gifimage.sum

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: # *-*-perl-*-*
    eval 'exec perl -S $0 "$@"'
    if $running_under_some_shell;

@F = split('/', $0); $prog = pop @F; undef @F;

die("usage: $prog gif-file\n")
	unless ($#ARGV == 0);

$giffile = shift;
$TMPDIR = $ENV{'TMPDIR'};
$TMPDIR = '/tmp' if ($TMPDIR eq '');

# First summarize the GIF file contents

die("gifinfo $giffile: $!\n")
	unless open(SUMMARY, "gifinfo $giffile|");
$ok = 0;
while (<SUMMARY>) {
    chop;
    ($attribute, $value) = split(/:/);
    &print_av($attribute, $value);
    $ok++;
}
close(SUMMARY);
exit(1) unless ($ok);

# Then create a thumbnail version of the GIF file

die("$TMPDIR: $!\n")
	unless chdir($TMPDIR);

$cmd1 = "giftopnm $giffile";
$cmd2 = "pnmscale -width 64 -height 64";
$cmd3 = "ppmquant 256";
$cmd4 = "ppmtogif";

$cmd = join (" | ", $cmd1, $cmd2, $cmd3, $cmd4);

die("$cmd: $!\n")
	unless open (T, "$cmd|");
undef $/;
$gifdata = <T>;
close T;

&print_av ('thumbnail-data', $gifdata);

exit 0;

sub print_av {
	local ($a, $v) = @_;
	$l = length($v);
	print "$a{$l}:\t" . $v . "\n"
		if ($l > 0 && $a !~ /\s/);
}