Merge pull request mathjax#577 from fred-wang/issue557

Issue557

Author: fred-wang

unpacked/config/default.js

@@ -432,20 +432,23 @@ MathJax.Hub.Config({
 
     //
     //  Controls whether mml2jax inserts MathJax_Preview spans to make a
-    //  preview available, and what preview to use, whrn it locates
-    //  mathematics on the page.  The default is "alttext", which means use
-    //  the <math> tag's alttext attribute as the preview (until it is
-    //  processed by MathJax), if the tag has one.  Set to "none" to
+    //  preview available, and what preview to use, when it locates
+    //  mathematics on the page.  The default is "mathml" which means use
+    //  the <math> tag as the preview (until it is processed by MathJax).
+    //  Set to "alttext", to use the  <math> tag's alttext attribute as the
+    //  preview, if the tag has one.  Set to "none" to
     //  prevent the previews from being inserted (the math will simply
-    //  disappear until it is typeset).  Set to an array containing the
+    //  disappear until it is typeset). Set to "altimg" to use an image
+    //  described by the altimg* attributes of the <math> element.
+    //  Set to an array containing the
     //  description of an HTML snippet in order to use the same preview for
     //  all equations on the page (e.g., you could have it say "[math]" or
     //  load an image).
     //  
     //  E.g.,     preview: ["[math]"],
     //  or        preview: [["img",{src: "http://myserver.com/images/mypic.jpg"}]]
     //  
-    preview: "alttext"
+    preview: "mathml"
 
   },
 

unpacked/extensions/mml2jax.js

@@ -29,8 +29,11 @@
 MathJax.Extension.mml2jax = {
   version: "2.2",
   config: {
-    preview: "alttext"      // Use the <math> element's alttext as the 
+    preview: "mathml"       // Use the <math> element as the
                             //   preview.  Set to "none" for no preview,
+                            //   set to "alttext" to use the alttext attribute
+                            //   of the <math> element, set to "altimg" to use
+                            //   an image described by the altimg* attributes
                             //   or set to an array specifying an HTML snippet
                             //   to use a fixed preview for all math
 
@@ -181,13 +184,35 @@ MathJax.Extension.mml2jax = {
   createPreview: function (math,script) {
     var preview = this.config.preview;
     if (preview === "none") return;
-    if (preview === "alttext") {
-      var text = math.getAttribute("alttext");
-      if (text != null) {preview = [this.filterPreview(text)]} else {preview = null}
-    } 
+    var isNodePreview = false;
+    if (preview === "mathml") {
+      isNodePreview = true;
+      // mathml preview does not work with IE < 9, so fallback to alttext.
+      if (this.MathTagBug) {preview = "alttext"} else {preview = math}
+    }
+    if (preview === "alttext" || preview === "altimg") {
+      isNodePreview = true;
+      var alttext = this.filterPreview(math.getAttribute("alttext"));
+      if (preview === "alttext") {
+        if (alttext != null) {preview = MathJax.HTML.TextNode(alttext)} else {preview = null}
+      } else {
+        var src = math.getAttribute("altimg");
+        if (src != null) {
+          // FIXME: use altimg-valign when display="inline"?
+          var style = {width: math.getAttribute("altimg-width"), height: math.getAttribute("altimg-height")};
+          preview = MathJax.HTML.Element("img",{src:src,alt:alttext,style:style});
+        } else {preview = null}
+      }
+    }
     if (preview) {
-      preview = MathJax.HTML.Element("span",{className:MathJax.Hub.config.preRemoveClass},preview);
-      script.parentNode.insertBefore(preview,script);
+      var span;
+      if (isNodePreview) {
+        span = MathJax.HTML.Element("span",{className:MathJax.Hub.config.preRemoveClass});
+        span.appendChild(preview);
+      } else {
+        span = MathJax.HTML.Element("span",{className:MathJax.Hub.config.preRemoveClass},preview);
+      }
+      script.parentNode.insertBefore(span,script);
     }
   },