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Diffstat (limited to 'share/extensions/inkex/units.py')
| -rw-r--r-- | share/extensions/inkex/units.py | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/share/extensions/inkex/units.py b/share/extensions/inkex/units.py new file mode 100644 index 0000000..cd69a39 --- /dev/null +++ b/share/extensions/inkex/units.py @@ -0,0 +1,107 @@ +# -*- 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(r'({})'.format('|'.join(UNITS))) +NUMBER_MATCH = re.compile(r'(([-+]?[0-9]+(\.[0-9]*)?|[-+]?\.[0-9]+)([eE][-+]?[0-9]+)?)') +BOTH_MATCH = re.compile(r'^\s*{}\s*{}\s*$'.format(NUMBER_MATCH.pattern, UNIT_MATCH.pattern)) + + +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): + """Returns userunits given a string representation of units in another system""" + value, from_unit = parse_unit(value, 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 "{:.6g}{:s}".format(value, unit) + except TypeError: + return '' |