share/extensions/funcplot.py

   1 #!/usr/bin/env python
   2 '''
   3 Copyright (C) 2007 Tavmjong Bah, tavmjong@free.fr
   4 Copyright (C) 2006 Georg Wiora, xorx@quarkbox.de
   5 Copyright (C) 2006 Johan Engelen, johan@shouraizou.nl
   6 Copyright (C) 2005 Aaron Spike, aaron@ekips.org
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21
  22 Changes:
  23  * This program is a modified version of wavy.py by Aaron Spike.
  24  * 22-Dec-2006: Wiora : Added axis and isotropic scaling
  25  * 21-Jun-2007: Tavmjong: Added polar coordinates
  26
  27 '''
  28 import inkex, simplepath, simplestyle
  29 from math import *
  30 from random import *
  31
  32 def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bottom,
  33     fx = "sin(x)", fpx = "cos(x)", fponum = True, times2pi = False, polar = False, isoscale = True, drawaxis = True):
  34
  35     if times2pi == True:
  36         xstart = 2 * pi * xstart
  37         xend   = 2 * pi * xend
  38
  39     # coords and scales based on the source rect
  40     scalex = width / (xend - xstart)
  41     xoff = left
  42     coordx = lambda x: (x - xstart) * scalex + xoff  #convert x-value to coordinate
  43     if polar :  # Set scale so that left side of rectangle is -1, right side is +1.
  44                 # (We can't use xscale for both range and scale.)
  45         centerx = left + width/2.0
  46         polar_scalex = width/2.0
  47         coordx = lambda x: x * polar_scalex + centerx  #convert x-value to coordinate
  48
  49     scaley = height / (ytop - ybottom)
  50     yoff = bottom
  51     coordy = lambda y: (ybottom - y) * scaley + yoff  #convert y-value to coordinate
  52
  53     # Check for isotropic scaling and use smaller of the two scales, correct ranges
  54     if isoscale and not polar:
  55       if scaley<scalex:
  56         # compute zero location
  57         xzero = coordx(0)
  58         # set scale
  59         scalex = scaley
  60         # correct x-offset
  61         xstart = (left-xzero)/scalex
  62         xend = (left+width-xzero)/scalex
  63       else :
  64         # compute zero location
  65         yzero = coordy(0)
  66         # set scale
  67         scaley = scalex
  68         # correct x-offset
  69         ybottom = (yzero-bottom)/scaley
  70         ytop = (bottom+height-yzero)/scaley
  71
  72     # functions specified by the user
  73     try:
  74         if fx != "":
  75             f = eval('lambda x: ' + fx.strip('"'))
  76         if fpx != "":
  77             fp = eval('lambda x: ' + fpx.strip('"'))
  78     # handle incomplete/invalid function gracefully
  79     except SyntaxError:
  80         return []
  81
  82     # step is the distance between nodes on x
  83     step = (xend - xstart) / (samples-1)
  84     third = step / 3.0
  85     ds = step * 0.001 # Step used in calculating derivatives
  86
  87     a = [] # path array
  88     # add axis
  89     if drawaxis :
  90       # check for visibility of x-axis
  91       if ybottom<=0 and ytop>=0:
  92         # xaxis
  93         a.append(['M ',[left, coordy(0)]])
  94         a.append([' l ',[width, 0]])
  95       # check for visibility of y-axis
  96       if xstart<=0 and xend>=0:
  97         # xaxis
  98         a.append([' M ',[coordx(0),bottom]])
  99         a.append([' l ',[0, -height]])
 100
 101     # initialize function and derivative for 0;
 102     # they are carried over from one iteration to the next, to avoid extra function calculations.
 103     x0 =   xstart
 104     y0 = f(xstart)
 105     if polar :
 106         xp0 = y0 * cos( x0 )
 107         yp0 = y0 * sin( x0 )
 108         x0 = xp0
 109         y0 = yp0
 110     if fponum or polar: # numerical derivative, using 0.001*step as the small differential
 111         x1 = xstart + ds # Second point AFTER first point (Good for first point)
 112         y1 = f(x1)
 113         if polar :
 114             xp1 = y1 * cos( x1 )
 115             yp1 = y1 * sin( x1 )
 116             x1 = xp1
 117             y1 = yp1
 118         dx0 = (x1 - x0)/ds
 119         dy0 = (y1 - y0)/ds
 120     else: # derivative given by the user
 121         dx0 = 1 # Only works for rectangular coordinates
 122         dy0 = fp(xstart)
 123
 124     # Start curve
 125     a.append([' M ',[coordx(x0), coordy(y0)]]) # initial moveto
 126
 127     for i in range(int(samples-1)):
 128         x1 = (i+1) * step + xstart
 129         x2 = x1 - ds # Second point BEFORE first point (Good for last point)
 130         y1 = f(x1)
 131         y2 = f(x2)
 132         if polar :
 133             xp1 = y1 * cos( x1 )
 134             yp1 = y1 * sin( x1 )
 135             xp2 = y2 * cos( x2 )
 136             yp2 = y2 * sin( x2 )
 137             x1 = xp1
 138             y1 = yp1
 139             x2 = xp2
 140             y2 = yp2
 141         if fponum or polar: # numerical derivative
 142             dx1 = (x1 - x2)/ds
 143             dy1 = (y1 - y2)/ds
 144         else: # derivative given by the user
 145             dx1 = 1 # Only works for rectangular coordinates
 146             dy1 = fp(x1)
 147         # create curve
 148         a.append([' C ',
 149                   [coordx(x0 + (dx0 * third)), coordy(y0 + (dy0 * third)),
 150                    coordx(x1 - (dx1 * third)), coordy(y1 - (dy1 * third)),
 151                    coordx(x1),                 coordy(y1)]
 152                   ])
 153         x0  = x1  # Next segment's start is this segments end
 154         y0  = y1
 155         dx0 = dx1 # Assume the function is smooth everywhere, so carry over the derivative too
 156         dy0 = dy1
 157     return a
 158
 159 class FuncPlot(inkex.Effect):
 160     def __init__(self):
 161         inkex.Effect.__init__(self)
 162         self.OptionParser.add_option("--xstart",
 163                         action="store", type="float",
 164                         dest="xstart", default=0.0,
 165                         help="Start x-value")
 166         self.OptionParser.add_option("--xend",
 167                         action="store", type="float",
 168                         dest="xend", default=1.0,
 169                         help="End x-value")
 170         self.OptionParser.add_option("--times2pi",
 171                         action="store", type="inkbool",
 172                         dest="times2pi", default=True,
 173                         help="Multiply x-range by 2*pi")
 174         self.OptionParser.add_option("--polar",
 175                         action="store", type="inkbool",
 176                         dest="polar", default=False,
 177                         help="Plot using polar coordinates")
 178         self.OptionParser.add_option("--ybottom",
 179                         action="store", type="float",
 180                         dest="ybottom", default=-1.0,
 181                         help="y-value of rectangle's bottom")
 182         self.OptionParser.add_option("--ytop",
 183                         action="store", type="float",
 184                         dest="ytop", default=1.0,
 185                         help="y-value of rectangle's top")
 186         self.OptionParser.add_option("-s", "--samples",
 187                         action="store", type="int",
 188                         dest="samples", default=8,
 189                         help="Samples")
 190         self.OptionParser.add_option("--fofx",
 191                         action="store", type="string",
 192                         dest="fofx", default="sin(x)",
 193                         help="f(x) for plotting")
 194         self.OptionParser.add_option("--fponum",
 195                         action="store", type="inkbool",
 196                         dest="fponum", default=True,
 197                         help="Calculate the first derivative numerically")
 198         self.OptionParser.add_option("--fpofx",
 199                         action="store", type="string",
 200                         dest="fpofx", default="cos(x)",
 201                         help="f'(x) for plotting")
 202         self.OptionParser.add_option("--remove",
 203                         action="store", type="inkbool",
 204                         dest="remove", default=True,
 205                         help="If True, source rectangle is removed")
 206         self.OptionParser.add_option("--isoscale",
 207                         action="store", type="inkbool",
 208                         dest="isoscale", default=True,
 209                         help="If True, isotropic scaling is used")
 210         self.OptionParser.add_option("--drawaxis",
 211                         action="store", type="inkbool",
 212                         dest="drawaxis", default=True,
 213                         help="If True, axis are drawn")
 214         self.OptionParser.add_option("--tab",
 215                         action="store", type="string",
 216                         dest="tab", default="sampling",
 217                         help="The selected UI-tab when OK was pressed")
 218         self.OptionParser.add_option("--funcplotuse",
 219                         action="store", type="string",
 220                         dest="funcplotuse", default="",
 221                         help="dummy")
 222         self.OptionParser.add_option("--pythonfunctions",
 223                         action="store", type="string",
 224                         dest="pythonfunctions", default="",
 225                         help="dummy")
 226
 227     def effect(self):
 228         for id, node in self.selected.iteritems():
 229             if node.tag == inkex.addNS('rect','svg'):
 230                 # create new path with basic dimensions of selected rectangle
 231                 newpath = inkex.etree.Element(inkex.addNS('path','svg'))
 232                 x = float(node.get('x'))
 233                 y = float(node.get('y'))
 234                 w = float(node.get('width'))
 235                 h = float(node.get('height'))
 236
 237                 #copy attributes of rect
 238                 s = node.get('style')
 239                 if s:
 240                     newpath.set('style', s)
 241
 242                 t = node.get('transform')
 243                 if t:
 244                     newpath.set('transform', t)
 245
 246                 # top and bottom were exchanged
 247                 newpath.set('d', simplepath.formatPath(
 248                             drawfunction(self.options.xstart,
 249                                 self.options.xend,
 250                                 self.options.ybottom,
 251                                 self.options.ytop,
 252                                 self.options.samples,
 253                                 w,h,x,y+h,
 254                                 self.options.fofx,
 255                                 self.options.fpofx,
 256                                 self.options.fponum,
 257                                 self.options.times2pi,
 258                                 self.options.polar,
 259                                 self.options.isoscale,
 260                                 self.options.drawaxis)))
 261                 newpath.set('title', self.options.fofx)
 262
 263                 #newpath.setAttribute('desc', '!func;' + self.options.fofx + ';'
 264                 #                                      + self.options.fpofx + ';'
 265                 #                                      + `self.options.fponum` + ';'
 266                 #                                      + `self.options.xstart` + ';'
 267                 #                                      + `self.options.xend` + ';'
 268                 #                                      + `self.options.samples`)
 269
 270                 # add path into SVG structure
 271                 node.getparent().append(newpath)
 272                 # option wether to remove the rectangle or not.
 273                 if self.options.remove:
 274                     node.getparent().remove(node)
 275
 276 if __name__ == '__main__':
 277     e = FuncPlot()
 278     e.affect()
 279
 280
 281 # vim: expandtab shiftwidth=4 tabstop=8 softtabstop=4 encoding=utf-8 textwidth=99