Changeset 164107 in webkit

Timestamp:

Feb 14, 2014 9:52:41 AM (10 years ago)

Author:

Chris Fleizach

Message:

AX: WebKit needs heuristics to differentiate lists used for layout from semantic data lists, similar to the heuristics for layout tables versus data tables.
​https://bugs.webkit.org/show_bug.cgi?id=122320

Reviewed by Mario Sanchez Prada.

Source/WebCore:

Many authors use lists for layout, rather than presenting data. Exposing these kinds of lists to accessibility users
makes the web harder to process and listen, while degrading the importance of real lists.

This introduces heuristics to filter out layout lists with the following:

1. If it's a named list, like ol or aria=list, then it's a list. 1a. Unless the list has no children, then it's not a list.
2. If it displays visible list markers, it's a list.
3. If it does not display list markers and has only one child, it's not a list.
4. If it does not have any listitem children, it's not a list.
5. Otherwise it's a list (for now).

Test: accessibility/list-detection.html

• accessibility/AccessibilityList.cpp:

(WebCore::AccessibilityList::determineAccessibilityRole):
(WebCore::AccessibilityList::roleValue):

• accessibility/AccessibilityList.h:

LayoutTests:

• accessibility/aria-roles.html:
• accessibility/list-detection-expected.txt: Added.
• accessibility/list-detection.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/accessibility/aria-roles.html (modified) (1 diff)
• LayoutTests/accessibility/list-detection-expected.txt (added)
• LayoutTests/accessibility/list-detection.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/accessibility/AccessibilityList.cpp (modified) (2 diffs)
• Source/WebCore/accessibility/AccessibilityList.h (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2014-02-14  Chris Fleizach  <cfleizach@apple.com>
+
+        AX: WebKit needs heuristics to differentiate lists used for layout from semantic data lists, similar to the heuristics for layout tables versus data tables.
+        https://bugs.webkit.org/show_bug.cgi?id=122320
+
+        Reviewed by Mario Sanchez Prada.
+
+        * accessibility/aria-roles.html:
+        * accessibility/list-detection-expected.txt: Added.
+        * accessibility/list-detection.html: Added.
+
 2014-02-13  Brent Fulgham  <bfulgham@apple.com>
 

trunk/LayoutTests/accessibility/aria-roles.html

@@ -147 +147 @@
   <div class="newRole">
     <p>The following should be a list:</p>
-    <p><span tabindex="0" role="list" id="ariaList">X</span></p>
+    <p><span tabindex="0" role="list" id="ariaList"><span role="listitem">X</span></span></p>
     <p>Actual list:</p>
     <ul id="realList">

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2014-02-14  Chris Fleizach  <cfleizach@apple.com>
+
+        AX: WebKit needs heuristics to differentiate lists used for layout from semantic data lists, similar to the heuristics for layout tables versus data tables.
+        https://bugs.webkit.org/show_bug.cgi?id=122320
+
+        Reviewed by Mario Sanchez Prada.
+
+        Many authors use lists for layout, rather than presenting data. Exposing these kinds of lists to accessibility users
+        makes the web harder to process and listen, while degrading the importance of real lists.
+
+        This introduces heuristics to filter out layout lists with the following:
+           1. If it's a named list, like ol or aria=list, then it's a list.
+             1a. Unless the list has no children, then it's not a list.
+           2. If it displays visible list markers, it's a list.
+           3. If it does not display list markers and has only one child, it's not a list.
+           4. If it does not have any listitem children, it's not a list.
+           5. Otherwise it's a list (for now).
+
+        Test: accessibility/list-detection.html
+
+        * accessibility/AccessibilityList.cpp:
+        (WebCore::AccessibilityList::determineAccessibilityRole):
+        (WebCore::AccessibilityList::roleValue):
+        * accessibility/AccessibilityList.h:
+
 2014-02-14  Brendan Long  <b.long@cablelabs.com>
 

trunk/Source/WebCore/accessibility/AccessibilityList.cpp

@@ -32 +32 @@
 #include "AXObjectCache.h"
 #include "HTMLNames.h"
+#include "RenderListItem.h"
 #include "RenderObject.h"
+#include "RenderStyle.h"
 
 namespace WebCore {
@@ -92 +94 @@
     
     Node* node = m_renderer->node();
-    return node && node->hasTagName(dlTag);    
+    return node && node->hasTagName(dlTag);
 }
 
+AccessibilityRole AccessibilityList::determineAccessibilityRole()
+{
+    m_ariaRole = determineAriaRoleAttribute();
+    
+    // Directory is mapped to list for now, but does not adhere to the same heuristics.
+    if (ariaRoleAttribute() == DirectoryRole)
+        return ListRole;
+    
+    // Heuristic to determine if this list is being used for layout or for content.
+    //   1. If it's a named list, like ol or aria=list, then it's a list.
+    //      1a. Unless the list has no children, then it's not a list.
+    //   2. If it displays visible list markers, it's a list.
+    //   3. If it does not display list markers and has only one child, it's not a list.
+    //   4. If it does not have any listitem children, it's not a list.
+    //   5. Otherwise it's a list (for now).
+    
+    AccessibilityRole role = ListRole;
+    
+    // Temporarily set role so that we can query children (otherwise canHaveChildren returns false).
+    m_role = role;
+    
+    unsigned listItemCount = 0;
+    bool hasVisibleMarkers = false;
+
+    const auto& children = this->children();
+    // DescriptionLists are always semantically a description list, so do not apply heuristics.
+    if (isDescriptionList() && children.size())
+        return DescriptionListRole;
+
+    for (const auto& child : children) {
+        if (child->ariaRoleAttribute() == ListItemRole)
+            listItemCount++;
+        else if (child->roleValue() == ListItemRole) {
+            RenderObject* listItem = child->renderer();
+            if (listItem && listItem->isListItem()) {
+                if (listItem->style().listStyleType() != NoneListStyle || listItem->style().listStyleImage())
+                    hasVisibleMarkers = true;
+                listItemCount++;
+            }
+        }
+    }
+    
+    bool unorderedList = isUnorderedList();
+    // Non <ul> lists and ARIA lists only need to have one child.
+    // <ul> lists need to have 1 child, or visible markers.
+    if (!unorderedList || ariaRoleAttribute() != UnknownRole) {
+        if (!listItemCount)
+            role = GroupRole;
+    } else if (unorderedList && listItemCount <= 1 && !hasVisibleMarkers)
+        role = GroupRole;
+
+    return role;
+}
+    
 AccessibilityRole AccessibilityList::roleValue() const
 {
-    if (isDescriptionList())
-        return DescriptionListRole;
-    
-    return ListRole;
+    ASSERT(m_role != UnknownRole);
+    return m_role;
 }
     

trunk/Source/WebCore/accessibility/AccessibilityList.h

@@ -50 +50 @@
 private:
     virtual bool computeAccessibilityIsIgnored() const override;
+    virtual AccessibilityRole determineAccessibilityRole() override;
 };