diff options
Diffstat (limited to 'share/extensions/wavy.py')
| -rwxr-xr-x | share/extensions/wavy.py | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/share/extensions/wavy.py b/share/extensions/wavy.py new file mode 100755 index 000000000..aa438e121 --- /dev/null +++ b/share/extensions/wavy.py @@ -0,0 +1,133 @@ +#!/usr/bin/env python +''' +Copyright (C) 2005 Aaron Spike, aaron@ekips.org + +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + + + +drawwave() was translated into python from the postscript version +described at http://www.ghostscript.com/person/toby/ and located +at http://www.telegraphics.com.au/sw/sine.ps . +http://www.tinaja.com/glib/bezsine.pdf shows another method for +approximating sine with beziers. + +The orginal postscript version displayed the following copyright +notice and was released under the terms of the GPL: +Copyright (C) 2001-3 Toby Thain, toby@telegraphics.com.au +''' +import inkex, simplepath, simplestyle +from math import * +from random import * + +def drawwave(samples, periods, width, height, left, top, + fx = "sin(x)", fpx = "cos(x)", fponum = True): + + # step is the distance between nodes on x + step = 2*pi / samples + third = step / 3.0 + + # coords and scales based on the source rect + xoff = left + yoff = top + (height / 2) + scalex = width / (2*pi * periods) + scaley = height / 2 + procx = lambda x: x * scalex + xoff + procy = lambda y: y * scaley + yoff + + # functions specified by the user + if fx != "": + f = eval('lambda x: ' + fx) + if fpx != "": + fp = eval('lambda x: ' + fpx) + + # initialize function and derivative for 0; + # they are carried over from one iteration to the next, to avoid extra function calculations + y0 = f(0) + if fponum == True: # numerical derivative, using 0.001*step as the small differential + d0 = (f(0 + 0.001*step) - y0)/(0.001*step) + else: # derivative given by the user + d0 = fp(0) + + a = [] # path array + a.append(['M',[procx(0.0), procy(y0)]]) # initial moveto + + for i in range(int(samples * periods)): + x = i * step + y1 = f(x + step) + if fponum == True: # numerical derivative + d1 = (y1 - f(x + step - 0.001*step))/(0.001*step) + else: # derivative given by the user + d1 = fp(x + step) + # create curve + a.append(['C',[procx(x + third), procy(y0 + (d0 * third)), + procx(x + (step - third)), procy(y1 - (d1 * third)), + procx(x + step), procy(y1)]]) + y0 = y1 # next segment's y0 is this segment's y1 + d0 = d1 # we assume the function is smooth everywhere, so carry over the derivative too + + return a + +class Wavy(inkex.Effect): + def __init__(self): + inkex.Effect.__init__(self) + self.OptionParser.add_option("-p", "--periods", + action="store", type="float", + dest="periods", default=4.0, + help="Periods (2*Pi each)") + self.OptionParser.add_option("-s", "--samples", + action="store", type="int", + dest="samples", default=8, + help="Samples per period") + self.OptionParser.add_option("--fofx", + action="store", type="string", + dest="fofx", default="sin(x)", + help="f(x) for plotting") + self.OptionParser.add_option("--fponum", + action="store", type="inkbool", + dest="fponum", default=True, + help="Calculate the first derivative numerically") + self.OptionParser.add_option("--fpofx", + action="store", type="string", + dest="fpofx", default="cos(x)", + help="f'(x) for plotting") + def effect(self): + for id, node in self.selected.iteritems(): + if node.tagName == 'rect': + new = self.document.createElement('svg:path') + x = float(node.attributes.getNamedItem('x').value) + y = float(node.attributes.getNamedItem('y').value) + w = float(node.attributes.getNamedItem('width').value) + h = float(node.attributes.getNamedItem('height').value) + + s = node.attributes.getNamedItem('style').value + new.setAttribute('style', s) + try: + t = node.attributes.getNamedItem('transform').value + new.setAttribute('transform', t) + except AttributeError: + pass + new.setAttribute('d', simplepath.formatPath( + drawwave(self.options.samples, + self.options.periods, + w,h,x,y, + self.options.fofx, + self.options.fpofx, + self.options.fponum))) + node.parentNode.appendChild(new) + node.parentNode.removeChild(node) + +e = Wavy() +e.affect() |