Merge pull request #933 from edx/jmclaus/bugfix_tabbing_captions

Tabbing through captions

common/lib/xmodule/xmodule/css/video/display.scss

@@ -525,12 +525,19 @@ div.video {
       margin-bottom: 8px;
       padding: 0;
       line-height: lh();
+      outline-width: 0px;
+      outline-style: none;
 
       &.current {
         color: #333;
         font-weight: 700;
       }
 
+      &.focused {
+        outline-width: 1px;
+        outline-style: dotted;
+      }
+
       &:hover {
         color: $blue;
       }

common/lib/xmodule/xmodule/js/spec/video/video_caption_spec.js

@@ -93,6 +93,7 @@
           $('.subtitles li[data-index]').each(function(index, link) {
             expect($(link)).toHaveData('index', index);
             expect($(link)).toHaveData('start', captionsData.start[index]);
+            expect($(link)).toHaveAttr('tabindex', 0);
             expect($(link)).toHaveText(captionsData.text[index]);
           });
         });
@@ -104,7 +105,13 @@
 
         it('bind all the caption link', function() {
           $('.subtitles li[data-index]').each(function(index, link) {
-            expect($(link)).toHandleWith('click', videoCaption.seekPlayer);
+            expect($(link)).toHandleWith('mouseover', videoCaption.captionMouseOverOut);
+            expect($(link)).toHandleWith('mouseout', videoCaption.captionMouseOverOut);
+            expect($(link)).toHandleWith('mousedown', videoCaption.captionMouseDown);
+            expect($(link)).toHandleWith('click', videoCaption.captionClick);
+            expect($(link)).toHandleWith('focus', videoCaption.captionFocus);
+            expect($(link)).toHandleWith('blur', videoCaption.captionBlur);
+            expect($(link)).toHandleWith('keydown', videoCaption.captionKeyDown);
           });
         });
 
@@ -278,6 +285,7 @@
           $('.subtitles li[data-index]').each(function(index, link) {
             expect($(link)).toHaveData('index', index);
             expect($(link)).toHaveData('start', captionsData.start[index]);
+            expect($(link)).toHaveAttr('tabindex', 0);
             expect($(link)).toHaveText(captionsData.text[index]);
           });
         });
@@ -289,7 +297,13 @@
 
         it('bind all the caption link', function() {
           $('.subtitles li[data-index]').each(function(index, link) {
-            expect($(link)).toHandleWith('click', videoCaption.seekPlayer);
+            expect($(link)).toHandleWith('mouseover', videoCaption.captionMouseOverOut);
+            expect($(link)).toHandleWith('mouseout', videoCaption.captionMouseOverOut);
+            expect($(link)).toHandleWith('mousedown', videoCaption.captionMouseDown);
+            expect($(link)).toHandleWith('click', videoCaption.captionClick);
+            expect($(link)).toHandleWith('focus', videoCaption.captionFocus);
+            expect($(link)).toHandleWith('blur', videoCaption.captionBlur);
+            expect($(link)).toHandleWith('keydown', videoCaption.captionKeyDown);
           });
         });
 
@@ -558,6 +572,99 @@
         });
       });
     });
+
+    describe('caption accessibility', function() {
+      beforeEach(function() {
+        initialize();
+      });
+
+      describe('when getting focus through TAB key', function() {
+        beforeEach(function() {
+          videoCaption.isMouseFocus = false;
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('focus'));
+        });
+
+        it('shows an outline around the caption', function() {
+          expect($('.subtitles li[data-index=0]')).toHaveClass('focused');
+        });
+
+        it('has automatic scrolling disabled', function() {
+          expect(videoCaption.autoScrolling).toBe(false);
+        });
+      });
+
+      describe('when loosing focus through TAB key', function() {
+        beforeEach(function() {
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('blur'));
+        });
+
+        it('does not show an outline around the caption', function() {
+          expect($('.subtitles li[data-index=0]')).not.toHaveClass('focused');
+        });
+
+        it('has automatic scrolling enabled', function() {
+          expect(videoCaption.autoScrolling).toBe(true);
+        });
+      });
+
+      describe('when same caption gets the focus through mouse after having focus through TAB key', function() {
+        beforeEach(function() {
+          videoCaption.isMouseFocus = false;
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('focus'));
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('mousedown'));
+        });
+
+        it('does not show an outline around it', function() {
+          expect($('.subtitles li[data-index=0]')).not.toHaveClass('focused');
+        });
+
+        it('has automatic scrolling enabled', function() {
+          expect(videoCaption.autoScrolling).toBe(true);
+        });
+      });
+
+      describe('when a second caption gets focus through mouse after first had focus through TAB key', function() {
+        beforeEach(function() {
+          videoCaption.isMouseFocus = false;
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('focus'));
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('blur'));
+          videoCaption.isMouseFocus = true;
+          $('.subtitles li[data-index=1]').trigger(jQuery.Event('mousedown'));
+        });
+
+        it('does not show an outline around the first', function() {
+          expect($('.subtitles li[data-index=0]')).not.toHaveClass('focused');
+        });
+
+        it('does not show an outline around the second', function() {
+          expect($('.subtitles li[data-index=1]')).not.toHaveClass('focused');
+        });
+
+        it('has automatic scrolling enabled', function() {
+          expect(videoCaption.autoScrolling).toBe(true);
+        });
+      });
+
+      describe('when enter key is pressed on a caption', function() {
+        beforeEach(function() {
+          var e;
+          spyOn(videoCaption, 'seekPlayer').andCallThrough();
+          videoCaption.isMouseFocus = false;
+          $('.subtitles li[data-index=0]').trigger(jQuery.Event('focus'));
+          e = jQuery.Event('keydown');
+          e.which = 13; // ENTER key
+          $('.subtitles li[data-index=0]').trigger(e);
+        });
+
+        it('shows an outline around it', function() {
+          expect($('.subtitles li[data-index=0]')).toHaveClass('focused');
+        });
+
+        it('calls seekPlayer', function() {
+           expect(videoCaption.seekPlayer).toHaveBeenCalled();
+        });
+      });
+    });
   });
 
 }).call(this);

common/lib/xmodule/xmodule/js/src/video/09_video_caption.js

@@ -62,6 +62,12 @@ function () {
         state.videoCaption.bindHandlers            = _.bind(bindHandlers, state);
         state.videoCaption.fetchCaption            = _.bind(fetchCaption, state);
         state.videoCaption.captionURL              = _.bind(captionURL, state);
+        state.videoCaption.captionMouseOverOut     = _.bind(captionMouseOverOut, state);
+        state.videoCaption.captionMouseDown        = _.bind(captionMouseDown, state);
+        state.videoCaption.captionClick            = _.bind(captionClick, state);
+        state.videoCaption.captionFocus            = _.bind(captionFocus, state);
+        state.videoCaption.captionBlur             = _.bind(captionBlur, state);
+        state.videoCaption.captionKeyDown          = _.bind(captionKeyDown, state);
     }
 
     // ***************************************************************
@@ -309,7 +315,8 @@ function () {
 
             liEl.attr({
                 'data-index': index,
-                'data-start': _this.videoCaption.start[index]
+                'data-start': _this.videoCaption.start[index],
+                'tabindex': 0
             });
 
             container.append(liEl);
@@ -317,7 +324,33 @@ function () {
 
         this.videoCaption.subtitlesEl.html(container.html());
 
-        this.videoCaption.subtitlesEl.find('li[data-index]').on('click', this.videoCaption.seekPlayer);
+        this.videoCaption.subtitlesEl.find('li[data-index]').on({
+            mouseover:  this.videoCaption.captionMouseOverOut,
+            mouseout:   this.videoCaption.captionMouseOverOut,
+            mousedown:  this.videoCaption.captionMouseDown,
+            click:      this.videoCaption.captionClick,
+            focus:      this.videoCaption.captionFocus,
+            blur:       this.videoCaption.captionBlur,
+            keydown:    this.videoCaption.captionKeyDown
+        });
+
+        // Enables or disables automatic scrolling of the captions when the
+        // video is playing. This feature has to be disabled when tabbing
+        // through them as it interferes with that action. Initially, have this
+        // flag enabled as we assume mouse use. Then, if the first caption 
+        // (through forward tabbing) or the last caption (through backwards
+        // tabbing) gets the focus, disable that feature. Renable it if tabbing
+        // then cycles out of the the captions. 
+        this.videoCaption.autoScrolling = true;
+        // Keeps track of where the focus is situated in the array of captions.
+        // Used to implement the automatic scrolling behavior and decide if the
+        // outline around a caption has to be hidden or shown on a mouseenter or
+        // mouseleave.
+        this.videoCaption.currentCaptionIndex = 0;
+        // Used to track if the focus is coming from a click or tabbing. This 
+        // has to be known to decide if, when a caption gets the focus, an 
+        // outline has to be drawn (tabbing) or not (mouse click).
+        this.videoCaption.isMouseFocus = false;
 
         this.videoCaption.subtitlesEl.prepend($('<li class="spacing">').height(this.videoCaption.topSpacingHeight()));
         this.videoCaption.subtitlesEl.append($('<li class="spacing">').height(this.videoCaption.bottomSpacingHeight()));
@@ -325,10 +358,85 @@ function () {
         this.videoCaption.rendered = true;
     }
 
+    // On mouseOver, hide the outline of a caption that has been tabbed to.
+    // On mouseOut, show the outline of a caption that has been tabbed to.
+    function captionMouseOverOut(event) {
+        var caption = $(event.target),
+            captionIndex = parseInt(caption.attr('data-index'), 10); 
+        if (captionIndex === this.videoCaption.currentCaptionIndex) {
+            if (event.type === 'mouseover') {
+                caption.removeClass('focused');
+            }
+            else { // mouseout
+                caption.addClass('focused');
+            }
+        } 
+    }
+
+    function captionMouseDown(event) {
+        var caption = $(event.target);
+        this.videoCaption.isMouseFocus = true;
+        this.videoCaption.autoScrolling = true;
+        caption.removeClass('focused');
+        this.videoCaption.currentCaptionIndex = -1;
+    }
+
+    function captionClick(event) {
+        this.videoCaption.seekPlayer(event);
+    }
+
+    function captionFocus(event) {
+        var caption = $(event.target),
+            captionIndex = parseInt(caption.attr('data-index'), 10);
+        // If the focus comes from a mouse click, hide the outline, turn on
+        // automatic scrolling and set currentCaptionIndex to point outside of
+        // caption list (ie -1) to disable mouseenter, mouseleave behavior. 
+        if (this.videoCaption.isMouseFocus) {
+            this.videoCaption.autoScrolling = true;
+            caption.removeClass('focused');
+            this.videoCaption.currentCaptionIndex = -1;
+        }
+        // If the focus comes from tabbing, show the outline and turn off 
+        // automatic scrolling.
+        else {
+            this.videoCaption.currentCaptionIndex = captionIndex;
+            caption.addClass('focused');
+            // The second and second to last elements turn automatic scrolling
+            // off again as it may have been enabled in captionBlur.    
+            if (captionIndex <= 1 || captionIndex >= this.videoCaption.captions.length-2) {
+                this.videoCaption.autoScrolling = false;
+            }
+        }
+    }
+
+    function captionBlur(event) {
+        var caption = $(event.target), 
+            captionIndex = parseInt(caption.attr('data-index'), 10);
+        caption.removeClass('focused');
+        // If we are on first or last index, we have to turn automatic scroll on
+        // again when losing focus. There is no way to know in what direction we
+        // are tabbing. So we could be on the first element and tabbing back out
+        // of the captions or on the last element and tabbing forward out of the
+        // captions.
+        if (captionIndex === 0 || 
+            captionIndex === this.videoCaption.captions.length-1) {
+            this.videoCaption.autoScrolling = true;
+        }
+    }
+
+    function captionKeyDown(event) {
+        this.videoCaption.isMouseFocus = false;
+        if (event.which === 13) { //Enter key
+            this.videoCaption.seekPlayer(event);
+        }
+    }
+
     function scrollCaption() {
         var el = this.videoCaption.subtitlesEl.find('.current:first');
 
-        if (!this.videoCaption.frozen && el.length) {
+        // Automatic scrolling gets disabled if one of the captions has received 
+        // focus through tabbing. 
+        if (!this.videoCaption.frozen && el.length && this.videoCaption.autoScrolling) {
             this.videoCaption.subtitlesEl.scrollTo(
                 el,
                 {