AX presentation role should be inherited to its required owned elements.

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 24 matching lines @@
 #include "core/html/HTMLDListElement.h"
 #include "core/html/HTMLFieldSetElement.h"
 #include "core/html/HTMLFrameElementBase.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLLabelElement.h"
 #include "core/html/HTMLLegendElement.h"
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLMeterElement.h"
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLSelectElement.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/parser/HTMLParserIdioms.h"
 #include "core/html/shadow/MediaControlElements.h"
 #include "core/layout/LayoutObject.h"
 #include "modules/accessibility/AXObjectCacheImpl.h"
 #include "platform/UserGestureIndicator.h"
 #include "wtf/text/StringBuilder.h"
 
 
 namespace blink {
@@ skipping 121 matching lines @@
         return true;
 
     // Ignore labels that are already referenced by a control's title UI element.
     AXObject* controlObject = correspondingControlForLabelElement();
     if (controlObject && !controlObject->exposesTitleUIElement() && controlObject->isCheckboxOrRadio())
         return true;
 
     return m_role == UnknownRole;
 }
 
+static bool isListElement(Node* node)
+{
+    return isHTMLUListElement(*node) || isHTMLOListElement(*node) || isHTMLDListElement(*node);
+}
+
+static bool isPresentationRoleInTable(AXObject* parent, Node* child)
+{
+    Node* parentNode = parent->node();
+    if (!parentNode || !parentNode->isElementNode())
+        return false;
+
+    // AXTable determines the role as checking isTableXXX.
+    // If Table has explicit role including presentation, AXTable doesn't assign implicit Role
+    // to a whole Table. That's why we should check it based on node.
+    // Normal Table Tree is that
+    // cell(its role)-> tr(tr role)-> tfoot, tbody, thead(ignored role) -> table(table role).
+    // If table has presentation role, it will be like
+    // cell(group)-> tr(unknown) -> tfoot, tbody, thead(ignored) -> table(presentation).
+    if (isHTMLTableCellElement(child) && isHTMLTableRowElement(*parentNode))
+        return parent->hasInheritedPresentationRole();
+
+    if (isHTMLTableRowElement(child) && isHTMLTableSectionElement(*parentNode)) {
+        // Because TableSections have ignored role, presentation should be checked with its parent node
+        AXObject* tableObject = parent->parentObject();
+        Node* tableNode = tableObject->node();
+        return isHTMLTableElement(tableNode) && tableObject->hasInheritedPresentationRole();
+    }
+    return false;
+}
+
+static bool isRequiredOwnedElement(AXObject* parent, AccessibilityRole childRole, Node* childNode)
+{
+    Node* parentNode = parent->node();
+    if (!parentNode || !parentNode->isElementNode())
+        return false;
+
+    if (childRole == ListItemRole)
+        return isListElement(parentNode);
+    if (childRole == ListMarkerRole)
+        return isHTMLLIElement(*parentNode);
+    if (childRole == MenuItemCheckBoxRole || childRole ==  MenuItemRole || childRole ==  MenuItemRadioRole)
+        return isHTMLMenuElement(*parentNode);
+
+    if (isHTMLTableCellElement(childNode))
+        return isHTMLTableRowElement(*parentNode);
+    if (isHTMLTableRowElement(childNode))
+        return isHTMLTableSectionElement(*parentNode);

[dmazzoni, 2015/04/01 15:27:55]

Aren't the table section elements optional in html? I usually write:

  <table>
    <tr>
      <td>Cell</td>
    </tr>
  </table>

Does this work correctly or do we also need to check if the parent of a table
row is a table element?

[je_julie(Not used), 2015/04/02 05:51:28]

AFIK, table section is automatically generated from
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit....

So, if we capture render tree with the example above, we can see the result
below.

#READY
Content-Type: text/plain
layer at (0,0) size 800x600
  LayoutView at (0,0) size 800x600
layer at (0,0) size 800x600
  LayoutBlockFlow {HTML} at (0,0) size 800x600
    LayoutBlockFlow {BODY} at (8,8) size 784x584
      LayoutTable {TABLE} at (0,0) size 30x26
        LayoutTableSection {TBODY} at (0,0) size 30x26
          LayoutTableRow {TR} at (0,2) size 30x22
            LayoutTableCell {TD} at (2,2) size 26x22 [r=0 c=0 rs=1 cs=1]
              LayoutText {#text} at (1,1) size 24x19
                text run at (1,1) width 24: "Cell"
#EOF

If I'm wrong, please correct me.
Thanks,

[dmazzoni, 2015/04/02 06:22:18]

You're right that the layout tree for a table is automatically generated and
it's normalized like that no matter what the HTML input.

However, your code isn't walking the layout tree, it's walking the DOM tree.
Usually, the DOM tree is basically whatever was parsed directly from the HTML. I
don't think it adds any other elements.

So, I think the parent of a <tr> might be several possible elements.

Probably the best thing to do would be to add some separate tests for these
specific cases, test;

<table role="presentation"><tr>
<table role="presentation"><tbody><tr>

...and see what the parent of the <tr> element is in each case, and what should
happen.

Some tips for debugging: to print out a node, use:
fprintf(stderr, "node name is: %s", node->nodeName().utf8().data());

To print a layoutObject:
fprintf(stderr, "layoutObject is: %s", layoutObject->debugName().utf8().data());

+
+    // In case of ListboxRole and it's child, ListBoxOptionRole,
+    // Inheritance of presentation role is handled in AXListBoxOption
+    // Because ListBoxOption Role doesn't have any child.
+    // If it's just ignored because of presentation, we can't see any AX tree related to ListBoxOption.
+    return false;
+}
+
+bool AXNodeObject::computeHasInheritedPresentationRole() const
+{
+    // ARIA states if an item can get focus, it should not be presentational.
+    if (canSetFocusAttribute())
+        return false;
+
+    if (roleValue() == NoneRole || roleValue() == PresentationalRole)

[dmazzoni, 2015/04/01 15:27:55]

This can be isPresentation()

[je_julie(Not used), 2015/04/02 05:51:28]

Done.

+        return true;
+
+    // http://www.w3.org/TR/wai-aria/complete#presentation
+    // ARIA spec says that the user agent MUST apply an inherited role of presentation
+    // to any owned elements that do not have an explicit role defined.
+    if (ariaRoleAttribute() != UnknownRole)
+        return false;
+
+    AXObject* parent = parentObject();
+    if (!parent)
+        return false;
+
+    Node* curNode = node();
+    if (!parent->isPresentation() && !parent->hasInheritedPresentationRole()
+        && !isPresentationRoleInTable(parent, curNode))
+        return false;
+
+    // ARIA spec says that when a parent object is presentational and this object
+    // is a required owned element of that parent, then this object is also presentational.
+    return isRequiredOwnedElement(parent, roleValue(), curNode);
+}
+
 AccessibilityRole AXNodeObject::determineAccessibilityRoleUtil()
 {
     if (!node())
         return UnknownRole;
     if (node()->isLink())
         return LinkRole;
     if (isHTMLButtonElement(*node()))
         return buttonRoleType();
     if (isHTMLDetailsElement(*node()))
         return DetailsRole;
@@ skipping 1801 matching lines @@
     float range = maxValueForRange() - minValueForRange();
     float value = valueForRange();
 
     value += range * (percentChange / 100);
     setValue(String::number(value));
 
     axObjectCache()->postNotification(node(), AXObjectCacheImpl::AXValueChanged);
 }
 
 } // namespace blink