Bug 652635 - Fallback missing @longdesc to aria-describedby pointing to <a href>, r=surkov, jonas

accessible/src/html/Makefile.in

@@ -75,6 +75,8 @@ LOCAL_INCLUDES = \
   -I$(srcdir)/../base \
   -I$(srcdir)/../generic \
   -I$(srcdir)/../xpcom \
+  -I$(srcdir)/../../../content/base/src \
+  -I$(srcdir)/../../../content/html/content/src \
   -I$(srcdir)/../../../layout/generic \
   -I$(srcdir)/../../../layout/xul/base/src \
   $(NULL)

accessible/src/html/nsHTMLImageAccessible.cpp

@@ -40,10 +40,12 @@
 
 #include "nsAccUtils.h"
 #include "Role.h"
+#include "AccIterator.h"
 #include "States.h"
 
 #include "imgIContainer.h"
 #include "imgIRequest.h"
+#include "nsGenericHTMLElement.h"
 #include "nsIDocument.h"
 #include "nsIImageLoadingContent.h"
 #include "nsILink.h"
@@ -146,7 +148,7 @@ nsHTMLImageAccessible::GetActionName(PRUint8 aIndex, nsAString& aName)
   if (IsDefunct())
     return NS_ERROR_FAILURE;
 
-  if (IsValidLongDescIndex(aIndex)) {
+  if (IsLongDescIndex(aIndex) && HasLongDesc()) {
     aName.AssignLiteral("showlongdesc"); 
     return NS_OK;
   }
@@ -159,24 +161,27 @@ nsHTMLImageAccessible::DoAction(PRUint8 aIndex)
   if (IsDefunct())
     return NS_ERROR_FAILURE;
 
-  if (IsValidLongDescIndex(aIndex)) {
-    //get the long description uri and open in a new window
-    nsCOMPtr<nsIDOMHTMLImageElement> element(do_QueryInterface(mContent));
-    NS_ENSURE_TRUE(element, NS_ERROR_FAILURE);
+  // Get the long description uri and open in a new window.
+  if (!IsLongDescIndex(aIndex))
+    return nsLinkableAccessible::DoAction(aIndex);
 
-    nsAutoString longDesc;
-    nsresult rv = element->GetLongDesc(longDesc);
-    NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIURI> uri = GetLongDescURI();
+  if (!uri)
+    return NS_ERROR_INVALID_ARG;
+
+  nsCAutoString utf8spec;
+  uri->GetSpec(utf8spec);
+  NS_ConvertUTF8toUTF16 spec(utf8spec);
+
+  nsIDocument* document = mContent->OwnerDoc();
+  nsCOMPtr<nsPIDOMWindow> piWindow = document->GetWindow();
+  nsCOMPtr<nsIDOMWindow> win = do_QueryInterface(piWindow);
+  NS_ENSURE_STATE(win);
+
+  nsCOMPtr<nsIDOMWindow> tmp;
+  return win->Open(spec, EmptyString(), EmptyString(),
+                   getter_AddRefs(tmp));
 
-    nsIDocument* document = mContent->OwnerDoc();
-    nsCOMPtr<nsPIDOMWindow> piWindow = document->GetWindow();
-    nsCOMPtr<nsIDOMWindow> win = do_QueryInterface(piWindow);
-    NS_ENSURE_TRUE(win, NS_ERROR_FAILURE);
-    nsCOMPtr<nsIDOMWindow> tmp;
-    return win->Open(longDesc, EmptyString(), EmptyString(),
-                     getter_AddRefs(tmp));
-  }
-  return nsLinkableAccessible::DoAction(aIndex);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -222,20 +227,42 @@ nsHTMLImageAccessible::GetAttributesInternal(nsIPersistentProperties *aAttribute
 ////////////////////////////////////////////////////////////////////////////////
 // Private methods
 
-bool
-nsHTMLImageAccessible::HasLongDesc()
+already_AddRefed<nsIURI>
+nsHTMLImageAccessible::GetLongDescURI() const
 {
-  if (IsDefunct())
-    return false;
+  if (mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::longdesc)) {
+    nsGenericHTMLElement* element = 
+      nsGenericHTMLElement::FromContent(mContent);
+    if (element) {
+      nsCOMPtr<nsIURI> uri;
+      element->GetURIAttr(nsGkAtoms::longdesc, nsnull, getter_AddRefs(uri));
+      return uri.forget();
+    }
+  }
 
-  return mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::longdesc);
+  nsDocAccessible* document = Document();
+  if (document) {
+    IDRefsIterator iter(document, mContent, nsGkAtoms::aria_describedby);
+    nsIContent* target = nsnull;
+    while (target = iter.NextElem()) {
+      if ((target->IsHTML(nsGkAtoms::a) || target->IsHTML(nsGkAtoms::area)) &&
+          target->HasAttr(kNameSpaceID_None, nsGkAtoms::href)) {
+        nsGenericHTMLElement* element =
+          nsGenericHTMLElement::FromContent(target);
+
+        nsCOMPtr<nsIURI> uri;
+        element->GetURIAttr(nsGkAtoms::href, nsnull, getter_AddRefs(uri));
+        return uri.forget();
+      }
+    }
+  }
+
+  return nsnull;
 }
 
 bool
-nsHTMLImageAccessible::IsValidLongDescIndex(PRUint8 aIndex)
+nsHTMLImageAccessible::IsLongDescIndex(PRUint8 aIndex)
 {
-  if (!HasLongDesc())
-    return false;
-
   return aIndex == nsLinkableAccessible::ActionCount();
 }
+

accessible/src/html/nsHTMLImageAccessible.h

@@ -42,6 +42,8 @@
 #include "nsBaseWidgetAccessible.h"
 #include "nsIAccessibleImage.h"
 
+class nsGenericHTMLElement;
+
 /* Accessible for supporting images
  * supports:
  * - gets name, role
@@ -74,26 +76,37 @@ public:
 
 private:
   /**
-   * Determine if this image accessible has a longdesc attribute.
-   *
-   * @returns  true if the longdesc attribute is present.
+   * Return whether the element has a longdesc URI.
    */
-  bool HasLongDesc();
-  
+  bool HasLongDesc() const
+  {
+    nsCOMPtr<nsIURI> uri = GetLongDescURI();
+    return uri;
+  }
+
+  /**
+   * Return an URI for showlongdesc action if any.
+   */
+  already_AddRefed<nsIURI> GetLongDescURI() const;
+
   /**
    * Used by GetActionName and DoAction to ensure the index for opening the
    * longdesc URL is valid.
    * It is always assumed that the highest possible index opens the longdesc.
+   * This doesn't check that there is actually a longdesc, just that the index
+   * would be correct if there was one.
    *
    * @param aIndex  The 0-based index to be tested.
    *
    * @returns  true if index is valid for longdesc action.
    */
-  bool IsValidLongDescIndex(PRUint8 aIndex);
+  inline bool IsLongDescIndex(PRUint8 aIndex);
+
 };
 
 ////////////////////////////////////////////////////////////////////////////////
 // nsAccessible downcasting method
+
 inline nsHTMLImageAccessible*
 nsAccessible::AsImage()
 {

accessible/tests/mochitest/test_nsIAccessibleImage.html

@@ -128,6 +128,12 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=429659
       testThis("click", "moz.png",
                89, 38, 1, actionNamesArray);
       
+      // Image with long desc
+      actionNamesArray = null;
+      actionNamesArray = new Array("showlongdesc");
+      testThis("longdesc2", "moz.png",
+               89, 38, 1, actionNamesArray);
+
       SimpleTest.finish();
     }
 
@@ -138,10 +144,17 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=429659
 <body>
 
   <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=429659">Mozilla Bug 429659</a>
+  <a target="_blank"
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=652635"
+    title="fall back missing @longdesc to aria-describedby pointing to a href">
+     Mozilla Bug 652635
+  </a>
+
   <p id="display"></p>
   <div id="content" style="display: none"></div>
   <pre id="test">
   </pre>
+
   <br>Simple image:<br>
   <img id="nonLinkedImage" src="moz.png"/>
   <br>Linked image:<br>
@@ -152,8 +165,15 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=429659
   <br>Image with click and longdesc:<br>
   <img id="clickAndLongdesc" src="moz.png" longdesc="longdesc_src.html"
        alt="Another image of Mozilla logo" onclick="alert('Clicked!');"/>
+
+  <br>image described by a link to be treated as longdesc<br>
+  <img id="longdesc2" src="moz.png" aria-describedby="describing_link"
+       alt="Second Image of Mozilla logo"/>
+  <a id="describing_link" href="longdesc_src.html">link to description of image</a>
+
   <br>Image with click:<br>
   <img id="click" src="moz.png"
        alt="A third image of Mozilla logo" onclick="alert('Clicked, too!');"/>
+
 </body>
 </html>

content/html/content/src/nsGenericHTMLElement.h

@@ -525,6 +525,14 @@ public:
    */
   NS_HIDDEN_(nsresult) GetURIAttr(nsIAtom* aAttr, nsIAtom* aBaseAttr, nsAString& aResult);
 
+  /**
+   * Gets the absolute URI values of an attribute, by resolving any relative
+   * URIs in the attribute against the baseuri of the element. If a substring
+   * isn't a relative URI, the substring is returned as is. Only works for
+   * attributes in null namespace.
+   */
+  bool GetURIAttr(nsIAtom* aAttr, nsIAtom* aBaseAttr, nsIURI** aURI) const;
+
   /**
    * Returns the current disabled state of the element.
    */
@@ -705,14 +713,6 @@ protected:
    */
   NS_HIDDEN_(nsresult) SetDoubleAttr(nsIAtom* aAttr, double aValue);
 
-  /**
-   * Helper for GetURIAttr and GetHrefURIForAnchors which returns an
-   * nsIURI in the out param.
-   *
-   * @return true if we had the attr, false otherwise.
-   */
-  NS_HIDDEN_(bool) GetURIAttr(nsIAtom* aAttr, nsIAtom* aBaseAttr, nsIURI** aURI) const;
-
   /**
    * This method works like GetURIAttr, except that it supports multiple
    * URIs separated by whitespace (one or more U+0020 SPACE characters).