pyx/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
  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 class length:
  77     """ PyX lengths
  78
  79     PyX lengths are composed of five components (t=true, u=user, v=visual,
  80     w=width, and x=TeX) which can be scaled separately (except for the true
  81     component, which is always unscaled). Lengths can be constructed in units
  82     of "pt", "mm", "cm", "m" and "inch". When no unit is given, a module
  83     default is used, which can be changed with the help of the module level function
  84     set().
  85     """
  86
  87     def __init__(self, f=0, type="u", unit=None):
  88         """ create a length instance of the given type with a length f
  89         in the given unit. If unit is not set, the currently set default unit is used.
  90         """
  91         self.t = self.u = self.v = self.w = self.x = 0
  92         l = float(f) * _m[unit or _default_unit]
  93         if type == "t":
  94             self.t = l
  95         elif type == "u":
  96             self.u = l
  97         elif type == "v":
  98             self.v = l
  99         elif type == "w":
 100             self.w = l
 101         elif type == "x":
 102             self.x = l
 103
 104     def __cmp__(self, other):
 105         # we try to convert self and other into meters and
 106         # if this fails, we give other a chance to do the comparison
 107         try:
 108             return cmp(tom(self), tom(other))
 109         except:
 110             # why does -cmp(other, self) not work?
 111             return -other.__cmp__(self)
 112
 113     def __mul__(self, factor):
 114         result = length()
 115         result.t = factor * self.t
 116         result.u = factor * self.u
 117         result.v = factor * self.v
 118         result.w = factor * self.w
 119         result.x = factor * self.x
 120         return result
 121
 122     __rmul__=__mul__
 123
 124     def __div__(self, divisor):
 125         if isinstance(divisor, length):
 126             return tom(self) / tom(divisor)
 127         result = length()
 128         result.t = self.t / divisor
 129         result.u = self.u / divisor
 130         result.v = self.v / divisor
 131         result.w = self.w / divisor
 132         result.x = self.x / divisor
 133         return result
 134
 135     __truediv__ = __div__
 136
 137     def __add__(self, other):
 138         # convert to length if necessary
 139         if not isinstance(other, length):
 140             # if other is not a length, we try to convert it into a length and
 141             # if this fails, we give other a chance to do the addition
 142             try:
 143                 other = length(other)
 144             except:
 145                 return other + self
 146         result = length()
 147         result.t = self.t + other.t
 148         result.u = self.u + other.u
 149         result.v = self.v + other.v
 150         result.w = self.w + other.w
 151         result.x = self.x + other.x
 152         return result
 153
 154     __radd__ = __add__
 155
 156     def __sub__(self, other):
 157         # convert to length if necessary
 158         if not isinstance(other, length):
 159             # if other is not a length, we try to convert it into a length and
 160             # if this fails, we give other a chance to do the subtraction
 161             try:
 162                 other = length(other)
 163             except:
 164                 return -other + self
 165         result = length()
 166         result.t = self.t - other.t
 167         result.u = self.u - other.u
 168         result.v = self.v - other.v
 169         result.w = self.w - other.w
 170         result.x = self.x - other.x
 171         return result
 172
 173     def __rsub__(self, other):
 174         # convert to length if necessary
 175         if not isinstance(other, length):
 176             other = length(other)
 177         result = length()
 178         result.t = other.t - self.t
 179         result.u = other.u - self.u
 180         result.v = other.v - self.v
 181         result.w = other.w - self.w
 182         result.x = other.x - self.x
 183         return result
 184
 185     def __neg__(self):
 186         result = length()
 187         result.t = -self.t
 188         result.u = -self.u
 189         result.v = -self.v
 190         result.w = -self.w
 191         result.x = -self.x
 192         return result
 193
 194     def __str__(self):
 195         return "(%(t)f t + %(u)f u + %(v)f v + %(w)f w + %(x)f x) m" % self.__dict__
 196
 197
 198 ################################################################################
 199 # predefined instances which can be used as length units
 200 ################################################################################
 201
 202 # user lengths and unqualified length which are also user length
 203 u_pt   = pt   = length(1, type="u", unit="pt")
 204 u_m    = m    = length(1, type="u", unit="m")
 205 u_mm   = mm   = length(1, type="u", unit="mm")
 206 u_cm   = cm   = length(1, type="u", unit="cm")
 207 u_inch = inch = length(1, type="u", unit="inch")
 208
 209 # true lengths
 210 t_pt   = length(1, type="t", unit="pt")
 211 t_m    = length(1, type="t", unit="m")
 212 t_mm   = length(1, type="t", unit="mm")
 213 t_cm   = length(1, type="t", unit="cm")
 214 t_inch = length(1, type="t", unit="inch")
 215
 216 # visual lengths
 217 v_pt   = length(1, type="v", unit="pt")
 218 v_m    = length(1, type="v", unit="m")
 219 v_mm   = length(1, type="v", unit="mm")
 220 v_cm   = length(1, type="v", unit="cm")
 221 v_inch = length(1, type="v", unit="inch")
 222
 223 # width lengths
 224 w_pt   = length(1, type="w", unit="pt")
 225 w_m    = length(1, type="w", unit="m")
 226 w_mm   = length(1, type="w", unit="mm")
 227 w_cm   = length(1, type="w", unit="cm")
 228 w_inch = length(1, type="w", unit="inch")
 229
 230 # TeX lengths
 231 x_pt   = length(1, type="x", unit="pt")
 232 x_m    = length(1, type="x", unit="m")
 233 x_mm   = length(1, type="x", unit="mm")
 234 x_cm   = length(1, type="x", unit="cm")
 235 x_inch = length(1, type="x", unit="inch")