pyx/unit.py

   1 #!/usr/bin/env python
   2 # -*- coding: ISO-8859-1 -*-
   3 #
   4 #
   5 # Copyright (C) 2002-2004 Jörg Lehmann <joergl@users.sourceforge.net>
   6 # Copyright (C) 2002-2004 André Wobst <wobsta@users.sourceforge.net>
   7 #
   8 # This file is part of PyX (http://pyx.sourceforge.net/).
   9 #
  10 # PyX is free software; you can redistribute it and/or modify
  11 # it under the terms of the GNU General Public License as published by
  12 # the Free Software Foundation; either version 2 of the License, or
  13 # (at your option) any later version.
  14 #
  15 # PyX is distributed in the hope that it will be useful,
  16 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 # GNU General Public License for more details.
  19 #
  20 # You should have received a copy of the GNU General Public License
  21 # along with PyX; if not, write to the Free Software
  22 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23
  24 import types
  25 import re
  26 import helper
  27
  28 scale = { 't':1, 'u':1, 'v':1, 'w':1, 'x':1 }
  29
  30 _default_unit = "cm"
  31
  32 unit_pattern = re.compile(r"""^\s*([+-]?\d*((\d\.?)|(\.?\d))\d*(E[+-]?\d+)?)
  33                               (\s+([t-x]))?
  34                               (\s+(([a-z][a-z]+)|[^t-x]))?\s*$""",
  35                           re.IGNORECASE | re.VERBOSE)
  36
  37
  38 _m = {
  39       'm' :   1,
  40       'cm':   0.01,
  41       'mm':   0.001,
  42       'inch': 0.01*2.54,
  43       'pt':   0.01*2.54/72,
  44     }
  45
  46 def set(uscale=None, vscale=None, wscale=None, xscale=None, defaultunit=None):
  47     if uscale is not None:
  48         scale['u'] = uscale
  49     if vscale is not None:
  50         scale['v'] = vscale
  51     if wscale is not None:
  52         scale['w'] = wscale
  53     if xscale is not None:
  54         scale['x'] = xscale
  55     if defaultunit is not None:
  56         global _default_unit
  57         _default_unit = defaultunit
  58
  59
  60 def _convert_to(l, dest_unit="m"):
  61     if type(l) in (types.IntType, types.LongType, types.FloatType):
  62         return l*_m[_default_unit]*scale['u']/_m[dest_unit]
  63     elif not isinstance(l, length):
  64         l=length(l)       # convert to length instance if necessary
  65
  66     return ( l.length['t']            +
  67              l.length['u']*scale['u'] +
  68              l.length['v']*scale['v'] +
  69              l.length['w']*scale['w'] +
  70              l.length['x']*scale['x'] ) / _m[dest_unit]
  71
  72 def tom(l):
  73     return _convert_to(l, "m")
  74
  75 def tocm(l):
  76     return _convert_to(l, "cm")
  77
  78 def tomm(l):
  79     return _convert_to(l, "mm")
  80
  81 def toinch(l):
  82     return _convert_to(l, "inch")
  83
  84 def topt(l):
  85     return _convert_to(l, "pt")
  86
  87 ################################################################################
  88 # class for generic length
  89 ################################################################################
  90
  91 class length:
  92     """ general lengths
  93
  94     Lengths can either be a initialized with a number or a string:
  95
  96      - a length specified as a number corresponds to the default values of
  97        unit_type and unit_name
  98      - a string has to consist of a maximum of three parts:
  99        -quantifier: integer/float value
 100        -unit_type:  "t", "u", "v", "w", or "x".
 101                     Optional, defaults to "u"
 102        -unit_name:  "m", "cm", "mm", "inch", "pt".
 103                     Optional, defaults to _default_unit
 104
 105     Internally all length are stored in units of m as a quadruple of the four
 106     unit_types.
 107
 108     """
 109
 110     def __init__(self, l=1, default_type="u", dunit=None):
 111         self.length = { 't': 0 , 'u': 0, 'v': 0, 'w': 0, 'x': 0 }
 112
 113         if isinstance(l, length):
 114             self.length = l.length
 115         elif helper.isnumber(l):
 116             self.length[default_type] = l*_m[dunit or _default_unit]
 117         # elif helper.isstring(l):
 118         #     unit_match = re.match(unit_pattern, l)
 119         #     if unit_match is None:
 120         #         raise ValueError("expecting number or string of the form 'number [u|v|w|x] unit'")
 121         #     else:
 122         #         self.prefactor = float(unit_match.group(1))
 123         #         self.unit_type = unit_match.group(7) or default_type
 124         #         self.unit_name = unit_match.group(9) or dunit or _default_unit
 125
 126         #         self.length[self.unit_type] = self.prefactor*_m[self.unit_name]
 127         else:
 128             raise NotImplementedError("cannot convert given argument to length type")
 129
 130     def __cmp__(self, other):
 131         return cmp(tom(self), tom(other))
 132
 133     def __mul__(self, factor):
 134         newlength = self.__class__()
 135         for unit_type in newlength.length.keys():
 136            newlength.length[unit_type] = self.length[unit_type]*factor
 137         return newlength
 138
 139     __rmul__=__mul__
 140
 141     def __div__(self, factor):
 142         newlength = self.__class__()
 143         for unit_type in newlength.length.keys():
 144            newlength.length[unit_type] = self.length[unit_type]/factor
 145         return newlength
 146
 147     def __add__(self, l):
 148         # convert to length if necessary
 149         ll = length(l)
 150         newlength = self.__class__()
 151         for unit_type in newlength.length.keys():
 152            newlength.length[unit_type] = self.length[unit_type] + ll.length[unit_type]
 153         return newlength
 154
 155     __radd__=__add__
 156
 157     def __sub__(self, l):
 158         # convert to length if necessary
 159         ll = length(l)
 160         newlength = self.__class__()
 161         for unit_type in newlength.length.keys():
 162            newlength.length[unit_type] = self.length[unit_type] - ll.length[unit_type]
 163         return newlength
 164
 165     def __rsub__(self, l):
 166         # convert to length if necessary
 167         ll = length(l)
 168         newlength = self.__class__()
 169         for unit_type in newlength.length.keys():
 170            newlength.length[unit_type] = ll.length[unit_type] - self.length[unit_type]
 171         return newlength
 172
 173     def __neg__(self):
 174         newlength = self.__class__()
 175         for unit_type in newlength.length.keys():
 176            newlength.length[unit_type] = -self.length[unit_type]
 177         return newlength
 178
 179     def __str__(self):
 180         return "(%(t)f t + %(u)f u + %(v)f v + %(w)f w + %(x)f x) m" % self.length
 181
 182
 183 ################################################################################
 184 # predefined instances which can be used as length units
 185 ################################################################################
 186
 187 # user lengths and unqualified length which are also user length
 188 u_pt = pt = length(1, "u", "pt")
 189 u_m = m = length(1, "u", "m")
 190 u_mm = mm = length(1, "u", "mm")
 191 u_cm = cm = length(1, "u", "cm")
 192 u_inch = inch = length(1, "u", "inch")
 193
 194 # true lengths
 195 t_pt = length(1, "t", "pt")
 196 t_m = length(1, "t", "m")
 197 t_mm = length(1, "t", "mm")
 198 t_cm = length(1, "t", "cm")
 199 t_inch = length(1, "t", "inch")
 200
 201 # visual lengths
 202 v_pt = length(1, "v", "pt")
 203 v_m = length(1, "v", "m")
 204 v_mm = length(1, "v", "mm")
 205 v_cm = length(1, "v", "cm")
 206 v_inch = length(1, "v", "inch")
 207
 208
 209 # width lengths
 210 w_pt = length(1, "w", "pt")
 211 w_m = length(1, "w", "m")
 212 w_mm = length(1, "w", "mm")
 213 w_cm = length(1, "w", "cm")
 214 w_inch = length(1, "w", "inch")
 215
 216 # TeX lengths
 217 x_pt = length(1, "x", "pt")
 218 x_m = length(1, "x", "m")
 219 x_mm = length(1, "x", "mm")
 220 x_cm = length(1, "x", "cm")
 221 x_inch = length(1, "x", "inch")