Math.php

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<?php
#
# Takes LaTeX fragments, sends them to a helper program (texvc) for rendering
# to rasterized PNG and HTML and MathML approximations. An appropriate
# rendering form is picked and returned.
#
# by Tomasz Wegrzanowski, with additions by Brion Vibber (2003, 2004)
#

class MathRenderer {
        var $mode = MW_MATH_MODERN;
        var $tex = "";
        var $inputhash = "";
        var $hash = "";
        var $html = "";
        var $mathml = "";
        var $conservativeness = 0;
        
        function MathRenderer( $tex ) {
                $this->tex = $tex;
        }
        
        function setOutputMode( $mode ) {
                $this->mode = $mode;
        }

        function render() {
                global $wgMathDirectory, $wgTmpDirectory, $wgInputEncoding;
                global $wgTexvc;
        
                if( $this->mode == MW_MATH_SOURCE ) {
                        # No need to render or parse anything more!
                        return ('$ '.htmlspecialchars( $this->tex ).' $');
                }
                
                if( !$this->_recall() ) {
                        # Ensure that the temp and output directories are available before continuing...
                        if( !file_exists( $wgMathDirectory ) ) {
                                if( !@mkdir( $wgMathDirectory ) ) {
                                        return $this->_error( "math_bad_output" );
                                }
                        } elseif( !is_dir( $wgMathDirectory ) || !is_writable( $wgMathDirectory ) ) {
                                return $this->_error( "math_bad_output" );
                        }
                        if( !file_exists( $wgTmpDirectory ) ) {
                                if( !@mkdir( $wgTmpDirectory ) ) {
                                        return $this->_error( "math_bad_tmpdir" );
                                }
                        } elseif( !is_dir( $wgTmpDirectory ) || !is_writable( $wgTmpDirectory ) ) {
                                return $this->_error( "math_bad_tmpdir" );
                        }
                        
                        if( !is_executable( $wgTexvc ) ) {
                                return $this->_error( "math_notexvc" );
                        }
                        $cmd = $wgTexvc." ".
                                escapeshellarg($wgTmpDirectory)." ".
                                escapeshellarg($wgMathDirectory)." ".
                                escapeshellarg($this->tex)." ".
                                escapeshellarg($wgInputEncoding);
                        wfDebug( "TeX: $cmd" );
                        $contents = `$cmd`;
                
                        if (strlen($contents) == 0) {
                                return $this->_error( "math_unknown_error" );
                        }
                        
                        $retval = substr ($contents, 0, 1);
                        if (($retval == "C") || ($retval == "M") || ($retval == "L")) {
                                if ($retval == "C")
                                        $this->conservativeness = 2;
                                else if ($retval == "M")
                                        $this->conservativeness = 1;
                                else
                                        $this->conservativeness = 0;
                                $outdata = substr ($contents, 33);
                
                                $i = strpos($outdata, "\000");
                
                                $this->html = substr($outdata, 0, $i);
                                $this->mathml = substr($outdata, $i+1);
                
                                $sql_html = "'".wfStrencode($this->html)."'";
                                $sql_mathml = "'".wfStrencode($this->mathml)."'";
                        } else if (($retval == "c") || ($retval == "m") || ($retval == "l"))  {
                                $this->html = substr ($contents, 33);
                                if ($retval == "c")
                                        $this->conservativeness = 2;
                                else if ($retval == "m")
                                        $this->conservativeness = 1;
                                else
                                        $this->conservativeness = 0;
                                $sql_html = "'".wfStrencode($this->html)."'";
                                $this->mathml = '';
                                $sql_mathml = 'NULL';
                        } else if ($retval == "X") {
                                $outhtml = '';
                                $this->mathml = substr ($contents, 33);
                                $sql_html = 'NULL';
                                $sql_mathml = "'".wfStrencode($this->mathml)."'";
                                $this->conservativeness = 0;
                        } else if ($retval == "+") {
                                $this->outhtml = '';
                                $this->mathml = '';
                                $sql_html = 'NULL';
                                $sql_mathml = 'NULL';
                                $this->conservativeness = 0;
                        } else {
                                $errbit = htmlspecialchars( substr($contents, 1) );
                                switch( $retval ) {
                                        case "E": return $this->_error( "math_lexing_error", $errbit );
                                        case "S": return $this->_error( "math_syntax_error", $errbit );
                                        case "F": return $this->_error( "math_unknown_function", $errbit );
                                        default:  return $this->_error( "math_unknown_error", $errbit );
                                }
                        }
                
                        $this->hash = substr ($contents, 1, 32);
                        if (!preg_match("/^[a-f0-9]{32}$/", $this->hash)) {
                                return $this->_error( "math_unknown_error" );
                        }
                
                        if( !file_exists( "$wgMathDirectory/{$this->hash}.png" ) ) {
                                return $this->_error( "math_image_error" );
                        }
                        
                        # Now save it back to the DB:
                        $outmd5_sql = wfStrencode(pack("H32", $this->hash));
                
                        $md5_sql = wfStrencode( pack("H32", $this->md5) ); # Binary packed, not hex
                        $sql = "REPLACE INTO math VALUES ('".$md5_sql."', '".$outmd5_sql."', ".$this->conservativeness.", ".$sql_html.", ".$sql_mathml.")";
                        
                        $res = wfQuery( $sql, DB_WRITE, "MathRenderer::render" );
                        # we don't really care if it fails
                }
                
                return $this->_doRender();
        }
        
        function _error( $msg, $append = "" ) {
                $mf   = htmlspecialchars( wfMsg( "math_failure" ) );
                $munk = htmlspecialchars( wfMsg( "math_unknown_error" ) );
                $errmsg = htmlspecialchars( wfMsg( $msg ) );
                $source = htmlspecialchars($this->tex);
                return "<strong class='error'>$mf ($errmsg$append): $source</strong>\n";
        }
        
        function _recall() {
                global $wgMathDirectory;
                
                $this->md5 = md5( $this->tex );
                
                $md5_sql = wfStrencode( pack("H32", $this->md5) ); # Binary packed, not hex
                $sql = "SELECT math_outputhash,math_html_conservativeness,math_html,math_mathml FROM math WHERE math_inputhash = '$md5_sql'";
                $res = wfQuery( $sql, DB_READ, "MathRenderer::_recall" );
                
                if( $rpage = wfFetchObject ( $res ) ) {
                        # Tailing 0x20s can get dropped by the database, add it back on if necessary:
                        $xhash = unpack( "H32md5", $rpage->math_outputhash . "                " );
                        $this->hash = $xhash ['md5'];
                        
                        $this->conservativeness = $rpage->math_html_conservativeness;
                        $this->html = $rpage->math_html;
                        $this->mathml = $rpage->math_mathml;
                        
                        if( file_exists( "$wgMathDirectory/{$this->hash}.png" ) ) {
                                return true;
                        }
                }
                
                # Missing from the database and/or the render cache
                return false;
        }

        # Select among PNG, HTML, or MathML output depending on 
        function _doRender() {
                if( $this->mode == MW_MATH_MATHML && $this->mathml != '' ) {
                        return "<math xmlns='http://www.w3.org/1998/Math/MathML'>{$this->mathml}</math>";
                }
                if (($this->mode == MW_MATH_PNG) || ($this->html == '') ||
                   (($this->mode == MW_MATH_SIMPLE) && ($this->conservativeness != 2)) ||
                   (($this->mode == MW_MATH_MODERN || $this->mode == MW_MATH_MATHML) && ($this->conservativeness == 0))) {
                        return $this->_linkToMathImage();
                } else {
                        return '<span class="texhtml">'.$this->html.'</span>';
                }
        }

        function _linkToMathImage() {
                global $wgMathPath;
                $url = htmlspecialchars( "$wgMathPath/{$this->hash}.png" );
                $alt = trim(str_replace("\n", ' ', htmlspecialchars( $this->tex )));
                return "<img class='tex' src=\"$url\" alt=\"$alt\" />";
        }

}

function renderMath( $tex ) {
        global $wgUser;
        $math = new MathRenderer( $tex );
        $math->setOutputMode( $wgUser->getOption("math"));
        return $math->render();
}

?>

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