io_curve_svg/svg_util.py

   1 # SPDX-FileCopyrightText: 2010-2022 Blender Foundation
   2 #
   3 # SPDX-License-Identifier: GPL-2.0-or-later
   4
   5 import re
   6
   7
   8 units = {"": 1.0,
   9          "px": 1.0,
  10          "in": 90.0,
  11          "mm": 90.0 / 25.4,
  12          "cm": 90.0 / 2.54,
  13          "pt": 1.25,
  14          "pc": 15.0,
  15          "em": 1.0,
  16          "ex": 1.0,
  17          "INVALID": 1.0,  # some DocBook files contain this
  18          }
  19
  20
  21 def srgb_to_linearrgb(c):
  22     if c < 0.04045:
  23         return 0.0 if c < 0.0 else c * (1.0 / 12.92)
  24     else:
  25         return pow((c + 0.055) * (1.0 / 1.055), 2.4)
  26
  27
  28 def check_points_equal(point_a, point_b):
  29     return (abs(point_a[0] - point_b[0]) < 1e-6 and
  30             abs(point_a[1] - point_b[1]) < 1e-6)
  31
  32 match_number = r"-?\d+(\.\d+)?([eE][-+]?\d+)?"
  33 match_first_comma = r"^\s*(?=,)"
  34 match_comma_pair = r",\s*(?=,)"
  35 match_last_comma = r",\s*$"
  36
  37 match_number_optional_parts = r"(-?\d+(\.\d*)?([eE][-+]?\d+)?)|(-?\.\d+([eE][-+]?\d+)?)"
  38 re_match_number_optional_parts = re.compile(match_number_optional_parts)
  39
  40 array_of_floats_pattern = f"({match_number_optional_parts})|{match_first_comma}|{match_comma_pair}|{match_last_comma}"
  41 re_array_of_floats_pattern = re.compile(array_of_floats_pattern)
  42
  43 def parse_array_of_floats(text):
  44     """
  45     Accepts comma or space separated list of floats (without units) and returns an array
  46     of floating point values.
  47     """
  48     elements = re_array_of_floats_pattern.findall(text)
  49     return [value_to_float(v[0]) for v in elements]
  50
  51
  52 def read_float(text: str, start_index: int = 0):
  53     """
  54     Reads floating point value from a string. Parsing starts at the given index.
  55
  56     Returns the value itself (as a string) and index of first character after the value.
  57     """
  58
  59     n = len(text)
  60
  61     # Skip leading whitespace characters and characters which we consider ignorable for float
  62     # (like values separator).
  63     while start_index < n and (text[start_index].isspace() or text[start_index] == ','):
  64         start_index += 1
  65     if start_index == n:
  66         return "0", start_index
  67
  68     text_part = text[start_index:]
  69     match = re_match_number_optional_parts.match(text_part)
  70
  71     if match is None:
  72         raise Exception('Invalid float value near ' + text[start_index:start_index + 10])
  73
  74     token = match.group(0)
  75     endptr = start_index + match.end(0)
  76
  77     return token, endptr
  78
  79
  80 def parse_coord(coord, size):
  81     """
  82     Parse coordinate component to common basis
  83
  84     Needed to handle coordinates set in cm, mm, inches.
  85     """
  86
  87     token, last_char = read_float(coord)
  88     val = float(token)
  89     unit = coord[last_char:].strip()  # strip() in case there is a space
  90
  91     if unit == '%':
  92         return float(size) / 100.0 * val
  93     else:
  94         return val * units[unit]
  95
  96     return val
  97
  98
  99 def value_to_float(value_encoded: str):
 100     """
 101     A simple wrapper around float() which supports empty strings (which are converted to 0).
 102     """
 103     if len(value_encoded) == 0:
 104         return 0
 105     return float(value_encoded)