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 copy
  25 import types
  26 import helper
  27
  28 scale = { 't':1, 'u':1, 'v':1, 'w':1, 'x':1 }
  29
  30 _default_unit = "cm"
  31
  32 _m = {
  33       'm' :   1,
  34       'cm':   0.01,
  35       'mm':   0.001,
  36       'inch': 0.01*2.54,
  37       'pt':   0.01*2.54/72,
  38     }
  39
  40 def set(uscale=None, vscale=None, wscale=None, xscale=None, defaultunit=None):
  41     if uscale is not None:
  42         scale['u'] = uscale
  43     if vscale is not None:
  44         scale['v'] = vscale
  45     if wscale is not None:
  46         scale['w'] = wscale
  47     if xscale is not None:
  48         scale['x'] = xscale
  49     if defaultunit is not None:
  50         global _default_unit
  51         _default_unit = defaultunit
  52
  53
  54 def _convert_to(l, dest_unit="m"):
  55     if type(l) in (types.IntType, types.LongType, types.FloatType):
  56         return l * _m[_default_unit] * scale['u'] / _m[dest_unit]
  57     elif not isinstance(l, length):
  58         l = length(l)       # convert to length instance if necessary
  59
  60     return (l.t + l.u*scale['u'] + l.v*scale['v'] + l.w*scale['w'] + l.x*scale['x']) / _m[dest_unit]
  61
  62 def tom(l):
  63     return _convert_to(l, "m")
  64
  65 def tocm(l):
  66     return _convert_to(l, "cm")
  67
  68 def tomm(l):
  69     return _convert_to(l, "mm")
  70
  71 def toinch(l):
  72     return _convert_to(l, "inch")
  73
  74 def topt(l):
  75     return _convert_to(l, "pt")
  76
  77 ################################################################################
  78 # class for generic length
  79 ################################################################################
  80
  81 class length:
  82     """ PyX lengths
  83
  84     PyX lengths are composed of five components (t=true, u=user, v=visual,
  85     w=width, and x=TeX) which can be scaled separately (except for the true
  86     component, which is always unscaled). Lengths can be constructed in units
  87     of "pt", "mm", "cm", "m" and "inch". When no unit is given, a module
  88     default is used, which can be changed with the help of the set method of
  89     the present module.
  90     """
  91
  92     def __init__(self, f, type="u", unit=None):
  93         """ create a length instance of the given type with a length f
  94         in the given unit. If unit is not set, the currently set default unit is used.
  95         """
  96         self.t = self.u = self.v = self.w = self.x = 0
  97         l = f * _m[unit or _default_unit]
  98         if type == "t":
  99             self.t = l
 100         elif type == "u":
 101             self.u = l
 102         elif type == "v":
 103             self.v = l
 104         elif type == "w":
 105             self.w = l
 106         elif type == "x":
 107             self.x = l
 108
 109     def __cmp__(self, other):
 110         return cmp(tom(self), tom(other))
 111
 112     def __mul__(self, factor):
 113         result = copy.copy(self)
 114         result.t *= factor
 115         result.u *= factor
 116         result.v *= factor
 117         result.w *= factor
 118         result.x *= factor
 119         return result
 120
 121     __rmul__=__mul__
 122
 123     def __div__(self, factor):
 124         result = copy.copy(self)
 125         result.t /= factor
 126         result.u /= factor
 127         result.v /= factor
 128         result.w /= factor
 129         result.x /= factor
 130         return result
 131
 132     def __add__(self, other):
 133         # convert to length if necessary
 134         if not isinstance(other, length):
 135             other = length(other)
 136         result = copy.copy(self)
 137         result.t += other.t
 138         result.u += other.u
 139         result.v += other.v
 140         result.w += other.w
 141         result.x += other.x
 142         return result
 143
 144     __radd__=__add__
 145
 146     def __sub__(self, other):
 147         # convert to length if necessary
 148         if not isinstance(other, length):
 149             other = length(other)
 150         result = copy.copy(self)
 151         result.t -= other.t
 152         result.u -= other.u
 153         result.v -= other.v
 154         result.w -= other.w
 155         result.x -= other.x
 156         return result
 157
 158     def __rsub__(self, other):
 159         # convert to length if necessary
 160         if not isinstance(other, length):
 161             other = length(other)
 162         result = copy.copy(self)
 163         result.t = other.t - self.t
 164         result.u = other.u - self.u
 165         result.v = other.v - self.v
 166         result.w = other.w - self.w
 167         result.x = other.x - self.x
 168         return result
 169
 170     def __neg__(self):
 171         result = copy.copy(self)
 172         result.t *= -1
 173         result.u *= -1
 174         result.v *= -1
 175         result.w *= -1
 176         result.x *= -1
 177         return result
 178
 179     def __str__(self):
 180         return "(%(t)f t + %(u)f u + %(v)f v + %(w)f w + %(x)f x) m" % self.__dict__
 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, type="u", unit="pt")
 189 u_m    = m    = length(1, type="u", unit="m")
 190 u_mm   = mm   = length(1, type="u", unit="mm")
 191 u_cm   = cm   = length(1, type="u", unit="cm")
 192 u_inch = inch = length(1, type="u", unit="inch")
 193
 194 # true lengths
 195 t_pt   = length(1, type="t", unit="pt")
 196 t_m    = length(1, type="t", unit="m")
 197 t_mm   = length(1, type="t", unit="mm")
 198 t_cm   = length(1, type="t", unit="cm")
 199 t_inch = length(1, type="t", unit="inch")
 200
 201 # visual lengths
 202 v_pt   = length(1, type="v", unit="pt")
 203 v_m    = length(1, type="v", unit="m")
 204 v_mm   = length(1, type="v", unit="mm")
 205 v_cm   = length(1, type="v", unit="cm")
 206 v_inch = length(1, type="v", unit="inch")
 207
 208 # width lengths
 209 w_pt   = length(1, type="w", unit="pt")
 210 w_m    = length(1, type="w", unit="m")
 211 w_mm   = length(1, type="w", unit="mm")
 212 w_cm   = length(1, type="w", unit="cm")
 213 w_inch = length(1, type="w", unit="inch")
 214
 215 # TeX lengths
 216 x_pt   = length(1, type="x", unit="pt")
 217 x_m    = length(1, type="x", unit="m")
 218 x_mm   = length(1, type="x", unit="mm")
 219 x_cm   = length(1, type="x", unit="cm")
 220 x_inch = length(1, type="x", unit="inch")