59 lines
2.1 KiB
Python
59 lines
2.1 KiB
Python
from fontTools.misc.textTools import safeEval
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from . import DefaultTable
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import struct
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import array
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# XXX I've lowered the strictness, to make sure Apple's own Chicago
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# XXX gets through. They're looking into it, I hope to raise the standards
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# XXX back to normal eventually.
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class table_L_T_S_H_(DefaultTable.DefaultTable):
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"""Linear Threshold table
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The ``LTSH`` table contains per-glyph settings indicating the ppem sizes
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at which the advance width metric should be scaled linearly, despite the
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effects of any TrueType instructions that might otherwise alter the
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advance width.
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See also https://learn.microsoft.com/en-us/typography/opentype/spec/ltsh
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"""
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def decompile(self, data, ttFont):
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version, numGlyphs = struct.unpack(">HH", data[:4])
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data = data[4:]
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assert version == 0, "unknown version: %s" % version
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assert (len(data) % numGlyphs) < 4, "numGlyphs doesn't match data length"
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# ouch: the assertion is not true in Chicago!
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# assert numGlyphs == ttFont['maxp'].numGlyphs
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yPels = array.array("B")
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yPels.frombytes(data)
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self.yPels = {}
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for i in range(numGlyphs):
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self.yPels[ttFont.getGlyphName(i)] = yPels[i]
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def compile(self, ttFont):
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version = 0
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names = list(self.yPels.keys())
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numGlyphs = len(names)
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yPels = [0] * numGlyphs
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# ouch: the assertion is not true in Chicago!
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# assert len(self.yPels) == ttFont['maxp'].numGlyphs == numGlyphs
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for name in names:
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yPels[ttFont.getGlyphID(name)] = self.yPels[name]
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yPels = array.array("B", yPels)
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return struct.pack(">HH", version, numGlyphs) + yPels.tobytes()
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def toXML(self, writer, ttFont):
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names = sorted(self.yPels.keys())
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for name in names:
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writer.simpletag("yPel", name=name, value=self.yPels[name])
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writer.newline()
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def fromXML(self, name, attrs, content, ttFont):
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if not hasattr(self, "yPels"):
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self.yPels = {}
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if name != "yPel":
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return # ignore unknown tags
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self.yPels[attrs["name"]] = safeEval(attrs["value"])
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