F__e_a_t.py 5.3 KB

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  1. from fontTools.misc import sstruct
  2. from fontTools.misc.fixedTools import floatToFixedToStr
  3. from fontTools.misc.textTools import safeEval
  4. from . import DefaultTable
  5. from . import grUtils
  6. import struct
  7. Feat_hdr_format = """
  8. >
  9. version: 16.16F
  10. """
  11. class table_F__e_a_t(DefaultTable.DefaultTable):
  12. """The ``Feat`` table is used exclusively by the Graphite shaping engine
  13. to store features and possible settings specified in GDL. Graphite features
  14. determine what rules are applied to transform a glyph stream.
  15. Not to be confused with ``feat``, or the OpenType Layout tables
  16. ``GSUB``/``GPOS``."""
  17. def __init__(self, tag=None):
  18. DefaultTable.DefaultTable.__init__(self, tag)
  19. self.features = {}
  20. def decompile(self, data, ttFont):
  21. (_, data) = sstruct.unpack2(Feat_hdr_format, data, self)
  22. self.version = float(floatToFixedToStr(self.version, precisionBits=16))
  23. (numFeats,) = struct.unpack(">H", data[:2])
  24. data = data[8:]
  25. allfeats = []
  26. maxsetting = 0
  27. for i in range(numFeats):
  28. if self.version >= 2.0:
  29. (fid, nums, _, offset, flags, lid) = struct.unpack(
  30. ">LHHLHH", data[16 * i : 16 * (i + 1)]
  31. )
  32. offset = int((offset - 12 - 16 * numFeats) / 4)
  33. else:
  34. (fid, nums, offset, flags, lid) = struct.unpack(
  35. ">HHLHH", data[12 * i : 12 * (i + 1)]
  36. )
  37. offset = int((offset - 12 - 12 * numFeats) / 4)
  38. allfeats.append((fid, nums, offset, flags, lid))
  39. maxsetting = max(maxsetting, offset + nums)
  40. data = data[16 * numFeats :]
  41. allsettings = []
  42. for i in range(maxsetting):
  43. if len(data) >= 4 * (i + 1):
  44. (val, lid) = struct.unpack(">HH", data[4 * i : 4 * (i + 1)])
  45. allsettings.append((val, lid))
  46. for i, f in enumerate(allfeats):
  47. (fid, nums, offset, flags, lid) = f
  48. fobj = Feature()
  49. fobj.flags = flags
  50. fobj.label = lid
  51. self.features[grUtils.num2tag(fid)] = fobj
  52. fobj.settings = {}
  53. fobj.default = None
  54. fobj.index = i
  55. for i in range(offset, offset + nums):
  56. if i >= len(allsettings):
  57. continue
  58. (vid, vlid) = allsettings[i]
  59. fobj.settings[vid] = vlid
  60. if fobj.default is None:
  61. fobj.default = vid
  62. def compile(self, ttFont):
  63. fdat = b""
  64. vdat = b""
  65. offset = 0
  66. for f, v in sorted(self.features.items(), key=lambda x: x[1].index):
  67. fnum = grUtils.tag2num(f)
  68. if self.version >= 2.0:
  69. fdat += struct.pack(
  70. ">LHHLHH",
  71. grUtils.tag2num(f),
  72. len(v.settings),
  73. 0,
  74. offset * 4 + 12 + 16 * len(self.features),
  75. v.flags,
  76. v.label,
  77. )
  78. elif fnum > 65535: # self healing for alphabetic ids
  79. self.version = 2.0
  80. return self.compile(ttFont)
  81. else:
  82. fdat += struct.pack(
  83. ">HHLHH",
  84. grUtils.tag2num(f),
  85. len(v.settings),
  86. offset * 4 + 12 + 12 * len(self.features),
  87. v.flags,
  88. v.label,
  89. )
  90. for s, l in sorted(
  91. v.settings.items(), key=lambda x: (-1, x[1]) if x[0] == v.default else x
  92. ):
  93. vdat += struct.pack(">HH", s, l)
  94. offset += len(v.settings)
  95. hdr = sstruct.pack(Feat_hdr_format, self)
  96. return hdr + struct.pack(">HHL", len(self.features), 0, 0) + fdat + vdat
  97. def toXML(self, writer, ttFont):
  98. writer.simpletag("version", version=self.version)
  99. writer.newline()
  100. for f, v in sorted(self.features.items(), key=lambda x: x[1].index):
  101. writer.begintag(
  102. "feature",
  103. fid=f,
  104. label=v.label,
  105. flags=v.flags,
  106. default=(v.default if v.default else 0),
  107. )
  108. writer.newline()
  109. for s, l in sorted(v.settings.items()):
  110. writer.simpletag("setting", value=s, label=l)
  111. writer.newline()
  112. writer.endtag("feature")
  113. writer.newline()
  114. def fromXML(self, name, attrs, content, ttFont):
  115. if name == "version":
  116. self.version = float(safeEval(attrs["version"]))
  117. elif name == "feature":
  118. fid = attrs["fid"]
  119. fobj = Feature()
  120. fobj.flags = int(safeEval(attrs["flags"]))
  121. fobj.label = int(safeEval(attrs["label"]))
  122. fobj.default = int(safeEval(attrs.get("default", "0")))
  123. fobj.index = len(self.features)
  124. self.features[fid] = fobj
  125. fobj.settings = {}
  126. for element in content:
  127. if not isinstance(element, tuple):
  128. continue
  129. tag, a, c = element
  130. if tag == "setting":
  131. fobj.settings[int(safeEval(a["value"]))] = int(safeEval(a["label"]))
  132. class Feature(object):
  133. pass