| 1 | #------------------------------------------------------------------------------
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| 2 | # File: WritePNG.pl
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| 3 | #
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| 4 | # Description: Write PNG meta information
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| 5 | #
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| 6 | # Revisions: 09/16/2005 - P. Harvey Created
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| 7 | #
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| 8 | # References: 1) http://www.libpng.org/pub/png/spec/1.2/
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| 9 | #------------------------------------------------------------------------------
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| 10 | package Image::ExifTool::PNG;
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| 11 |
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| 12 | use strict;
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| 13 |
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| 14 | #------------------------------------------------------------------------------
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| 15 | # Calculate CRC or update running CRC (ref 1)
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| 16 | # Inputs: 0) data reference, 1) running crc to update (undef initially)
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| 17 | # 2) data position (undef for 0), 3) data length (undef for all data),
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| 18 | # Returns: updated CRC
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| 19 | my @crcTable;
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| 20 | sub CalculateCRC($;$$$)
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| 21 | {
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| 22 | my ($dataPt, $crc, $pos, $len) = @_;
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| 23 | $crc = 0 unless defined $crc;
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| 24 | $pos = 0 unless defined $pos;
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| 25 | $len = length($$dataPt) - $pos unless defined $len;
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| 26 | $crc ^= 0xffffffff; # undo 1's complement
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| 27 | # build lookup table unless done already
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| 28 | unless (@crcTable) {
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| 29 | my ($c, $n, $k);
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| 30 | for ($n=0; $n<256; ++$n) {
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| 31 | for ($k=0, $c=$n; $k<8; ++$k) {
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| 32 | $c = ($c & 1) ? 0xedb88320 ^ ($c >> 1) : $c >> 1;
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| 33 | }
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| 34 | $crcTable[$n] = $c;
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| 35 | }
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| 36 | }
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| 37 | # calculate the CRC
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| 38 | foreach (unpack("x${pos}C$len", $$dataPt)) {
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| 39 | $crc = $crcTable[($crc^$_) & 0xff] ^ ($crc >> 8);
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| 40 | }
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| 41 | return $crc ^ 0xffffffff; # return 1's complement
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| 42 | }
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| 43 |
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| 44 | #------------------------------------------------------------------------------
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| 45 | # Encode data in ASCII Hex
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| 46 | # Inputs: 0) input data reference
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| 47 | # Returns: Hex-encoded data (max 72 chars per line)
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| 48 | sub HexEncode($)
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| 49 | {
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| 50 | my $dataPt = shift;
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| 51 | my $len = length($$dataPt);
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| 52 | my $hex = '';
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| 53 | my $pos;
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| 54 | for ($pos = 0; $pos < $len; $pos += 36) {
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| 55 | my $n = $len - $pos;
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| 56 | $n > 36 and $n = 36;
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| 57 | $hex .= unpack('H*',substr($$dataPt,$pos,$n)) . "\n";
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| 58 | }
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| 59 | return $hex;
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| 60 | }
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| 61 |
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| 62 | #------------------------------------------------------------------------------
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| 63 | # Write profile chunk (possibly compressed if Zlib is available)
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| 64 | # Inputs: 0) outfile, 1) Raw profile type, 2) data ref
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| 65 | # 3) profile header type (undef if not a text profile)
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| 66 | # Returns: 1 on success
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| 67 | sub WriteProfile($$$;$)
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| 68 | {
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| 69 | my ($outfile, $rawType, $dataPt, $profile) = @_;
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| 70 | my ($buff, $prefix, $chunk, $deflate);
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| 71 | if ($rawType ne $stdCase{exif} and eval { require Compress::Zlib }) {
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| 72 | $deflate = Compress::Zlib::deflateInit();
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| 73 | }
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| 74 | if (not defined $profile) {
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| 75 | # write ICC profile as compressed iCCP chunk if possible
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| 76 | if ($rawType eq 'icm') {
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| 77 | return 0 unless $deflate;
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| 78 | $chunk = 'iCCP';
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| 79 | $prefix = "$rawType\0\0";
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| 80 | } else {
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| 81 | $chunk = $rawType;
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| 82 | if ($rawType eq $stdCase{zxif}) {
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| 83 | $prefix = "\0" . pack('N', length $$dataPt); # (proposed compressed EXIF)
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| 84 | } else {
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| 85 | $prefix = ''; # standard EXIF
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| 86 | }
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| 87 | }
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| 88 | if ($deflate) {
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| 89 | $buff = $deflate->deflate($$dataPt);
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| 90 | return 0 unless defined $buff;
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| 91 | $buff .= $deflate->flush();
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| 92 | $dataPt = \$buff;
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| 93 | }
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| 94 | } else {
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| 95 | # write as ASCII-hex encoded profile in tEXt or zTXt chunk
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| 96 | my $txtHdr = sprintf("\n$profile profile\n%8d\n", length($$dataPt));
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| 97 | $buff = $txtHdr . HexEncode($dataPt);
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| 98 | $chunk = 'tEXt'; # write as tEXt if deflate not available
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| 99 | $prefix = "Raw profile type $rawType\0";
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| 100 | $dataPt = \$buff;
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| 101 | # write profile as zTXt chunk if possible
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| 102 | if ($deflate) {
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| 103 | my $buf2 = $deflate->deflate($buff);
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| 104 | if (defined $buf2) {
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| 105 | $dataPt = \$buf2;
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| 106 | $buf2 .= $deflate->flush();
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| 107 | $chunk = 'zTXt';
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| 108 | $prefix .= "\0"; # compression type byte (0=deflate)
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| 109 | }
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| 110 | }
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| 111 | }
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| 112 | my $hdr = pack('Na4', length($prefix) + length($$dataPt), $chunk) . $prefix;
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| 113 | my $crc = CalculateCRC(\$hdr, undef, 4);
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| 114 | $crc = CalculateCRC($dataPt, $crc);
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| 115 | return Write($outfile, $hdr, $$dataPt, pack('N',$crc));
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| 116 | }
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| 117 |
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| 118 | #------------------------------------------------------------------------------
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| 119 | # Add iCCP chunk to the PNG image if necessary (must come before PLTE and IDAT)
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| 120 | # Inputs: 0) ExifTool object ref, 1) output file or scalar ref
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| 121 | # Returns: true on success
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| 122 | sub Add_iCCP($$)
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| 123 | {
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| 124 | my ($et, $outfile) = @_;
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| 125 | if ($$et{ADD_DIRS}{ICC_Profile}) {
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| 126 | # write new ICC data
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| 127 | my $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::ICC_Profile::Main');
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| 128 | my %dirInfo = ( Parent => 'PNG', DirName => 'ICC_Profile' );
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| 129 | my $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
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| 130 | if (defined $buff and length $buff and WriteProfile($outfile, 'icm', \$buff)) {
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| 131 | $et->VPrint(0, "Created ICC profile\n");
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| 132 | delete $$et{ADD_DIRS}{ICC_Profile}; # don't add it again
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| 133 | }
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| 134 | }
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| 135 | return 1;
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| 136 | }
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| 137 |
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| 138 | #------------------------------------------------------------------------------
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| 139 | # This routine is called after we edit an existing directory
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| 140 | # Inputs: 0) ExifTool ref, 1) dir name, 2) output data ref
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| 141 | # 3) flag set if location is non-standard (to update, but not create from scratch)
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| 142 | # - on return, $$outBuff is set to '' if the directory is to be deleted
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| 143 | sub DoneDir($$$;$)
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| 144 | {
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| 145 | my ($et, $dir, $outBuff, $nonStandard) = @_;
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| 146 | my $saveDir = $dir;
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| 147 | $dir = 'EXIF' if $dir eq 'IFD0';
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| 148 | # don't add this directory again unless this is in a non-standard location
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| 149 | if (not $nonStandard) {
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| 150 | delete $$et{ADD_DIRS}{$dir};
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| 151 | delete $$et{ADD_DIRS}{IFD0} if $dir eq 'EXIF';
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| 152 | } elsif ($$et{DEL_GROUP}{$dir} or $$et{DEL_GROUP}{$saveDir}) {
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| 153 | $et->VPrint(0," Deleting non-standard $dir\n");
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| 154 | $$outBuff = '';
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| 155 | }
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| 156 | }
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| 157 |
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| 158 | #------------------------------------------------------------------------------
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| 159 | # Generate tEXt, zTXt or iTXt data for writing
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| 160 | # Inputs: 0) ExifTool ref, 1) tagID, 2) tagInfo ref, 3) value string, 4) language code
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| 161 | # Returns: chunk data (not including 8-byte chunk header)
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| 162 | # Notes: Sets ExifTool TextChunkType member to the type of chunk written
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| 163 | sub BuildTextChunk($$$$$)
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| 164 | {
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| 165 | my ($et, $tag, $tagInfo, $val, $lang) = @_;
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| 166 | my ($xtra, $compVal, $iTXt, $comp);
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| 167 | if ($$tagInfo{SubDirectory}) {
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| 168 | if ($$tagInfo{Name} eq 'XMP') {
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| 169 | $iTXt = 2; # write as iTXt but flag to avoid encoding
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| 170 | # (never compress XMP)
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| 171 | } else {
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| 172 | $comp = 2; # compress raw profile if possible
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| 173 | }
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| 174 | } else {
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| 175 | # compress if specified
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| 176 | $comp = 1 if $et->Options('Compress');
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| 177 | if ($lang) {
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| 178 | $iTXt = 1; # write as iTXt if it has a language code
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| 179 | $tag =~ s/-$lang$//; # remove language code from tagID
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| 180 | } elsif ($$et{OPTIONS}{Charset} ne 'Latin' and $val =~ /[\x80-\xff]/) {
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| 181 | $iTXt = 1; # write as iTXt if it contains non-Latin special characters
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| 182 | }
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| 183 | }
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| 184 | if ($comp) {
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| 185 | my $warn;
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| 186 | if (eval { require Compress::Zlib }) {
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| 187 | my $deflate = Compress::Zlib::deflateInit();
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| 188 | $compVal = $deflate->deflate($val) if $deflate;
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| 189 | if (defined $compVal) {
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| 190 | $compVal .= $deflate->flush();
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| 191 | # only compress if it actually saves space
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| 192 | unless (length($compVal) < length($val)) {
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| 193 | undef $compVal;
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| 194 | $warn = 'uncompressed data is smaller';
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| 195 | }
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| 196 | } else {
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| 197 | $warn = 'deflate error';
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| 198 | }
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| 199 | } else {
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| 200 | $warn = 'Compress::Zlib not available';
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| 201 | }
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| 202 | # warn if any user-specified compression fails
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| 203 | if ($warn and $comp == 1) {
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| 204 | $et->Warn("PNG:$$tagInfo{Name} not compressed ($warn)", 1);
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| 205 | }
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| 206 | }
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| 207 | # decide whether to write as iTXt, zTXt or tEXt
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| 208 | if ($iTXt) {
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| 209 | $$et{TextChunkType} = 'iTXt';
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| 210 | $xtra = (defined $compVal ? "\x01\0" : "\0\0") . ($lang || '') . "\0\0";
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| 211 | # iTXt is encoded as UTF-8 (but note that XMP is already UTF-8)
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| 212 | $val = $et->Encode($val, 'UTF8') if $iTXt == 1;
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| 213 | } elsif (defined $compVal) {
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| 214 | $$et{TextChunkType} = 'zTXt';
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| 215 | $xtra = "\0";
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| 216 | } else {
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| 217 | $$et{TextChunkType} = 'tEXt';
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| 218 | $xtra = '';
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| 219 | }
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| 220 | return $tag . "\0" . $xtra . (defined $compVal ? $compVal : $val);
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| 221 | }
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| 222 |
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| 223 | #------------------------------------------------------------------------------
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| 224 | # Add any outstanding new chunks to the PNG image
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| 225 | # Inputs: 0) ExifTool object ref, 1) output file or scalar ref
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| 226 | # 2-N) dirs to add (empty to add all except EXIF 'IFD0', including PNG tags)
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| 227 | # Returns: true on success
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| 228 | sub AddChunks($$;@)
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| 229 | {
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| 230 | my ($et, $outfile, @add) = @_;
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| 231 | my ($addTags, $tag, $dir, $err, $tagTablePtr, $specified);
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| 232 |
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| 233 | if (@add) {
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| 234 | $addTags = { }; # don't add any PNG tags
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| 235 | $specified = 1;
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| 236 | } else {
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| 237 | $addTags = $$et{ADD_PNG}; # add all PNG tags...
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| 238 | delete $$et{ADD_PNG}; # ...once
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| 239 | # add all directories
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| 240 | @add = sort keys %{$$et{ADD_DIRS}};
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| 241 | }
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| 242 | # write any outstanding PNG tags
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| 243 | foreach $tag (sort keys %$addTags) {
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| 244 | my $tagInfo = $$addTags{$tag};
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| 245 | my $nvHash = $et->GetNewValueHash($tagInfo);
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| 246 | # (native PNG information is always preferred, so don't check IsCreating)
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| 247 | next unless $et->IsOverwriting($nvHash);
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| 248 | my $val = $et->GetNewValue($nvHash);
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| 249 | if (defined $val) {
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| 250 | next if $$nvHash{EditOnly};
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| 251 | my $data;
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| 252 | if ($$tagInfo{Table} eq \%Image::ExifTool::PNG::TextualData) {
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| 253 | $data = BuildTextChunk($et, $tag, $tagInfo, $val, $$tagInfo{LangCode});
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| 254 | $data = $$et{TextChunkType} . $data;
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| 255 | delete $$et{TextChunkType};
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| 256 | } else {
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| 257 | $data = "$tag$val";
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| 258 | }
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| 259 | my $hdr = pack('N', length($data) - 4);
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| 260 | my $cbuf = pack('N', CalculateCRC(\$data, undef));
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| 261 | Write($outfile, $hdr, $data, $cbuf) or $err = 1;
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| 262 | $et->VerboseValue("+ PNG:$$tagInfo{Name}", $val);
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| 263 | ++$$et{CHANGED};
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| 264 | }
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| 265 | }
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| 266 | # create any necessary directories
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| 267 | foreach $dir (@add) {
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| 268 | next unless $$et{ADD_DIRS}{$dir}; # make sure we want to add it first
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| 269 | my $buff;
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| 270 | my %dirInfo = (
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| 271 | Parent => 'PNG',
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| 272 | DirName => $dir,
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| 273 | );
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| 274 | if ($dir eq 'IFD0') {
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| 275 | next unless $specified; # wait until specifically asked to write EXIF 'IFD0'
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| 276 | my $chunk = $stdCase{exif};
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| 277 | # (zxIf was not adopted)
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| 278 | #if ($et->Options('Compress')) {
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| 279 | # if (eval { require Compress::Zlib }) {
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| 280 | # $chunk = $stdCase{zxif};
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| 281 | # } else {
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| 282 | # $et->Warn("Creating uncompressed $stdCase{exif} chunk (Compress::Zlib not available)");
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| 283 | # }
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| 284 | #}
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| 285 | $et->VPrint(0, "Creating $chunk chunk:\n");
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| 286 | $$et{TIFF_TYPE} = 'APP1';
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| 287 | $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::Exif::Main');
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| 288 | $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr, \&Image::ExifTool::WriteTIFF);
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| 289 | if (defined $buff and length $buff) {
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| 290 | WriteProfile($outfile, $chunk, \$buff) or $err = 1;
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| 291 | }
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| 292 | } elsif ($dir eq 'XMP') {
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| 293 | $et->VPrint(0, "Creating XMP iTXt chunk:\n");
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| 294 | $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::XMP::Main');
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| 295 | $dirInfo{ReadOnly} = 1;
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| 296 | $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
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| 297 | if (defined $buff and length $buff and
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| 298 | # the packet is read-only (because of CRC)
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| 299 | Image::ExifTool::XMP::ValidateXMP(\$buff, 'r'))
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| 300 | {
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| 301 | # (previously, XMP was created as a non-standard XMP profile chunk)
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| 302 | # $buff = $Image::ExifTool::xmpAPP1hdr . $buff;
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| 303 | # WriteProfile($outfile, 'APP1', \$buff, 'generic') or $err = 1;
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| 304 | # (but now write XMP iTXt chunk according to XMP specification)
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| 305 | $buff = "iTXtXML:com.adobe.xmp\0\0\0\0\0" . $buff;
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| 306 | my $hdr = pack('N', length($buff) - 4);
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| 307 | my $cbuf = pack('N', CalculateCRC(\$buff, undef));
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| 308 | Write($outfile, $hdr, $buff, $cbuf) or $err = 1;
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| 309 | }
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| 310 | } elsif ($dir eq 'IPTC') {
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| 311 | $et->Warn('Creating non-standard IPTC in PNG', 1);
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| 312 | $et->VPrint(0, "Creating IPTC profile:\n");
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| 313 | # write new IPTC data (stored in a Photoshop directory)
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| 314 | $dirInfo{DirName} = 'Photoshop';
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| 315 | $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::Photoshop::Main');
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| 316 | $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
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| 317 | if (defined $buff and length $buff) {
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| 318 | WriteProfile($outfile, 'iptc', \$buff, 'IPTC') or $err = 1;
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| 319 | }
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| 320 | } elsif ($dir eq 'ICC_Profile') {
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| 321 | $et->VPrint(0, "Creating ICC profile:\n");
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| 322 | # write new ICC data (only done if we couldn't create iCCP chunk)
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| 323 | $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::ICC_Profile::Main');
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| 324 | $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
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| 325 | if (defined $buff and length $buff) {
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| 326 | WriteProfile($outfile, 'icm', \$buff, 'ICC') or $err = 1;
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| 327 | $et->Warn('Wrote ICC as a raw profile (no Compress::Zlib)');
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| 328 | }
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| 329 | } elsif ($dir eq 'PNG-pHYs') {
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| 330 | $et->VPrint(0, "Creating pHYs chunk (default 2834 pixels per meter):\n");
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| 331 | $tagTablePtr = Image::ExifTool::GetTagTable('Image::ExifTool::PNG::PhysicalPixel');
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| 332 | my $blank = "\0\0\x0b\x12\0\0\x0b\x12\x01"; # 2834 pixels per meter (72 dpi)
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| 333 | $dirInfo{DataPt} = \$blank;
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| 334 | $buff = $et->WriteDirectory(\%dirInfo, $tagTablePtr);
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| 335 | if (defined $buff and length $buff) {
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| 336 | $buff = 'pHYs' . $buff; # CRC includes chunk name
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| 337 | my $hdr = pack('N', length($buff) - 4);
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| 338 | my $cbuf = pack('N', CalculateCRC(\$buff, undef));
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| 339 | Write($outfile, $hdr, $buff, $cbuf) or $err = 1;
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| 340 | }
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| 341 | } else {
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| 342 | next;
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| 343 | }
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| 344 | delete $$et{ADD_DIRS}{$dir}; # don't add again
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| 345 | }
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| 346 | return not $err;
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| 347 | }
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| 348 |
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| 349 |
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| 350 | 1; # end
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| 351 |
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| 352 | __END__
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| 353 |
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| 354 | =head1 NAME
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| 355 |
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| 356 | Image::ExifTool::WritePNG.pl - Write PNG meta information
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| 357 |
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| 358 | =head1 SYNOPSIS
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| 359 |
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| 360 | These routines are autoloaded by Image::ExifTool::PNG.
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| 361 |
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| 362 | =head1 DESCRIPTION
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| 363 |
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| 364 | This file contains routines to write PNG metadata.
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| 365 |
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| 366 | =head1 NOTES
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| 367 |
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| 368 | Compress::Zlib is required to write compressed text.
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| 369 |
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| 370 | Existing text tags are always rewritten in their original form (compressed
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| 371 | zTXt, uncompressed tEXt or international iTXt), so pre-existing compressed
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| 372 | information can only be modified if Compress::Zlib is available.
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| 373 |
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| 374 | Newly created textual information is written in uncompressed tEXt form by
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| 375 | default, or as compressed zTXt if the Compress option is used and
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| 376 | Compress::Zlib is available (but only if the resulting compressed data is
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| 377 | smaller than the original text, which isn't always the case for short text
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| 378 | strings).
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| 379 |
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| 380 | =head1 AUTHOR
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| 381 |
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| 382 | Copyright 2003-2021, Phil Harvey (philharvey66 at gmail.com)
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| 383 |
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| 384 | This library is free software; you can redistribute it and/or modify it
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| 385 | under the same terms as Perl itself.
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| 386 |
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| 387 | =head1 SEE ALSO
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| 388 |
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| 389 | L<Image::ExifTool::PNG(3pm)|Image::ExifTool::PNG>,
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| 390 | L<Image::ExifTool(3pm)|Image::ExifTool>
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| 391 |
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| 392 | =cut
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