Math.php

Original mediawiki 1.4.7 version, after making the changes described in [1], in the section 'HOW TO MAKE FONT-SIZED PNGs'.

<?php
/**
 * Contain everything related to <math> </math> parsing
 * @package MediaWiki
 */

/**
 * 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)
 *
 * @package MediaWiki
 */
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;
        $fname = 'MathRenderer::render';

        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 = $wgTexvc.' '.
                wfEscapeShellArg($wgTmpDirectory).' '.
                wfEscapeShellArg($wgMathDirectory).' '.
                wfEscapeShellArg($this->tex).' '.
                wfEscapeShellArg($wgInputEncoding);
            wfDebug( 'TeX: '.$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, $i+1);
            } else if (($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;
                $this->mathml = NULL;
            } else if ($retval == 'X') {
                $this->html = NULL;
                $this->mathml = substr ($contents, 33);
                $this->conservativeness = 0;
            } else if ($retval == '+') {
                $this->html = NULL;
                $this->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:
            if ( !wfReadOnly() ) {
                $outmd5_sql = pack('H32', $this->hash);

                $md5_sql = pack('H32', $this->md5); # Binary packed, not hex

                $dbw =& wfGetDB( DB_MASTER );
                $dbw->replace( 'math', array( 'math_inputhash' ),
                  array(
                    'math_inputhash' => $md5_sql,
                    'math_outputhash' => $outmd5_sql,
                    'math_html_conservativeness' => $this->conservativeness,
                    'math_html' => $this->html,
                    'math_mathml' => $this->mathml,
                  ), $fname, array( 'IGNORE' )
                );
            }

        }

        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;
        $fname = 'MathRenderer::_recall';

        $this->md5 = md5( $this->tex );
        $dbr =& wfGetDB( DB_SLAVE );
        $rpage = $dbr->selectRow( 'math',
            array( 'math_outputhash','math_html_conservativeness','math_html','math_mathml' ),
            array( 'math_inputhash' => pack("H32", $this->md5)), # Binary packed, not hex
            $fname
        );

        if( $rpage !== false ) {
            # 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, $wgMathDirectory;
                $url = htmlspecialchars( "$wgMathPath/{$this->hash}.png" );
                $alt = trim(str_replace("\n", ' ', htmlspecialchars( $this->tex )));
#               return "<img class='tex' src=\"$url\" alt=\"$alt\" />";

                $wgGetTexImageHeightInEx = './math/getTexImageHeightInEx.sh';
                $cmd = $wgGetTexImageHeightInEx.' '.
                        wfEscapeShellArg( "$wgMathDirectory/{$this->hash}.png" );
                $heightInEx = chop(`$cmd`)."ex";
                return "<img class='tex' src=\"$url\" alt=\"$alt\" style=\"height:$heightInEx\" />";
    }

}

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

?>