From 05ed42de4fb52ec916b2fcc6e5a78d2d5ea164ad Mon Sep 17 00:00:00 2001
From: Marcy Sutton <marcy@substantial.com>
Date: Mon, 22 Sep 2014 16:00:56 -0700
Subject: [PATCH] fix(material-radio): Radio button a11y

Closes #310
---
 src/components/radioButton/radioButton.js     | 44 +++++++++++++++----
 .../radioButton/radioButton.spec.js           |  7 ++-
 src/core/constant.js                          |  8 ++--
 3 files changed, 45 insertions(+), 14 deletions(-)

diff --git a/src/components/radioButton/radioButton.js b/src/components/radioButton/radioButton.js
index 8fd2632bafa..5c7fa3112b2 100644
--- a/src/components/radioButton/radioButton.js
+++ b/src/components/radioButton/radioButton.js
@@ -53,7 +53,7 @@ function materialRadioGroupDirective() {
 
   return {
     restrict: 'E',
-    controller: RadioGroupController,
+    controller: ['$element', RadioGroupController],
     require: ['materialRadioGroup', '?ngModel'],
     link: link
   };
@@ -65,12 +65,11 @@ function materialRadioGroupDirective() {
       };
 
     function keydownListener(ev) {
-
-      if (ev.which === Constant.KEY_CODE.LEFT_ARROW) {
+      if (ev.which === Constant.KEY_CODE.LEFT_ARROW || ev.which === Constant.KEY_CODE.UP_ARROW) {
         ev.preventDefault();
         rgCtrl.selectPrevious(element);
       }
-      else if (ev.which === Constant.KEY_CODE.RIGHT_ARROW) {
+      else if (ev.which === Constant.KEY_CODE.RIGHT_ARROW || ev.which === Constant.KEY_CODE.DOWN_ARROW) {
         ev.preventDefault();
         rgCtrl.selectNext(element);
       }
@@ -85,8 +84,9 @@ function materialRadioGroupDirective() {
     .on('keydown', keydownListener);
   }
 
-  function RadioGroupController() {
+  function RadioGroupController($element) {
     this._radioButtonRenderFns = [];
+    this.$element = $element;
   }
 
   function createRadioGroupControllerProto() {
@@ -122,6 +122,9 @@ function materialRadioGroupDirective() {
       },
       selectPrevious : function(element) {
         return selectButton('previous', element);
+      },
+      setActiveDescendant: function (radioId) {
+        this.$element.attr('aria-activedescendant', radioId);
       }
     };
   }
@@ -221,6 +224,8 @@ function materialRadioButtonDirective($aria) {
   function link(scope, element, attr, rgCtrl) {
     var lastChecked;
 
+    configureAria(element, scope);
+
     rgCtrl.add(render);
     attr.$observe('value', render);
 
@@ -228,10 +233,7 @@ function materialRadioButtonDirective($aria) {
       .on('click', listener)
       .on('$destroy', function() {
         rgCtrl.remove(render);
-      })
-      .attr('role', 'radio');
-
-    $aria.expect(element, 'aria-label', element.text());
+      });
 
     function listener(ev) {
       if (element[0].hasAttribute('disabled')) return;
@@ -250,10 +252,34 @@ function materialRadioButtonDirective($aria) {
       element.attr('aria-checked', checked);
       if (checked) {
         element.addClass(CHECKED_CSS);
+        rgCtrl.setActiveDescendant(element.attr('id'));
       } else {
         element.removeClass(CHECKED_CSS);
       }
     }
+    /**
+     * Inject ARIA-specific attributes appropriate for each radio button
+     */
+    function configureAria( element, scope ){
+      scope.ariaId = buildAriaID();
+
+      element.attr({
+        'id' :  scope.ariaId,
+        'role' : 'radio',
+        'aria-checked' : 'false'
+      });
+
+      $aria.expect(element, 'aria-label', element.text());
+
+      /**
+       * Build a unique ID for each radio button that will be used with aria-activedescendant.
+       * Preserve existing ID if already specified.
+       * @returns {*|string}
+       */
+      function buildAriaID() {
+        return attr.id || ( 'radio' + "_" + Util.nextUid() );
+      }
+    }
   }
 }
 
diff --git a/src/components/radioButton/radioButton.spec.js b/src/components/radioButton/radioButton.spec.js
index 97b474ab1d3..ba7b6afa9b1 100644
--- a/src/components/radioButton/radioButton.spec.js
+++ b/src/components/radioButton/radioButton.spec.js
@@ -19,7 +19,7 @@ describe('radioButton', function() {
     expect(rbElements.eq(1).hasClass(CHECKED_CSS)).toEqual(true);
   }));
 
-  it('should set aria roles', inject(function($compile, $rootScope) {
+  it('should set roles', inject(function($compile, $rootScope) {
 
     var element = $compile('<material-radio-group ng-model="color">' +
                             '<material-radio-button value="blue"></material-radio-button>' +
@@ -31,7 +31,7 @@ describe('radioButton', function() {
     expect(rbGroupElement.find('material-radio-button').eq(0).attr('role')).toEqual('radio');
   }));
 
-  it('should set aria-check attributes', inject(function($compile, $rootScope) {
+  it('should set aria attributes', inject(function($compile, $rootScope) {
     var element = $compile('<material-radio-group ng-model="color">' +
                             '<material-radio-button value="blue"></material-radio-button>' +
                             '<material-radio-button value="green"></material-radio-button>' +
@@ -45,6 +45,9 @@ describe('radioButton', function() {
 
     expect(rbElements.eq(0).attr('aria-checked')).toEqual('false');
     expect(rbElements.eq(1).attr('aria-checked')).toEqual('true');
+
+    expect(element.attr('aria-activedescendant')).toEqual(rbElements.eq(1).attr('id'));
+    expect(element.attr('aria-activedescendant')).not.toEqual(rbElements.eq(0).attr('id'));
   }));
 
   it('should be operable via arrow keys', inject(function($compile, $rootScope) {
diff --git a/src/core/constant.js b/src/core/constant.js
index d0a3008d55a..5bd1a87ad95 100644
--- a/src/core/constant.js
+++ b/src/core/constant.js
@@ -1,9 +1,11 @@
 var Constant = {
   KEY_CODE: {
+    ENTER: 13,
     ESCAPE: 27,
     SPACE: 32,
-    LEFT_ARROW: 37,
-    RIGHT_ARROW: 39,
-    ENTER: 13
+    LEFT_ARROW : 37,
+    UP_ARROW : 38,
+    RIGHT_ARROW : 39,
+    DOWN_ARROW : 40
   }
 };