package Font::TTF::Glat;

=head1 TITLE

Font::TTF::Glat - Hold glyph attributes

=head1 DESCRIPTION

Holds glyph attributes associated with each glyph.

=over 4

=item Version

Table format version

=item attribs

An array of hashes. On array entry for each glyph id. Since the glyph attributes are usually in a sparse
array, they are stored in a hash keyed by the attribute id and with the value as attribute value.

=cut

use Font::TTF::Table;
use Font::TTF::Utils;
use strict;
use vars qw(@ISA);
@ISA = qw(Font::TTF::Table);

sub read
{
    my ($self) = @_;
    my ($gloc) = $self->{' PARENT'}{'Gloc'};
    my ($fh) = $self->{' INFILE'};
    my ($numGlyphs);
    my ($base) = $self->{' OFFSET'};
    my ($dat, $i);

    $self->SUPER::read or return $self;
    $gloc->read;
    $numGlyphs = $gloc->{'numGlyphs'};
    $fh->seek($base, 0);
    $fh->read($dat, 4);
    ($self->{'Version'}) = TTF_Unpack('v', $dat);

    for ($i = 0; $i < $numGlyphs; $i++)
    {
        my ($j) = 0;
        my ($num) = $gloc->{'locations'}[$i + 1] - $gloc->{'locations'}[$i];
        my ($first, $number, @vals);
        $fh->seek($base + $gloc->{'locations'}[$i], 0);
        $fh->read($dat, $num);
        while ($j < $num)
        {
            if ($self->{'Version'} > 1)
            {
                ($first, $number) = unpack("n2", substr($dat, $j, 4));
                @vals = unpack("n$number", substr($dat, $j + 4, $number * 2));
                $j += ($number + 2) * 2;
            }
            else
            {
                ($first, $number) = unpack("C2", substr($dat, $j, 2));
                @vals = unpack("n$number", substr($dat, $j + 2, $number * 2));
                $j += $number * 2 + 2;
            }
            for (my $k = 0; $k < $number; $k++)
            { $self->{'attribs'}[$i]{$first + $k} = $vals[$k]; }
        }
    }
}

sub out
{
    my ($self, $fh) = @_;
    my ($gloc) = $self->{' PARENT'}{'Gloc'};
    my ($numGlyphs) = 0;
    my ($base) = $fh->tell();
    my ($i, $type);

    return $self->SUPER::out($fh) unless ($self->{' read'});
    $numGlyphs = scalar @{$self->{'attribs'}};
    if ($gloc->{'numAttrib'} > 256)
    {
        $self->{'Version'} = 2;
        $type = "n";
    }
    else
    {
        $self->{'Version'} = 1;
        $type = "C";
    }

    $gloc->{'locations'} = [];
    $fh->print(TTF_Pack('v', $self->{'Version'}));
    for ($i = 0; $i < $numGlyphs; $i++)
    {
        my (@a) = sort {$a <=> $b} keys %{$self->{'attribs'}[$i]};
        push(@{$gloc->{'locations'}}, $fh->tell() - $base);
        while (@a)
        {
            my ($first) = shift(@a);
            my ($next) = $first;
            my (@v, $j);
            while (@a and $a[0] <= $next + 2)
            { $next = shift(@a); }
            for ($j = $first; $j <= $next; $j++)
            { push (@v, $self->{'attribs'}[$i]{$j}); }
            { $fh->print(pack("${type}2n*", $first, $next - $first + 1, @v)); }
        }
    }
    push(@{$gloc->{'locations'}}, $fh->tell() - $base);
}

=back

=head2 $t->minsize()

Returns the minimum size this table can be. If it is smaller than this, then the table
must be bad and should be deleted or whatever.

=cut

sub minsize
{
    return 4;
}

1;

=head1 AUTHOR

Martin Hosken L<Martin_Hosken@sil.org>. 


=head1 LICENSING

Copyright (c) 1998-2013, SIL International (http://www.sil.org) 

This module is released under the terms of the Artistic License 2.0. 
For details, see the full text of the license in the file LICENSE.

The test suite contains test fonts released under the SIL Open Font License 1.1, see OFL.txt.

=cut