node));
+}
+
+void InspectorAccessibilityAgent::populateRelatives(
+    AXObject& axObject,
+    AXObject* inspectedAXObject,
+    AXNode& nodeObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  AXObject* parentObject = axObject.parentObject();
+  if (parentObject && parentObject != inspectedAXObject) {
+    // Use unignored parent unless parent is inspected ignored object.
+    parentObject = axObject.parentObjectUnignored();
+  }
+  if (parentObject)
+    nodeObject.setParentId(String::number(parentObject->axObjectID()));
+
+  std::unique_ptr<protocol::Array<AXNodeId>> childIds =
+      protocol::Array<AXNodeId>::create();
+  if (!inspectedAXObject) {
+    // If there is no AXObject for the inspected node, the caller will populate
+    // its relatives.
+    return;
+  }
+
+  if (&axObject == inspectedAXObject->parentObjectUnignored() &&
+      inspectedAXObject->accessibilityIsIgnored()) {
+    // This is the parent of an ignored object, so search for its siblings.
+    addSiblingsOfIgnored(childIds, axObject, inspectedAXObject, nodes, cache);
+  } else {
+    addChildren(axObject, *inspectedAXObject, childIds, nodes, cache);
+  }
+  nodeObject.setChildIds(std::move(childIds));
+}
+
+void InspectorAccessibilityAgent::addSiblingsOfIgnored(
+    std::unique_ptr<protocol::Array<AXNodeId>>& childIds,
+    AXObject& parentAXObject,
+    AXObject* inspectedAXObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  for (AXObject* childAXObject = parentAXObject.rawFirstChild(); childAXObject;

[dmazzoni, 2016/10/21 20:09:42]

rawFirstChild skips over some important corner cases like
children of a <canvas> element or children with aria-hidden=false.

[aboxhall, 2016/10/31 19:33:25]

I added a test for <canvas> fallback content.
I'm not sure about aria-hidden=false. I can't see any evidence in tests or code
for it working today for this case:
<div style="display: none">
  <span aria-hidden="false">
    The span is ignored but this text shouldn't be
  </span>
</span>

I added a test for the more straightforward case:
<div style="display: none">
  <button aria-hidden="false">Not hidden button</button>
</div>

Although I note that in the content tests, aria-hidden=false doesn't seem to
have any actual effect anyway - it doesn't seem to be exposed on any platform as
far as I can tell.

+       childAXObject = childAXObject->rawNextSibling()) {
+    if (childAXObject != inspectedAXObject &&
+        childAXObject->accessibilityIsIgnored()) {
+      if (isAncestorOf(childAXObject, inspectedAXObject)) {
+        addSiblingsOfIgnored(childIds, *childAXObject, inspectedAXObject, nodes,
+                             cache);
+        continue;
+      }
+      const AXObject::AXObjectVector& indirectChildren =
+          childAXObject->children();
+      for (unsigned i = 0; i < indirectChildren.size(); ++i) {
+        addChild(childIds, *(indirectChildren[i]), inspectedAXObject, nodes,
+                 cache);
+      }
+      continue;
+    }
+    addChild(childIds, *childAXObject, inspectedAXObject, nodes, cache);
+  }
+}
+
+void InspectorAccessibilityAgent::addChild(
+    std::unique_ptr<protocol::Array<AXNodeId>>& childIds,
+    AXObject& childAXObject,
+    AXObject* inspectedAXObject,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  childIds->addItem(String::number(childAXObject.axObjectID()));
+  if (&childAXObject == inspectedAXObject)
+    return;
+  nodes->addItem(
+      buildProtocolAXObject(childAXObject, inspectedAXObject, nodes, cache));
+}
+
+void InspectorAccessibilityAgent::addChildren(
+    AXObject& axObject,
+    AXObject& inspectedAXObject,
+    std::unique_ptr<protocol::Array<AXNodeId>>& childIds,
+    std::unique_ptr<protocol::Array<AXNode>>& nodes,
+    AXObjectCacheImpl& cache) const {
+  const AXObject::AXObjectVector& children = axObject.children();
+  for (unsigned i = 0; i < children.size(); i++) {
+    AXObject& childAXObject = *children[i].get();
+    childIds->addItem(String::number(childAXObject.axObjectID()));
+    if (&axObject == &inspectedAXObject ||
+        &axObject == inspectedAXObject.parentObjectUnignored()) {
+      // Only add children/siblings of inspected node to returned nodes.
+      nodes->addItem(buildProtocolAXObject(childAXObject, &inspectedAXObject,
+                                           nodes, cache));
+    }
+  }
 }
 
 DEFINE_TRACE(InspectorAccessibilityAgent) {
   visitor->trace(m_page);
   visitor->trace(m_domAgent);
   InspectorBaseAgent::trace(visitor);
 }
 
 }  // namespace blink