COSC4606-Assignment-02

ttfparser.php (17951B)

---

 <?php
 /*******************************************************************************
 * Class to parse and subset TrueType fonts                                     *
 *                                                                              *
 * Version: 1.11                                                                *
 * Date:    2021-04-18                                                          *
 * Author:  Olivier PLATHEY                                                     *
 *******************************************************************************/
 
 class TTFParser
 {
 	protected $f;
 	protected $tables;
 	protected $numberOfHMetrics;
 	protected $numGlyphs;
 	protected $glyphNames;
 	protected $indexToLocFormat;
 	protected $subsettedChars;
 	protected $subsettedGlyphs;
 	public $chars;
 	public $glyphs;
 	public $unitsPerEm;
 	public $xMin, $yMin, $xMax, $yMax;
 	public $postScriptName;
 	public $embeddable;
 	public $bold;
 	public $typoAscender;
 	public $typoDescender;
 	public $capHeight;
 	public $italicAngle;
 	public $underlinePosition;
 	public $underlineThickness;
 	public $isFixedPitch;
 
 	function __construct($file)
 	{
 		$this->f = fopen($file, 'rb');
 		if(!$this->f)
 			$this->Error('Can\'t open file: '.$file);
 	}
 
 	function __destruct()
 	{
 		if(is_resource($this->f))
 			fclose($this->f);
 	}
 
 	function Parse()
 	{
 		$this->ParseOffsetTable();
 		$this->ParseHead();
 		$this->ParseHhea();
 		$this->ParseMaxp();
 		$this->ParseHmtx();
 		$this->ParseLoca();
 		$this->ParseGlyf();
 		$this->ParseCmap();
 		$this->ParseName();
 		$this->ParseOS2();
 		$this->ParsePost();
 	}
 
 	function ParseOffsetTable()
 	{
 		$version = $this->Read(4);
 		if($version=='OTTO')
 			$this->Error('OpenType fonts based on PostScript outlines are not supported');
 		if($version!="\x00\x01\x00\x00")
 			$this->Error('Unrecognized file format');
 		$numTables = $this->ReadUShort();
 		$this->Skip(3*2); // searchRange, entrySelector, rangeShift
 		$this->tables = array();
 		for($i=0;$i<$numTables;$i++)
 		{
 			$tag = $this->Read(4);
 			$checkSum = $this->Read(4);
 			$offset = $this->ReadULong();
 			$length = $this->ReadULong();
 			$this->tables[$tag] = array('offset'=>$offset, 'length'=>$length, 'checkSum'=>$checkSum);
 		}
 	}	
 
 	function ParseHead()
 	{
 		$this->Seek('head');
 		$this->Skip(3*4); // version, fontRevision, checkSumAdjustment
 		$magicNumber = $this->ReadULong();
 		if($magicNumber!=0x5F0F3CF5)
 			$this->Error('Incorrect magic number');
 		$this->Skip(2); // flags
 		$this->unitsPerEm = $this->ReadUShort();
 		$this->Skip(2*8); // created, modified
 		$this->xMin = $this->ReadShort();
 		$this->yMin = $this->ReadShort();
 		$this->xMax = $this->ReadShort();
 		$this->yMax = $this->ReadShort();
 		$this->Skip(3*2); // macStyle, lowestRecPPEM, fontDirectionHint
 		$this->indexToLocFormat = $this->ReadShort();
 	}
 
 	function ParseHhea()
 	{
 		$this->Seek('hhea');
 		$this->Skip(4+15*2);
 		$this->numberOfHMetrics = $this->ReadUShort();
 	}
 
 	function ParseMaxp()
 	{
 		$this->Seek('maxp');
 		$this->Skip(4);
 		$this->numGlyphs = $this->ReadUShort();
 	}
 
 	function ParseHmtx()
 	{
 		$this->Seek('hmtx');
 		$this->glyphs = array();
 		for($i=0;$i<$this->numberOfHMetrics;$i++)
 		{
 			$advanceWidth = $this->ReadUShort();
 			$lsb = $this->ReadShort();
 			$this->glyphs[$i] = array('w'=>$advanceWidth, 'lsb'=>$lsb);
 		}
 		for($i=$this->numberOfHMetrics;$i<$this->numGlyphs;$i++)
 		{
 			$lsb = $this->ReadShort();
 			$this->glyphs[$i] = array('w'=>$advanceWidth, 'lsb'=>$lsb);
 		}
 	}
 
 	function ParseLoca()
 	{
 		$this->Seek('loca');
 		$offsets = array();
 		if($this->indexToLocFormat==0)
 		{
 			// Short format
 			for($i=0;$i<=$this->numGlyphs;$i++)
 				$offsets[] = 2*$this->ReadUShort();
 		}
 		else
 		{
 			// Long format
 			for($i=0;$i<=$this->numGlyphs;$i++)
 				$offsets[] = $this->ReadULong();
 		}
 		for($i=0;$i<$this->numGlyphs;$i++)
 		{
 			$this->glyphs[$i]['offset'] = $offsets[$i];
 			$this->glyphs[$i]['length'] = $offsets[$i+1] - $offsets[$i];
 		}
 	}
 
 	function ParseGlyf()
 	{
 		$tableOffset = $this->tables['glyf']['offset'];
 		foreach($this->glyphs as &$glyph)
 		{
 			if($glyph['length']>0)
 			{
 				fseek($this->f, $tableOffset+$glyph['offset'], SEEK_SET);
 				if($this->ReadShort()<0)
 				{
 					// Composite glyph
 					$this->Skip(4*2); // xMin, yMin, xMax, yMax
 					$offset = 5*2;
 					$a = array();
 					do
 					{
 						$flags = $this->ReadUShort();
 						$index = $this->ReadUShort();
 						$a[$offset+2] = $index;
 						if($flags & 1) // ARG_1_AND_2_ARE_WORDS
 							$skip = 2*2;
 						else
 							$skip = 2;
 						if($flags & 8) // WE_HAVE_A_SCALE
 							$skip += 2;
 						elseif($flags & 64) // WE_HAVE_AN_X_AND_Y_SCALE
 							$skip += 2*2;
 						elseif($flags & 128) // WE_HAVE_A_TWO_BY_TWO
 							$skip += 4*2;
 						$this->Skip($skip);
 						$offset += 2*2 + $skip;
 					}
 					while($flags & 32); // MORE_COMPONENTS
 					$glyph['components'] = $a;
 				}
 			}
 		}
 	}
 
 	function ParseCmap()
 	{
 		$this->Seek('cmap');
 		$this->Skip(2); // version
 		$numTables = $this->ReadUShort();
 		$offset31 = 0;
 		for($i=0;$i<$numTables;$i++)
 		{
 			$platformID = $this->ReadUShort();
 			$encodingID = $this->ReadUShort();
 			$offset = $this->ReadULong();
 			if($platformID==3 && $encodingID==1)
 				$offset31 = $offset;
 		}
 		if($offset31==0)
 			$this->Error('No Unicode encoding found');
 
 		$startCount = array();
 		$endCount = array();
 		$idDelta = array();
 		$idRangeOffset = array();
 		$this->chars = array();
 		fseek($this->f, $this->tables['cmap']['offset']+$offset31, SEEK_SET);
 		$format = $this->ReadUShort();
 		if($format!=4)
 			$this->Error('Unexpected subtable format: '.$format);
 		$this->Skip(2*2); // length, language
 		$segCount = $this->ReadUShort()/2;
 		$this->Skip(3*2); // searchRange, entrySelector, rangeShift
 		for($i=0;$i<$segCount;$i++)
 			$endCount[$i] = $this->ReadUShort();
 		$this->Skip(2); // reservedPad
 		for($i=0;$i<$segCount;$i++)
 			$startCount[$i] = $this->ReadUShort();
 		for($i=0;$i<$segCount;$i++)
 			$idDelta[$i] = $this->ReadShort();
 		$offset = ftell($this->f);
 		for($i=0;$i<$segCount;$i++)
 			$idRangeOffset[$i] = $this->ReadUShort();
 
 		for($i=0;$i<$segCount;$i++)
 		{
 			$c1 = $startCount[$i];
 			$c2 = $endCount[$i];
 			$d = $idDelta[$i];
 			$ro = $idRangeOffset[$i];
 			if($ro>0)
 				fseek($this->f, $offset+2*$i+$ro, SEEK_SET);
 			for($c=$c1;$c<=$c2;$c++)
 			{
 				if($c==0xFFFF)
 					break;
 				if($ro>0)
 				{
 					$gid = $this->ReadUShort();
 					if($gid>0)
 						$gid += $d;
 				}
 				else
 					$gid = $c+$d;
 				if($gid>=65536)
 					$gid -= 65536;
 				if($gid>0)
 					$this->chars[$c] = $gid;
 			}
 		}
 	}
 
 	function ParseName()
 	{
 		$this->Seek('name');
 		$tableOffset = $this->tables['name']['offset'];
 		$this->postScriptName = '';
 		$this->Skip(2); // format
 		$count = $this->ReadUShort();
 		$stringOffset = $this->ReadUShort();
 		for($i=0;$i<$count;$i++)
 		{
 			$this->Skip(3*2); // platformID, encodingID, languageID
 			$nameID = $this->ReadUShort();
 			$length = $this->ReadUShort();
 			$offset = $this->ReadUShort();
 			if($nameID==6)
 			{
 				// PostScript name
 				fseek($this->f, $tableOffset+$stringOffset+$offset, SEEK_SET);
 				$s = $this->Read($length);
 				$s = str_replace(chr(0), '', $s);
 				$s = preg_replace('|[ \[\](){}<>/%]|', '', $s);
 				$this->postScriptName = $s;
 				break;
 			}
 		}
 		if($this->postScriptName=='')
 			$this->Error('PostScript name not found');
 	}
 
 	function ParseOS2()
 	{
 		$this->Seek('OS/2');
 		$version = $this->ReadUShort();
 		$this->Skip(3*2); // xAvgCharWidth, usWeightClass, usWidthClass
 		$fsType = $this->ReadUShort();
 		$this->embeddable = ($fsType!=2) && ($fsType & 0x200)==0;
 		$this->Skip(11*2+10+4*4+4);
 		$fsSelection = $this->ReadUShort();
 		$this->bold = ($fsSelection & 32)!=0;
 		$this->Skip(2*2); // usFirstCharIndex, usLastCharIndex
 		$this->typoAscender = $this->ReadShort();
 		$this->typoDescender = $this->ReadShort();
 		if($version>=2)
 		{
 			$this->Skip(3*2+2*4+2);
 			$this->capHeight = $this->ReadShort();
 		}
 		else
 			$this->capHeight = 0;
 	}
 
 	function ParsePost()
 	{
 		$this->Seek('post');
 		$version = $this->ReadULong();
 		$this->italicAngle = $this->ReadShort();
 		$this->Skip(2); // Skip decimal part
 		$this->underlinePosition = $this->ReadShort();
 		$this->underlineThickness = $this->ReadShort();
 		$this->isFixedPitch = ($this->ReadULong()!=0);
 		if($version==0x20000)
 		{
 			// Extract glyph names
 			$this->Skip(4*4); // min/max usage
 			$this->Skip(2); // numberOfGlyphs
 			$glyphNameIndex = array();
 			$names = array();
 			$numNames = 0;
 			for($i=0;$i<$this->numGlyphs;$i++)
 			{
 				$index = $this->ReadUShort();
 				$glyphNameIndex[] = $index;
 				if($index>=258 && $index-257>$numNames)
 					$numNames = $index-257;
 			}
 			for($i=0;$i<$numNames;$i++)
 			{
 				$len = ord($this->Read(1));
 				$names[] = $this->Read($len);
 			}
 			foreach($glyphNameIndex as $i=>$index)
 			{
 				if($index>=258)
 					$this->glyphs[$i]['name'] = $names[$index-258];
 				else
 					$this->glyphs[$i]['name'] = $index;
 			}
 			$this->glyphNames = true;
 		}
 		else
 			$this->glyphNames = false;
 	}
 
 	function Subset($chars)
 	{
 		$this->subsettedGlyphs = array();
 		$this->AddGlyph(0);
 		$this->subsettedChars = array();
 		foreach($chars as $char)
 		{
 			if(isset($this->chars[$char]))
 			{
 				$this->subsettedChars[] = $char;
 				$this->AddGlyph($this->chars[$char]);
 			}
 		}
 	}
 
 	function AddGlyph($id)
 	{
 		if(!isset($this->glyphs[$id]['ssid']))
 		{
 			$this->glyphs[$id]['ssid'] = count($this->subsettedGlyphs);
 			$this->subsettedGlyphs[] = $id;
 			if(isset($this->glyphs[$id]['components']))
 			{
 				foreach($this->glyphs[$id]['components'] as $cid)
 					$this->AddGlyph($cid);
 			}
 		}
 	}
 
 	function Build()
 	{
 		$this->BuildCmap();
 		$this->BuildHhea();
 		$this->BuildHmtx();
 		$this->BuildLoca();
 		$this->BuildGlyf();
 		$this->BuildMaxp();
 		$this->BuildPost();
 		return $this->BuildFont();
 	}
 
 	function BuildCmap()
 	{
 		if(!isset($this->subsettedChars))
 			return;
 
 		// Divide charset in contiguous segments
 		$chars = $this->subsettedChars;
 		sort($chars);
 		$segments = array();
 		$segment = array($chars[0], $chars[0]);
 		for($i=1;$i<count($chars);$i++)
 		{
 			if($chars[$i]>$segment[1]+1)
 			{
 				$segments[] = $segment;
 				$segment = array($chars[$i], $chars[$i]);
 			}
 			else
 				$segment[1]++;
 		}
 		$segments[] = $segment;
 		$segments[] = array(0xFFFF, 0xFFFF);
 		$segCount = count($segments);
 
 		// Build a Format 4 subtable
 		$startCount = array();
 		$endCount = array();
 		$idDelta = array();
 		$idRangeOffset = array();
 		$glyphIdArray = '';
 		for($i=0;$i<$segCount;$i++)
 		{
 			list($start, $end) = $segments[$i];
 			$startCount[] = $start;
 			$endCount[] = $end;
 			if($start!=$end)
 			{
 				// Segment with multiple chars
 				$idDelta[] = 0;
 				$idRangeOffset[] = strlen($glyphIdArray) + ($segCount-$i)*2;
 				for($c=$start;$c<=$end;$c++)
 				{
 					$ssid = $this->glyphs[$this->chars[$c]]['ssid'];
 					$glyphIdArray .= pack('n', $ssid);
 				}
 			}
 			else
 			{
 				// Segment with a single char
 				if($start<0xFFFF)
 					$ssid = $this->glyphs[$this->chars[$start]]['ssid'];
 				else
 					$ssid = 0;
 				$idDelta[] = $ssid - $start;
 				$idRangeOffset[] = 0;
 			}
 		}
 		$entrySelector = 0;
 		$n = $segCount;
 		while($n!=1)
 		{
 			$n = $n>>1;
 			$entrySelector++;
 		}
 		$searchRange = (1<<$entrySelector)*2;
 		$rangeShift = 2*$segCount - $searchRange;
 		$cmap = pack('nnnn', 2*$segCount, $searchRange, $entrySelector, $rangeShift);
 		foreach($endCount as $val)
 			$cmap .= pack('n', $val);
 		$cmap .= pack('n', 0); // reservedPad
 		foreach($startCount as $val)
 			$cmap .= pack('n', $val);
 		foreach($idDelta as $val)
 			$cmap .= pack('n', $val);
 		foreach($idRangeOffset as $val)
 			$cmap .= pack('n', $val);
 		$cmap .= $glyphIdArray;
 
 		$data = pack('nn', 0, 1); // version, numTables
 		$data .= pack('nnN', 3, 1, 12); // platformID, encodingID, offset
 		$data .= pack('nnn', 4, 6+strlen($cmap), 0); // format, length, language
 		$data .= $cmap;
 		$this->SetTable('cmap', $data);
 	}
 
 	function BuildHhea()
 	{
 		$this->LoadTable('hhea');
 		$numberOfHMetrics = count($this->subsettedGlyphs);
 		$data = substr_replace($this->tables['hhea']['data'], pack('n',$numberOfHMetrics), 4+15*2, 2);
 		$this->SetTable('hhea', $data);
 	}
 
 	function BuildHmtx()
 	{
 		$data = '';
 		foreach($this->subsettedGlyphs as $id)
 		{
 			$glyph = $this->glyphs[$id];
 			$data .= pack('nn', $glyph['w'], $glyph['lsb']);
 		}
 		$this->SetTable('hmtx', $data);
 	}
 
 	function BuildLoca()
 	{
 		$data = '';
 		$offset = 0;
 		foreach($this->subsettedGlyphs as $id)
 		{
 			if($this->indexToLocFormat==0)
 				$data .= pack('n', $offset/2);
 			else
 				$data .= pack('N', $offset);
 			$offset += $this->glyphs[$id]['length'];
 		}
 		if($this->indexToLocFormat==0)
 			$data .= pack('n', $offset/2);
 		else
 			$data .= pack('N', $offset);
 		$this->SetTable('loca', $data);
 	}
 
 	function BuildGlyf()
 	{
 		$tableOffset = $this->tables['glyf']['offset'];
 		$data = '';
 		foreach($this->subsettedGlyphs as $id)
 		{
 			$glyph = $this->glyphs[$id];
 			fseek($this->f, $tableOffset+$glyph['offset'], SEEK_SET);
 			$glyph_data = $this->Read($glyph['length']);
 			if(isset($glyph['components']))
 			{
 				// Composite glyph
 				foreach($glyph['components'] as $offset=>$cid)
 				{
 					$ssid = $this->glyphs[$cid]['ssid'];
 					$glyph_data = substr_replace($glyph_data, pack('n',$ssid), $offset, 2);
 				}
 			}
 			$data .= $glyph_data;
 		}
 		$this->SetTable('glyf', $data);
 	}
 
 	function BuildMaxp()
 	{
 		$this->LoadTable('maxp');
 		$numGlyphs = count($this->subsettedGlyphs);
 		$data = substr_replace($this->tables['maxp']['data'], pack('n',$numGlyphs), 4, 2);
 		$this->SetTable('maxp', $data);
 	}
 
 	function BuildPost()
 	{
 		$this->Seek('post');
 		if($this->glyphNames)
 		{
 			// Version 2.0
 			$numberOfGlyphs = count($this->subsettedGlyphs);
 			$numNames = 0;
 			$names = '';
 			$data = $this->Read(2*4+2*2+5*4);
 			$data .= pack('n', $numberOfGlyphs);
 			foreach($this->subsettedGlyphs as $id)
 			{
 				$name = $this->glyphs[$id]['name'];
 				if(is_string($name))
 				{
 					$data .= pack('n', 258+$numNames);
 					$names .= chr(strlen($name)).$name;
 					$numNames++;
 				}
 				else
 					$data .= pack('n', $name);
 			}
 			$data .= $names;
 		}
 		else
 		{
 			// Version 3.0
 			$this->Skip(4);
 			$data = "\x00\x03\x00\x00";
 			$data .= $this->Read(4+2*2+5*4);
 		}
 		$this->SetTable('post', $data);
 	}
 
 	function BuildFont()
 	{
 		$tags = array();
 		foreach(array('cmap', 'cvt ', 'fpgm', 'glyf', 'head', 'hhea', 'hmtx', 'loca', 'maxp', 'name', 'post', 'prep') as $tag)
 		{
 			if(isset($this->tables[$tag]))
 				$tags[] = $tag;
 		}
 		$numTables = count($tags);
 		$offset = 12 + 16*$numTables;
 		foreach($tags as $tag)
 		{
 			if(!isset($this->tables[$tag]['data']))
 				$this->LoadTable($tag);
 			$this->tables[$tag]['offset'] = $offset;
 			$offset += strlen($this->tables[$tag]['data']);
 		}
 
 		// Build offset table
 		$entrySelector = 0;
 		$n = $numTables;
 		while($n!=1)
 		{
 			$n = $n>>1;
 			$entrySelector++;
 		}
 		$searchRange = 16*(1<<$entrySelector);
 		$rangeShift = 16*$numTables - $searchRange;
 		$offsetTable = pack('nnnnnn', 1, 0, $numTables, $searchRange, $entrySelector, $rangeShift);
 		foreach($tags as $tag)
 		{
 			$table = $this->tables[$tag];
 			$offsetTable .= $tag.$table['checkSum'].pack('NN', $table['offset'], $table['length']);
 		}
 
 		// Compute checkSumAdjustment (0xB1B0AFBA - font checkSum)
 		$s = $this->CheckSum($offsetTable);
 		foreach($tags as $tag)
 			$s .= $this->tables[$tag]['checkSum'];
 		$a = unpack('n2', $this->CheckSum($s));
 		$high = 0xB1B0 + ($a[1]^0xFFFF);
 		$low = 0xAFBA + ($a[2]^0xFFFF) + 1;
 		$checkSumAdjustment = pack('nn', $high+($low>>16), $low);
 		$this->tables['head']['data'] = substr_replace($this->tables['head']['data'], $checkSumAdjustment, 8, 4);
 
 		$font = $offsetTable;
 		foreach($tags as $tag)
 			$font .= $this->tables[$tag]['data'];
 
 		return $font;
 	}
 
 	function LoadTable($tag)
 	{
 		$this->Seek($tag);
 		$length = $this->tables[$tag]['length'];
 		$n = $length % 4;
 		if($n>0)
 			$length += 4 - $n;
 		$this->tables[$tag]['data'] = $this->Read($length);
 	}
 
 	function SetTable($tag, $data)
 	{
 		$length = strlen($data);
 		$n = $length % 4;
 		if($n>0)
 			$data = str_pad($data, $length+4-$n, "\x00");
 		$this->tables[$tag]['data'] = $data;
 		$this->tables[$tag]['length'] = $length;
 		$this->tables[$tag]['checkSum'] = $this->CheckSum($data);
 	}
 
 	function Seek($tag)
 	{
 		if(!isset($this->tables[$tag]))
 			$this->Error('Table not found: '.$tag);
 		fseek($this->f, $this->tables[$tag]['offset'], SEEK_SET);
 	}
 
 	function Skip($n)
 	{
 		fseek($this->f, $n, SEEK_CUR);
 	}
 
 	function Read($n)
 	{
 		return $n>0 ? fread($this->f, $n) : '';
 	}
 
 	function ReadUShort()
 	{
 		$a = unpack('nn', fread($this->f,2));
 		return $a['n'];
 	}
 
 	function ReadShort()
 	{
 		$a = unpack('nn', fread($this->f,2));
 		$v = $a['n'];
 		if($v>=0x8000)
 			$v -= 65536;
 		return $v;
 	}
 
 	function ReadULong()
 	{
 		$a = unpack('NN', fread($this->f,4));
 		return $a['N'];
 	}
 
 	function CheckSum($s)
 	{
 		$n = strlen($s);
 		$high = 0;
 		$low = 0;
 		for($i=0;$i<$n;$i+=4)
 		{
 			$high += (ord($s[$i])<<8) + ord($s[$i+1]);
 			$low += (ord($s[$i+2])<<8) + ord($s[$i+3]);
 		}
 		return pack('nn', $high+($low>>16), $low);
 	}
 
 	function Error($msg)
 	{
 		throw new Exception($msg);
 	}
 }
 ?>