Bug 495390 - If a link has a non-breaking space as screen text, try to fall back to other means like @title, marcoz, davidb

accessible/src/base/nsTextEquivUtils.cpp

@@ -75,7 +75,8 @@ nsTextEquivUtils::GetNameFromSubtree(nsIAccessible *aAccessible,
       nsAutoString name;
       AppendFromAccessibleChildren(aAccessible, &name);
       name.CompressWhitespace();
-      aName = name;
+      if (!IsWhitespaceString(name))
+        aName = name;
     }
   }
 
@@ -419,6 +420,27 @@ nsTextEquivUtils::AppendString(nsAString *aString,
   return PR_TRUE;
 }
 
+PRBool
+nsTextEquivUtils::IsWhitespaceString(const nsSubstring& aString)
+{
+  nsSubstring::const_char_iterator iterBegin, iterEnd;
+
+  aString.BeginReading(iterBegin);
+  aString.EndReading(iterEnd);
+
+  while (iterBegin != iterEnd && IsWhitespace(*iterBegin))
+    ++iterBegin;
+
+  return iterBegin == iterEnd;
+}
+
+PRBool
+nsTextEquivUtils::IsWhitespace(PRUnichar aChar)
+{
+  return aChar == ' ' || aChar == '\n' ||
+    aChar == '\r' || aChar == '\t' || aChar == 0xa0;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Name rules to role map.
 

accessible/src/base/nsTextEquivUtils.h

@@ -159,6 +159,18 @@ private:
   static PRBool AppendString(nsAString *aString,
                              const nsAString& aTextEquivalent);
 
+  /**
+   * Returns true if the given string is empty or contains whitespace symbols
+   * only. In contrast to nsWhitespaceTokenizer class it takes into account
+   * non-breaking space (0xa0).
+   */
+  static PRBool IsWhitespaceString(const nsSubstring& aString);
+
+  /**
+   * Returns true if the given character is whitespace symbol.
+   */
+  static PRBool IsWhitespace(PRUnichar aChar);
+
   /**
    * Map array from roles to name rules (constants of ETextEquivRule).
    */

accessible/tests/mochitest/test_name.html

@@ -92,6 +92,9 @@
       // Gets the name from html:input value, ignore @title attribute on input
       testName("from_input_ignoretitle", "Custom country");
 
+      // Gets the name from @title, ignore whitespace content
+      testName("from_label_ignore_ws_subtree", "about");
+
       //////////////////////////////////////////////////////////////////////////
       // label element
 
@@ -303,6 +306,9 @@
          value="Custom country"
          title="Input your country of origin"/ >
 
+  <!-- no name from subtree because it holds whitespaces only -->
+  <a id="from_label_ignore_ws_subtree" href="about:" title="about">&nbsp;&nbsp;  </a>
+
   <!-- label element, label contains the button -->
   <label>text<button id="btn_label_inside">10</button>text</label>
   <br/>