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# -*- coding: utf-8 -*-
#
# Copyright (c) Aaron Spike <aaron@ekips.org>
# Aurélio A. Heckert <aurium(a)gmail.com>
# Bulia Byak <buliabyak@users.sf.net>
# Nicolas Dufour, nicoduf@yahoo.fr
# Peter J. R. Moulder <pjrm@users.sourceforge.net>
# Martin Owens <doctormo@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
"""
Convert to and from various units and find the closest matching unit.
"""
import re
# a dictionary of unit to user unit conversion factors
CONVERSIONS = {
"in": 96.0,
"pt": 1.3333333333333333,
"px": 1.0,
"mm": 3.779527559055118,
"cm": 37.79527559055118,
"m": 3779.527559055118,
"km": 3779527.559055118,
"Q": 0.94488188976378,
"pc": 16.0,
"yd": 3456.0,
"ft": 1152.0,
"": 1.0, # Default px
}
# allowed unit types, including percentages, relative units, and others
# that are not suitable for direct conversion to a length.
# Note that this is _not_ an exhaustive list of allowed unit types.
UNITS = [
"in",
"pt",
"px",
"mm",
"cm",
"m",
"km",
"Q",
"pc",
"yd",
"ft",
"",
"%",
"em",
"ex",
"ch",
"rem",
"vw",
"vh",
"vmin",
"vmax",
"deg",
"grad",
"rad",
"turn",
"s",
"ms",
"Hz",
"kHz",
"dpi",
"dpcm",
"dppx",
]
UNIT_MATCH = re.compile(rf"({'|'.join(UNITS)})")
NUMBER_MATCH = re.compile(r"(([-+]?[0-9]+(\.[0-9]*)?|[-+]?\.[0-9]+)([eE][-+]?[0-9]+)?)")
BOTH_MATCH = re.compile(rf"^\s*{NUMBER_MATCH.pattern}\s*{UNIT_MATCH.pattern}\s*$")
def parse_unit(value, default_unit="px", default_value=None):
"""
Takes a value such as 55.32px and returns (55.32, 'px')
Returns default (None) if no match can be found
"""
ret = BOTH_MATCH.match(str(value))
if ret:
return float(ret.groups()[0]), ret.groups()[-1] or default_unit
return (default_value, default_unit) if default_value is not None else None
def are_near_relative(point_a, point_b, eps=0.01):
"""Return true if the points are near to eps"""
return (point_a - point_b <= point_a * eps) and (
point_a - point_b >= -point_a * eps
)
def discover_unit(value, viewbox, default="px"):
"""Attempt to detect the unit being used based on the viewbox"""
# Default 100px when width can't be parsed
(value, unit) = parse_unit(value, default_value=100.0)
if unit not in CONVERSIONS:
return default
this_factor = CONVERSIONS[unit] * value / viewbox
# try to find the svgunitfactor in the list of units known. If we don't find
# something, ...
for unit, unit_factor in CONVERSIONS.items():
if unit != "":
# allow 1% error in factor
if are_near_relative(this_factor, unit_factor, eps=0.01):
return unit
return default
def convert_unit(value, to_unit, default="px"):
"""Returns userunits given a string representation of units in another system
Args:
value: <length> string
to_unit: unit to convert to
default: if ``value`` contains no unit, what unit should be assumed.
.. versionadded:: 1.1
"""
value, from_unit = parse_unit(value, default_unit=default, default_value=0.0)
if from_unit in CONVERSIONS and to_unit in CONVERSIONS:
return (
value * CONVERSIONS[from_unit] / CONVERSIONS.get(to_unit, CONVERSIONS["px"])
)
return 0.0
def render_unit(value, unit):
"""Checks and then renders a number with its unit"""
try:
if isinstance(value, str):
(value, unit) = parse_unit(value, default_unit=unit)
return f"{value:.6g}{ unit:s}"
except TypeError:
return ""
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