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AssistiveMML.js (5942B)

---

 /* -*- Mode: Javascript; indent-tabs-mode:nil; js-indent-level: 2 -*- */
 /* vim: set ts=2 et sw=2 tw=80: */
 
 /*************************************************************
  *
  *  MathJax/extensions/AssistiveMML.js
  *  
  *  Implements an extension that inserts hidden MathML into the
  *  page for screen readers or other asistive technology.
  *  
  *  ---------------------------------------------------------------------
  *  
  *  Copyright (c) 2015 The MathJax Consortium
  * 
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
  *  You may obtain a copy of the License at
  * 
  *      http://www.apache.org/licenses/LICENSE-2.0
  * 
  *  Unless required by applicable law or agreed to in writing, software
  *  distributed under the License is distributed on an "AS IS" BASIS,
  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  */
 
 (function (AJAX,CALLBACK,HUB,HTML) {
   var SETTINGS = HUB.config.menuSettings;
   
   var AssistiveMML = MathJax.Extension["AssistiveMML"] = {
     version: "2.6.1",
     
     config: HUB.CombineConfig("AssistiveMML",{
       disabled: false,
       styles: {
         ".MJX_Assistive_MathML": {
           position:"absolute!important",
           top: 0, left: 0,
           clip: (HUB.Browser.isMSIE && (document.documentMode||0) < 8 ?
                  "rect(1px 1px 1px 1px)" : "rect(1px, 1px, 1px, 1px)"),
           padding: "1px 0 0 0!important",
           border: "0!important",
           height: "1px!important",
           width: "1px!important",
           overflow: "hidden!important",
           display:"block!important",
           //
           //  Don't allow the assistive MathML become part of the selection
           //
           "-webkit-touch-callout": "none",
           "-webkit-user-select": "none",
           "-khtml-user-select": "none",
           "-moz-user-select": "none",
           "-ms-user-select": "none",
           "user-select": "none"
         },
         ".MJX_Assistive_MathML.MJX_Assistive_MathML_Block": {
           width: "100%!important"
         }
       }
     }),
     
     Config: function () {
       if (!this.config.disabled && SETTINGS.assistiveMML == null)
         HUB.Config({menuSettings:{assistiveMML:true}});
       AJAX.Styles(this.config.styles);
       HUB.Register.MessageHook("End Math",function (msg) {
         if (SETTINGS.assistiveMML) return AssistiveMML.AddAssistiveMathML(msg[1])
       });
     },
     
     //
     //  This sets up a state object that lists the jax and index into the jax,
     //    and a dummy callback that is used to synchronizing with MathJax.
     //    It will be called when the jax are all processed, and that will
     //    let the MathJax queue continue (it will block until then).
     //
     AddAssistiveMathML: function (node) {
       var state = {
         jax: HUB.getAllJax(node), i: 0,
         callback: MathJax.Callback({})
       };
       this.HandleMML(state);
       return state.callback;
     },
 
     //
     //  This removes the data-mathml attribute and the assistive MathML from
     //  all the jax.
     //
     RemoveAssistiveMathML: function (node) {
       var jax = HUB.getAllJax(node), frame;
       for (var i = 0, m = jax.length; i < m; i++) {
         frame = document.getElementById(jax[i].inputID+"-Frame");
         if (frame && frame.getAttribute("data-mathml")) {
           frame.removeAttribute("data-mathml");
           if (frame.lastChild && frame.lastChild.className.match(/MJX_Assistive_MathML/))
             frame.removeChild(frame.lastChild);
         }
       }
     },
 
     //
     //  For each jax in the state, look up the frame.
     //  If the jax doesn't use NativeMML and hasn't already been handled:
     //    Get the MathML for the jax, taking resets into account.
     //    Add a data-mathml attribute to the frame, and
     //    Create a span that is not visible on screen and put the MathML in it,
     //      and add it to the frame.
     //  When all the jax are processed, call the callback.
     //
     HandleMML: function (state) {
       var m = state.jax.length, jax, mml, frame, span;
       while (state.i < m) {
         jax = state.jax[state.i];
         frame = document.getElementById(jax.inputID+"-Frame");
         if (jax.outputJax !== "NativeMML" && frame && !frame.getAttribute("data-mathml")) {
           try {
             mml = jax.root.toMathML("").replace(/\n */g,"").replace(/<!--.*?-->/g,"");
           } catch (err) {
             if (!err.restart) throw err; // an actual error
             return MathJax.Callback.After(["HandleMML",this,state],err.restart);
           }
           frame.setAttribute("data-mathml",mml);
           span = HTML.addElement(frame,"span",{
             isMathJax: true, unselectable: "on",
             className: "MJX_Assistive_MathML"
               + (jax.root.Get("display") === "block" ? " MJX_Assistive_MathML_Block" : "")
           });
           span.innerHTML = mml;
           frame.style.position = "relative";
           frame.setAttribute("role","presentation");
           frame.firstChild.setAttribute("aria-hidden","true");
           span.setAttribute("role","presentation");
         }
         state.i++;
       }
       state.callback();
     }
     
   };
 
   HUB.Startup.signal.Post("AssistiveMML Ready");
 
 })(MathJax.Ajax,MathJax.Callback,MathJax.Hub,MathJax.HTML);
 
 //
 //  Make sure the toMathML extension is loaded before we signal
 //  the load complete for this extension.  Then wait for the end
 //  of the user configuration before configuring this extension. 
 //
 MathJax.Callback.Queue(
   ["Require",MathJax.Ajax,"[MathJax]/extensions/toMathML.js"],
   ["loadComplete",MathJax.Ajax,"[MathJax]/extensions/AssistiveMML.js"],
   function () {
     MathJax.Hub.Register.StartupHook("End Config",["Config",MathJax.Extension.AssistiveMML]);
   }
 );