color.py

   1 # -*- encoding: utf-8 -*-
   2 #
   3 #
   4 # Copyright (C) 2002-2004, 2006 Jörg Lehmann <joergl@users.sourceforge.net>
   5 # Copyright (C) 2003-2006 Michael Schindler <m-schindler@users.sourceforge.net>
   6 # Copyright (C) 2002-2007 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  23
  24 import binascii, colorsys, math, struct, warnings
  25 import attr, style, pdfwriter
  26
  27 # device-dependend (nonlinear) functions for color conversion
  28 # UCRx : [0,1] -> [-1, 1] UnderColorRemoval (removes black from c, y, m)
  29 # BG   : [0,1] -> [0, 1]  BlackGeneration (generate the black from the nominal k-value)
  30 # as long as we have no further knowledge we define them linearly with constants 1
  31 def _UCRc(x): return x
  32 def _UCRm(x): return x
  33 def _UCRy(x): return x
  34 def _BG(x): return x
  35
  36 def set(UCRc=None, UCRm=None, UCRy=None, BG=None):
  37     global _UCRc
  38     global _UCRm
  39     global _UCRy
  40     global _BG
  41
  42     if UCRc is not None:
  43         _UCRc = UCRc
  44     if UCRm is not None:
  45         _UCRm = UCRm
  46     if UCRy is not None:
  47         _UCRy = UCRy
  48     if BG is not None:
  49         _BG = BG
  50
  51
  52 class color(attr.exclusiveattr, style.strokestyle, style.fillstyle):
  53
  54     """base class for all colors"""
  55
  56     def __init__(self):
  57         attr.exclusiveattr.__init__(self, color)
  58
  59
  60 clear = attr.clearclass(color)
  61
  62
  63 class grey(color):
  64
  65     """grey tones"""
  66
  67     def __init__(self, gray):
  68         color.__init__(self)
  69         if gray<0 or gray>1: raise ValueError
  70         self.color = {"gray": gray}
  71
  72     def processPS(self, file, writer, context, registry, bbox):
  73         file.write("%(gray)g setgray\n" % self.color)
  74
  75     def processPDF(self, file, writer, context, registry, bbox):
  76         if context.strokeattr:
  77             file.write("%(gray)f G\n" % self.color)
  78         if context.fillattr:
  79             file.write("%(gray)f g\n" % self.color)
  80
  81     def cmyk(self):
  82         return cmyk(0, 0, 0, 1 - self.color["gray"])
  83
  84     def grey(self):
  85         return grey(**self.color)
  86     gray = grey
  87
  88     def hsb(self):
  89         return hsb(0, 0, self.color["gray"])
  90
  91     def rgb(self):
  92         return rgb(self.color["gray"], self.color["gray"], self.color["gray"])
  93
  94     def colorspacestring(self):
  95         return "/DeviceGray"
  96
  97     def to8bitstring(self):
  98         return chr(int(self.color["gray"]*255))
  99
 100 grey.black = grey(0.0)
 101 grey.white = grey(1.0)
 102 gray = grey
 103
 104
 105 class rgb(color):
 106
 107     """rgb colors"""
 108
 109     def __init__(self, r=0.0, g=0.0, b=0.0):
 110         color.__init__(self)
 111         if r<0 or r>1 or g<0 or g>1 or b<0 or b>1: raise ValueError
 112         self.color = {"r": r, "g": g, "b": b}
 113
 114     def processPS(self, file, writer, context, registry, bbox):
 115         file.write("%(r)g %(g)g %(b)g setrgbcolor\n" % self.color)
 116
 117     def processPDF(self, file, writer, context, registry, bbox):
 118         if context.strokeattr:
 119             file.write("%(r)f %(g)f %(b)f RG\n" % self.color)
 120         if context.fillattr:
 121             file.write("%(r)f %(g)f %(b)f rg\n" % self.color)
 122
 123     def cmyk(self):
 124         # conversion to cmy
 125         c, m, y = 1 - self.color["r"], 1 - self.color["g"], 1 - self.color["b"]
 126         # conversion from cmy to cmyk with device-dependent functions
 127         k = min([c, m, y])
 128         return cmyk(min(1, max(0, c - _UCRc(k))),
 129                     min(1, max(0, m - _UCRm(k))),
 130                     min(1, max(0, y - _UCRy(k))),
 131                     _BG(k))
 132
 133     def grey(self):
 134         return grey(0.3*self.color["r"] + 0.59*self.color["g"] + 0.11*self.color["b"])
 135     gray = grey
 136
 137     def hsb(self):
 138
 139         values = self.color.values()
 140         values.sort()
 141         z, y, x = values
 142         r, g, b = self.color["r"], self.color["g"], self.color["b"]
 143         try:
 144             if r == x and g == z:
 145                 return hsb((5 + (x-b)/(x-z)) / 6.0, (x - z) / x, x)
 146             elif r == x and g > z:
 147                 return hsb((1 - (x-g)/(x-z)) / 6.0, (x - z) / x, x)
 148             elif g == x and b == z:
 149                 return hsb((1 + (x-r)/(x-z)) / 6.0, (x - z) / x, x)
 150             elif g == x and b > z:
 151                 return hsb((3 - (x-b)/(x-z)) / 6.0, (x - z) / x, x)
 152             elif b == x and r == z:
 153                 return hsb((3 + (x-g)/(x-z)) / 6.0, (x - z) / x, x)
 154             elif b == x and r > z:
 155                 return hsb((5 - (x-r)/(x-z)) / 6.0, (x - z) / x, x)
 156             else:
 157                 raise ValueError
 158         except ZeroDivisionError:
 159             return hsb(0, 0, x)
 160
 161     def rgb(self):
 162         return rgb(**self.color)
 163
 164     def colorspacestring(self):
 165         return "/DeviceRGB"
 166
 167     def to8bitstring(self):
 168         return struct.pack("BBB", int(self.color["r"]*255), int(self.color["g"]*255), int(self.color["b"]*255))
 169
 170     def tohexstring(self, cssstrip=1, addhash=1):
 171         hexstring = binascii.b2a_hex(self.to8bitstring())
 172         if cssstrip and hexstring[0] == hexstring[1] and hexstring[2] == hexstring[3] and hexstring[4] == hexstring[5]:
 173             hexstring = "".join([hexstring[0], hexstring[1], hexstring[2]])
 174         if addhash:
 175             hexstring = "#" + hexstring
 176         return hexstring
 177
 178
 179 def rgbfromhexstring(hexstring):
 180     hexstring = hexstring.strip().lstrip("#")
 181     if len(hexstring) == 3:
 182         hexstring = "".join([hexstring[0], hexstring[0], hexstring[1], hexstring[1], hexstring[2], hexstring[2]])
 183     elif len(hexstring) != 6:
 184         raise ValueError("3 or 6 digit hex number expected (with optional leading hash character)")
 185     return rgb(*[value/255.0 for value in struct.unpack("BBB", binascii.a2b_hex(hexstring))])
 186
 187 rgb.red   = rgb(1, 0, 0)
 188 rgb.green = rgb(0, 1, 0)
 189 rgb.blue  = rgb(0, 0, 1)
 190 rgb.white = rgb(1, 1, 1)
 191 rgb.black = rgb(0, 0, 0)
 192
 193
 194 class hsb(color):
 195
 196     """hsb colors"""
 197
 198     def __init__(self, h=0.0, s=0.0, b=0.0):
 199         color.__init__(self)
 200         if h<0 or h>1 or s<0 or s>1 or b<0 or b>1: raise ValueError
 201         self.color = {"h": h, "s": s, "b": b}
 202
 203     def processPS(self, file, writer, context, registry, bbox):
 204         file.write("%(h)g %(s)g %(b)g sethsbcolor\n" % self.color)
 205
 206     def processPDF(self, file, writer, context, registry, bbox):
 207         r, g, b = colorsys.hsv_to_rgb(self.color["h"], self.color["s"], self.color["b"])
 208         rgb(r, g, b).processPDF(file, writer, context, registry, bbox)
 209
 210     def cmyk(self):
 211         return self.rgb().cmyk()
 212
 213     def grey(self):
 214         return self.rgb().grey()
 215     gray = grey
 216
 217     def hsb(self):
 218         return hsb(**self.color)
 219
 220     def rgb(self):
 221         h, s, b = self.color["h"], self.color["s"], self.color["b"]
 222         i = int(6*h)
 223         f = 6*h - i
 224         m, n, k = 1 - s, 1 - s*f, 1 - s*(1-f)
 225         if i == 1:
 226             return rgb(b*n, b, b*m)
 227         elif i == 2:
 228             return rgb(b*m, b, b*k)
 229         elif i == 3:
 230             return rgb(b*m, b*n, b)
 231         elif i == 4:
 232             return rgb(b*k, b*m, b)
 233         elif i == 5:
 234             return rgb(b, b*m, b*n)
 235         else:
 236             return rgb(b, b*k, b*m)
 237
 238     def colorspacestring(self):
 239         raise RuntimeError("colorspace string not available for hsb colors")
 240
 241
 242 class cmyk(color):
 243
 244     """cmyk colors"""
 245
 246     def __init__(self, c=0.0, m=0.0, y=0.0, k=0.0):
 247         color.__init__(self)
 248         if c<0 or c>1 or m<0 or m>1 or y<0 or y>1 or k<0 or k>1: raise ValueError
 249         self.color = {"c": c, "m": m, "y": y, "k": k}
 250
 251     def processPS(self, file, writer, context, registry, bbox):
 252         file.write("%(c)g %(m)g %(y)g %(k)g setcmykcolor\n" % self.color)
 253
 254     def processPDF(self, file, writer, context, registry, bbox):
 255         if context.strokeattr:
 256             file.write("%(c)f %(m)f %(y)f %(k)f K\n" % self.color)
 257         if context.fillattr:
 258             file.write("%(c)f %(m)f %(y)f %(k)f k\n" % self.color)
 259
 260     def cmyk(self):
 261         return cmyk(**self.color)
 262
 263     def grey(self):
 264         return grey(1 - min([1, 0.3*self.color["c"] + 0.59*self.color["m"] +
 265                                 0.11*self.color["y"] + self.color["k"]]))
 266     gray = grey
 267
 268     def hsb(self):
 269         return self.rgb().hsb()
 270
 271     def rgb(self):
 272         # conversion to cmy:
 273         c = min(1, self.color["c"] + self.color["k"])
 274         m = min(1, self.color["m"] + self.color["k"])
 275         y = min(1, self.color["y"] + self.color["k"])
 276         # conversion from cmy to rgb:
 277         return rgb(1 - c, 1 - m, 1 - y)
 278
 279     def colorspacestring(self):
 280         return "/DeviceCMYK"
 281
 282     def to8bitstring(self):
 283         return struct.pack("BBBB", int(self.color["c"]*255), int(self.color["m"]*255), int(self.color["y"]*255), int(self.color["k"]*255))
 284
 285 cmyk.GreenYellow    = cmyk(0.15, 0, 0.69, 0)
 286 cmyk.Yellow         = cmyk(0, 0, 1, 0)
 287 cmyk.Goldenrod      = cmyk(0, 0.10, 0.84, 0)
 288 cmyk.Dandelion      = cmyk(0, 0.29, 0.84, 0)
 289 cmyk.Apricot        = cmyk(0, 0.32, 0.52, 0)
 290 cmyk.Peach          = cmyk(0, 0.50, 0.70, 0)
 291 cmyk.Melon          = cmyk(0, 0.46, 0.50, 0)
 292 cmyk.YellowOrange   = cmyk(0, 0.42, 1, 0)
 293 cmyk.Orange         = cmyk(0, 0.61, 0.87, 0)
 294 cmyk.BurntOrange    = cmyk(0, 0.51, 1, 0)
 295 cmyk.Bittersweet    = cmyk(0, 0.75, 1, 0.24)
 296 cmyk.RedOrange      = cmyk(0, 0.77, 0.87, 0)
 297 cmyk.Mahogany       = cmyk(0, 0.85, 0.87, 0.35)
 298 cmyk.Maroon         = cmyk(0, 0.87, 0.68, 0.32)
 299 cmyk.BrickRed       = cmyk(0, 0.89, 0.94, 0.28)
 300 cmyk.Red            = cmyk(0, 1, 1, 0)
 301 cmyk.OrangeRed      = cmyk(0, 1, 0.50, 0)
 302 cmyk.RubineRed      = cmyk(0, 1, 0.13, 0)
 303 cmyk.WildStrawberry = cmyk(0, 0.96, 0.39, 0)
 304 cmyk.Salmon         = cmyk(0, 0.53, 0.38, 0)
 305 cmyk.CarnationPink  = cmyk(0, 0.63, 0, 0)
 306 cmyk.Magenta        = cmyk(0, 1, 0, 0)
 307 cmyk.VioletRed      = cmyk(0, 0.81, 0, 0)
 308 cmyk.Rhodamine      = cmyk(0, 0.82, 0, 0)
 309 cmyk.Mulberry       = cmyk(0.34, 0.90, 0, 0.02)
 310 cmyk.RedViolet      = cmyk(0.07, 0.90, 0, 0.34)
 311 cmyk.Fuchsia        = cmyk(0.47, 0.91, 0, 0.08)
 312 cmyk.Lavender       = cmyk(0, 0.48, 0, 0)
 313 cmyk.Thistle        = cmyk(0.12, 0.59, 0, 0)
 314 cmyk.Orchid         = cmyk(0.32, 0.64, 0, 0)
 315 cmyk.DarkOrchid     = cmyk(0.40, 0.80, 0.20, 0)
 316 cmyk.Purple         = cmyk(0.45, 0.86, 0, 0)
 317 cmyk.Plum           = cmyk(0.50, 1, 0, 0)
 318 cmyk.Violet         = cmyk(0.79, 0.88, 0, 0)
 319 cmyk.RoyalPurple    = cmyk(0.75, 0.90, 0, 0)
 320 cmyk.BlueViolet     = cmyk(0.86, 0.91, 0, 0.04)
 321 cmyk.Periwinkle     = cmyk(0.57, 0.55, 0, 0)
 322 cmyk.CadetBlue      = cmyk(0.62, 0.57, 0.23, 0)
 323 cmyk.CornflowerBlue = cmyk(0.65, 0.13, 0, 0)
 324 cmyk.MidnightBlue   = cmyk(0.98, 0.13, 0, 0.43)
 325 cmyk.NavyBlue       = cmyk(0.94, 0.54, 0, 0)
 326 cmyk.RoyalBlue      = cmyk(1, 0.50, 0, 0)
 327 cmyk.Blue           = cmyk(1, 1, 0, 0)
 328 cmyk.Cerulean       = cmyk(0.94, 0.11, 0, 0)
 329 cmyk.Cyan           = cmyk(1, 0, 0, 0)
 330 cmyk.ProcessBlue    = cmyk(0.96, 0, 0, 0)
 331 cmyk.SkyBlue        = cmyk(0.62, 0, 0.12, 0)
 332 cmyk.Turquoise      = cmyk(0.85, 0, 0.20, 0)
 333 cmyk.TealBlue       = cmyk(0.86, 0, 0.34, 0.02)
 334 cmyk.Aquamarine     = cmyk(0.82, 0, 0.30, 0)
 335 cmyk.BlueGreen      = cmyk(0.85, 0, 0.33, 0)
 336 cmyk.Emerald        = cmyk(1, 0, 0.50, 0)
 337 cmyk.JungleGreen    = cmyk(0.99, 0, 0.52, 0)
 338 cmyk.SeaGreen       = cmyk(0.69, 0, 0.50, 0)
 339 cmyk.Green          = cmyk(1, 0, 1, 0)
 340 cmyk.ForestGreen    = cmyk(0.91, 0, 0.88, 0.12)
 341 cmyk.PineGreen      = cmyk(0.92, 0, 0.59, 0.25)
 342 cmyk.LimeGreen      = cmyk(0.50, 0, 1, 0)
 343 cmyk.YellowGreen    = cmyk(0.44, 0, 0.74, 0)
 344 cmyk.SpringGreen    = cmyk(0.26, 0, 0.76, 0)
 345 cmyk.OliveGreen     = cmyk(0.64, 0, 0.95, 0.40)
 346 cmyk.RawSienna      = cmyk(0, 0.72, 1, 0.45)
 347 cmyk.Sepia          = cmyk(0, 0.83, 1, 0.70)
 348 cmyk.Brown          = cmyk(0, 0.81, 1, 0.60)
 349 cmyk.Tan            = cmyk(0.14, 0.42, 0.56, 0)
 350 cmyk.Gray           = cmyk(0, 0, 0, 0.50)
 351 cmyk.Grey           = cmyk.Gray
 352 cmyk.Black          = cmyk(0, 0, 0, 1)
 353 cmyk.White          = cmyk(0, 0, 0, 0)
 354 cmyk.white          = cmyk.White
 355 cmyk.black          = cmyk.Black
 356
 357 class palette(attr.changelist):
 358     """color palettes
 359
 360     A color palette is a discrete, ordered list of colors"""
 361
 362 palette.clear = attr.clearclass(palette)
 363
 364
 365 class gradient(attr.changeattr):
 366
 367     """base class for color gradients
 368
 369     A gradient is a continuous collection of colors with a single parameter ranging from 0 to 1
 370     to address them"""
 371
 372     def getcolor(self, param):
 373         """return color corresponding to param"""
 374         pass
 375
 376     def select(self, index, n_indices):
 377         """return a color corresponding to an index out of n_indices"""
 378         if n_indices == 1:
 379             param = 0
 380         else:
 381             param = index / (n_indices - 1.0)
 382         return self.getcolor(param)
 383
 384 gradient.clear = attr.clearclass(gradient)
 385
 386
 387 class lineargradient(gradient):
 388
 389     """collection of two colors for a linear transition between them"""
 390
 391     def __init__(self, mincolor, maxcolor):
 392         if mincolor.__class__ != maxcolor.__class__:
 393             raise ValueError
 394         self.colorclass = mincolor.__class__
 395         self.mincolor = mincolor
 396         self.maxcolor = maxcolor
 397
 398     def getcolor(self, param):
 399         colordict = {}
 400         for key in self.mincolor.color.keys():
 401             colordict[key] = param * self.maxcolor.color[key] + (1 - param) * self.mincolor.color[key]
 402         return self.colorclass(**colordict)
 403
 404
 405 class functiongradient(gradient):
 406
 407     """collection of colors for an arbitray non-linear transition between them
 408
 409     parameters:
 410     functions: a dictionary for the color values
 411     type:      a string indicating the color class
 412     """
 413
 414     def __init__(self, functions, cls):
 415         self.functions = functions
 416         self.cls = cls
 417
 418     def getcolor(self, param):
 419         colordict = {}
 420         for key in self.functions.keys():
 421             colordict[key] = self.functions[key](param)
 422         return self.cls(**colordict)
 423
 424
 425 class rgbgradient:
 426
 427     "a gradient, which takes another gradient and returns rgb colors"
 428
 429     def __init__(self, gradient):
 430         self.gradient = gradient
 431
 432     def getcolor(self, param):
 433         return self.gradient.getcolor(param).rgb()
 434
 435
 436 class cmykgradient:
 437
 438     "a gradient, which takes another gradient and returns cmyk colors"
 439
 440     def __init__(self, gradient):
 441         self.gradient = gradient
 442
 443     def getcolor(self, param):
 444         return self.gradient.getcolor(param).cmyk()
 445
 446
 447
 448 gradient.Gray           = lineargradient(gray.white, gray.black)
 449 gradient.Grey           = gradient.Gray
 450 gradient.ReverseGray    = lineargradient(gray.black, gray.white)
 451 gradient.ReverseGrey    = gradient.ReverseGray
 452 gradient.BlackYellow    = functiongradient({ # compare this with reversegray above
 453     "r":(lambda x: 2*x*(1-x)**5 + 3.5*x**2*(1-x)**3 + 2.1*x*x*(1-x)**2 + 3.0*x**3*(1-x)**2 + x**0.5*(1-(1-x)**2)),
 454     "g":(lambda x: 1.5*x**2*(1-x)**3 - 0.8*x**3*(1-x)**2 + 2.0*x**4*(1-x) + x**4),
 455     "b":(lambda x: 5*x*(1-x)**5 - 0.5*x**2*(1-x)**3 + 0.3*x*x*(1-x)**2 + 5*x**3*(1-x)**2 + 0.5*x**6)},
 456     rgb)
 457 gradient.YellowBlack    = functiongradient({
 458     "r":(lambda x: 2*(1-x)*x**5 + 3.5*(1-x)**2*x**3 + 2.1*(1-x)*(1-x)*x**2 + 3.0*(1-x)**3*x**2 + (1-x)**0.5*(1-x**2)),
 459     "g":(lambda x: 1.5*(1-x)**2*x**3 - 0.8*(1-x)**3*x**2 + 2.0*(1-x)**4*x + (1-x)**4),
 460     "b":(lambda x: 5*(1-x)*x**5 - 0.5*(1-x)**2*x**3 + 0.3*(1-x)*(1-x)*x**2 + 5*(1-x)**3*x**2 + 0.5*(1-x)**6)},
 461     rgb)
 462 gradient.RedGreen       = lineargradient(rgb.red, rgb.green)
 463 gradient.RedBlue        = lineargradient(rgb.red, rgb.blue)
 464 gradient.GreenRed       = lineargradient(rgb.green, rgb.red)
 465 gradient.GreenBlue      = lineargradient(rgb.green, rgb.blue)
 466 gradient.BlueRed        = lineargradient(rgb.blue, rgb.red)
 467 gradient.BlueGreen      = lineargradient(rgb.blue, rgb.green)
 468 gradient.RedBlack       = lineargradient(rgb.red, rgb.black)
 469 gradient.BlackRed       = lineargradient(rgb.black, rgb.red)
 470 gradient.RedWhite       = lineargradient(rgb.red, rgb.white)
 471 gradient.WhiteRed       = lineargradient(rgb.white, rgb.red)
 472 gradient.GreenBlack     = lineargradient(rgb.green, rgb.black)
 473 gradient.BlackGreen     = lineargradient(rgb.black, rgb.green)
 474 gradient.GreenWhite     = lineargradient(rgb.green, rgb.white)
 475 gradient.WhiteGreen     = lineargradient(rgb.white, rgb.green)
 476 gradient.BlueBlack      = lineargradient(rgb.blue, rgb.black)
 477 gradient.BlackBlue      = lineargradient(rgb.black, rgb.blue)
 478 gradient.BlueWhite      = lineargradient(rgb.blue, rgb.white)
 479 gradient.WhiteBlue      = lineargradient(rgb.white, rgb.blue)
 480 gradient.Rainbow        = lineargradient(hsb(0, 1, 1), hsb(2.0/3.0, 1, 1))
 481 gradient.ReverseRainbow = lineargradient(hsb(2.0/3.0, 1, 1), hsb(0, 1, 1))
 482 gradient.Hue            = lineargradient(hsb(0, 1, 1), hsb(1, 1, 1))
 483 gradient.ReverseHue     = lineargradient(hsb(1, 1, 1), hsb(0, 1, 1))
 484 rgbgradient.Rainbow        = rgbgradient(gradient.Rainbow)
 485 rgbgradient.ReverseRainbow = rgbgradient(gradient.ReverseRainbow)
 486 rgbgradient.Hue            = rgbgradient(gradient.Hue)
 487 rgbgradient.ReverseHue     = rgbgradient(gradient.ReverseHue)
 488 cmykgradient.Rainbow        = cmykgradient(gradient.Rainbow)
 489 cmykgradient.ReverseRainbow = cmykgradient(gradient.ReverseRainbow)
 490 cmykgradient.Hue            = cmykgradient(gradient.Hue)
 491 cmykgradient.ReverseHue     = cmykgradient(gradient.ReverseHue)
 492 def jet_r(x):
 493     if x < 0.38: return 0
 494     elif x < 0.62: return (x-0.38)/(0.62-0.38)
 495     elif x < 0.87: return 1
 496     else: return 0.5 + 0.5*(1-x)/(1-0.87)
 497 def jet_g(x):
 498     if x < 0.13: return 0
 499     elif x < 0.38: return (x-0.13)/(0.38-0.13)
 500     elif x < 0.62: return 1
 501     elif x < 0.87: return (0.87-x)/(0.87-0.62)
 502     else: return 0
 503 def jet_b(x):
 504     if x < 0.13: return 0.5 + 0.5*x/0.13
 505     elif x < 0.38: return 1
 506     elif x < 0.62: return 1-(x-0.38)/(0.62-0.38)
 507     else: return 0
 508 gradient.Jet = functiongradient({"r":jet_r, "g":jet_g, "b":jet_b}, rgb)
 509 gradient.ReverseJet = functiongradient({"r":lambda x: jet_r(1-x), "g":lambda x: jet_g(1-x), "b":lambda x: jet_b(1-x)}, rgb)
 510 cmykgradient.Jet = cmykgradient(gradient.Jet)
 511 cmykgradient.ReverseJet = cmykgradient(gradient.ReverseJet)
 512
 513
 514
 515 class PDFextgstate(pdfwriter.PDFobject):
 516
 517     def __init__(self, name, extgstate, registry):
 518         pdfwriter.PDFobject.__init__(self, "extgstate", name)
 519         registry.addresource("ExtGState", name, self)
 520         self.name = name
 521         self.extgstate = extgstate
 522
 523     def write(self, file, writer, registry):
 524         file.write("%s\n" % self.extgstate)
 525
 526
 527 class transparency(attr.exclusiveattr, style.strokestyle, style.fillstyle):
 528
 529     def __init__(self, value):
 530         self.value = 1-value
 531         attr.exclusiveattr.__init__(self, transparency)
 532
 533     def processPS(self, file, writer, context, registry, bbox):
 534         warnings.warn("Transparency not available in PostScript, proprietary ghostscript extension code inserted.")
 535         file.write("%f .setshapealpha\n" % self.value)
 536
 537     def processPDF(self, file, writer, context, registry, bbox):
 538         if context.strokeattr and context.fillattr:
 539             registry.add(PDFextgstate("Transparency-%f" % self.value,
 540                                       "<< /Type /ExtGState /CA %f /ca %f >>" % (self.value, self.value), registry))
 541             file.write("/Transparency-%f gs\n" % self.value)
 542         elif context.strokeattr:
 543             registry.add(PDFextgstate("Transparency-Stroke-%f" % self.value,
 544                                       "<< /Type /ExtGState /CA %f >>" % self.value, registry))
 545             file.write("/Transparency-Stroke-%f gs\n" % self.value)
 546         elif context.fillattr:
 547             registry.add(PDFextgstate("Transparency-Fill-%f" % self.value,
 548                                       "<< /Type /ExtGState /ca %f >>" % self.value, registry))
 549             file.write("/Transparency-Fill-%f gs\n" % self.value)
 550