我有一份黑底白/黄字的PDF文件。
在打印之前如何去除黑色背景并将文字的颜色反转?
perl recolor.pl input.pdf '1 0 0 rg' '0 1 0 rg' out.pdf
#!/usr/bin/perl -w
use strict;
use CAM::PDF;
use CAM::PDF::Content;
my %COLOROPS = map {$_ => 1} qw(rg RG g G k K sc SC);
my $pdf = CAM::PDF->new(shift) || die $CAM::PDF::errstr;
my @oldcolors;
my @newcolors;
while (@ARGV >= 2) {
push @oldcolors, parseColor(shift);
push @newcolors, parseColor(shift);
}
my $out = shift || '-';
for my $p (1 .. $pdf->numPages) {
my $page = $pdf->getPageContentTree($p);
traverse($page->{blocks});
$pdf->setPageContent($p, $page->toString());
}
$pdf->cleanoutput($out);
sub parseColor {
my ($in) = @_;
my $ops = CAM::PDF::Content->new($in);
die 'Invalid color syntax in ' . $in if !$ops->validate();
my @blocks = @{$ops->{blocks}};
die 'Expected one color operator in ' . $in if @blocks != 1;
my $color = $blocks[0];
die 'Not a color operator in ' . $in if !exists $COLOROPS{$color->{name}};
return $color;
}
sub traverse {
my ($blocks) = @_;
for my $op (@{$blocks}) {
if ($op->{type} eq 'block') {
traverse($op->{value});
} elsif (exists $COLOROPS{$op->{name}}) {
COLOR:
for (my $i=0; $i < @oldcolors; ++$i) {
my $old = $oldcolors[$i];
if ($old->{name} eq $op->{name} && @{$old->{args}} == @{$op->{args}}) {
for (my $v=0; $v < @{$op->{args}}; ++$v) {
next COLOR if $old->{args}->[$v]->{value} != $op->{args}->[$v]->{value};
}
# match! so we will replace
$op->{name} = $newcolors[$i]->{name};
@{$op->{args}} = @{$newcolors[$i]->{args}};
last COLOR;
}
}
}
}
}