up follow livre

venv/lib/python3.13/site-packages/fontTools/misc/roundTools.py

@@ -0,0 +1,110 @@
+"""
+Various round-to-integer helpers.
+"""
+
+import math
+import functools
+import logging
+
+log = logging.getLogger(__name__)
+
+__all__ = [
+    "noRound",
+    "otRound",
+    "maybeRound",
+    "roundFunc",
+    "nearestMultipleShortestRepr",
+]
+
+
+def noRound(value):
+    return value
+
+
+def otRound(value):
+    """Round float value to nearest integer towards ``+Infinity``.
+
+    The OpenType spec (in the section on `"normalization" of OpenType Font Variations <https://docs.microsoft.com/en-us/typography/opentype/spec/otvaroverview#coordinate-scales-and-normalization>`_)
+    defines the required method for converting floating point values to
+    fixed-point. In particular it specifies the following rounding strategy:
+
+            for fractional values of 0.5 and higher, take the next higher integer;
+            for other fractional values, truncate.
+
+    This function rounds the floating-point value according to this strategy
+    in preparation for conversion to fixed-point.
+
+    Args:
+            value (float): The input floating-point value.
+
+    Returns
+            float: The rounded value.
+    """
+    # See this thread for how we ended up with this implementation:
+    # https://github.com/fonttools/fonttools/issues/1248#issuecomment-383198166
+    return int(math.floor(value + 0.5))
+
+
+def maybeRound(v, tolerance, round=otRound):
+    rounded = round(v)
+    return rounded if abs(rounded - v) <= tolerance else v
+
+
+def roundFunc(tolerance, round=otRound):
+    if tolerance < 0:
+        raise ValueError("Rounding tolerance must be positive")
+
+    if tolerance == 0:
+        return noRound
+
+    if tolerance >= 0.5:
+        return round
+
+    return functools.partial(maybeRound, tolerance=tolerance, round=round)
+
+
+def nearestMultipleShortestRepr(value: float, factor: float) -> str:
+    """Round to nearest multiple of factor and return shortest decimal representation.
+
+    This chooses the float that is closer to a multiple of the given factor while
+    having the shortest decimal representation (the least number of fractional decimal
+    digits).
+
+    For example, given the following:
+
+    >>> nearestMultipleShortestRepr(-0.61883544921875, 1.0/(1<<14))
+    '-0.61884'
+
+    Useful when you need to serialize or print a fixed-point number (or multiples
+    thereof, such as F2Dot14 fractions of 180 degrees in COLRv1 PaintRotate) in
+    a human-readable form.
+
+    Args:
+        value (value): The value to be rounded and serialized.
+        factor (float): The value which the result is a close multiple of.
+
+    Returns:
+        str: A compact string representation of the value.
+    """
+    if not value:
+        return "0.0"
+
+    value = otRound(value / factor) * factor
+    eps = 0.5 * factor
+    lo = value - eps
+    hi = value + eps
+    # If the range of valid choices spans an integer, return the integer.
+    if int(lo) != int(hi):
+        return str(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)
+    return fmt % value