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Add pdf_file_data(), rewrite write_pdf().
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@deven
deven committed Dec 14, 2020
1 parent 6b56333 commit 1351b84
Showing 1 changed file with 80 additions and 54 deletions.
134 changes: 80 additions & 54 deletions lib/PDF/Data.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,9 @@ use List::Util qw[max];
use POSIX qw[mktime strftime];
use Scalar::Util qw[blessed reftype];

# Use byte strings instead of Unicode character strings.
use bytes;

# Basic parsing regular expressions.
our $n = qr/(?:\n|\r\n?)/; # Match a newline. (LF, CRLF or CR)
our $ws = qr/(?:(?:(?>%[^\r\n]*)?\s+)+)/; # Match whitespace, including PDF comments.
Expand Down Expand Up @@ -180,6 +183,30 @@ sub read_pdf {
sub write_pdf {
my ($self, $file) = @_;

# Generate PDF file data.
my $pdf_data = $self->pdf_file_data;

# Check if standard output is wanted.
if ($file eq "-") {
# Write PDF file data to standard output.
binmode STDOUT or croak "<standard output>: $!\n";
print STDOUT $pdf_data or croak "<standard output>: $!\n";
} else {
# Write PDF file data to specified output file.
open my $OUT, ">", $file or croak "$file $!\n";
binmode $OUT or croak "$file $!\n";
print $OUT $pdf_data or croak "$file $!\n";
close $OUT or croak "$file $!\n";

# Print success message.
print STDERR "Wrote new PDF file \"$file\".\n\n";
}
}

# Generate PDF file data suitable for writing to an output PDF file.
sub pdf_file_data {
my $self = shift;

# Validate the PDF structure.
$self->validate;

Expand All @@ -189,44 +216,35 @@ sub write_pdf {
# Array of indirect objects, with lookup hash as first element.
my $objects = [{}];

# Objects seen while writing the PDF file.
# Objects seen while generating the PDF file data.
my $seen = {};

# Use "stdout" instead of "-" to describe standard input.
my $filename = $file =~ s/^-$/stdout/r;

# Open output file.
open my $OUT, ">$file" or croak "$filename: $!\n";
# Start with PDF header.
my $pdf_file_data = "%PDF-1.4\n%\xBF\xF7\xA2\xFE\n\n";

# Write PDF header.
print $OUT "%PDF-1.4\n%\xBF\xF7\xA2\xFE\n\n";
# Write all indirect objects.
my $xrefs = $self->write_indirect_objects(\$pdf_file_data, $objects, $seen);

# Write all indirect objects to PDF file.
my $xrefs = $self->write_indirect_objects($OUT, $objects, $seen);

# Write cross-reference table.
my $startxref = tell $OUT;
printf $OUT "xref\n0 %d\n", scalar @{$xrefs};
print $OUT @{$xrefs};
# Add cross-reference table.
my $startxref = length($pdf_file_data);
$pdf_file_data .= sprintf "xref\n0 %d\n", scalar @{$xrefs};
$pdf_file_data .= @{$xrefs};

# Save correct size in trailer dictionary.
$self->{Size} = scalar @{$xrefs};

# Write trailer dictionary.
print $OUT "trailer ";
$self->write_object($OUT, $objects, $seen, $self, 0);
$pdf_file_data .= "trailer ";
$self->write_object(\$pdf_file_data, $objects, $seen, $self, 0);

# Write startxref value.
print $OUT "startxref\n$startxref\n";
$pdf_file_data .= "startxref\n$startxref\n";

# End of PDF file.
print $OUT "%%EOF\n";
# End of PDF file data.
$pdf_file_data .= "%%EOF\n";

# Close the output file.
close $OUT or croak "$filename: $!\n";

# Print success message.
print STDERR "Wrote new PDF file \"$file\".\n\n" unless $file eq "-";
# Return PDF file data.
return $pdf_file_data;
}

# Dump internal structure of PDF file.
Expand Down Expand Up @@ -568,9 +586,9 @@ sub resolve_references {
return $object;
}

# Write all indirect objects to PDF file.
# Write all indirect objects to PDF file data.
sub write_indirect_objects {
my ($self, $OUT, $objects, $seen) = @_;
my ($self, $pdf_file_data, $objects, $seen) = @_;

# Enumerate all indirect objects.
$self->enumerate_indirect_objects($objects);
Expand All @@ -581,16 +599,16 @@ sub write_indirect_objects {
# Loop across indirect objects.
for (my $i = 1; $i <= $#{$objects}; $i++) {
# Save file offset for cross-reference table.
push @{$xrefs}, sprintf "%010d 00000 n \n", tell $OUT;
push @{$xrefs}, sprintf "%010d 00000 n \n", length(${$pdf_file_data});

# Write the indirect object header.
print $OUT "$i 0 obj\n";
${$pdf_file_data} .= "$i 0 obj\n";

# Write the object itself.
$self->write_object($OUT, $objects, $seen, $objects->[$i], 0);
$self->write_object($pdf_file_data, $objects, $seen, $objects->[$i], 0);

# Write the indirect object trailer.
print $OUT "endobj\n\n";
${$pdf_file_data} .= "endobj\n\n";
}

# Return cross-reference file offsets.
Expand Down Expand Up @@ -710,9 +728,9 @@ sub add_indirect_objects {
}
}

# Write a direct object to the PDF file.
# Write a direct object to the string of PDF file data.
sub write_object {
my ($self, $OUT, $objects, $seen, $object, $indent) = @_;
my ($self, $pdf_file_data, $objects, $seen, $object, $indent) = @_;

# Make sure the same object isn't written twice.
if (ref $object and $seen->{$object}++) {
Expand All @@ -725,59 +743,59 @@ sub write_object {
$object->{Length} = length $object->{-data} if exists $object->{-data};

# Dictionary object.
print $OUT "<<\n";
${$pdf_file_data} .= "<<\n";
foreach my $key (sort { fc($a) cmp fc($b) || $a cmp $b; } keys %{$object}) {
next if $key =~ /^-/;
my $obj = $object->{$key};
$self->add_indirect_objects($objects, $obj) if is_stream $obj;
print $OUT " " x ($indent + 2), "/$key ";
${$pdf_file_data} .= join "", " " x ($indent + 2), "/$key ";
if (not ref $obj) {
print $OUT "$obj\n";
${$pdf_file_data} .= "$obj\n";
} elsif ($objects->[0]{$obj}) {
print $OUT "$objects->[0]{$obj} 0 R\n";
${$pdf_file_data} .= "$objects->[0]{$obj} 0 R\n";
} else {
$self->write_object($OUT, $objects, $seen, $object->{$key}, ref $object ? $indent + 2 : 0);
$self->write_object($pdf_file_data, $objects, $seen, $object->{$key}, ref $object ? $indent + 2 : 0);
}
}
print $OUT " " x $indent, ">>\n";
${$pdf_file_data} .= join "", " " x $indent, ">>\n";

# For streams, write the stream data.
if (exists $object->{-data}) {
croak "Stream written as direct object!\n" if $indent;
my $newline = substr($object->{-data}, -1) eq "\n" ? "" : "\n";
print $OUT "stream\n$object->{-data}${newline}endstream\n";
${$pdf_file_data} .= "stream\n$object->{-data}${newline}endstream\n";
}
} elsif (is_array $object and not grep { ref $_; } @{$object}) {
# Array of simple objects.
print $OUT "[ @{$object} ]\n";
${$pdf_file_data} .= "[ @{$object} ]\n";
} elsif (is_array $object) {
# Array object.
print $OUT "[\n";
${$pdf_file_data} .= "[\n";
my $spaces = " " x ($indent + 2);
foreach my $obj (@{$object}) {
$self->add_indirect_objects($objects, $obj) if is_stream $obj;
print $OUT $spaces;
${$pdf_file_data} .= $spaces;
if (not ref $obj) {
print $OUT $obj;
${$pdf_file_data} .= $obj;
$spaces = " ";
} elsif ($objects->[0]{$obj}) {
print $OUT "$objects->[0]{$obj} 0 R\n";
${$pdf_file_data} .= "$objects->[0]{$obj} 0 R\n";
$spaces = " " x ($indent + 2);
} else {
$self->write_object($OUT, $objects, $seen, $obj, $indent + 2);
$self->write_object($pdf_file_data, $objects, $seen, $obj, $indent + 2);
$spaces = " " x ($indent + 2);
}
}
print $OUT "\n" if $spaces eq " ";
print $OUT " " x $indent, "]\n";
${$pdf_file_data} .= "\n" if $spaces eq " ";
${$pdf_file_data} .= join "", " " x $indent, "]\n";
} elsif (reftype($object) eq "SCALAR") {
# Unresolved indirect reference.
my ($id, $gen) = split /-/, ${$object};
$gen ||= "0";
print $OUT " " x $indent, "($id $gen R)\n";
${$pdf_file_data} .= join "", " " x $indent, "($id $gen R)\n";
} else {
# Simple object.
print $OUT " " x $indent, "$object\n";
${$pdf_file_data} .= join "", " " x $indent, "$object\n";
}
}

Expand Down Expand Up @@ -962,6 +980,13 @@ Read and parse a PDF file, returning a new object instance.
Generate and write a new PDF file from the current state of the PDF data.
=head2 pdf_file_data
Generate PDF file data from the current state of the PDF data structure,
suitable for writing to an output PDF file. This method is used by the
C<write_pdf()> method to generate the raw string of bytes to be written
to the output PDF file.
=head2 dump_pdf
$pdf->dump_pdf($file);
Expand Down Expand Up @@ -1040,9 +1065,10 @@ direct references to the objects in question.
=head2 write_indirect_objects
my $xrefs = $pdf->write_indirect_objects($OUT, $objects, $seen);
my $xrefs = $pdf->write_indirect_objects($pdf_file_data, $objects, $seen);
Used by write_pdf() to write all indirect objects to a new PDF file.
Used by write_pdf() to write all indirect objects to a string of new
PDF file data.
=head2 enumerate_indirect_objects
Expand All @@ -1067,10 +1093,10 @@ add objects to the list of indirect objects to be written out.
=head2 write_object
$pdf->write_object($OUT, $objects, $seen, $object, $indent);
$pdf->write_object($pdf_file_data, $objects, $seen, $object, $indent);
Used by write_indirect_objects(), and called by itself recursively, to
write direct objects out to the PDF file.
write direct objects out to the string of new PDF file data.
=head2 dump_object
Expand Down

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