Added 3 new methods to HTMLCS.util to support presentation roles and …

…aria-hidden attributes for #149 and #151.

isAccessibilityHidden() tests whether a given element is visible to an accessibility API.

isVisuallyHidden() was previously isHidden() and tests only if the element is visible in the browser.

getAllElements() replaces a private method in HTMLCS called _getAllTags(). The function accepts a parent element and returns an array of child elements that are not hidden from accessibility APIs. HTMLCS uses this as an initial gather of elements to test, but there are still many core query selectors used in individual sniffs which may need to be made aware of hidden elements and react accordingly.

Intially these seems to work with most common use case of avoiding tests of an element and all of it's children.

Auditor/HTMLCSAuditor.js

@@ -1815,7 +1815,7 @@ var HTMLCSAuditor = new function()
             }
 
             // Do not point to elem if its hidden. Use computed styles.
-            if (HTMLCS.util.isHidden(elem) === true) {
+            if (HTMLCS.util.isVisuallyHidden(elem) === true) {
                 return false;
             }
 

HTMLCS.Util.js

@@ -172,7 +172,7 @@ HTMLCS.util = function() {
     };
 
     /**
-     * Return true if an element is hidden.
+     * Return true if an element is hidden visually.
      *
      * If the computed style of an element cannot be determined for some reason,
      * it is presumed it is NOT hidden.
@@ -181,7 +181,7 @@ HTMLCS.util = function() {
      *
      * @returns {Boolean}
      */
-    self.isHidden = function(element) {
+    self.isVisuallyHidden = function(element) {
         var hidden = false;
 
         // Do not point to elem if its hidden. Use computed styles.
@@ -203,6 +203,38 @@ HTMLCS.util = function() {
         return hidden;
     };
 
+
+    /**
+     * Returns true if the element is hidden from Accessibility APIs.
+     *
+     * @param {Node} element The element to check.
+     *
+     * @return {Boolean}
+     */
+    self.isAccessibilityHidden = function(element) {
+
+        // WAI-ARIA presentation role.
+        if (element.hasAttribute('role') && element.getAttribute('role') === 'presentation') {
+                    console.log(element);
+            return true;
+        }
+
+        // WAI-ARIA hidden attribute.
+        if (element.hasAttribute('aria-hidden') && element.getAttribute('aria-hidden') === 'true') {
+            return true;
+        }
+
+        // Accessibility APIs will ignore visibility: hidden and display: none.
+        var style = self.style(element);
+        if (style !== null) {
+            if (style.visibility === 'hidden' || style.display === 'none') {
+                return true;
+            }
+        }
+
+        return false;
+    };
+
     /**
      * Return true if an element is disabled.
      *
@@ -247,6 +279,42 @@ HTMLCS.util = function() {
         return true;
     };
 
+    /**
+     * Returns all elements that are visible to the accessibility API.
+     *
+     * @param {Node} element The parent element to search.
+     *
+     * @return {Array}
+     */
+    self.getAllElements = function(element) {
+        element      = element || document;
+        var elements = Array.prototype.slice.call(element.getElementsByTagName('*'));
+        var hidden   = elements.filter(function(elem) {
+            return HTMLCS.util.isAccessibilityHidden(elem) === true;
+        });
+
+        // We shouldn't be testing elements inside the injected auditor code if it's present.
+        var auditor = document.getElementById('HTMLCS-wrapper');
+        if (auditor) {
+            elements = elements.filter(function(elem) {
+                return auditor.contains(elem) === false;
+            });
+        }
+
+        return elements
+            .filter(function(elem) {
+                // Filter out direct matches to hidden elems.
+                return hidden.indexOf(elem) === -1;
+            })
+            .filter(function(elem) {
+                // Filter out children of hidden elements.
+                return hidden.filter(function(hiddenElem) {
+                    console.log(hiddenElem, elem, hiddenElem.contains(elem));
+                    return hiddenElem.contains(elem);
+                }).length ? false : true;
+            });
+    };
+
     /**
      * Returns true if the passed child is contained by the passed parent.
      *

HTMLCS.js

@@ -107,7 +107,7 @@ var HTMLCS = new function()
                     }
                 }
 
-                var elements = _getAllTags(element);
+                var elements = HTMLCS.util.getAllElements(element);
                 elements.unshift(element);
                 _run(elements, element, callback);
             }
@@ -143,7 +143,7 @@ var HTMLCS = new function()
 
         // Get all the elements in the parent element.
         // Add the parent element too, which will trigger "_top" element codes.
-        var elements = _getAllTags(element);
+        var elements = HTMLCS.util.getAllElements(element);
         elements.unshift(element);
 
         // Run the sniffs.
@@ -574,24 +574,4 @@ var HTMLCS = new function()
             document.getElementsByTagName('head')[0].appendChild(script);
         }
     };
-
-    /**
-     * Returns all the child elements in the given element.
-     *
-     * @param {Node|Document} [element=document] The parent element.
-     *
-     * @returns {Array} Array of Node objects.
-     */
-    var _getAllTags = function(element) {
-        element      = element || document;
-        var elements = element.getElementsByTagName('*');
-
-        // Convert to array. We can't use array features on a NodeList.
-        var elArray = [];
-        for (var i = 0; i < elements.length; i++) {
-            elArray.push(elements[i]);
-        }
-
-        return elArray;
-    };
 };

Standards/WCAG2AAA/Sniffs/Principle1/Guideline1_4/1_4_3_Contrast.js

@@ -29,7 +29,7 @@ var HTMLCS_WCAG2AAA_Sniffs_Principle1_Guideline1_4_1_4_3_Contrast = {
             var node = toProcess.shift();
 
             // This is an element.
-            if (node && (node.nodeType === 1) && (HTMLCS.util.isHidden(node) === false) && (HTMLCS.util.isDisabled(node) === false)) {
+            if (node && (node.nodeType === 1) && (HTMLCS.util.isVisuallyHidden(node) === false) && (HTMLCS.util.isDisabled(node) === false)) {
                 var processNode = false;
                 for (var i = 0; i < node.childNodes.length; i++) {
                     // Load up new nodes, but also only process this node when