--- loncom/xml/lontexconvert.pm	2011/12/06 16:10:53	1.109
+++ loncom/xml/lontexconvert.pm	2016/04/09 14:48:13	1.119
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.109 2011/12/06 16:10:53 dseaton Exp $
+# $Id: lontexconvert.pm,v 1.119 2016/04/09 14:48:13 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -50,6 +50,78 @@ use LONCAPA;
 use URI::Escape;
 use IO::Socket::INET;
 
+
+#
+# Table of substitutions to unicode characters.
+#
+
+my %unicode_harpoons = (
+                        '\rightleftharpoons'  => 0x21cc,
+                      );
+
+my %unicode_translations = (
+
+# Brackets - unicode for browsers/OS which support it.
+
+    ''             => 0x23a1,
+    ''             => 0x23a2,
+    ''             => 0x23a3,
+    ''             => 0x23a4,
+    ''             => 0x23a5,
+    ''             => 0x23a6,
+
+#  Parens - unicode for browsers/OS which support it
+
+    ''              => 0x239b,
+    ''              => 0x239c,
+    ''              => 0x239d,
+    ''              => 0x239e,
+    ''              => 0x239f,
+    ''              => 0x23a0,
+
+);
+
+my %ascii_8bit_translations = (
+
+# Brackets - pure 8-bit ascii ugliness for browsers/OS which can't handle unicode
+
+    ''              => 0x5b,
+    ''              => 0x5b,    # '['
+    ''              => 0x5b,
+    ''              => 0x5d,    # ']'
+    ''              => 0x5d,
+    ''              => 0x5d,
+
+# Parens - pure 8-bit ascii ugliness for browsers/OS which can't handle unicode
+
+    ''              => 0x28,
+    ''              => 0x28,      # '('
+    ''              => 0x28,
+    ''              => 0x29,
+    ''              => 0x29,      # '('
+    ''              => 0x29,
+
+);
+
+##
+# Utility to convert elements of a string to unicode:
+#
+# @param input - Input string
+# @param pattern - Pattern to convert
+# @param unicode - Unicode to substitute for pattern.
+#
+# @return string - resulting string.
+# 
+sub unicode_subst {
+    my ($input, $pattern, $unicode) = @_;
+    
+    my $char = pack('U', $unicode);
+
+    $input =~ s/$pattern/$char/g;
+
+    return $input;
+}
+
 # ====================================================================== Header
 
 sub init_tth {
@@ -106,15 +178,38 @@ sub convert_real {
     $xmlstring=~s/^\s*\<br clear\=\"all\"/\<br/s;
     $xmlstring=~s/^\s*//;
     $xmlstring=~s/\s*$//;
+    $xmlstring=~s/^<br \/><table/<table/;
+    &Apache::lonxml::end_alarm();
+
     #
-    # \rightleftharpoons is not converted by tth but maps
-    # reasonably well to &#8660;.  If we get many more of these,
-    # we're going to need to have a translation sub.
-    #
-    my $lrharpoon = pack("U", 0x21cc);
-    $xmlstring=~s/\\rightleftharpoons/$lrharpoon/g;
+    # Several strings produced by tth require
+    # transliteration -> unicode equivalents to render reliably
+    # in browsers. %unicode_translations and %unicode_harpoons are tables of
+    # string->substitution which we now apply. (%ascii_8bit_translations used
+    # instead for Windows XP and mobile devices.
+
+    my $use_ascii;
+    if ($env{'browser.os'} eq 'win') {
+        if (($env{'browser.osversion'}) && ($env{'browser.osversion'} < 6.0)) {
+            $use_ascii = 1;
+        }
+    }
+    if ($env{'browser.mobile'}) {
+        $use_ascii = 1;
+    }
+
+    foreach my $pattern (keys(%unicode_translations)) {
+	my $unicode = $unicode_translations{$pattern};
+	if ($use_ascii) {
+	    $unicode = $ascii_8bit_translations{$pattern};
+	}
+	$xmlstring = &unicode_subst($xmlstring, $pattern, $unicode);
+    }
+
+    foreach my $pattern (keys(%unicode_harpoons)) {
+        $xmlstring = &unicode_subst($xmlstring, $pattern, $unicode_harpoons{$pattern});
+    }
 
-    &Apache::lonxml::end_alarm();
     return ($xmlstring,$errorstring);
 }
 
@@ -214,77 +309,35 @@ sub MathJax_converted {
     #}
 }
 
-
-sub jsMath_converted {
-    my $texstring=shift;
-    my $tag='span';
-    if (&displaystyle($texstring)) { $tag='div'; }
-    &clean_out_math_mode($texstring);
-    return &jsMath_header().
-	'<'.$tag.' class="math">'.$$texstring.'</'.$tag.'>';
-}
-
-{
-    my @jsMath_sent_header;
-    sub jsMath_reset {
-	undef(@jsMath_sent_header);
-    }
-    sub jsMath_push {
-	push(@jsMath_sent_header,0);
-    }
-    sub jsMath_header {
-	if (!@jsMath_sent_header) {
-	    &Apache::lonnet::logthis("mismatched calls of jsMath_header and jsMath_process");
-	    return '';
-	}
-	return '' if $jsMath_sent_header[-1];
-	$jsMath_sent_header[-1]=1;
-	return
-            '<script type="text/javascript">
-                     function NoFontMessage () {}
-                     jsMath = {Parser: {prototype: {environments: {\'eqnarray*\' :[\'Array\',null,null,\'rcl\',[5/18,5/18],3,\'D\']}}}};
-                   </script>'."\n".
-	    '<script type="text/javascript" src="/adm/jsMath/jsMath.js"></script>'."\n";
-    }
-    sub jsMath_process {
-	my $state = pop(@jsMath_sent_header);
-	return '' if !$state;
-	return "\n".
-	    '<script type="text/javascript">jsMath.Process()</script>'."\n";
-    }
-    sub jsMath_state {
-	my ($level) = @_;
-	return $jsMath_sent_header[$level];
-    }
-}
-
 sub tex_engine {
     if (exists($env{'form.texengine'})) {
 	if ($env{'form.texengine'} ne '') {
+            if (lc($env{'form.texengine'}) eq 'jsmath') {
+                return 'MathJax'; 
+            }
             return $env{'form.texengine'};
         }
     }    
     if ($env{'request.course.id'}
 	&& exists($env{'course.'.$env{'request.course.id'}.'.texengine'})) {
+        if (lc($env{'course.'.$env{'request.course.id'}.'.texengine'}) eq 'jsmath') {
+            return 'MathJax';
+        }
 	return $env{'course.'.$env{'request.course.id'}.'.texengine'};
     }
     if (exists($env{'environment.texengine'})) {
+        if (lc($env{'environment.texengine'}) eq 'jsmath') {
+            return 'MathJax';
+        }
 	return $env{'environment.texengine'};
     }
     return 'tth';
 }
 
 sub init_math_support {
-    my ($inherit_jsmath) = @_;
     &init_tth();
-    &Apache::lontexconvert::jsMath_push();
-    if (lc(&tex_engine()) eq 'jsmath' ||
-	($inherit_jsmath && &jsMath_state(-2))) {
-	return &Apache::lontexconvert::jsMath_header();
-    }
     &Apache::lontexconvert::MathJax_push();
-    if (lc(&tex_engine()) eq 'mathjax') { # ||
-        #($inherit_jsmath && &jsMath_state(-2))) {
+    if (lc(&tex_engine()) eq 'mathjax') {
         return &Apache::lontexconvert::MathJax_header();
     }
     return;
@@ -346,7 +399,7 @@ sub converted {
     if ($mode =~ /tth/i) {
 	return &tth_converted($string);
     } elsif ($mode =~ /jsmath/i) {
-	return &jsMath_converted($string);
+        return &MathJax_converted($string);
     } elsif ($mode =~ /mathjax/i) {
 	return &MathJax_converted($string);
     } elsif ($mode =~ /mimetex/i) {
@@ -428,7 +481,7 @@ sub msgtexconverted {
     foreach my $fragment (split(/(?:\&lt\;|\<)\/*algebra\s*(?:\&gt\;|\>)/i,
 				$message)) {
 	if ($tex) {
-        my $algebra = &algebra($fragment, 'web', undef, undef, undef, undef, 'tth');
+        my $algebra = &algebra($fragment, 'web', undef, undef, undef, 'tth');
 	    if ($email) {
 		$outmessage.='</pre><tt>'.$algebra.'</tt><pre>';
 		$tex=0;
@@ -495,7 +548,7 @@ sub postprocess_algebra {
     # $string =~s/\\fun/ /g;
 
     # sqrt(3,4) means the 4 root of 3
-    $string =~s/\\sqrt{([^,]+),([^\}]+)}/\\sqrt[$2]{$1}/gs;
+    $string =~s/\\sqrt\{([^,]+),([^\}]+)}/\\sqrt[$2]{$1}/gs;
 
     # log(3,4) means the log base 4 of 3
     $string =~s/\\log\\left\((.+?),(.+?)\\right\)/\\log_{$2}\\left($1\\right)/gs;
@@ -513,6 +566,8 @@ sub postprocess_algebra {
     $string =~s/\\lim\\left\((.+?),(.+?),(.+?)\\right\)/\\lim_{$2\\to $3}$1/gs;
     return $string;
 }
+
+
 1;
 __END__
 
@@ -555,14 +610,10 @@ Header
 =item displaystyle()
 
 
-=item jsMath_converted()
-
 =item MathJax_converted()
-	- Mimics the jsMath functionality
 
 =item tex_engine()
 
-
 =item init_math_support()
 
 =item mimetex_valign()