path: root/IkiWiki/Plugin/teximg.pm

#!/usr/bin/perl
# Licensed under GPL v2 or greater
# (c) 2007 Patrick Winnertz <patrick.winnertz@skolelinux.org>

package IkiWiki::Plugin::teximg;
use warnings;
use strict;
use Digest::MD5 qw(md5_hex);
use File::Temp qw(tempdir);
use HTML::Entities;
use IkiWiki 2.00;

my $default_prefix = <<EOPREFIX;
\\documentclass{article}
\\usepackage{amsmath}
\\usepackage{amsfonts}
\\usepackage{amssymb}
\\pagestyle{empty}
\\begin{document}
EOPREFIX

my $default_postfix = '\\end{document}';

sub import {
    hook(type => "getsetup", id => "teximg", call => \&getsetup);
    hook(type => "preprocess", id => "teximg", call => \&preprocess);
}

sub getsetup () {
    return
        plugin => {
            safe => 1,
            rebuild => undef,
        },
        teximg_dvipng => {
            type => "boolean",
            description => "Should teximg use dvipng to render, or dvips and convert?",
            safe => 0,
            rebuild => undef,
        },
        teximg_prefix => {
            type => "string",
            example => $default_prefix,
            description => "LaTeX prefix for teximg plugin",
            safe => 0, # Not sure how secure LaTeX is...
            rebuild => 1,
        },
        teximg_postfix => {
            type => "string",
            example => $default_postfix,
            description => "LaTeX postfix for teximg plugin",
            safe => 0, # Not sure how secure LaTeX is...
            rebuild => 1,
        },
}

sub preprocess (@) {
    my %params = @_;
    
    my $height = $params{height};
    if (! defined $height || ! length $height) {
        $height = 12;
    }
    else {
        $height =~ s#(\d+)#$1#;
    }
    
    my $code = $params{code};
    if (! defined $code && ! length $code) {
        error gettext("missing tex code");
    }

    if (check($code)) {
        return create($code, check_height($height), \%params);
    }
    else {
        error gettext("code includes disallowed latex commands")
    }
}

sub check_height ($) {
    # Since latex doesn't support unlimited scaling this function
    # returns the closest supported size.
    my $height =shift;

    my @allowed=(8,9,10,11,12,14,17,20);

    my $ret;
    my $fit;
    foreach my $val (@allowed) {
        my $f = abs($val - $height);
        if (! defined($fit) || $f < $fit ) {
            $ret=$val;
            $fit=$f;
        }
    }
    return $ret;
}

sub create ($$$) {
    # This function calls the image generating function and returns
    # the <img .. /> for the generated image.
    my $code = shift;
    my $height = shift;
    my $params = shift;

    if (! defined($height) and not length($height) ) {
        $height = 12;
    }

    my $digest = md5_hex($code, $height);

    my $imglink= $params->{page} . "/$digest.png";
    my $imglog =  $params->{page} .  "/$digest.log";
    will_render($params->{page}, $imglink);
    will_render($params->{page}, $imglog);

    my $imgurl=urlto($imglink, $params->{destpage});
    my $logurl=urlto($imglog, $params->{destpage});
    
    if (-e "$config{destdir}/$imglink" ||
        gen_image($code, $height, $digest, $params->{page})) {
        return qq{<img src="$imgurl" alt="}
            .(exists $params->{alt} ? $params->{alt} : encode_entities($code))
            .qq{" class="teximg" />};
    }
    else {
        error qq{<a href="$logurl">}.gettext("failed to generate image from code")."</a>";
    }
}

sub gen_image ($$$$) {
    # Actually creates the image.
    my $code = shift;
    my $height = shift;
    my $digest = shift;
    my $imagedir = shift;

    if (!defined $config{teximg_prefix}) {
        $config{teximg_prefix} = $default_prefix;
    }
    if (!defined $config{teximg_postfix}) {
        $config{teximg_postfix} = $default_postfix;
    }
    if (!defined $config{teximg_dvipng}) {
        $config{teximg_dvipng} = length `which dvipng 2>/dev/null`;
    }
    
    my $tex = $config{teximg_prefix};
    $tex .= '$$'.$code.'$$';
    $tex .= $config{teximg_postfix};
    $tex =~ s!\\documentclass{article}!\\documentclass[${height}pt]{article}!g;
    $tex =~ s!\\documentclass{scrartcl}!\\documentclass[${height}pt]{scrartcl}!g;

    my $tmp = eval { create_tmp_dir($digest) };
    if (! $@ &&
        writefile("$digest.tex", $tmp, $tex) &&
        system("cd $tmp; latex --interaction=nonstopmode $tmp/$digest.tex > /dev/null") == 0 &&
        # ensure destination directory exists
        writefile("$imagedir/$digest.png", $config{destdir}, "") &&
        (($config{teximg_dvipng} &&
            system("dvipng -D 120 -bg Transparent -T tight -o $config{destdir}/$imagedir/$digest.png $tmp/$digest.dvi > $tmp/$digest.log") == 0
        ) || (!$config{teximg_dvipng} &&
            system("dvips -E $tmp/$digest.dvi -o $tmp/$digest.ps 2> $tmp/$digest.log") == 0 &&
            system("convert -density 120  -trim -transparent \"#FFFFFF\" $tmp/$digest.ps $config{destdir}/$imagedir/$digest.png > $tmp/$digest.log") == 0
        ))) {
        return 1;
    }
    else {
        # store failure log
        my $log="";
        {
            if (open(my $f, '<', "$tmp/$digest.log")) {
                local $/=undef;
                $log = <$f>;
                close($f);
            }
        }
        writefile("$digest.log", "$config{destdir}/$imagedir", $log);

        return 0;
    }
}

sub create_tmp_dir ($) {
    # Create a temp directory, it will be removed when ikiwiki exits.
    my $base = shift;

    my $template = $base.".XXXXXXXXXX";
    my $tmpdir = tempdir($template, TMPDIR => 1, CLEANUP => 1);
    return $tmpdir;
}

sub check ($) {
    # Check if the code is ok
    my $code = shift;

    my @badthings = (
        qr/\$\$/,
        qr/\\include/,
        qr/\\includegraphic/,
        qr/\\usepackage/,
        qr/\\newcommand/, 
        qr/\\renewcommand/,
        qr/\\def/,
        qr/\\input/,
        qr/\\open/,
        qr/\\loop/,
        qr/\\errorstopmode/,
        qr/\\scrollmode/,
        qr/\\batchmode/,
        qr/\\read/,
        qr/\\write/,
    );
    
    foreach my $thing (@badthings) {
        if ($code =~ m/$thing/ ) {
            return 0;
        }
    }
    return 1;
}

1