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+#!/usr/bin/env python
+# coding=utf-8
+#
+# Copyright (C) 2009 Michel Chatelain.
+# 2007 Tavmjong Bah, tavmjong@free.fr
+# 2006 Georg Wiora, xorx@quarkbox.de
+# 2006 Johan Engelen, johan@shouraizou.nl
+# 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# Changes:
+# * This program is derived by Michel Chatelain from funcplot.py.
+# His changes are in the Public Domain.
+# * Michel Chatelain, 17-18 janvier 2009, a partir de funcplot.py
+# * 20 janvier 2009 : adaptation a la version 0.46 a partir de la nouvelle version de funcplot.py
+#
+"""
+Parametric Curves has no real description, even in the inx file, which is really odd.
+"""
+
+from math import pi, cos, sin, tan
+
+import inkex
+
+def maths_eval(user_function):
+ """Try and make the eval safer"""
+ func = 'lambda t: ' + (user_function.strip('"') or 't')
+ return eval( # pylint: disable=eval-used
+ func,
+ {
+ 'pi': pi, 'sin': sin, 'cos': cos, 'tan': tan,
+ }, {})
+
+def drawfunction(t_start, t_end, xleft, xright, ybottom, ytop, samples, width, height, left, bottom,
+ fx="cos(3*t)", fy="sin(5*t)", times2pi=False, isoscale=True, drawaxis=True):
+ if times2pi:
+ t_start *= 2 * pi
+ t_end *= 2 * pi
+
+ # coords and scales based on the source rect
+ scalex = width / (xright - xleft)
+ xoff = left
+ coordx = lambda x: (x - xleft) * scalex + xoff # convert x-value to coordinate
+ scaley = height / (ytop - ybottom)
+ yoff = bottom
+ coordy = lambda y: (ybottom - y) * scaley + yoff # convert y-value to coordinate
+
+ # Check for isotropic scaling and use smaller of the two scales, correct ranges
+ if isoscale:
+ if scaley < scalex:
+ # compute zero location
+ xzero = coordx(0)
+ # set scale
+ scalex = scaley
+ # correct x-offset
+ xleft = (left - xzero) / scalex
+ xright = (left + width - xzero) / scalex
+ else:
+ # compute zero location
+ yzero = coordy(0)
+ # set scale
+ scaley = scalex
+ # correct x-offset
+ ybottom = (yzero - bottom) / scaley
+ ytop = (bottom + height - yzero) / scaley
+
+ # functions specified by the user
+ f1 = maths_eval(fx)
+ f2 = maths_eval(fy)
+
+ # step is increment of t
+ step = (t_end - t_start) / (samples - 1)
+ third = step / 3.0
+ ds = step * 0.001 # Step used in calculating derivatives
+
+ a = [] # path array
+ # add axis
+ if drawaxis:
+ # check for visibility of x-axis
+ if ybottom <= 0 <= ytop:
+ # xaxis
+ a.append(['M', [left, coordy(0)]])
+ a.append(['l', [width, 0]])
+ # check for visibility of y-axis
+ if xleft <= 0 <= xright:
+ # xaxis
+ a.append(['M', [coordx(0), bottom]])
+ a.append(['l', [0, -height]])
+
+ # initialize functions and derivatives for 0;
+ # they are carried over from one iteration to the next, to avoid extra function calculations.
+ #print("RET: {}".format(f1(1)))
+ x0 = f1(t_start)
+ y0 = f2(t_start)
+
+ # numerical derivatives, using 0.001*step as the small differential
+ t1 = t_start + ds # Second point AFTER first point (Good for first point)
+ x1 = f1(t1)
+ y1 = f2(t1)
+ dx0 = (x1 - x0) / ds
+ dy0 = (y1 - y0) / ds
+
+ # Start curve
+ a.append(['M', [coordx(x0), coordy(y0)]]) # initial moveto
+ for i in range(int(samples - 1)):
+ t1 = (i + 1) * step + t_start
+ t2 = t1 - ds # Second point BEFORE first point (Good for last point)
+ x1 = f1(t1)
+ x2 = f1(t2)
+ y1 = f2(t1)
+ y2 = f2(t2)
+
+ # numerical derivatives
+ dx1 = (x1 - x2) / ds
+ dy1 = (y1 - y2) / ds
+
+ # create curve
+ a.append(['C',
+ [coordx(x0 + (dx0 * third)), coordy(y0 + (dy0 * third)),
+ coordx(x1 - (dx1 * third)), coordy(y1 - (dy1 * third)),
+ coordx(x1), coordy(y1)]
+ ])
+ t0 = t1 # Next segment's start is this segments end
+ x0 = x1
+ y0 = y1
+ dx0 = dx1 # Assume the functions are smooth everywhere, so carry over the derivatives too
+ dy0 = dy1
+ return a
+
+
+class ParamCurves(inkex.EffectExtension):
+ def add_arguments(self, pars):
+ pars.add_argument("--t_start", type=float, default=0.0, help="Start t-value")
+ pars.add_argument("--t_end", type=float, default=1.0, help="End t-value")
+ pars.add_argument("--times2pi", type=inkex.Boolean, default=True,
+ help="Multiply t-range by 2*pi")
+ pars.add_argument("--xleft", type=float, default=-1.0, help="x-value of left")
+ pars.add_argument("--xright", type=float, default=1.0, help="x-value of right")
+ pars.add_argument("--ybottom", type=float, default=-1.0, help="y-value of bottom")
+ pars.add_argument("--ytop", type=float, default=1.0, help="y-value of top")
+ pars.add_argument("-s", "--samples", type=int, default=8, help="Samples")
+ pars.add_argument("--fofx", default="cos(3*t)", help="fx(t) for plotting")
+ pars.add_argument("--fofy", default="sin(5*t)", help="fy(t) for plotting")
+ pars.add_argument("--remove", type=inkex.Boolean, default=True, help="Remove rectangle")
+ pars.add_argument("--isoscale", type=inkex.Boolean, default=True, help="Isotropic scaling")
+ pars.add_argument("--drawaxis", type=inkex.Boolean, default=True)
+ pars.add_argument("--tab", default="sampling")
+
+ def effect(self):
+ for node in self.svg.selected.values():
+ if isinstance(node, inkex.Rectangle):
+ # create new path with basic dimensions of selected rectangle
+ newpath = inkex.PathElement()
+ x = float(node.get('x'))
+ y = float(node.get('y'))
+ width = float(node.get('width'))
+ height = float(node.get('height'))
+
+ # copy attributes of rect
+ newpath.style = node.style
+ newpath.transform = node.transform
+
+ # top and bottom were exchanged
+ newpath.path = \
+ drawfunction(self.options.t_start,
+ self.options.t_end,
+ self.options.xleft,
+ self.options.xright,
+ self.options.ybottom,
+ self.options.ytop,
+ self.options.samples,
+ width, height, x, y + height,
+ self.options.fofx,
+ self.options.fofy,
+ self.options.times2pi,
+ self.options.isoscale,
+ self.options.drawaxis)
+ newpath.set('title', self.options.fofx + " " + self.options.fofy)
+
+ # newpath.set('desc', '!func;' + self.options.fofx + ';' + self.options.fofy + ';'
+ # + `self.options.t_start` + ';'
+ # + `self.options.t_end` + ';'
+ # + `self.options.samples`)
+
+ # add path into SVG structure
+ node.getparent().append(newpath)
+ # option whether to remove the rectangle or not.
+ if self.options.remove:
+ node.getparent().remove(node)
+
+
+if __name__ == '__main__':
+ ParamCurves().run()
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