Include relationship ARIA objects in serialized accessibility tree

content/browser/accessibility/browser_accessibility_cocoa.mm

 // Copyright (c) 2012 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 <execinfo.h>
 
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 
 #include <map>
 
@@ skipping 269 matching lines @@
     { NSAccessibilityVisibleCellsAttribute, @"visibleCells" },
     { NSAccessibilityVisibleColumnsAttribute, @"visibleColumns" },
     { NSAccessibilityVisibleRowsAttribute, @"visibleRows" },
     { NSAccessibilityWindowAttribute, @"window" },
     { @"AXAccessKey", @"accessKey" },
     { @"AXARIAAtomic", @"ariaAtomic" },
     { @"AXARIABusy", @"ariaBusy" },
     { @"AXARIALive", @"ariaLive" },
     { @"AXARIARelevant", @"ariaRelevant" },
     { @"AXInvalid", @"invalid" },
+    { @"AXLinkedUIElements", @"linkedUIElements" },

[David Tseng, 2014/03/12 00:30:56]

This is a native OS X attribute,s o let's use
NSAccessibilityLinkedUIElementsAttribute

[aboxhall, 2014/03/12 17:50:47]

Done.

     { @"AXLoaded", @"loaded" },
     { @"AXLoadingProgress", @"loadingProgress" },
     { @"AXRequired", @"required" },
     { @"AXVisited", @"visited" },
   };
 
   NSMutableDictionary* dict = [[NSMutableDictionary alloc] init];
   const size_t numAttributes = sizeof(attributeToMethodNameContainer) /
                                sizeof(attributeToMethodNameContainer[0]);
   for (size_t i = 0; i < numAttributes; ++i) {
@@ skipping 544 matching lines @@
 
 - (id)titleUIElement {
   int titleElementId;
   if (browserAccessibility_->GetIntAttribute(
           ui::AX_ATTR_TITLE_UI_ELEMENT, &titleElementId)) {
     BrowserAccessibility* titleElement =
         browserAccessibility_->manager()->GetFromRendererID(titleElementId);
     if (titleElement)
       return titleElement->ToBrowserAccessibilityCocoa();
   }
+  std::vector<int32> labelledby_ids =
+      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LABELLEDBY_IDS);
+  if (labelledby_ids.size() == 1) {

[David Tseng, 2014/03/12 00:30:56]

This is an interesting case.

Mac, unfortunately, doesn't have a good match for labelled by. The closest is
ServesAsTitleForUIElements
which maps from the label to an array of ui elements it labels. Perhaps we could
fill in that relationship using labelled by when a BAC/BAMac gets initialized.
(i.e. get the object pointed to by labelled by and fill in the elements it
labels as the originating object). The only disadvantage besides having to keep
more state around is that this won't work if the labelled by object hasn't
itself been initialized.

[aboxhall, 2014/03/12 17:50:47]

I don't completely follow, sorry. The spec says:
If aria-labelledby references a single element, expose the labeling relationship
as element AXTitleUIElement.

If aria-labelledby references multiple elements, or if the labeling element is
invisible or otherwise not exposed in the accessibility tree, use in calculating
the accessible name as described in Name Computation and expose value as string
AXDescription.

I believe we're already doing the latter in Blink?

[David Tseng, 2014/03/12 18:30:17]

No; this is Mac specific:
NSString *const NSAccessibilityServesAsTitleForUIElementsAttribute;

https://developer.apple.com/library/mac/documentation/cocoa/reference/applica...

[aboxhall, 2014/03/12 20:51:47]

Added TODO as discussed.

+    BrowserAccessibility* titleElement =
+        browserAccessibility_->manager()->GetFromRendererID(labelledby_ids[0]);
+    if (titleElement)
+      return titleElement->ToBrowserAccessibilityCocoa();
+  }
+
   return nil;
 }
 
+- (NSArray*)linkedUIElements {

[David Tseng, 2014/03/12 00:30:56]

Keep these methods sorted.

[aboxhall, 2014/03/12 17:50:47]

Done.

+  NSMutableArray* ret = [[[NSMutableArray alloc] init] autorelease];
+  const std::vector<int32>& ownsIds =
+      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_OWNS_IDS);

[dmazzoni, 2014/03/11 23:37:52]

These are all analogous, maybe a helper function to call three times with
AX_ATTR_OWNS_IDS, ten AX_ATTR_CONTROLS_IDS, and so on?

You could call the same from titleUIElement, too - and then only return the
first one.

[aboxhall, 2014/03/12 17:50:47]

Done.
I don't think that's accurate, since the spec says it should only be exposed as
TitleUIElement if there is exactly one.

+  for (size_t i = 0; i < ownsIds.size(); ++i) {
+    BrowserAccessibility* ownsElement =
+        browserAccessibility_->manager()->GetFromRendererID(ownsIds[i]);
+    if (ownsElement)
+      [ret addObject:ownsElement->ToBrowserAccessibilityCocoa()];
+  }
+  const std::vector<int32>& controlsIds =
+      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_CONTROLS_IDS);
+  for (size_t i = 0; i < controlsIds.size(); ++i) {
+    BrowserAccessibility* controlsElement =
+        browserAccessibility_->manager()->GetFromRendererID(controlsIds[i]);
+    if (controlsElement)
+      [ret addObject:controlsElement->ToBrowserAccessibilityCocoa()];
+  }
+  const std::vector<int32>& flowtoIds =
+      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_FLOWTO_IDS);
+  for (size_t i = 0; i < flowtoIds.size(); ++i) {
+    BrowserAccessibility* flowtoElement =
+        browserAccessibility_->manager()->GetFromRendererID(flowtoIds[i]);
+    if (flowtoElement)
+      [ret addObject:flowtoElement->ToBrowserAccessibilityCocoa()];
+  }
+  if ([ret count] == 0)
+    return nil;
+  return ret;
+}
+
 - (NSString*)url {
   StringAttribute urlAttribute =
       [[self role] isEqualToString:@"AXWebArea"] ?
           ui::AX_ATTR_DOC_URL :
           ui::AX_ATTR_URL;
   return NSStringForStringAttribute(browserAccessibility_, urlAttribute);
 }
 
 - (id)value {
   // WebCore uses an attachmentView to get the below behavior.
@@ skipping 383 matching lines @@
       NSAccessibilitySubroleAttribute,
       NSAccessibilityTitleAttribute,
       NSAccessibilityTopLevelUIElementAttribute,
       NSAccessibilityValueAttribute,
       NSAccessibilityWindowAttribute,
       NSAccessibilityURLAttribute,
       @"AXAccessKey",
       @"AXInvalid",
       @"AXRequired",
       @"AXVisited",
+      @"AXLinkedUIElements",

[David Tseng, 2014/03/12 00:30:56]

Ditto.

[aboxhall, 2014/03/12 17:50:47]

Done.

[aboxhall, 2014/03/12 17:50:47]

Done.

       nil];
 
   // Specific role attributes.
   NSString* role = [self role];
   NSString* subrole = [self subrole];
   if ([role isEqualToString:NSAccessibilityTableRole] ||
       [role isEqualToString:NSAccessibilityGridRole]) {
     [ret addObjectsFromArray:[NSArray arrayWithObjects:
         NSAccessibilityColumnsAttribute,
         NSAccessibilityVisibleColumnsAttribute,
@@ skipping 79 matching lines @@
   }
   if (browserAccessibility_->HasStringAttribute(
           ui::AX_ATTR_CONTAINER_LIVE_STATUS)) {
     [ret addObjectsFromArray:[NSArray arrayWithObjects:
         @"AXARIAAtomic",
         @"AXARIABusy",
         nil]];
   }
 
   // Title UI Element.
-  if (browserAccessibility_->HasIntAttribute(
-          ui::AX_ATTR_TITLE_UI_ELEMENT)) {
+  if (browserAccessibility_->HasIntAttribute(ui::AX_ATTR_TITLE_UI_ELEMENT) ||
+      browserAccessibility_->HasIntListAttribute(ui::AX_ATTR_LABELLEDBY_IDS)) {

[David Tseng, 2014/03/12 00:30:56]

Technically, only if there's exactly one labelled by id.

[aboxhall, 2014/03/12 17:50:47]

True. I'll change it, but would there be an issue if it always "supported" it
but sometimes returned nil?

[David Tseng, 2014/03/12 18:30:17]

Well, a client could request the attributes supported by this accessibility node
and react in some way, so I would say it could make a difference.

     [ret addObjectsFromArray:[NSArray arrayWithObjects:
          NSAccessibilityTitleUIElementAttribute,
          nil]];
   }
 
   return ret;
 }
 
 // Returns the index of the child in this objects array of children.
 - (NSUInteger)accessibilityGetIndexOf:(id)child {
@@ skipping 128 matching lines @@
     return [super hash];
   return browserAccessibility_->renderer_id();
 }
 
 - (BOOL)accessibilityShouldUseUniqueId {
   return YES;
 }
 
 @end