#------------------------------------------------------------------------------
# File: GIF.pm
#
# Description: Read and write GIF meta information
#
# Revisions: 10/18/2005 - P. Harvey Separated from ExifTool.pm
# 05/23/2008 - P. Harvey Added ability to read/write XMP
# 10/28/2011 - P. Harvey Added ability to read/write ICC_Profile
#
# References: 1) http://www.w3.org/Graphics/GIF/spec-gif89a.txt
# 2) http://www.adobe.com/devnet/xmp/
# 3) http://graphcomp.com/info/specs/ani_gif.html
# 4) http://www.color.org/icc_specs2.html
#------------------------------------------------------------------------------
package Image::ExifTool::GIF;
use strict;
use vars qw($VERSION);
use Image::ExifTool qw(:DataAccess :Utils);
$VERSION = '1.12';
# road map of directory locations in GIF images
my %gifMap = (
XMP => 'GIF',
ICC_Profile => 'GIF',
);
%Image::ExifTool::GIF::Main = (
GROUPS => { 2 => 'Image' },
VARS => { NO_ID => 1 },
NOTES => q{
This table lists information extracted from GIF images. See
L<http://www.w3.org/Graphics/GIF/spec-gif89a.txt> for the official GIF89a
specification.
},
GIFVersion => { },
FrameCount => { Notes => 'number of animated images' },
Text => { Notes => 'text displayed in image' },
Comment => {
# for documentation only -- flag as writable for the docs, but
# it won't appear in the TagLookup because there is no WRITE_PROC
Writable => 1,
},
Duration => {
Notes => 'duration of a single animation iteration',
PrintConv => 'sprintf("%.2f s",$val)',
},
ScreenDescriptor => {
SubDirectory => { TagTable => 'Image::ExifTool::GIF::Screen' },
},
# GIF89a application extensions:
ExtensionAnimation => {
SubDirectory => { TagTable => 'Image::ExifTool::GIF::Animate' },
},
ExtensionXMP => { # (for documentation only)
SubDirectory => { TagTable => 'Image::ExifTool::XMP::Main' },
},
ExtensionICC => { # (for documentation only)
SubDirectory => { TagTable => 'Image::ExifTool::ICC_Profile::Main' },
},
);
# GIF locical screen descriptor
%Image::ExifTool::GIF::Screen = (
PROCESS_PROC => \&Image::ExifTool::ProcessBinaryData,
GROUPS => { 2 => 'Image' },
NOTES => 'Information extracted from the GIF logical screen descriptor.',
0 => {
Name => 'ImageWidth',
Format => 'int16u',
},
2 => {
Name => 'ImageHeight',
Format => 'int16u',
},
4.1 => {
Name => 'HasColorMap',
Mask => 0x80,
PrintConv => { 0x00 => 'No', 0x80 => 'Yes' },
},
4.2 => {
Name => 'ColorResolutionDepth',
Mask => 0x70,
ValueConv => '($val >> 4) + 1',
},
4.3 => {
Name => 'BitsPerPixel',
Mask => 0x07,
ValueConv => '$val + 1',
},
5 => 'BackgroundColor',
);
# GIF Netscape 2.0 animation extension
%Image::ExifTool::GIF::Animate = (
PROCESS_PROC => \&Image::ExifTool::ProcessBinaryData,
GROUPS => { 2 => 'Image' },
NOTES => 'Information extracted from the "NETSCAPE2.0" animation extension.',
2 => {
Name => 'AnimationIterations',
Format => 'int16u',
PrintConv => '$val ? $val : "Infinite"',
},
);
#------------------------------------------------------------------------------
# Process meta information in GIF image
# Inputs: 0) ExifTool object reference, 1) Directory information ref
# Returns: 1 on success, 0 if this wasn't a valid GIF file, or -1 if
# an output file was specified and a write error occurred
sub ProcessGIF($$)
{
my ($et, $dirInfo) = @_;
my $outfile = $$dirInfo{OutFile};
my $raf = $$dirInfo{RAF};
my $verbose = $et->Options('Verbose');
my $out = $et->Options('TextOut');
my ($a, $s, $ch, $length, $buff);
my ($err, $newComment, $setComment, $nvComment);
my ($addDirs, %doneDir);
my ($frameCount, $delayTime) = (0, 0);
# verify this is a valid GIF file
return 0 unless $raf->Read($buff, 6) == 6
and $buff =~ /^GIF(8[79]a)$/
and $raf->Read($s, 7) == 7;
my $ver = $1;
my $rtnVal = 0;
my $tagTablePtr = GetTagTable('Image::ExifTool::GIF::Main');
SetByteOrder('II');
if ($outfile) {
$et->InitWriteDirs(\%gifMap, 'XMP'); # make XMP the preferred group for GIF
$addDirs = $$et{ADD_DIRS};
# determine if we are editing the File:Comment tag
my $delGroup = $$et{DEL_GROUP};
$newComment = $et->GetNewValue('Comment', \$nvComment);
$setComment = 1 if $nvComment or $$delGroup{File};
# change to GIF 89a if adding comment, XMP or ICC_Profile
$buff = 'GIF89a' if $$addDirs{XMP} or $$addDirs{ICC_Profile} or defined $newComment;
Write($outfile, $buff, $s) or $err = 1;
} else {
$et->SetFileType(); # set file type
$et->HandleTag($tagTablePtr, 'GIFVersion', $ver);
$et->HandleTag($tagTablePtr, 'ScreenDescriptor', $s);
}
my $flags = Get8u(\$s, 4);
if ($flags & 0x80) { # does this image contain a color table?
# calculate color table size
$length = 3 * (2 << ($flags & 0x07));
$raf->Read($buff, $length) == $length or return 0; # skip color table
Write($outfile, $buff) or $err = 1 if $outfile;
}
#
# loop through GIF blocks
#
Block:
for (;;) {
last unless $raf->Read($ch, 1);
# write out any new metadata now if this isn't an extension block
if ($outfile and ord($ch) != 0x21) {
# write the comment first if necessary
if (defined $newComment and $$nvComment{IsCreating}) {
# write comment marker
Write($outfile, "\x21\xfe") or $err = 1;
$verbose and print $out " + Comment = $newComment\n";
my $len = length($newComment);
# write out the comment in 255-byte chunks, each
# chunk beginning with a length byte
my $n;
for ($n=0; $n<$len; $n+=255) {
my $size = $len - $n;
$size > 255 and $size = 255;
my $str = substr($newComment,$n,$size);
Write($outfile, pack('C',$size), $str) or $err = 1;
}
Write($outfile, "\0") or $err = 1; # empty chunk as terminator
undef $newComment;
undef $nvComment; # delete any other extraneous comments
++$$et{CHANGED}; # increment file changed flag
}
# add application extension containing XMP block if necessary
# (this will place XMP before the first non-extension block)
if (exists $$addDirs{XMP} and not defined $doneDir{XMP}) {
$doneDir{XMP} = 1;
# write new XMP data
my $xmpTable = GetTagTable('Image::ExifTool::XMP::Main');
my %dirInfo = ( Parent => 'GIF' );
$verbose and print $out "Creating XMP application extension block:\n";
$buff = $et->WriteDirectory(\%dirInfo, $xmpTable);
if (defined $buff and length $buff) {
my $lz = pack('C*',1,reverse(0..255),0);
Write($outfile, "\x21\xff\x0bXMP DataXMP", $buff, $lz) or $err = 1;
++$doneDir{XMP}; # set to 2 to indicate we added XMP
} else {
$verbose and print $out " -> no XMP to add\n";
}
}
# add application extension containing ICC_Profile if necessary
if (exists $$addDirs{ICC_Profile} and not defined $doneDir{ICC_Profile}) {
$doneDir{ICC_Profile} = 1;
# write new ICC_Profile
my $iccTable = GetTagTable('Image::ExifTool::ICC_Profile::Main');
my %dirInfo = ( Parent => 'GIF' );
$verbose and print $out "Creating ICC_Profile application extension block:\n";
$buff = $et->WriteDirectory(\%dirInfo, $iccTable);
if (defined $buff and length $buff) {
my $pos = 0;
Write($outfile, "\x21\xff\x0bICCRGBG1012") or $err = 1;
my $len = length $buff;
while ($pos < $len) {
my $n = $len - $pos;
$n = 255 if $n > 255;
Write($outfile, chr($n), substr($buff, $pos, $n)) or $err = 1;
$pos += $n;
}
Write($outfile, "\0") or $err = 1; # write null terminator
++$doneDir{ICC_Profile}; # set to 2 to indicate we added a new profile
} else {
$verbose and print $out " -> no ICC_Profile to add\n";
}
}
}
if (ord($ch) == 0x2c) {
++$frameCount;
Write($outfile, $ch) or $err = 1 if $outfile;
# image descriptor
last unless $raf->Read($buff, 8) == 8 and $raf->Read($ch, 1);
Write($outfile, $buff, $ch) or $err = 1 if $outfile;
if ($verbose) {
my ($left, $top, $w, $h) = unpack('v*', $buff);
print $out "Image: left=$left top=$top width=$w height=$h\n";
}
if (ord($ch) & 0x80) { # does color table exist?
$length = 3 * (2 << (ord($ch) & 0x07));
# skip the color table
last unless $raf->Read($buff, $length) == $length;
Write($outfile, $buff) or $err = 1 if $outfile;
}
# skip "LZW Minimum Code Size" byte
last unless $raf->Read($buff, 1);
Write($outfile,$buff) or $err = 1 if $outfile;
# skip image blocks
for (;;) {
last unless $raf->Read($ch, 1);
Write($outfile, $ch) or $err = 1 if $outfile;
last unless ord($ch);
last unless $raf->Read($buff, ord($ch));
Write($outfile,$buff) or $err = 1 if $outfile;
}
next; # continue with next field
}
# last if ord($ch) == 0x3b; # normal end of GIF marker
unless (ord($ch) == 0x21) {
if ($outfile) {
Write($outfile, $ch) or $err = 1;
# copy the rest of the file
while ($raf->Read($buff, 65536)) {
Write($outfile, $buff) or $err = 1;
}
}
$rtnVal = 1;
last;
}
# get extension block type/size
last unless $raf->Read($s, 2) == 2;
# get marker and block size
($a,$length) = unpack("C"x2, $s);
if ($a == 0xfe) { # comment extension
my $comment = '';
while ($length) {
last unless $raf->Read($buff, $length) == $length;
if ($verbose > 2 and not $outfile) {
HexDump(\$buff, undef, Out => $out);
}
# add buffer to comment string
$comment .= $buff;
last unless $raf->Read($ch, 1); # read next block header
$length = ord($ch); # get next block size
}
last if $length; # was a read error if length isn't zero
if ($outfile) {
my $isOverwriting;
if ($setComment) {
if ($nvComment) {
$isOverwriting = $et->IsOverwriting($nvComment,$comment);
# get new comment again (may have been shifted)
$newComment = $et->GetNewValue($nvComment) if defined $newComment;
} else {
# group delete, or deleting additional comments after writing one
$isOverwriting = 1;
}
}
if ($isOverwriting) {
++$$et{CHANGED}; # increment file changed flag
$et->VerboseValue('- Comment', $comment);
$comment = $newComment;
$et->VerboseValue('+ Comment', $comment) if defined $comment;
undef $nvComment; # just delete remaining comments
} else {
undef $setComment; # leave remaining comments alone
}
if (defined $comment) {
# write comment marker
Write($outfile, "\x21\xfe") or $err = 1;
my $len = length($comment);
# write out the comment in 255-byte chunks, each
# chunk beginning with a length byte
my $n;
for ($n=0; $n<$len; $n+=255) {
my $size = $len - $n;
$size > 255 and $size = 255;
my $str = substr($comment,$n,$size);
Write($outfile, pack('C',$size), $str) or $err = 1;
}
Write($outfile, "\0") or $err = 1; # empty chunk as terminator
}
undef $newComment; # don't write the new comment again
} else {
$rtnVal = 1;
$et->FoundTag('Comment', $comment) if $comment;
undef $comment;
# assume no more than one comment in FastScan mode
last if $et->Options('FastScan');
}
next;
} elsif ($a == 0xff and $length == 0x0b) { # application extension
last unless $raf->Read($buff, $length) == $length;
if ($verbose) {
my @a = unpack('a8a3', $buff);
s/\0.*//s foreach @a;
print $out "Application Extension: @a\n";
}
if ($buff eq 'XMP DataXMP') { # XMP data (ref 2)
my $hdr = "$ch$s$buff";
# read XMP data
my $xmp = '';
for (;;) {
$raf->Read($ch, 1) or last Block; # read next block header
$length = ord($ch) or last; # get next block size
$raf->Read($buff, $length) == $length or last Block;
$xmp .= $ch . $buff;
}
# get length of XMP without landing zone data
# (note that LZ data may not be exactly the same as what we use)
my $xmpLen;
if ($xmp =~ /<\?xpacket end=['"][wr]['"]\?>/g) {
$xmpLen = pos($xmp);
} else {
$xmpLen = length($xmp);
}
my %dirInfo = (
DataPt => \$xmp,
DataLen => length $xmp,
DirLen => $xmpLen,
Parent => 'GIF',
);
my $xmpTable = GetTagTable('Image::ExifTool::XMP::Main');
if ($outfile) {
if ($doneDir{XMP} and $doneDir{XMP} > 1) {
$et->Warn('Duplicate XMP block created');
}
$buff = $et->WriteDirectory(\%dirInfo, $xmpTable);
if (not defined $buff) {
# rewrite original XMP with landing zone (adding back null terminator)
Write($outfile, $hdr, $xmp, "\0") or $err = 1;
$doneDir{XMP} = 1;
} elsif (length $buff) {
if ($buff =~ /\0/) { # (check just to be safe)
$et->Error('XMP contained NULL character');
} else {
# write new XMP and landing zone
my $lz = pack('C*',1,reverse(0..255),0);
Write($outfile, $hdr, $buff, $lz) or $err = 1;
}
$doneDir{XMP} = 1;
} # else we are deleting the XMP
} else {
$et->ProcessDirectory(\%dirInfo, $xmpTable);
}
next;
} elsif ($buff eq 'ICCRGBG1012') { # ICC_Profile extension (ref 4)
my $hdr = "$ch$s$buff";
# read ICC profile data
my $icc_profile = '';
for (;;) {
$raf->Read($ch, 1) or last Block; # read next block header
$length = ord($ch) or last; # get next block size
$raf->Read($buff, $length) == $length or last Block;
$icc_profile .= $buff;
}
my %dirInfo = (
DataPt => \$icc_profile,
DataLen => length $icc_profile,
DirLen => length $icc_profile,
Parent => 'GIF',
);
my $iccTable = GetTagTable('Image::ExifTool::ICC_Profile::Main');
if ($outfile) {
if ($doneDir{ICC_Profile} and $doneDir{ICC_Profile} > 1) {
$et->Warn('Duplicate ICC_Profile block created');
}
$buff = $et->WriteDirectory(\%dirInfo, $iccTable);
# rewrite original ICC_Profile if nothing changed
$buff = $icc_profile unless defined $buff;
if (length $buff) {
# write ICC profile sub-blocks
my $pos = 0;
Write($outfile, $hdr) or $err = 1;
my $len = length $buff;
while ($pos < $len) {
my $n = $len - $pos;
$n = 255 if $n > 255;
Write($outfile, chr($n), substr($buff, $pos, $n)) or $err = 1;
$pos += $n;
}
Write($outfile, "\0") or $err = 1; # write null terminator
$doneDir{ICC_Profile} = 1;
} # else we are deleting the ICC profile
} else {
$et->ProcessDirectory(\%dirInfo, $iccTable);
}
next;
} elsif ($buff eq 'NETSCAPE2.0') { # animated GIF extension (ref 3)
$raf->Read($buff, 5) == 5 or last;
# make sure this contains the expected data
if ($buff =~ /^\x03\x01(..)\0$/s) {
$et->HandleTag($tagTablePtr, 'ExtensionAnimation', $buff);
}
$raf->Seek(-$length-5, 1) or last; # seek back to start of block
} else {
# rewind to start of application extension to copy the unknown block
$raf->Seek(-$length, 1) or last;
}
} elsif ($a == 0xf9 and $length == 4) { # graphic control extension
last unless $raf->Read($buff, $length) == $length;
# sum the indivual delay times
my $delay = Get16u(\$buff, 1);
$delayTime += $delay;
$verbose and printf $out "Graphic Control: delay=%.2f\n", $delay / 100;
$raf->Seek(-$length, 1) or last;
} elsif ($a == 0x01 and $length == 12) { # plain text extension
last unless $raf->Read($buff, $length) == $length;
Write($outfile, $ch, $s, $buff) or $err = 1 if $outfile;
if ($verbose) {
my ($left, $top, $w, $h) = unpack('v4', $buff);
print $out "Text: left=$left top=$top width=$w height=$h\n";
}
my $text = '';
for (;;) {
last unless $raf->Read($ch, 1);
$length = ord($ch) or last;
last unless $raf->Read($buff, $length) == $length;
Write($outfile, $ch, $buff) or $err = 1 if $outfile; # write block
$text .= $buff;
}
Write($outfile, "\0") or $err = 1 if $outfile; # write terminator block
$et->HandleTag($tagTablePtr, 'Text', $text);
next;
}
Write($outfile, $ch, $s) or $err = 1 if $outfile;
# skip the block
while ($length) {
last unless $raf->Read($buff, $length) == $length;
Write($outfile, $buff) or $err = 1 if $outfile;
last unless $raf->Read($ch, 1); # read next block header
Write($outfile, $ch) or $err = 1 if $outfile;
$length = ord($ch); # get next block size
}
}
unless ($outfile) {
$et->HandleTag($tagTablePtr, 'FrameCount', $frameCount) if $frameCount > 1;
$et->HandleTag($tagTablePtr, 'Duration', $delayTime/100) if $delayTime;
}
# set return value to -1 if we only had a write error
$rtnVal = -1 if $rtnVal and $err;
return $rtnVal;
}
1; #end
__END__
=head1 NAME
Image::ExifTool::GIF - Read and write GIF meta information
=head1 SYNOPSIS
This module is loaded automatically by Image::ExifTool when required.
=head1 DESCRIPTION
This module contains definitions required by Image::ExifTool to read and
write GIF meta information.
=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 REFERENCES
=over 4
=item L<http://www.w3.org/Graphics/GIF/spec-gif89a.txt>
=item L<http://www.adobe.com/devnet/xmp/>
=item L<http://graphcomp.com/info/specs/ani_gif.html>
=item L<http://www.color.org/icc_specs2.html>
=back
=head1 SEE ALSO
L<Image::ExifTool(3pm)|Image::ExifTool>
=cut