summaryrefslogtreecommitdiffstats
path: root/share/extensions/inkex/units.py
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--share/extensions/inkex/units.py150
1 files changed, 150 insertions, 0 deletions
diff --git a/share/extensions/inkex/units.py b/share/extensions/inkex/units.py
new file mode 100644
index 0000000..fec0e87
--- /dev/null
+++ b/share/extensions/inkex/units.py
@@ -0,0 +1,150 @@
+# -*- 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 ""