CODEWITHSUNDEEP
javascriptandroidstringreplacemathml
kiting_and_coding
kiting_and_coding

Reputation: 31

How to escape MathML String in Android for Javascript in WebView

I am trying to display MathML in a WebView using MathJax.

When displaying my own MathML this works well:

        w.evaluateJavascript("javascript:document.getElementById('math').innerHTML='"
                + "New <math xmlns=\"http://www.w3.org/1998/Math/MathML\">"
                + "<mi>d</mi><mo>&#x2260;</mo><mn>13</mn>"
                + "</math>'",
                null);
        w.loadUrl("javascript:MathJax.Hub.Queue(['Typeset',MathJax.Hub]);");

However, when I try to display MathML which I get from a widget, the following does not work:

        mlOutput = mlOutput.replaceAll("(\\r|\\n)", ""); //some random trial and error
        mlOutput = mlOutput.replaceAll("'", "\\'");
        mlOutput = mlOutput.replaceAll("\'", "\\\'");
        mlOutput = mlOutput.replaceAll("'", "\\\'");

        w.evaluateJavascript("javascript:document.getElementById('math').innerHTML='"
                        + mlOutput+ "'",
                null);
        w.loadUrl("javascript:MathJax.Hub.Queue(['Typeset',MathJax.Hub]);");

mlOutput is a String which is printed to Logcat like this (before my string replacing):

<math xmlns='http://www.w3.org/1998/Math/MathML'>
<mfrac>
<mrow>
<mn> 2 </mn>
</mrow>
<mrow>
<mn> 3 </mn>
</mrow>
</mfrac>
</math>

Also I get the following Info from chromium:

I/chromium﹕ [INFO:CONSOLE(1)] "Uncaught SyntaxError: Unexpected identifier", source:  (1)

Any help on how to appropriately escape the mlOutput MathML-String so that I can use it within Javascript would be highly appreciated!

So far the best I could find was something about the Apache StringEscapeUtils.escapeJavaScript function. But as far as I know this can not be used within Android? I just imported the 500KB .jar library but this was not the solution.

Edit: the solution was some method from this MathJax sample implementation app https://github.com/leathrum/android-apps/tree/master/MathJaxApp

mlOutput = doubleEscape(mlOutput);

private String doubleEscape(String s) {
String t="";
for (int i=0; i < s.length(); i++) {
  if (s.charAt(i) == '\'') t += '\\';
  if (s.charAt(i) != '\n') t += s.charAt(i);
  if (s.charAt(i) == '\\') t += "\\";
}
return t;
}

Upvotes: 0

Views: 305

Answers (1)

kiting_and_coding
kiting_and_coding

Reputation: 31

the solution was some method from this MathJax sample implementation app https://github.com/leathrum/android-apps/tree/master/MathJaxApp

mlOutput = doubleEscape(mlOutput);

private String doubleEscape(String s) {
String t="";
for (int i=0; i < s.length(); i++) {
  if (s.charAt(i) == '\'') t += '\\';
  if (s.charAt(i) != '\n') t += s.charAt(i);
  if (s.charAt(i) == '\\') t += "\\";
}
return t;
}

Upvotes: 1

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