Improve accessibility for modules and lang menus

Ever since the contents of the modules and lang menus started
being populated upon click, the flow for screenreader users has
been potentially confusing.

This patch introduces a11y-toggle into the mix:
https://github.com/edenspiekermann/a11y-toggle
Checkboxes were changed into buttons. This hopefully makes it
clear we want the user to click them.

The contents tree still uses the checkbox hack, because its items
are populated upon page load.

Change-Id: I3482bea0c8669f96794498fc37d9d18fe3f829d5
Reviewed-on: https://gerrit.libreoffice.org/72467
Tested-by: Jenkins
Tested-by: Olivier Hallot <olivier.hallot@libreoffice.org>
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>

5 files changed, 142 insertions, 26 deletions

diff --git a/Package_html_static.mk b/Package_html_static.mk
index d1ebbbb1b3..249783c220 100644
--- a/Package_html_static.mk
+++ b/Package_html_static.mk
@@ -17,6 +17,7 @@ $(eval $(call gb_Package_add_files,helpcontent2_html_static,$(LIBO_SHARE_HELP_FO
 $(eval $(call gb_Package_add_file,helpcontent2_html_static,$(LIBO_SHARE_HELP_FOLDER)$(if $(HELP_ONLINE),/$(PRODUCTVERSION))/index.html,index2.html))
 
 $(eval $(call gb_Package_add_files,helpcontent2_html_static,$(LIBO_SHARE_HELP_FOLDER)$(if $(HELP_ONLINE),/$(PRODUCTVERSION)),\
+	a11y-toggle.js \
 	default.css \
 	fuzzysort.js \
 	help.js \
diff --git a/help3xsl/a11y-toggle.js b/help3xsl/a11y-toggle.js
new file mode 100644
index 0000000000..821a8e0272
--- /dev/null
+++ b/help3xsl/a11y-toggle.js
@@ -0,0 +1,100 @@
+/*
+MIT License
+
+Copyright (c) 2016 Edenspiekermann
+
+*/
+
+(function () {
+  'use strict';
+
+  var internalId = 0;
+  var togglesMap = {};
+  var targetsMap = {};
+
+  function $ (selector, context) {
+    return Array.prototype.slice.call(
+      (context || document).querySelectorAll(selector)
+    );
+  }
+
+  function getClosestToggle (element) {
+    if (element.closest) {
+      return element.closest('[data-a11y-toggle]');
+    }
+
+    while (element) {
+      if (element.nodeType === 1 && element.hasAttribute('data-a11y-toggle')) {
+        return element;
+      }
+
+      element = element.parentNode;
+    }
+
+    return null;
+  }
+
+  function handleToggle (toggle) {
+    var target = toggle && targetsMap[toggle.getAttribute('aria-controls')];
+
+    if (!target) {
+      return false;
+    }
+
+    var toggles = togglesMap['#' + target.id];
+    var isExpanded = target.getAttribute('aria-hidden') === 'false';
+
+    target.setAttribute('aria-hidden', isExpanded);
+    toggles.forEach(function (toggle) {
+      toggle.setAttribute('aria-expanded', !isExpanded);
+    });
+  }
+
+  var initA11yToggle = function (context) {
+    togglesMap = $('[data-a11y-toggle]', context).reduce(function (acc, toggle) {
+      var selector = '#' + toggle.getAttribute('data-a11y-toggle');
+      acc[selector] = acc[selector] || [];
+      acc[selector].push(toggle);
+      return acc;
+    }, togglesMap);
+
+    var targets = Object.keys(togglesMap);
+    targets.length && $(targets).forEach(function (target) {
+      var toggles = togglesMap['#' + target.id];
+      var isExpanded = target.hasAttribute('data-a11y-toggle-open');
+      var labelledby = [];
+
+      toggles.forEach(function (toggle) {
+        toggle.id || toggle.setAttribute('id', 'a11y-toggle-' + internalId++);
+        toggle.setAttribute('aria-controls', target.id);
+        toggle.setAttribute('aria-expanded', isExpanded);
+        labelledby.push(toggle.id);
+      });
+
+      target.setAttribute('aria-hidden', !isExpanded);
+      target.hasAttribute('aria-labelledby') || target.setAttribute('aria-labelledby', labelledby.join(' '));
+
+      targetsMap[target.id] = target;
+    });
+  };
+
+  document.addEventListener('DOMContentLoaded', function () {
+    initA11yToggle();
+  });
+
+  document.addEventListener('click', function (event) {
+    var toggle = getClosestToggle(event.target);
+    handleToggle(toggle);
+  });
+
+  document.addEventListener('keyup', function (event) {
+    if (event.which === 13 || event.which === 32) {
+      var toggle = getClosestToggle(event.target);
+      if (toggle && toggle.getAttribute('role') === 'button') {
+        handleToggle(toggle);
+      }
+    }
+  });
+
+  window && (window.a11yToggle = initA11yToggle);
+})();
diff --git a/help3xsl/default.css b/help3xsl/default.css
index bf1358ee11..482f3ed6d4 100644
--- a/help3xsl/default.css
+++ b/help3xsl/default.css
@@ -375,7 +375,11 @@ header {
     height: 60px;
     margin-right: 10px;
 }
-.lang nav, .modules nav {
+[aria-hidden='true'],
+[data-a11y-toggle]:not([aria-controls]) {
+  display: none;
+}
+#langs-nav:not([aria-hidden='true']), #modules-nav:not([aria-hidden='true']) {
     z-index: 100;
     /* line them up horizontally */
     display: flex;
@@ -386,7 +390,7 @@ header {
     /* make it smooth on iOS */
     -webkit-overflow-scrolling: touch;
 }
-.lang nav a, .modules nav a {
+#langs-nav a, #modules-nav a {
     color: #fff;
     background-color: #233336;
     display: block;
@@ -411,7 +415,6 @@ footer p {
     background-color: transparent !important;
     padding: 3px 0 0 0 !important;
 }
-.modules input[type=checkbox], .lang input[type=checkbox],
 .contents-treeview input[type=checkbox], aside input[type=checkbox] {
     position: absolute;
     opacity: 0;
@@ -604,7 +607,7 @@ li.disabled a {
     border-bottom: 2px solid #f3f3f3;
     background-color: #233336;
 }
-.modules label:after, .lang label:after {
+#modules:after, #langs:after {
     font-size: 30px;
     color: #fff;
     content:"⌄";
@@ -612,10 +615,10 @@ li.disabled a {
 .lang {
     background-color: #233336;
 }
-.lang label, .modules label {
+#langs, #modules {
     display: none;
 }
-.modules nav div {
+#modules-nav div {
     background-repeat: no-repeat;
     background-size: contain;
     float: left;
@@ -739,24 +742,30 @@ li.disabled a {
     }
 }
 @media screen and (min-width: 960px) {
-    .lang nav {
+    #langs-nav {
         display: none;
     }
-    .lang nav a {
+    #langs-nav a {
         font-size: 19px;
         white-space: normal;
     }
-    .lang label, .modules label {
+    /* these are buttons, so also reset some default stylings */
+    #langs, #modules {
         cursor: pointer;
         color: #fff;
         font-size: 19px;
         position: relative;
         top: 40px;
         display: block;
+        background: transparent;
+        border: none;
+        text-transform: none;
+        padding:0;
+        line-height: normal;
     }
-    /* change the menu direction to stacked */
 
-    .lang input[type="checkbox"]:checked ~ nav, .modules input[type="checkbox"]:checked ~ nav {
+    /* change the menu direction to stacked */
+    #langs-nav:not([aria-hidden='true']), #modules-nav:not([aria-hidden='true']) {
         display: flex;
         flex-direction: column;
         max-width: 120px;
@@ -766,17 +775,14 @@ li.disabled a {
         position: absolute;
         top: 80px;
     }
-    .modules input[type="checkbox"]:checked ~ nav {
+    #modules-nav {
         background-color: #101820;
         text-align: left;
     }
-    .modules nav {
-        display: none;
-    }
-    .modules nav div {
+    #modules-nav div {
         display: block;
     }
-    .modules nav a {
+    #modules-nav a {
         font-size: 19px;
     }
     aside {
diff --git a/help3xsl/help2.js b/help3xsl/help2.js
index f62105dc62..54dd195ab3 100644
--- a/help3xsl/help2.js
+++ b/help3xsl/help2.js
@@ -217,10 +217,16 @@ debugInfo(getParameterByName("Debug"));
 
 // Mobile devices need the modules and langs on page load
 if (Math.max(document.documentElement.clientWidth, window.innerWidth || 0) < 960) {
-    var e = new Event('change');
-    var modules = document.getElementById('modules');
-    var langs = document.getElementById('langs');
-    modules.dispatchEvent(e);
-    langs.dispatchEvent(e);
+    var e = new Event('click');
+    var modulesBtn = document.getElementById('modules');
+    var langsBtn = document.getElementById('langs');
+    var modules = document.getElementById('modules-nav');
+    var langs = document.getElementById('langs-nav');
+    modules.setAttribute('data-a11y-toggle-open', '');
+    modulesBtn.dispatchEvent(e);
+    if (langs) {
+        langs.setAttribute('data-a11y-toggle-open', '');
+        langsBtn.dispatchEvent(e);
+    }
 }
 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/help3xsl/online_transform.xsl b/help3xsl/online_transform.xsl
index 95d19bc56a..2ca8deded7 100644
--- a/help3xsl/online_transform.xsl
+++ b/help3xsl/online_transform.xsl
@@ -154,6 +154,7 @@
         <script type="text/javascript" src="{$target}fuzzysort.js"></script>
         <script type="text/javascript" src="{$target}prism.js"></script>
         <script type="text/javascript" src="{$target}help2.js" defer=""></script>
+        <script type="text/javascript" src="{$target}a11y-toggle.js" defer=""></script>
         <script type="text/javascript" src="{$target}{$lang}/langnames.js" defer=""></script>
         <script type="text/javascript" src="{$target}paginathing.js" defer=""></script>
         <script type="text/javascript" src="{$target}{$lang}/bookmarks.js" defer=""></script>
@@ -179,14 +180,16 @@
             </div>
         </header>
         <div class="modules">
-            <input id="modules" name="modules" type="checkbox" onchange="setupModules('{$target}', '{$lang}');"/>
-            <label for="modules"><xsl:value-of select="$ui_module"/></label>
+            <button type="button" data-a11y-toggle="modules-nav" id="modules" onclick="setupModules('{$target}', '{$lang}');">
+                <xsl:value-of select="$ui_module"/>
+            </button>
 	    <nav id="modules-nav"/><!-- is filled in via setupModules() on demand -->
         </div>
         <xsl:if test="$online">
             <div class="lang">
-                <input id="langs" name="language-menu" type="checkbox" onchange="setupLanguages('{$target}', '{$htmlpage}');"/>
-                <label for="langs"><xsl:value-of select="$ui_language"/></label>
+                <button type="button" data-a11y-toggle="langs-nav" id="langs" onclick="setupLanguages('{$target}', '{$htmlpage}');">
+                    <xsl:value-of select="$ui_language"/>
+                </button>
                 <nav id="langs-nav"/><!-- is filled in via setupLanguages() on demand -->
             </div>
         </xsl:if>