unit.py

   1 # -*- encoding: utf-8 -*-
   2 #
   3 #
   4 # Copyright (C) 2002-2004 Jörg Lehmann <joergl@users.sourceforge.net>
   5 # Copyright (C) 2002-2004 André Wobst <wobsta@users.sourceforge.net>
   6 #
   7 # This file is part of PyX (http://pyx.sourceforge.net/).
   8 #
   9 # PyX is free software; you can redistribute it and/or modify
  10 # it under the terms of the GNU General Public License as published by
  11 # the Free Software Foundation; either version 2 of the License, or
  12 # (at your option) any later version.
  13 #
  14 # PyX is distributed in the hope that it will be useful,
  15 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 # GNU General Public License for more details.
  18 #
  19 # You should have received a copy of the GNU General Public License
  20 # along with PyX; if not, write to the Free Software
  21 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  22
  23 import types, functools
  24
  25 scale = dict(u=1, v=1, w=1, x=1)
  26
  27 _default_unit = "cm"
  28
  29 _m = {
  30       "m":   1,
  31       "cm":   0.01,
  32       "mm":   0.001,
  33       "inch": 0.01*2.54,
  34       "pt":   0.01*2.54/72,
  35     }
  36
  37 def set(uscale=None, vscale=None, wscale=None, xscale=None, defaultunit=None):
  38     if uscale is not None:
  39         scale["u"] = uscale
  40     if vscale is not None:
  41         scale["v"] = vscale
  42     if wscale is not None:
  43         scale["w"] = wscale
  44     if xscale is not None:
  45         scale["x"] = xscale
  46     if defaultunit is not None:
  47         global _default_unit
  48         _default_unit = defaultunit
  49
  50
  51 def _convert_to(l, dest_unit="m"):
  52     if isinstance(l, length):
  53        return (l.t + l.u*scale["u"] + l.v*scale["v"] + l.w*scale["w"] + l.x*scale["x"]) / _m[dest_unit]
  54     else:
  55         return l * _m[_default_unit] * scale["u"] / _m[dest_unit]
  56
  57 def tom(l):
  58     return _convert_to(l, "m")
  59
  60 def tocm(l):
  61     return _convert_to(l, "cm")
  62
  63 def tomm(l):
  64     return _convert_to(l, "mm")
  65
  66 def toinch(l):
  67     return _convert_to(l, "inch")
  68
  69 def topt(l):
  70     return _convert_to(l, "pt")
  71
  72 ################################################################################
  73 # class for generic length
  74 ################################################################################
  75
  76 @functools.total_ordering
  77 class length:
  78     """ PyX lengths
  79
  80     PyX lengths are composed of five components (t=true, u=user, v=visual,
  81     w=width, and x=TeX) which can be scaled separately (except for the true
  82     component, which is always unscaled). Lengths can be constructed in units
  83     of "pt", "mm", "cm", "m" and "inch". When no unit is given, a module
  84     default is used, which can be changed with the help of the module level function
  85     set().
  86     """
  87
  88     def __init__(self, f=0, type="u", unit=None):
  89         """ create a length instance of the given type with a length f
  90         in the given unit. If unit is not set, the currently set default unit is used.
  91         """
  92         self.t = self.u = self.v = self.w = self.x = 0
  93         l = float(f) * _m[unit or _default_unit]
  94         if type == "t":
  95             self.t = l
  96         elif type == "u":
  97             self.u = l
  98         elif type == "v":
  99             self.v = l
 100         elif type == "w":
 101             self.w = l
 102         elif type == "x":
 103             self.x = l
 104
 105     def __eq__(self, other):
 106         try:
 107             return tom(self) == tom(other)
 108         except TypeError:
 109             return NotImplemented
 110
 111     def __lt__(self, other):
 112         try:
 113             return tom(self) < tom(other)
 114         except TypeError:
 115             return NotImplemented
 116
 117     def __mul__(self, factor):
 118         result = length()
 119         result.t = factor * self.t
 120         result.u = factor * self.u
 121         result.v = factor * self.v
 122         result.w = factor * self.w
 123         result.x = factor * self.x
 124         return result
 125
 126     __rmul__=__mul__
 127
 128     def __div__(self, divisor):
 129         if isinstance(divisor, length):
 130             return tom(self) / tom(divisor)
 131         result = length()
 132         result.t = self.t / divisor
 133         result.u = self.u / divisor
 134         result.v = self.v / divisor
 135         result.w = self.w / divisor
 136         result.x = self.x / divisor
 137         return result
 138
 139     __truediv__ = __div__
 140
 141     def __add__(self, other):
 142         # convert to length if necessary
 143         if not isinstance(other, length):
 144             # if other is not a length, we try to convert it into a length and
 145             # if this fails, we give other a chance to do the addition
 146             try:
 147                 other = length(other)
 148             except:
 149                 return other + self
 150         result = length()
 151         result.t = self.t + other.t
 152         result.u = self.u + other.u
 153         result.v = self.v + other.v
 154         result.w = self.w + other.w
 155         result.x = self.x + other.x
 156         return result
 157
 158     __radd__ = __add__
 159
 160     def __sub__(self, other):
 161         # convert to length if necessary
 162         if not isinstance(other, length):
 163             # if other is not a length, we try to convert it into a length and
 164             # if this fails, we give other a chance to do the subtraction
 165             try:
 166                 other = length(other)
 167             except:
 168                 return -other + self
 169         result = length()
 170         result.t = self.t - other.t
 171         result.u = self.u - other.u
 172         result.v = self.v - other.v
 173         result.w = self.w - other.w
 174         result.x = self.x - other.x
 175         return result
 176
 177     def __rsub__(self, other):
 178         # convert to length if necessary
 179         if not isinstance(other, length):
 180             other = length(other)
 181         result = length()
 182         result.t = other.t - self.t
 183         result.u = other.u - self.u
 184         result.v = other.v - self.v
 185         result.w = other.w - self.w
 186         result.x = other.x - self.x
 187         return result
 188
 189     def __neg__(self):
 190         result = length()
 191         result.t = -self.t
 192         result.u = -self.u
 193         result.v = -self.v
 194         result.w = -self.w
 195         result.x = -self.x
 196         return result
 197
 198     def __str__(self):
 199         return "(%(t)f t + %(u)f u + %(v)f v + %(w)f w + %(x)f x) m" % self.__dict__
 200
 201
 202 ################################################################################
 203 # predefined instances which can be used as length units
 204 ################################################################################
 205
 206 # user lengths and unqualified length which are also user length
 207 u_pt   = pt   = length(1, type="u", unit="pt")
 208 u_m    = m    = length(1, type="u", unit="m")
 209 u_mm   = mm   = length(1, type="u", unit="mm")
 210 u_cm   = cm   = length(1, type="u", unit="cm")
 211 u_inch = inch = length(1, type="u", unit="inch")
 212
 213 # true lengths
 214 t_pt   = length(1, type="t", unit="pt")
 215 t_m    = length(1, type="t", unit="m")
 216 t_mm   = length(1, type="t", unit="mm")
 217 t_cm   = length(1, type="t", unit="cm")
 218 t_inch = length(1, type="t", unit="inch")
 219
 220 # visual lengths
 221 v_pt   = length(1, type="v", unit="pt")
 222 v_m    = length(1, type="v", unit="m")
 223 v_mm   = length(1, type="v", unit="mm")
 224 v_cm   = length(1, type="v", unit="cm")
 225 v_inch = length(1, type="v", unit="inch")
 226
 227 # width lengths
 228 w_pt   = length(1, type="w", unit="pt")
 229 w_m    = length(1, type="w", unit="m")
 230 w_mm   = length(1, type="w", unit="mm")
 231 w_cm   = length(1, type="w", unit="cm")
 232 w_inch = length(1, type="w", unit="inch")
 233
 234 # TeX lengths
 235 x_pt   = length(1, type="x", unit="pt")
 236 x_m    = length(1, type="x", unit="m")
 237 x_mm   = length(1, type="x", unit="mm")
 238 x_cm   = length(1, type="x", unit="cm")
 239 x_inch = length(1, type="x", unit="inch")