352 lines
8.4 KiB
Perl
352 lines
8.4 KiB
Perl
package Font::TTF::Coverage;
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=head1 NAME
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Font::TTF::Coverage - Opentype coverage and class definition objects
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=head1 DESCRIPTION
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Coverage tables and class definition objects are virtually identical concepts
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in OpenType. Their difference comes purely in their storage. Therefore we can
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say that a coverage table is a class definition in which the class definition
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for each glyph is the corresponding index in the coverage table. The resulting
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data structure is that a Coverage table has the following fields:
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=over
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=item cover
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A boolean to indicate whether this table is a coverage table (TRUE) or a
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class definition (FALSE)
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=item val
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A hash of glyph ids against values (either coverage index or class value)
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=item fmt
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The storage format used is given here, but is recalculated when the table
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is written out.
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=item count
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A count of the elements in a coverage table for use with add. Each subsequent
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addition is added with the current count and increments the count.
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=item max
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Maximum class value in a class table.
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=back
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=head1 METHODS
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=cut
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=head2 new($isCover [, vals])
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Creates a new coverage table or class definition table, depending upon the
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value of $isCover. if $isCover then vals may be a list of glyphs to include in order.
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If no $isCover, then vals is a hash of glyphs against class values.
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=cut
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our $dontsort;
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sub new
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{
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my ($class) = shift;
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my ($isCover) = shift;
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my ($self) = {};
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$self->{'cover'} = $isCover;
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if ($isCover)
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{
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$self->{'count'} = 0;
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my ($v);
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foreach $v (@_)
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{ $self->{'val'}{$v} = $self->{'count'}++; }
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}
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else
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{
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$self->{'max'} = 0;
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$self->{'val'} = {@_};
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foreach (values %{$self->{'val'}}) {$self->{'max'} = $_ if $_ > $self->{'max'}}
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}
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bless $self, $class;
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}
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=head2 read($fh)
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Reads the coverage/class table from the given file handle
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=cut
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sub read
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{
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my ($self, $fh) = @_;
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my ($dat, $fmt, $num, $i, $c);
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$fh->read($dat, 4);
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($fmt, $num) = unpack("n2", $dat);
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$self->{'fmt'} = $fmt;
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if ($self->{'cover'})
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{
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if ($fmt == 1)
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{
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$fh->read($dat, $num << 1);
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map {$self->{'val'}{$_} = $i++} unpack("n*", $dat);
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$self->{'count'} = $num;
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} elsif ($fmt == 2)
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{
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$fh->read($dat, $num * 6);
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for ($i = 0; $i < $num; $i++)
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{
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($first, $last, $c) = unpack("n3", substr($dat, $i * 6, 6));
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map {$self->{'val'}{$_} = $c++} ($first .. $last);
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}
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$self->{'count'} = $c;
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}
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} elsif ($fmt == 1)
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{
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$fh->read($dat, 2);
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$first = $num;
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($num) = unpack("n", $dat);
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$fh->read($dat, $num << 1);
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map {$self->{'val'}{$first++} = $_; $self->{'max'} = $_ if ($_ > $self->{'max'})} unpack("n*", $dat);
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} elsif ($fmt == 2)
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{
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$fh->read($dat, $num * 6);
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for ($i = 0; $i < $num; $i++)
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{
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($first, $last, $c) = unpack("n3", substr($dat, $i * 6, 6));
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map {$self->{'val'}{$_} = $c} ($first .. $last);
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$self->{'max'} = $c if ($c > $self->{'max'});
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}
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}
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$self;
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}
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=head2 out($fh, $state)
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Writes the coverage/class table to the given file handle. If $state is 1 then
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the output string is returned rather than being output to a filehandle.
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=cut
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sub out
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{
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my ($self, $fh, $state) = @_;
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my ($g, $eff, $grp, $out);
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my ($shipout) = ($state ? sub {$out .= $_[0];} : sub {$fh->print($_[0]);});
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my (@gids) = sort {$a <=> $b} keys %{$self->{'val'}};
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if ($self->{'cover'})
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{ $self->sort() unless ($self->{'dontsort'} or $dontsort); }
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else
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{ @gids = grep {$self->{'val'}{$_} > 0} @gids;} # class value=0 is not explicitly coded in class table
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$fmt = 1; $grp = 1; $eff = 0;
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for ($i = 1; $i <= $#gids; $i++)
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{
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if ($self->{'val'}{$gids[$i]} < $self->{'val'}{$gids[$i-1]} && $self->{'cover'})
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{
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$fmt = 2;
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last;
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} elsif ($gids[$i] == $gids[$i-1] + 1 && ($self->{'cover'} || $self->{'val'}{$gids[$i]} == $self->{'val'}{$gids[$i-1]}))
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{ $eff++; }
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else
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{
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$grp++;
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$eff += $gids[$i] - $gids[$i-1] if (!$self->{'cover'});
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}
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}
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# if ($self->{'cover'})
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{ $fmt = 2 if ($eff / $grp > 3 || scalar (@gids) == 0); }
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# else
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# { $fmt = 2 if ($grp > 1); }
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if ($fmt == 1 && $self->{'cover'})
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{
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my ($last) = 0;
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&$shipout(pack('n2', 1, scalar @gids));
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&$shipout(pack('n*', @gids));
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} elsif ($fmt == 1)
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{
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my ($last) = $gids[0];
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&$shipout(pack("n3", 1, $last, $gids[-1] - $last + 1));
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foreach $g (@gids)
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{
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if ($g > $last + 1)
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{ &$shipout(pack('n*', (0) x ($g - $last - 1))); }
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&$shipout(pack('n', $self->{'val'}{$g}));
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$last = $g;
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}
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} else
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{
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my ($start, $end, $ind, $numloc, $endloc, $num);
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&$shipout(pack("n2", 2, 0));
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$numloc = $fh->tell() - 2 unless $state;
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$start = 0; $end = 0; $num = 0;
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while ($end < $#gids)
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{
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if ($gids[$end + 1] == $gids[$end] + 1
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&& $self->{'val'}{$gids[$end + 1]}
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== $self->{'val'}{$gids[$end]}
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+ ($self->{'cover'} ? 1 : 0))
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{
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$end++;
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next;
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}
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&$shipout(pack("n3", $gids[$start], $gids[$end],
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$self->{'val'}{$gids[$start]}));
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$start = $end + 1;
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$end++;
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$num++;
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}
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if (scalar(@gids))
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{
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&$shipout(pack("n3", $gids[$start], $gids[$end],
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$self->{'val'}{$gids[$start]}));
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$num++;
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}
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if ($state)
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{ substr($out, 2, 2) = pack('n', $num); }
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else
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{
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$endloc = $fh->tell();
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$fh->seek($numloc, 0);
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$fh->print(pack("n", $num));
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$fh->seek($endloc, 0);
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}
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}
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return ($state ? $out : $self);
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}
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=head2 $c->add($glyphid[, $class])
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Adds a glyph id to the coverage or class table.
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Returns the index or class number of the glyphid added.
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=cut
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sub add
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{
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my ($self, $gid, $class) = @_;
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return $self->{'val'}{$gid} if (defined $self->{'val'}{$gid});
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if ($self->{'cover'})
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{
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$self->{'val'}{$gid} = $self->{'count'};
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return $self->{'count'}++;
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}
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else
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{
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$self->{'val'}{$gid} = $class || '0';
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$self->{'max'} = $class if ($class > $self->{'max'});
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return $class;
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}
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}
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=head2 $c->signature
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Returns a vector of all the glyph ids covered by this coverage table or class
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=cut
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sub signature
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{
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my ($self) = @_;
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my ($vec, $range, $size);
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if (0)
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{
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if ($self->{'cover'})
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{ $range = 1; $size = 1; }
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else
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{
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$range = $self->{'max'};
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$size = 1;
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while ($range > 1)
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{
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$size = $size << 1;
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$range = $range >> 1;
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}
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$range = $self->{'max'} + 1;
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}
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foreach (keys %{$self->{'val'}})
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{ vec($vec, $_, $size) = $self->{'val'}{$_} > $range ? $range : $self->{'val'}{$_}; }
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length($vec) . ":" . $vec;
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}
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$vec = join(";", map{"$_,$self->{'val'}{$_}"} sort { $a <=> $b} keys %{$self->{'val'}});
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}
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=head2 @map=$c->sort
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Sorts the coverage table so that indexes are in ascending order of glyphid.
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Returns a map such that $map[$new_index]=$old_index.
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=cut
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sub sort
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{
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my ($self) = @_;
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my (@res, $i);
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foreach (sort {$a <=> $b} keys %{$self->{'val'}})
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{
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push(@res, $self->{'val'}{$_});
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$self->{'val'}{$_} = $i++;
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}
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@res;
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}
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=head2 $c->out_xml($context)
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Outputs this coverage/class in XML
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=cut
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sub out_xml
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{
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my ($self, $context, $depth) = @_;
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my ($fh) = $context->{'fh'};
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$fh->print("$depth<" . ($self->{'cover'} ? 'coverage' : 'class') . ">\n");
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foreach $gid (sort {$a <=> $b} keys %{$self->{'val'}})
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{
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$fh->printf("$depth$context->{'indent'}<gref glyph='%s' val='%s'/>\n", $gid, $self->{'val'}{$gid});
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}
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$fh->print("$depth</" . ($self->{'cover'} ? 'coverage' : 'class') . ">\n");
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$self;
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}
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sub release
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{ }
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1;
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=head1 AUTHOR
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Martin Hosken L<http://scripts.sil.org/FontUtils>.
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=head1 LICENSING
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Copyright (c) 1998-2016, SIL International (http://www.sil.org)
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This module is released under the terms of the Artistic License 2.0.
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For details, see the full text of the license in the file LICENSE.
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=cut
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