blob: c5119abd6255bc283a68d9b9d74d2e33e532ef92 [file] [log] [blame]
 """fontTools.misc.fixedTools.py -- tools for working with fixed numbers. """ from __future__ import print_function, division, absolute_import from fontTools.misc.py23 import * import math import logging log = logging.getLogger(__name__) __all__ = [ "otRound", "fixedToFloat", "floatToFixed", "floatToFixedToFloat", "ensureVersionIsLong", "versionToFixed", ] def otRound(value): """Round float value to nearest integer towards +Infinity. For fractional values of 0.5 and higher, take the next higher integer; for other fractional values, truncate. https://docs.microsoft.com/en-us/typography/opentype/spec/otvaroverview https://github.com/fonttools/fonttools/issues/1248#issuecomment-383198166 """ return int(math.floor(value + 0.5)) def fixedToFloat(value, precisionBits): """Converts a fixed-point number to a float, choosing the float that has the shortest decimal reprentation. Eg. to convert a fixed number in a 2.14 format, use precisionBits=14. This is pretty slow compared to a simple division. Use sporadically. precisionBits is only supported up to 16. """ if not value: return 0.0 scale = 1 << precisionBits value /= scale eps = .5 / scale lo = value - eps hi = value + eps # If the range of valid choices spans an integer, return the integer. if int(lo) != int(hi): return float(round(value)) fmt = "%.8f" lo = fmt % lo hi = fmt % hi assert len(lo) == len(hi) and lo != hi for i in range(len(lo)): if lo[i] != hi[i]: break period = lo.find('.') assert period < i fmt = "%%.%df" % (i - period) value = fmt % value return float(value) def floatToFixed(value, precisionBits): """Converts a float to a fixed-point number given the number of precisionBits. Ie. round(value * (1<