Package: libzbar0
Version: 0.10+doc-7+b2
As it was pointed out [1] by Ben Morrow in a recent
news:comp.lang.perl.misc thread, libzbar0 appears to assume
ISO-8859-1 encoding for the input QR-encoded 8-bit data, and
attempts to unconditionally recode it into UTF-8, thus giving
(possibly) incorrect results.
The issue arises with both the zbarimg(1) command-line tool
(which disregards the locale currently in effect), and the
Perl's Barcode::ZBar interface (suggesting that the resulting
UTF-8-coded string is not being properly passed back to the
calling Perl code.)
As was suggested, I've used the “level L” Imager::QRCode option
and a test vector of 17 ‘\xFF’ octets. As expected, the
resulting QR code was 21 by 21 dots, thus ruling out the
possibility of ISO-8859-1 to UTF-8 expansion happening within
the generating Imager::QRCode module.
Consider, e. g. (the code is MIME'd):
$ LC_ALL=C perl -- z97wbjf3xptrg36ymsrczz5ggy.perl
Blob: pack("H*","ffffffffffffffffffffffffffffffffff")
Image: 42 by 42
[["QR-Code", ("\xC3\xBF" x 17)]]
$
Where \xC3\xBF's are ISO-8859-1 \xFF's recoded into UTF-8:
$ printf \\xc3\\xbf \
| iconv -f UTF-8 -t ISO-8859-1 \
| od -t x1
0000000 ff
0000001
$
[1] news:u0m61a-t5i1....@anubis.morrow.me.uk
--
FSF associate member #7257
### z97wbjf3xptrg36ymsrczz5ggy.perl -*- Perl -*-
## A simplistic Imager::QRCode vs. Barcode::ZBar test.
### Ivan Shmakov, 2013
## To the extent possible under law, the author(s) have dedicated all
## copyright and related and neighboring rights to this software to the
## public domain worldwide. This software is distributed without any
## warranty.
## You should have received a copy of the CC0 Public Domain Dedication
## along with this software. If not, see
## <http://creativecommons.org/publicdomain/zero/1.0/>.
### Code:
use common::sense;
require Barcode::ZBar;
require Data::Dump;
require Imager::QRCode;
my $qr
= Imager::QRCode->new (qw (mode 8-bit casesensitive 1),
qw (level L margin 0 size 2));
my $blob
= pack ("H*", ("FF" x 17));
print ("Blob: ", Data::Dump::dump ($blob), "\n");
my $img
= $qr->plot ($blob);
print ("Image: ", $img->getwidth (),
" by ", $img->getheight (), "\n");
my $jpeg
= undef;
$img->write ("data" => \$jpeg, "type" => "jpeg")
or die ();
my $bi
= Barcode::ZBar::Image->new ();
$bi->set_format ("JPEG");
$bi->set_size ($img->getwidth (), $img->getheight ());
$bi->set_data ($jpeg);
my $reader
= Barcode::ZBar::Processor->new();
$reader->process_image($bi);
my @xsym
= map {
## .
[ $_->get_type (), $_->get_data () ];
} ($bi->get_symbols ());
print ("", Data::Dump::dump ([ @xsym ]), "\n");
### Emacs trailer
## Local variables:
## coding: us-ascii
## fill-column: 72
## indent-tabs-mode: nil
## ispell-local-dictionary: "american"
## End:
### z97wbjf3xptrg36ymsrczz5ggy.perl ends here
