#------------------------------------------------------------------------------
# File: WritePNG.pl
#
# Description: Write PNG meta information
#
# Revisions: 09/16/2005 - P. Harvey Created
#
# References: 1) http://www.libpng.org/pub/png/spec/1.2/
#------------------------------------------------------------------------------
package Image::ExifTool::PNG;
use strict;
#------------------------------------------------------------------------------
# Calculate CRC or update running CRC (ref 1)
# Inputs: 0) data reference, 1) running crc to update (undef intially)
# 2) data position (undef for 0), 3) data length (undef for all data),
# Returns: updated CRC
my @crcTable;
sub CalculateCRC($;$$$)
{
my ($dataPt, $crc, $pos, $len) = @_;
$crc = 0 unless defined $crc;
$pos = 0 unless defined $pos;
$len = length($$dataPt) - $pos unless defined $len;
$crc ^= 0xffffffff; # undo 1's complement
# build lookup table unless done already
unless (@crcTable) {
my ($c, $n, $k);
for ($n=0; $n<256; ++$n) {
for ($k=0, $c=$n; $k<8; ++$k) {
$c = ($c & 1) ? 0xedb88320 ^ ($c >> 1) : $c >> 1;
}
$crcTable[$n] = $c;
}
}
# calculate the CRC
foreach (unpack("x${pos}C$len", $$dataPt)) {
$crc = $crcTable[($crc^$_) & 0xff] ^ ($crc >> 8);
}
return $crc ^ 0xffffffff; # return 1's complement
}
#------------------------------------------------------------------------------
# Encode data in ASCII Hex
# Inputs: 0) input data reference
# Returns: Hex-encoded data (max 72 chars per line)
sub HexEncode($)
{
my $dataPt = shift;
my $len = length($$dataPt);
my $hex = '';
my $pos;
for ($pos = 0; $pos < $len; $pos += 36) {
my $n = $len - $pos;
$n > 36 and $n = 36;
$hex .= unpack('H*',substr($$dataPt,$pos,$n)) . "\n";
}
return $hex;
}
#------------------------------------------------------------------------------
# Write profile to tEXt or zTXt chunk (zTXt if Zlib is available)
# Inputs: 0) outfile, 1) Raw profile type, 2) data ref
# 3) profile header type (undef if not a text profile)
# Returns: 1 on success
sub WriteProfile($$$;$)
{
my ($outfile, $rawType, $dataPt, $profile) = @_;
my ($buff, $prefix, $chunk, $deflate);
if (eval { require Compress::Zlib }) {
$deflate = Compress::Zlib::deflateInit();
}
if (not defined $profile) {
# write ICC profile as compressed iCCP chunk if possible
return 0 unless $deflate;
$buff = $deflate->deflate($$dataPt);
return 0 unless defined $buff;
$buff .= $deflate->flush();
my %rawTypeChunk = ( icm => 'iCCP' );
$chunk = $rawTypeChunk{$rawType} or return 0;
$prefix = "$rawType\0\0";
$dataPt = \$buff;
} else {
# write as ASCII-hex encoded profile in tEXt or zTXt chunk
my $txtHdr = sprintf("\n$profile profile\n%8d\n", length($$dataPt));
$buff = $txtHdr . HexEncode($dataPt);
$chunk = 'tEXt'; # write as tEXt if deflate not available
$prefix = "Raw profile type $rawType\0";
$dataPt = \$buff;
# write profile as zTXt chunk if possible
if ($deflate) {
my $buf2 = $deflate->deflate($buff);
if (defined $buf2) {
$dataPt = \$buf2;
$buf2 .= $deflate->flush();
$chunk = 'zTXt';
$prefix .= "\0"; # compression type byte (0=deflate)
}
}
}
my $hdr = pack('Na4', length($prefix) + length($$dataPt), $chunk) . $prefix;
my $crc = CalculateCRC(\$hdr, undef, 4);
$crc = CalculateCRC($dataPt, $crc);
return Write($outfile, $hdr, $$dataPt, pack('N',$crc));
}
#------------------------------------------------------------------------------
# Add iCCP to the PNG image if necessary (must come before PLTE and IDAT)
# Inputs: 0) ExifTool object ref, 1) output file or scalar ref
# Returns: true on success
sub Add_iCCP($$)
{
my ($et, $outfile) = @_;
if ($$et{ADD_DIRS}{ICC_Profile}) {
# write new ICC data
my $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::ICC_Profile::Main');
my %dirInfo = ( Parent => 'PNG', DirName => 'ICC_Profile' );
my $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
if (defined $buff and length $buff and WriteProfile($outfile, 'icm', \$buff)) {
$et->VPrint(0, "Created ICC profile\n");
delete $$et{ADD_DIRS}{ICC_Profile}; # don't add it again
$$et{PNGDoneDir}{ICC_Profile} = 2;
}
}
return 1;
}
#------------------------------------------------------------------------------
# This routine is called after we edit an existing directory
# Inputs: 0) ExifTool ref, 1) dir name, 2) output data ref
# 3) flag set if location is non-standard (to update, but not create from scratch)
# - on return, $$outBuff is set to '' if the directory is to be deleted
sub DoneDir($$$;$)
{
my ($et, $dir, $outBuff, $nonStandard) = @_;
# don't add this directory again unless this is in a non-standard location
delete $$et{ADD_DIRS}{$dir} unless $nonStandard;
# handle problem with duplicate XMP when using PNGEarlyXMP option
return unless $dir eq 'XMP' and defined $$outBuff and length $$outBuff;
if ($nonStandard and $$et{DEL_GROUP}{$dir}) {
$et->VPrint(0," Deleting non-standard $dir\n");
$$outBuff = '';
} elsif (not $$et{PNGDoneDir}{$dir}) {
$$et{PNGDoneDir}{$dir} = 1; # set flag indicating the directory exists
} elsif ($$et{OPTIONS}{PNGEarlyXMP}) {
if ($$et{PNGDoneDir}{$dir} == 2) {
if ($$et{OPTIONS}{IgnoreMinorErrors}) {
$et->Warn("Deleted existing $dir");
} else {
$et->Error("Duplicate $dir created. Ignore to delete existing $dir", 1);
return;
}
} elsif ($et->Warn("Duplicate $dir. Ignore to delete", 2)) {
return; # warning not ignored: don't delete the duplicate
}
$et->VPrint(0," Deleting duplicate $dir\n");
$$outBuff = '';
}
}
#------------------------------------------------------------------------------
# Generate tEXt, zTXt or iTXt data for writing
# Inputs: 0) ExifTool ref, 1) tagID, 2) tagInfo ref, 3) value string, 4) language code
# Returns: chunk data (not including 8-byte chunk header)
# Notes: Sets ExifTool TextChunkType member to the type of chunk written
sub BuildTextChunk($$$$$)
{
my ($et, $tag, $tagInfo, $val, $lang) = @_;
my ($xtra, $compVal, $iTXt, $comp);
if ($$tagInfo{SubDirectory}) {
if ($$tagInfo{Name} eq 'XMP') {
$iTXt = 2; # write as iTXt but flag to avoid encoding
# (never compress XMP)
} else {
$comp = 2; # compress raw profile if possible
}
} else {
# compress if specified
$comp = 1 if $et->Options('Compress');
if ($lang) {
$iTXt = 1; # write as iTXt if it has a language code
$tag =~ s/-$lang$//; # remove language code from tagID
} elsif ($$et{OPTIONS}{Charset} ne 'Latin' and $val =~ /[\x80-\xff]/) {
$iTXt = 1; # write as iTXt if it contains non-Latin special characters
}
}
if ($comp) {
my $warn;
if (eval { require Compress::Zlib }) {
my $deflate = Compress::Zlib::deflateInit();
$compVal = $deflate->deflate($val) if $deflate;
if (defined $compVal) {
$compVal .= $deflate->flush();
# only compress if it actually saves space
unless (length($compVal) < length($val)) {
undef $compVal;
$warn = 'uncompressed data is smaller';
}
} else {
$warn = 'deflate error';
}
} else {
$warn = 'Compress::Zlib not available';
}
# warn if any user-specified compression fails
if ($warn and $comp == 1) {
$et->Warn("PNG:$$tagInfo{Name} not compressed ($warn)", 1);
}
}
# decide whether to write as iTXt, zTXt or tEXt
if ($iTXt) {
$$et{TextChunkType} = 'iTXt';
$xtra = (defined $compVal ? "\x01\0" : "\0\0") . ($lang || '') . "\0\0";
# iTXt is encoded as UTF-8 (but note that XMP is already UTF-8)
$val = $et->Encode($val, 'UTF8') if $iTXt == 1;
} elsif (defined $compVal) {
$$et{TextChunkType} = 'zTXt';
$xtra = "\0";
} else {
$$et{TextChunkType} = 'tEXt';
$xtra = '';
}
return $tag . "\0" . $xtra . (defined $compVal ? $compVal : $val);
}
#------------------------------------------------------------------------------
# Add any outstanding new chunks to the PNG image
# Inputs: 0) ExifTool object ref, 1) output file or scalar ref
# 2-N) dirs to add (empty to add all, including PNG tags)
# Returns: true on success
sub AddChunks($$;@)
{
my ($et, $outfile, @add) = @_;
my ($addTags, $tag, $dir, $err, $tagTablePtr);
if (@add) {
$addTags = { }; # don't add any PNG tags
} else {
$addTags = $$et{ADD_PNG}; # add all PNG tags...
delete $$et{ADD_PNG}; # ...once
# add all directories
@add = sort keys %{$$et{ADD_DIRS}};
}
# write any outstanding PNG tags
foreach $tag (sort keys %$addTags) {
my $tagInfo = $$addTags{$tag};
my $nvHash = $et->GetNewValueHash($tagInfo);
# (native PNG information is always preferred, so don't check IsCreating)
next unless $et->IsOverwriting($nvHash);
my $val = $et->GetNewValue($nvHash);
if (defined $val) {
next if $$nvHash{EditOnly};
my $data;
if ($$tagInfo{Table} eq \%Image::ExifTool::PNG::TextualData) {
$data = BuildTextChunk($et, $tag, $tagInfo, $val, $$tagInfo{LangCode});
$data = $$et{TextChunkType} . $data;
delete $$et{TextChunkType};
} else {
$data = "$tag$val";
}
my $hdr = pack('N', length($data) - 4);
my $cbuf = pack('N', CalculateCRC(\$data, undef));
Write($outfile, $hdr, $data, $cbuf) or $err = 1;
$et->VerboseValue("+ PNG:$$tagInfo{Name}", $val);
$$et{PNGDoneTag}{$tag} = 1; # set flag indicating this tag was added
++$$et{CHANGED};
}
}
# create any necessary directories
foreach $dir (@add) {
next unless $$et{ADD_DIRS}{$dir}; # make sure we want to add it first
my $buff;
my %dirInfo = (
Parent => 'PNG',
DirName => $dir,
);
if ($dir eq 'IFD0') {
$et->Warn('Creating non-standard EXIF in PNG', 1);
$et->VPrint(0, "Creating EXIF profile:\n");
$$et{TIFF_TYPE} = 'APP1';
$tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::Exif::Main');
$buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr, \&Image::ExifTool::WriteTIFF);
if (defined $buff and length $buff) {
$buff = $Image::ExifTool::exifAPP1hdr . $buff;
WriteProfile($outfile, 'APP1', \$buff, 'generic') or $err = 1;
}
} elsif ($dir eq 'XMP') {
$et->VPrint(0, "Creating XMP iTXt chunk:\n");
$tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::XMP::Main');
$dirInfo{ReadOnly} = 1;
$buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
if (defined $buff and length $buff and
# the packet is read-only (because of CRC)
Image::ExifTool::XMP::ValidateXMP(\$buff, 'r'))
{
# (previously, XMP was created as a non-standard XMP profile chunk)
# $buff = $Image::ExifTool::xmpAPP1hdr . $buff;
# WriteProfile($outfile, 'APP1', \$buff, 'generic') or $err = 1;
# (but now write XMP iTXt chunk according to XMP specification)
$buff = "iTXtXML:com.adobe.xmp\0\0\0\0\0" . $buff;
my $hdr = pack('N', length($buff) - 4);
my $cbuf = pack('N', CalculateCRC(\$buff, undef));
Write($outfile, $hdr, $buff, $cbuf) or $err = 1;
}
} elsif ($dir eq 'IPTC') {
$et->Warn('Creating non-standard EXIF in PNG', 1);
$et->VPrint(0, "Creating IPTC profile:\n");
# write new IPTC data (stored in a Photoshop directory)
$dirInfo{DirName} = 'Photoshop';
$tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::Photoshop::Main');
$buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
if (defined $buff and length $buff) {
WriteProfile($outfile, 'iptc', \$buff, 'IPTC') or $err = 1;
}
} elsif ($dir eq 'ICC_Profile') {
$et->VPrint(0, "Creating ICC profile:\n");
# write new ICC data (only done if we couldn't create iCCP chunk)
$tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::ICC_Profile::Main');
$buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
if (defined $buff and length $buff) {
WriteProfile($outfile, 'icm', \$buff, 'ICC') or $err = 1;
$et->Warn('Wrote ICC as a raw profile (no Compress::Zlib)');
}
} elsif ($dir eq 'PNG-pHYs') {
$et->VPrint(0, "Creating pHYs chunk:\n");
$tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::PNG::PhysicalPixel');
my $blank = "\0\0\x0b\x12\0\0\x0b\x12\x01"; # 2834 pixels per meter (72 dpi)
$dirInfo{DataPt} = \$blank;
$buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
if (defined $buff and length $buff) {
$buff = 'pHYs' . $buff; # CRC includes chunk name
my $hdr = pack('N', length($buff) - 4);
my $cbuf = pack('N', CalculateCRC(\$buff, undef));
Write($outfile, $hdr, $buff, $cbuf) or $err = 1;
}
} else {
next;
}
delete $$et{ADD_DIRS}{$dir}; # don't add again
# keep track of the directories that we added
$$et{PNGDoneDir}{$dir} = 2 if defined $buff and length $buff;
}
return not $err;
}
1; # end
__END__
=head1 NAME
Image::ExifTool::WritePNG.pl - Write PNG meta information
=head1 SYNOPSIS
These routines are autoloaded by Image::ExifTool::PNG.
=head1 DESCRIPTION
This file contains routines to write PNG metadata.
=head1 NOTES
Compress::Zlib is required to write compressed text.
Existing text tags are always rewritten in their original form (compressed
zTXt, uncompressed tEXt or international iTXt), so pre-existing compressed
information can only be modified if Compress::Zlib is available.
Newly created textual information is written in uncompressed tEXt form by
default, or as compressed zTXt if the Compress option is used and
Compress::Zlib is available (but only if the resulting compressed data is
smaller than the original text, which isn't always the case for short text
strings).
=head1 AUTHOR
Copyright 2003-2016, Phil Harvey (phil at owl.phy.queensu.ca)
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=head1 SEE ALSO
L<Image::ExifTool::PNG(3pm)|Image::ExifTool::PNG>,
L<Image::ExifTool(3pm)|Image::ExifTool>
=cut