""" TrueType Font parser. Documents: - "An Introduction to TrueType Fonts: A look inside the TTF format" written by "NRSI: Computers & Writing Systems" http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&item_id=IWS-Chapter08 Author: Victor Stinner Creation date: 2007-02-08 """ from hachoir.parser import Parser from hachoir.field import (FieldSet, ParserError, UInt16, UInt32, Bit, Bits, PaddingBits, NullBytes, String, RawBytes, Bytes, Enum, TimestampMac32) from hachoir.core.endian import BIG_ENDIAN from hachoir.core.text_handler import textHandler, hexadecimal, filesizeHandler MAX_NAME_COUNT = 300 MIN_NB_TABLE = 3 MAX_NB_TABLE = 30 DIRECTION_NAME = { 0: u"Mixed directional", 1: u"Left to right", 2: u"Left to right + neutrals", -1: u"Right to left", -2: u"Right to left + neutrals", } NAMEID_NAME = { 0: u"Copyright notice", 1: u"Font family name", 2: u"Font subfamily name", 3: u"Unique font identifier", 4: u"Full font name", 5: u"Version string", 6: u"Postscript name", 7: u"Trademark", 8: u"Manufacturer name", 9: u"Designer", 10: u"Description", 11: u"URL Vendor", 12: u"URL Designer", 13: u"License Description", 14: u"License info URL", 16: u"Preferred Family", 17: u"Preferred Subfamily", 18: u"Compatible Full", 19: u"Sample text", 20: u"PostScript CID findfont name", } PLATFORM_NAME = { 0: "Unicode", 1: "Macintosh", 2: "ISO", 3: "Microsoft", 4: "Custom", } CHARSET_MAP = { # (platform, encoding) => charset 0: {3: "UTF-16-BE"}, 1: {0: "MacRoman"}, 3: {1: "UTF-16-BE"}, } class TableHeader(FieldSet): def createFields(self): yield String(self, "tag", 4) yield textHandler(UInt32(self, "checksum"), hexadecimal) yield UInt32(self, "offset") yield filesizeHandler(UInt32(self, "size")) def createDescription(self): return "Table entry: %s (%s)" % (self["tag"].display, self["size"].display) class NameHeader(FieldSet): def createFields(self): yield Enum(UInt16(self, "platformID"), PLATFORM_NAME) yield UInt16(self, "encodingID") yield UInt16(self, "languageID") yield Enum(UInt16(self, "nameID"), NAMEID_NAME) yield UInt16(self, "length") yield UInt16(self, "offset") def getCharset(self): platform = self["platformID"].value encoding = self["encodingID"].value try: return CHARSET_MAP[platform][encoding] except KeyError: self.warning("TTF: Unknown charset (%s,%s)" % (platform, encoding)) return "ISO-8859-1" def createDescription(self): platform = self["platformID"].display name = self["nameID"].display return "Name record: %s (%s)" % (name, platform) def parseFontHeader(self): yield UInt16(self, "maj_ver", "Major version") yield UInt16(self, "min_ver", "Minor version") yield UInt16(self, "font_maj_ver", "Font major version") yield UInt16(self, "font_min_ver", "Font minor version") yield textHandler(UInt32(self, "checksum"), hexadecimal) yield Bytes(self, "magic", 4, r"Magic string (\x5F\x0F\x3C\xF5)") if self["magic"].value != "\x5F\x0F\x3C\xF5": raise ParserError("TTF: invalid magic of font header") # Flags yield Bit(self, "y0", "Baseline at y=0") yield Bit(self, "x0", "Left sidebearing point at x=0") yield Bit(self, "instr_point", "Instructions may depend on point size") yield Bit(self, "ppem", "Force PPEM to integer values for all") yield Bit(self, "instr_width", "Instructions may alter advance width") yield Bit(self, "vertical", "e laid out vertically?") yield PaddingBits(self, "reserved[]", 1) yield Bit(self, "linguistic", "Requires layout for correct linguistic rendering?") yield Bit(self, "gx", "Metamorphosis effects?") yield Bit(self, "strong", "Contains strong right-to-left glyphs?") yield Bit(self, "indic", "contains Indic-style rearrangement effects?") yield Bit(self, "lossless", "Data is lossless (Agfa MicroType compression)") yield Bit(self, "converted", "Font converted (produce compatible metrics)") yield Bit(self, "cleartype", "Optimised for ClearType") yield Bits(self, "adobe", 2, "(used by Adobe)") yield UInt16(self, "unit_per_em", "Units per em") if not (16 <= self["unit_per_em"].value <= 16384): raise ParserError("TTF: Invalid unit/em value") yield UInt32(self, "created_high") yield TimestampMac32(self, "created") yield UInt32(self, "modified_high") yield TimestampMac32(self, "modified") yield UInt16(self, "xmin") yield UInt16(self, "ymin") yield UInt16(self, "xmax") yield UInt16(self, "ymax") # Mac style yield Bit(self, "bold") yield Bit(self, "italic") yield Bit(self, "underline") yield Bit(self, "outline") yield Bit(self, "shadow") yield Bit(self, "condensed", "(narrow)") yield Bit(self, "expanded") yield PaddingBits(self, "reserved[]", 9) yield UInt16(self, "lowest", "Smallest readable size in pixels") yield Enum(UInt16(self, "font_dir", "Font direction hint"), DIRECTION_NAME) yield Enum(UInt16(self, "ofst_format"), {0: "short offsets", 1: "long"}) yield UInt16(self, "glyph_format", "(=0)") def parseNames(self): # Read header yield UInt16(self, "format") if self["format"].value != 0: raise ParserError("TTF (names): Invalid format (%u)" % self["format"].value) yield UInt16(self, "count") yield UInt16(self, "offset") if MAX_NAME_COUNT < self["count"].value: raise ParserError("Invalid number of names (%s)" % self["count"].value) # Read name index entries = [] for index in xrange(self["count"].value): entry = NameHeader(self, "header[]") yield entry entries.append(entry) # Sort names by their offset entries.sort(key=lambda field: field["offset"].value) # Read name value last = None for entry in entries: # Skip duplicates values new = (entry["offset"].value, entry["length"].value) if last and last == new: self.warning("Skip duplicate %s %s" % (entry.name, new)) continue last = (entry["offset"].value, entry["length"].value) # Skip negative offset offset = entry["offset"].value + self["offset"].value if offset < self.current_size // 8: self.warning("Skip value %s (negative offset)" % entry.name) continue # Add padding if any padding = self.seekByte(offset, relative=True, null=True) if padding: yield padding # Read value size = entry["length"].value if size: yield String(self, "value[]", size, entry.description, charset=entry.getCharset()) padding = (self.size - self.current_size) // 8 if padding: yield NullBytes(self, "padding_end", padding) class Table(FieldSet): TAG_INFO = { "head": ("header", "Font header", parseFontHeader), "name": ("names", "Names", parseNames), } def __init__(self, parent, name, table, **kw): FieldSet.__init__(self, parent, name, **kw) self.table = table tag = table["tag"].value if tag in self.TAG_INFO: self._name, self._description, self.parser = self.TAG_INFO[tag] else: self.parser = None def createFields(self): if self.parser: for field in self.parser(self): yield field else: yield RawBytes(self, "content", self.size // 8) def createDescription(self): return "Table %s (%s)" % (self.table["tag"].value, self.table.path) class TrueTypeFontFile(Parser): endian = BIG_ENDIAN PARSER_TAGS = { "id": "ttf", "category": "misc", "file_ext": ("ttf",), "min_size": 10 * 8, # FIXME "description": "TrueType font", } def validate(self): if self["maj_ver"].value != 1: return "Invalid major version (%u)" % self["maj_ver"].value if self["min_ver"].value != 0: return "Invalid minor version (%u)" % self["min_ver"].value if not (MIN_NB_TABLE <= self["nb_table"].value <= MAX_NB_TABLE): return "Invalid number of table (%u)" % self["nb_table"].value return True def createFields(self): yield UInt16(self, "maj_ver", "Major version") yield UInt16(self, "min_ver", "Minor version") yield UInt16(self, "nb_table") yield UInt16(self, "search_range") yield UInt16(self, "entry_selector") yield UInt16(self, "range_shift") tables = [] for index in xrange(self["nb_table"].value): table = TableHeader(self, "table_hdr[]") yield table tables.append(table) tables.sort(key=lambda field: field["offset"].value) for table in tables: padding = self.seekByte(table["offset"].value, null=True) if padding: yield padding size = table["size"].value if size: yield Table(self, "table[]", table, size=size * 8) padding = self.seekBit(self.size, null=True) if padding: yield padding