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+#!/usr/bin/env python
+# coding=utf-8
+#
+# Copyright (C) 2007 Tavmjong Bah, tavmjong@free.fr
+# Copyright (C) 2006 Georg Wiora, xorx@quarkbox.de
+# Copyright (C) 2006 Johan Engelen, johan@shouraizou.nl
+# 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# Changes:
+# * This program is a modified version of wavy.py by Aaron Spike.
+# * 22-Dec-2006: Wiora : Added axis and isotropic scaling
+# * 21-Jun-2007: Tavmjong: Added polar coordinates
+#
+import random
+import math
+from math import cos, pi, sin
+
+import inkex
+from inkex import ClipPath, Rectangle
+
+EVAL_GLOBALS = {}
+EVAL_GLOBALS.update(random.__dict__)
+EVAL_GLOBALS.update(math.__dict__)
+
+
+def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bottom,
+ fx="sin(x)", fpx="cos(x)", fponum=True, times2pi=False, polar=False, isoscale=True, drawaxis=True, endpts=False):
+ if times2pi:
+ xstart = 2 * pi * xstart
+ xend = 2 * pi * xend
+
+ # coords and scales based on the source rect
+ if xstart == xend:
+ inkex.errormsg("x-interval cannot be zero. Please modify 'Start X value' or 'End X value'")
+ return []
+ scalex = width / (xend - xstart)
+ xoff = left
+ coordx = lambda x: (x - xstart) * scalex + xoff # convert x-value to coordinate
+ if polar: # Set scale so that left side of rectangle is -1, right side is +1.
+ # (We can't use xscale for both range and scale.)
+ centerx = left + width / 2.0
+ polar_scalex = width / 2.0
+ coordx = lambda x: x * polar_scalex + centerx # convert x-value to coordinate
+
+ if ytop == ybottom:
+ inkex.errormsg("y-interval cannot be zero. Please modify 'Y value of rectangle's top' or 'Y value of rectangle's bottom'")
+ return []
+ 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 and not polar:
+ if scaley < scalex:
+ # compute zero location
+ xzero = coordx(0)
+ # set scale
+ scalex = scaley
+ # correct x-offset
+ xstart = (left - xzero) / scalex
+ xend = (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
+ try:
+ if fx != "":
+ f = eval('lambda x: ' + fx, EVAL_GLOBALS, {})
+ if fpx != "":
+ fp = eval('lambda x: ' + fpx, EVAL_GLOBALS, {})
+ # handle incomplete/invalid function gracefully
+ except SyntaxError:
+ return []
+
+ # step is the distance between nodes on x
+ step = (xend - xstart) / (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 xstart <= 0 <= xend:
+ # xaxis
+ a.append(['M', [coordx(0), bottom]])
+ a.append(['l', [0, -height]])
+
+ # initialize function and derivative for 0;
+ # they are carried over from one iteration to the next, to avoid extra function calculations.
+ x0 = xstart
+ y0 = f(xstart)
+ if polar:
+ xp0 = y0 * cos(x0)
+ yp0 = y0 * sin(x0)
+ x0 = xp0
+ y0 = yp0
+ if fponum or polar: # numerical derivative, using 0.001*step as the small differential
+ x1 = xstart + ds # Second point AFTER first point (Good for first point)
+ y1 = f(x1)
+ if polar:
+ xp1 = y1 * cos(x1)
+ yp1 = y1 * sin(x1)
+ x1 = xp1
+ y1 = yp1
+ dx0 = (x1 - x0) / ds
+ dy0 = (y1 - y0) / ds
+ else: # derivative given by the user
+ dx0 = 1 # Only works for rectangular coordinates
+ dy0 = fp(xstart)
+
+ # Start curve
+ if endpts:
+ a.append(['M', [left, coordy(0)]])
+ a.append(['L', [coordx(x0), coordy(y0)]])
+ else:
+ a.append(['M', [coordx(x0), coordy(y0)]]) # initial moveto
+
+ for i in range(int(samples - 1)):
+ x1 = (i + 1) * step + xstart
+ x2 = x1 - ds # Second point BEFORE first point (Good for last point)
+ y1 = f(x1)
+ y2 = f(x2)
+ if polar:
+ xp1 = y1 * cos(x1)
+ yp1 = y1 * sin(x1)
+ xp2 = y2 * cos(x2)
+ yp2 = y2 * sin(x2)
+ x1 = xp1
+ y1 = yp1
+ x2 = xp2
+ y2 = yp2
+ if fponum or polar: # numerical derivative
+ dx1 = (x1 - x2) / ds
+ dy1 = (y1 - y2) / ds
+ else: # derivative given by the user
+ dx1 = 1 # Only works for rectangular coordinates
+ dy1 = fp(x1)
+ # 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)]
+ ])
+ x0 = x1 # Next segment's start is this segments end
+ y0 = y1
+ dx0 = dx1 # Assume the function is smooth everywhere, so carry over the derivative too
+ dy0 = dy1
+ if endpts:
+ a.append(['L', [left + width, coordy(0)]])
+ return a
+
+
+class FuncPlot(inkex.EffectExtension):
+ def add_arguments(self, pars):
+ pars.add_argument("--tab")
+ pars.add_argument("--xstart", type=float, default=0.0, help="Start x-value")
+ pars.add_argument("--xend", type=float, default=1.0, help="End x-value")
+ pars.add_argument("--times2pi", type=inkex.Boolean, default=True, help="* x-range by 2*pi")
+ pars.add_argument("--polar", type=inkex.Boolean, default=False, help="Use polar coords")
+ pars.add_argument("--ybottom", type=float, default=-1.0, help="y-value of rect's bottom")
+ pars.add_argument("--ytop", type=float, default=1.0, help="y-value of rectangle's top")
+ pars.add_argument("--samples", type=int, default=8, help="Samples")
+ pars.add_argument("--fofx", default="sin(x)", help="f(x) for plotting")
+ pars.add_argument("--fponum", type=inkex.Boolean, default=True, help="Numerical 1st deriv")
+ pars.add_argument("--fpofx", default="cos(x)", help="f'(x) for plotting")
+ pars.add_argument("--clip", type=inkex.Boolean, default=False, help="Clip with source rect")
+ pars.add_argument("--remove", type=inkex.Boolean, default=True, help="Remove source rect")
+ pars.add_argument("--isoscale", type=inkex.Boolean, default=True, help="Isotropic scaling")
+ pars.add_argument("--drawaxis", type=inkex.Boolean, default=True, help="Draw axis")
+ pars.add_argument("--endpts", type=inkex.Boolean, default=False, help="Add end points")
+
+ def effect(self):
+ newpath = None
+ for node in self.svg.selected.values():
+ if isinstance(node, Rectangle):
+ # create new path with basic dimensions of selected rectangle
+ newpath = inkex.PathElement()
+ x = float(node.get('x'))
+ y = float(node.get('y'))
+ w = float(node.get('width'))
+ h = 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.xstart,
+ self.options.xend,
+ self.options.ybottom,
+ self.options.ytop,
+ self.options.samples,
+ w, h, x, y + h,
+ self.options.fofx,
+ self.options.fpofx,
+ self.options.fponum,
+ self.options.times2pi,
+ self.options.polar,
+ self.options.isoscale,
+ self.options.drawaxis,
+ self.options.endpts)
+ newpath.set('title', self.options.fofx)
+
+ # add path into SVG structure
+ node.getparent().append(newpath)
+ # option whether to clip the path with rect or not.
+ if self.options.clip:
+ clip = self.svg.defs.add(ClipPath())
+ clip.set_random_id()
+ clip.append(node.copy())
+ newpath.set('clip-path', 'url(#' + clip.get_id() + ')')
+ # option whether to remove the rectangle or not.
+ if self.options.remove:
+ node.getparent().remove(node)
+ if newpath is None:
+ inkex.errormsg("Please select a rectangle")
+
+
+if __name__ == '__main__':
+ FuncPlot().run()