198 lines
4.7 KiB
Perl
198 lines
4.7 KiB
Perl
package Font::TTF::Loca;
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=head1 NAME
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Font::TTF::Loca - the Locations table, which is intimately tied to the glyf table
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=head1 DESCRIPTION
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The location table holds the directory of locations of each glyph within the
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glyf table. Due to this relationship and the unimportance of the actual locations
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when it comes to holding glyphs in memory, reading the location table results
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in the creation of glyph objects for each glyph and stores them here.
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So if you are looking for glyphs, do not look in the C<glyf> table, look here
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instead.
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Things get complicated if you try to change the glyph list within the one table.
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The recommendation is to create another clean location object to replace this
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table in the font, ensuring that the old table is read first and to transfer
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or copy glyphs across from the read table to the new table.
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=head1 INSTANCE VARIABLES
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The instance variables do not start with a space
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=over 4
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=item glyphs
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An array of glyph objects for each glyph.
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=item glyphtype
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A string containing the class name to create for each new glyph. If empty,
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defaults to L<Font::TTF::Glyph>.
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=back
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=head1 METHODS
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=cut
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use strict;
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use vars qw(@ISA);
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@ISA = qw(Font::TTF::Table);
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require Font::TTF::Glyph;
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=head2 $t->new
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Creates a new location table making sure it has a glyphs array
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=cut
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sub new
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{
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my ($class) = shift;
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my ($res) = $class->SUPER::new(@_);
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$res->{'glyphs'} = [];
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$res;
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}
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=head2 $t->read
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Reads the location table creating glyph objects (L<Font::TTF::Glyph>) for each glyph
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allowing their later reading.
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=cut
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sub read
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{
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my ($self) = @_;
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# Do this before $self->SUPER::read because this can alter the file pointer:
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my ($glyfLoc) = $self->{' PARENT'}{'glyf'}->_read->{' OFFSET'}; # May seek on $fh!
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$self->SUPER::read or return $self;
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my ($fh) = $self->{' INFILE'};
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my ($locFmt) = $self->{' PARENT'}{'head'}{'indexToLocFormat'};
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my ($numGlyphs) = $self->{' PARENT'}{'maxp'}{'numGlyphs'};
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my ($dat, $last, $i, $loc);
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$fh->read($dat, $locFmt ? 4 : 2);
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$last = unpack($locFmt ? "N" : "n", $dat);
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for ($i = 0; $i < $numGlyphs; $i++)
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{
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$fh->read($dat, $locFmt ? 4 : 2);
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$loc = unpack($locFmt ? "N" : "n", $dat);
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$self->{'glyphs'}[$i] = ($self->{'glyphtype'} || "Font::TTF::Glyph")->new(
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LOC => $last << ($locFmt ? 0 : 1),
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OUTLOC => $last << ($locFmt ? 0 : 1),
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PARENT => $self->{' PARENT'},
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INFILE => $self->{' PARENT'}{'glyf'}{' INFILE'},
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BASE => $glyfLoc,
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OUTLEN => ($loc - $last) << ($locFmt ? 0 : 1),
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LEN => ($loc - $last) << ($locFmt ? 0 : 1)) if ($loc != $last);
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$last = $loc;
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}
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$self;
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}
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=head2 $t->out($fh)
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Writes the location table out to $fh. Notice that not having read the location
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table implies that the glyf table has not been read either, so the numbers in
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the location table are still valid. Let's hope that C<maxp/numGlyphs> and
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C<head/indexToLocFmt> haven't changed otherwise we are in big trouble.
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The function uses the OUTLOC location in the glyph calculated when the glyf
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table was attempted to be output.
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=cut
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sub out
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{
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my ($self, $fh) = @_;
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my ($locFmt) = $self->{' PARENT'}{'head'}{'indexToLocFormat'};
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my ($numGlyphs) = $self->{' PARENT'}{'maxp'}{'numGlyphs'};
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my ($count, $i, $offset, $g);
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return $self->SUPER::out($fh) unless ($self->{' read'});
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$count = 0;
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for ($i = 0; $i < $numGlyphs; $i++)
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{
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$g = ($self->{'glyphs'}[$i]) || "";
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unless ($g)
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{
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$count++;
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next;
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} else
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{
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if ($locFmt)
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{ $fh->print(pack("N", $g->{' OUTLOC'}) x ($count + 1)); }
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else
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{ $fh->print(pack("n", $g->{' OUTLOC'} >> 1) x ($count + 1)); }
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$count = 0;
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$offset = $g->{' OUTLOC'} + $g->{' OUTLEN'};
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}
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}
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$fh->print(pack($locFmt ? "N" : "n", ($locFmt ? $offset: $offset >> 1)) x ($count + 1));
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}
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=head2 $t->out_xml($context, $depth)
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No need to output a loca table, this is dynamically generated
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=cut
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sub out_xml
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{ return $_[0]; }
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=head2 $t->glyphs_do(&func)
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Calls func for each glyph in this location table in numerical order:
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&func($glyph, $glyph_num)
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=cut
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sub glyphs_do
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{
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my ($self, $func) = @_;
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my ($i);
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for ($i = 0; $i <= $#{$self->{'glyphs'}}; $i++)
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{ &$func($self->{'glyphs'}[$i], $i) if defined $self->{'glyphs'}[$i]; }
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$self;
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}
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1;
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=head1 BUGS
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None known
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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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