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1""" 

2This is a python interface to Adobe Font Metrics Files. Although a 

3number of other python implementations exist, and may be more complete 

4than this, it was decided not to go with them because they were either: 

5 

61) copyrighted or used a non-BSD compatible license 

72) had too many dependencies and a free standing lib was needed 

83) did more than needed and it was easier to write afresh rather than 

9 figure out how to get just what was needed. 

10 

11It is pretty easy to use, and requires only built-in python libs: 

12 

13>>> import matplotlib as mpl 

14>>> from pathlib import Path 

15>>> afm_path = Path(mpl.get_data_path(), 'fonts', 'afm', 'ptmr8a.afm') 

16>>> 

17>>> from matplotlib.afm import AFM 

18>>> with afm_path.open('rb') as fh: 

19... afm = AFM(fh) 

20>>> afm.string_width_height('What the heck?') 

21(6220.0, 694) 

22>>> afm.get_fontname() 

23'Times-Roman' 

24>>> afm.get_kern_dist('A', 'f') 

250 

26>>> afm.get_kern_dist('A', 'y') 

27-92.0 

28>>> afm.get_bbox_char('!') 

29[130, -9, 238, 676] 

30 

31As in the Adobe Font Metrics File Format Specification, all dimensions 

32are given in units of 1/1000 of the scale factor (point size) of the font 

33being used. 

34""" 

35 

36from collections import namedtuple 

37import logging 

38import re 

39 

40 

41from ._mathtext_data import uni2type1 

42from matplotlib.cbook import deprecated 

43 

44 

45_log = logging.getLogger(__name__) 

46 

47 

48def _to_int(x): 

49 # Some AFM files have floats where we are expecting ints -- there is 

50 # probably a better way to handle this (support floats, round rather than 

51 # truncate). But I don't know what the best approach is now and this 

52 # change to _to_int should at least prevent Matplotlib from crashing on 

53 # these. JDH (2009-11-06) 

54 return int(float(x)) 

55 

56 

57def _to_float(x): 

58 # Some AFM files use "," instead of "." as decimal separator -- this 

59 # shouldn't be ambiguous (unless someone is wicked enough to use "," as 

60 # thousands separator...). 

61 if isinstance(x, bytes): 

62 # Encoding doesn't really matter -- if we have codepoints >127 the call 

63 # to float() will error anyways. 

64 x = x.decode('latin-1') 

65 return float(x.replace(',', '.')) 

66 

67 

68def _to_str(x): 

69 return x.decode('utf8') 

70 

71 

72def _to_list_of_ints(s): 

73 s = s.replace(b',', b' ') 

74 return [_to_int(val) for val in s.split()] 

75 

76 

77def _to_list_of_floats(s): 

78 return [_to_float(val) for val in s.split()] 

79 

80 

81def _to_bool(s): 

82 if s.lower().strip() in (b'false', b'0', b'no'): 

83 return False 

84 else: 

85 return True 

86 

87 

88def _parse_header(fh): 

89 """ 

90 Reads the font metrics header (up to the char metrics) and returns 

91 a dictionary mapping *key* to *val*. *val* will be converted to the 

92 appropriate python type as necessary; e.g.: 

93 

94 * 'False'->False 

95 * '0'->0 

96 * '-168 -218 1000 898'-> [-168, -218, 1000, 898] 

97 

98 Dictionary keys are 

99 

100 StartFontMetrics, FontName, FullName, FamilyName, Weight, 

101 ItalicAngle, IsFixedPitch, FontBBox, UnderlinePosition, 

102 UnderlineThickness, Version, Notice, EncodingScheme, CapHeight, 

103 XHeight, Ascender, Descender, StartCharMetrics 

104 

105 """ 

106 header_converters = { 

107 b'StartFontMetrics': _to_float, 

108 b'FontName': _to_str, 

109 b'FullName': _to_str, 

110 b'FamilyName': _to_str, 

111 b'Weight': _to_str, 

112 b'ItalicAngle': _to_float, 

113 b'IsFixedPitch': _to_bool, 

114 b'FontBBox': _to_list_of_ints, 

115 b'UnderlinePosition': _to_float, 

116 b'UnderlineThickness': _to_float, 

117 b'Version': _to_str, 

118 # Some AFM files have non-ASCII characters (which are not allowed by 

119 # the spec). Given that there is actually no public API to even access 

120 # this field, just return it as straight bytes. 

121 b'Notice': lambda x: x, 

122 b'EncodingScheme': _to_str, 

123 b'CapHeight': _to_float, # Is the second version a mistake, or 

124 b'Capheight': _to_float, # do some AFM files contain 'Capheight'? -JKS 

125 b'XHeight': _to_float, 

126 b'Ascender': _to_float, 

127 b'Descender': _to_float, 

128 b'StdHW': _to_float, 

129 b'StdVW': _to_float, 

130 b'StartCharMetrics': _to_int, 

131 b'CharacterSet': _to_str, 

132 b'Characters': _to_int, 

133 } 

134 

135 d = {} 

136 first_line = True 

137 for line in fh: 

138 line = line.rstrip() 

139 if line.startswith(b'Comment'): 

140 continue 

141 lst = line.split(b' ', 1) 

142 key = lst[0] 

143 if first_line: 

144 # AFM spec, Section 4: The StartFontMetrics keyword 

145 # [followed by a version number] must be the first line in 

146 # the file, and the EndFontMetrics keyword must be the 

147 # last non-empty line in the file. We just check the 

148 # first header entry. 

149 if key != b'StartFontMetrics': 

150 raise RuntimeError('Not an AFM file') 

151 first_line = False 

152 if len(lst) == 2: 

153 val = lst[1] 

154 else: 

155 val = b'' 

156 try: 

157 converter = header_converters[key] 

158 except KeyError: 

159 _log.error('Found an unknown keyword in AFM header (was %r)' % key) 

160 continue 

161 try: 

162 d[key] = converter(val) 

163 except ValueError: 

164 _log.error('Value error parsing header in AFM: %s, %s', key, val) 

165 continue 

166 if key == b'StartCharMetrics': 

167 break 

168 else: 

169 raise RuntimeError('Bad parse') 

170 return d 

171 

172 

173CharMetrics = namedtuple('CharMetrics', 'width, name, bbox') 

174CharMetrics.__doc__ = """ 

175 Represents the character metrics of a single character. 

176 

177 Notes 

178 ----- 

179 The fields do currently only describe a subset of character metrics 

180 information defined in the AFM standard. 

181 """ 

182CharMetrics.width.__doc__ = """The character width (WX).""" 

183CharMetrics.name.__doc__ = """The character name (N).""" 

184CharMetrics.bbox.__doc__ = """ 

185 The bbox of the character (B) as a tuple (*llx*, *lly*, *urx*, *ury*).""" 

186 

187 

188def _parse_char_metrics(fh): 

189 """ 

190 Parse the given filehandle for character metrics information and return 

191 the information as dicts. 

192 

193 It is assumed that the file cursor is on the line behind 

194 'StartCharMetrics'. 

195 

196 Returns 

197 ------- 

198 ascii_d : dict 

199 A mapping "ASCII num of the character" to `.CharMetrics`. 

200 name_d : dict 

201 A mapping "character name" to `.CharMetrics`. 

202 

203 Notes 

204 ----- 

205 This function is incomplete per the standard, but thus far parses 

206 all the sample afm files tried. 

207 """ 

208 required_keys = {'C', 'WX', 'N', 'B'} 

209 

210 ascii_d = {} 

211 name_d = {} 

212 for line in fh: 

213 # We are defensively letting values be utf8. The spec requires 

214 # ascii, but there are non-compliant fonts in circulation 

215 line = _to_str(line.rstrip()) # Convert from byte-literal 

216 if line.startswith('EndCharMetrics'): 

217 return ascii_d, name_d 

218 # Split the metric line into a dictionary, keyed by metric identifiers 

219 vals = dict(s.strip().split(' ', 1) for s in line.split(';') if s) 

220 # There may be other metrics present, but only these are needed 

221 if not required_keys.issubset(vals): 

222 raise RuntimeError('Bad char metrics line: %s' % line) 

223 num = _to_int(vals['C']) 

224 wx = _to_float(vals['WX']) 

225 name = vals['N'] 

226 bbox = _to_list_of_floats(vals['B']) 

227 bbox = list(map(int, bbox)) 

228 metrics = CharMetrics(wx, name, bbox) 

229 # Workaround: If the character name is 'Euro', give it the 

230 # corresponding character code, according to WinAnsiEncoding (see PDF 

231 # Reference). 

232 if name == 'Euro': 

233 num = 128 

234 elif name == 'minus': 

235 num = ord("\N{MINUS SIGN}") # 0x2212 

236 if num != -1: 

237 ascii_d[num] = metrics 

238 name_d[name] = metrics 

239 raise RuntimeError('Bad parse') 

240 

241 

242def _parse_kern_pairs(fh): 

243 """ 

244 Return a kern pairs dictionary; keys are (*char1*, *char2*) tuples and 

245 values are the kern pair value. For example, a kern pairs line like 

246 ``KPX A y -50`` 

247 

248 will be represented as:: 

249 

250 d[ ('A', 'y') ] = -50 

251 

252 """ 

253 

254 line = next(fh) 

255 if not line.startswith(b'StartKernPairs'): 

256 raise RuntimeError('Bad start of kern pairs data: %s' % line) 

257 

258 d = {} 

259 for line in fh: 

260 line = line.rstrip() 

261 if not line: 

262 continue 

263 if line.startswith(b'EndKernPairs'): 

264 next(fh) # EndKernData 

265 return d 

266 vals = line.split() 

267 if len(vals) != 4 or vals[0] != b'KPX': 

268 raise RuntimeError('Bad kern pairs line: %s' % line) 

269 c1, c2, val = _to_str(vals[1]), _to_str(vals[2]), _to_float(vals[3]) 

270 d[(c1, c2)] = val 

271 raise RuntimeError('Bad kern pairs parse') 

272 

273 

274CompositePart = namedtuple('CompositePart', 'name, dx, dy') 

275CompositePart.__doc__ = """ 

276 Represents the information on a composite element of a composite char.""" 

277CompositePart.name.__doc__ = """Name of the part, e.g. 'acute'.""" 

278CompositePart.dx.__doc__ = """x-displacement of the part from the origin.""" 

279CompositePart.dy.__doc__ = """y-displacement of the part from the origin.""" 

280 

281 

282def _parse_composites(fh): 

283 """ 

284 Parse the given filehandle for composites information return them as a 

285 dict. 

286 

287 It is assumed that the file cursor is on the line behind 'StartComposites'. 

288 

289 Returns 

290 ------- 

291 composites : dict 

292 A dict mapping composite character names to a parts list. The parts 

293 list is a list of `.CompositePart` entries describing the parts of 

294 the composite. 

295 

296 Example 

297 ------- 

298 A composite definition line:: 

299 

300 CC Aacute 2 ; PCC A 0 0 ; PCC acute 160 170 ; 

301 

302 will be represented as:: 

303 

304 composites['Aacute'] = [CompositePart(name='A', dx=0, dy=0), 

305 CompositePart(name='acute', dx=160, dy=170)] 

306 

307 """ 

308 composites = {} 

309 for line in fh: 

310 line = line.rstrip() 

311 if not line: 

312 continue 

313 if line.startswith(b'EndComposites'): 

314 return composites 

315 vals = line.split(b';') 

316 cc = vals[0].split() 

317 name, numParts = cc[1], _to_int(cc[2]) 

318 pccParts = [] 

319 for s in vals[1:-1]: 

320 pcc = s.split() 

321 part = CompositePart(pcc[1], _to_float(pcc[2]), _to_float(pcc[3])) 

322 pccParts.append(part) 

323 composites[name] = pccParts 

324 

325 raise RuntimeError('Bad composites parse') 

326 

327 

328def _parse_optional(fh): 

329 """ 

330 Parse the optional fields for kern pair data and composites. 

331 

332 Returns 

333 ------- 

334 kern_data : dict 

335 A dict containing kerning information. May be empty. 

336 See `._parse_kern_pairs`. 

337 composites : dict 

338 A dict containing composite information. May be empty. 

339 See `._parse_composites`. 

340 """ 

341 optional = { 

342 b'StartKernData': _parse_kern_pairs, 

343 b'StartComposites': _parse_composites, 

344 } 

345 

346 d = {b'StartKernData': {}, 

347 b'StartComposites': {}} 

348 for line in fh: 

349 line = line.rstrip() 

350 if not line: 

351 continue 

352 key = line.split()[0] 

353 

354 if key in optional: 

355 d[key] = optional[key](fh) 

356 

357 return d[b'StartKernData'], d[b'StartComposites'] 

358 

359 

360class AFM: 

361 

362 def __init__(self, fh): 

363 """Parse the AFM file in file object *fh*.""" 

364 self._header = _parse_header(fh) 

365 self._metrics, self._metrics_by_name = _parse_char_metrics(fh) 

366 self._kern, self._composite = _parse_optional(fh) 

367 

368 def get_bbox_char(self, c, isord=False): 

369 if not isord: 

370 c = ord(c) 

371 return self._metrics[c].bbox 

372 

373 def string_width_height(self, s): 

374 """ 

375 Return the string width (including kerning) and string height 

376 as a (*w*, *h*) tuple. 

377 """ 

378 if not len(s): 

379 return 0, 0 

380 total_width = 0 

381 namelast = None 

382 miny = 1e9 

383 maxy = 0 

384 for c in s: 

385 if c == '\n': 

386 continue 

387 wx, name, bbox = self._metrics[ord(c)] 

388 

389 total_width += wx + self._kern.get((namelast, name), 0) 

390 l, b, w, h = bbox 

391 miny = min(miny, b) 

392 maxy = max(maxy, b + h) 

393 

394 namelast = name 

395 

396 return total_width, maxy - miny 

397 

398 def get_str_bbox_and_descent(self, s): 

399 """Return the string bounding box and the maximal descent.""" 

400 if not len(s): 

401 return 0, 0, 0, 0, 0 

402 total_width = 0 

403 namelast = None 

404 miny = 1e9 

405 maxy = 0 

406 left = 0 

407 if not isinstance(s, str): 

408 s = _to_str(s) 

409 for c in s: 

410 if c == '\n': 

411 continue 

412 name = uni2type1.get(ord(c), 'question') 

413 try: 

414 wx, _, bbox = self._metrics_by_name[name] 

415 except KeyError: 

416 name = 'question' 

417 wx, _, bbox = self._metrics_by_name[name] 

418 total_width += wx + self._kern.get((namelast, name), 0) 

419 l, b, w, h = bbox 

420 left = min(left, l) 

421 miny = min(miny, b) 

422 maxy = max(maxy, b + h) 

423 

424 namelast = name 

425 

426 return left, miny, total_width, maxy - miny, -miny 

427 

428 def get_str_bbox(self, s): 

429 """Return the string bounding box.""" 

430 return self.get_str_bbox_and_descent(s)[:4] 

431 

432 def get_name_char(self, c, isord=False): 

433 """Get the name of the character, i.e., ';' is 'semicolon'.""" 

434 if not isord: 

435 c = ord(c) 

436 return self._metrics[c].name 

437 

438 def get_width_char(self, c, isord=False): 

439 """ 

440 Get the width of the character from the character metric WX field. 

441 """ 

442 if not isord: 

443 c = ord(c) 

444 return self._metrics[c].width 

445 

446 def get_width_from_char_name(self, name): 

447 """Get the width of the character from a type1 character name.""" 

448 return self._metrics_by_name[name].width 

449 

450 def get_height_char(self, c, isord=False): 

451 """Get the bounding box (ink) height of character *c* (space is 0).""" 

452 if not isord: 

453 c = ord(c) 

454 return self._metrics[c].bbox[-1] 

455 

456 def get_kern_dist(self, c1, c2): 

457 """ 

458 Return the kerning pair distance (possibly 0) for chars *c1* and *c2*. 

459 """ 

460 name1, name2 = self.get_name_char(c1), self.get_name_char(c2) 

461 return self.get_kern_dist_from_name(name1, name2) 

462 

463 def get_kern_dist_from_name(self, name1, name2): 

464 """ 

465 Return the kerning pair distance (possibly 0) for chars 

466 *name1* and *name2*. 

467 """ 

468 return self._kern.get((name1, name2), 0) 

469 

470 def get_fontname(self): 

471 """Return the font name, e.g., 'Times-Roman'.""" 

472 return self._header[b'FontName'] 

473 

474 def get_fullname(self): 

475 """Return the font full name, e.g., 'Times-Roman'.""" 

476 name = self._header.get(b'FullName') 

477 if name is None: # use FontName as a substitute 

478 name = self._header[b'FontName'] 

479 return name 

480 

481 def get_familyname(self): 

482 """Return the font family name, e.g., 'Times'.""" 

483 name = self._header.get(b'FamilyName') 

484 if name is not None: 

485 return name 

486 

487 # FamilyName not specified so we'll make a guess 

488 name = self.get_fullname() 

489 extras = (r'(?i)([ -](regular|plain|italic|oblique|bold|semibold|' 

490 r'light|ultralight|extra|condensed))+$') 

491 return re.sub(extras, '', name) 

492 

493 @property 

494 def family_name(self): 

495 """The font family name, e.g., 'Times'.""" 

496 return self.get_familyname() 

497 

498 def get_weight(self): 

499 """Return the font weight, e.g., 'Bold' or 'Roman'.""" 

500 return self._header[b'Weight'] 

501 

502 def get_angle(self): 

503 """Return the fontangle as float.""" 

504 return self._header[b'ItalicAngle'] 

505 

506 def get_capheight(self): 

507 """Return the cap height as float.""" 

508 return self._header[b'CapHeight'] 

509 

510 def get_xheight(self): 

511 """Return the xheight as float.""" 

512 return self._header[b'XHeight'] 

513 

514 def get_underline_thickness(self): 

515 """Return the underline thickness as float.""" 

516 return self._header[b'UnderlineThickness'] 

517 

518 def get_horizontal_stem_width(self): 

519 """ 

520 Return the standard horizontal stem width as float, or *None* if 

521 not specified in AFM file. 

522 """ 

523 return self._header.get(b'StdHW', None) 

524 

525 def get_vertical_stem_width(self): 

526 """ 

527 Return the standard vertical stem width as float, or *None* if 

528 not specified in AFM file. 

529 """ 

530 return self._header.get(b'StdVW', None)