add cjkCharWidth option

Author: ambar

README.md

@@ -112,6 +112,7 @@ The following are the default input options.
   useGlobalCache: false,          // use common <defs> for all equations?
   linebreaks: false,              // automatic linebreaking
   equationNumbers: "none",        // automatic equation numbering ("none", "AMS" or "all")
+  cjkCharWidth: 13,               // width of CJK character
 
   math: "",                       // the math string to typeset
   format: "TeX",                  // the input format (TeX, inline-TeX, AsciiMath, or MathML)

lib/main.js

@@ -48,6 +48,7 @@ var defaults = {
   useGlobalCache: false,          // use common <defs> for all equations?
   linebreaks: false,              // do linebreaking?
   equationNumbers: "none",        // or "AMS" or "all"
+  cjkCharWidth: 13,               // width of CJK character
 
   math: "",                       // the math to typeset
   format: "TeX",                  // the input format (TeX, inline-TeX, AsciiMath, or MathML)
@@ -311,7 +312,7 @@ function ConfigureMathJax() {
             this.SUPER(arguments).Init.call(this,def);
             SVG.addText(this.element,text);
             var textWidth = text.split('')
-              .map(function(c) { return isFullwidthCodePoint(c.codePointAt()) ? 13 : 8.5 })
+              .map(function(c) { return isFullwidthCodePoint(c.codePointAt()) ? data.cjkCharWidth : 8.5 })
               .reduce(function(a, b) { return a + b }, 0);
             var bbox = {width: textWidth, height: 18, y: -12};
             scale *= 1000/SVG.em;