1#!/usr/local/bin/python3.8
2# coding=utf-8
3#
4# Copyright (C) 2007 Tavmjong Bah, tavmjong@free.fr
5# Copyright (C) 2006 Georg Wiora, xorx@quarkbox.de
6# Copyright (C) 2006 Johan Engelen, johan@shouraizou.nl
7# Copyright (C) 2005 Aaron Spike, aaron@ekips.org
8#
9# This program is free software; you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation; either version 2 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program; if not, write to the Free Software
21# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
22#
23# Changes:
24#  * This program is a modified version of wavy.py by Aaron Spike.
25#  * 22-Dec-2006: Wiora : Added axis and isotropic scaling
26#  * 21-Jun-2007: Tavmjong: Added polar coordinates
27#
28from math import cos, pi, sin
29
30import inkex
31from inkex import ClipPath, Rectangle
32from inkex.utils import math_eval
33
34def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bottom,
35                 fx="sin(x)", fpx="cos(x)", fponum=True, times2pi=False, polar=False, isoscale=True, drawaxis=True, endpts=False):
36    if times2pi:
37        xstart = 2 * pi * xstart
38        xend = 2 * pi * xend
39
40    # coords and scales based on the source rect
41    if xstart == xend:
42        inkex.errormsg("x-interval cannot be zero. Please modify 'Start X value' or 'End X value'")
43        return []
44    scalex = width / (xend - xstart)
45    xoff = left
46    coordx = lambda x: (x - xstart) * scalex + xoff  # convert x-value to coordinate
47    if polar:  # Set scale so that left side of rectangle is -1, right side is +1.
48        # (We can't use xscale for both range and scale.)
49        centerx = left + width / 2.0
50        polar_scalex = width / 2.0
51        coordx = lambda x: x * polar_scalex + centerx  # convert x-value to coordinate
52
53    if ytop == ybottom:
54        inkex.errormsg("y-interval cannot be zero. Please modify 'Y value of rectangle's top' or 'Y value of rectangle's bottom'")
55        return []
56    scaley = height / (ytop - ybottom)
57    yoff = bottom
58    coordy = lambda y: (ybottom - y) * scaley + yoff  # convert y-value to coordinate
59
60    # Check for isotropic scaling and use smaller of the two scales, correct ranges
61    if isoscale and not polar:
62        if scaley < scalex:
63            # compute zero location
64            xzero = coordx(0)
65            # set scale
66            scalex = scaley
67            # correct x-offset
68            xstart = (left - xzero) / scalex
69            xend = (left + width - xzero) / scalex
70        else:
71            # compute zero location
72            yzero = coordy(0)
73            # set scale
74            scaley = scalex
75            # correct x-offset
76            ybottom = (yzero - bottom) / scaley
77            ytop = (bottom + height - yzero) / scaley
78
79    f = math_eval(fx)
80    fp = math_eval(fpx)
81    if (f is None or (fp is None and not(fponum))):
82        raise inkex.AbortExtension(_("Invalid function specification"))
83
84    # step is the distance between nodes on x
85    step = (xend - xstart) / (samples - 1)
86    third = step / 3.0
87    ds = step * 0.001  # Step used in calculating derivatives
88
89    a = []  # path array
90    # add axis
91    if drawaxis:
92        # check for visibility of x-axis
93        if ybottom <= 0 <= ytop:
94            # xaxis
95            a.append(['M', [left, coordy(0)]])
96            a.append(['l', [width, 0]])
97        # check for visibility of y-axis
98        if xstart <= 0 <= xend:
99            # xaxis
100            a.append(['M', [coordx(0), bottom]])
101            a.append(['l', [0, -height]])
102
103    # initialize function and derivative for 0;
104    # they are carried over from one iteration to the next, to avoid extra function calculations.
105    x0 = xstart
106    y0 = f(xstart)
107    if polar:
108        xp0 = y0 * cos(x0)
109        yp0 = y0 * sin(x0)
110        x0 = xp0
111        y0 = yp0
112    if fponum or polar:  # numerical derivative, using 0.001*step as the small differential
113        x1 = xstart + ds  # Second point AFTER first point (Good for first point)
114        y1 = f(x1)
115        if polar:
116            xp1 = y1 * cos(x1)
117            yp1 = y1 * sin(x1)
118            x1 = xp1
119            y1 = yp1
120        dx0 = (x1 - x0) / ds
121        dy0 = (y1 - y0) / ds
122    else:  # derivative given by the user
123        dx0 = 1  # Only works for rectangular coordinates
124        dy0 = fp(xstart)
125
126    # Start curve
127    if endpts:
128        a.append(['M', [left, coordy(0)]])
129        a.append(['L', [coordx(x0), coordy(y0)]])
130    else:
131        a.append(['M', [coordx(x0), coordy(y0)]])  # initial moveto
132
133    for i in range(int(samples - 1)):
134        x1 = (i + 1) * step + xstart
135        x2 = x1 - ds  # Second point BEFORE first point (Good for last point)
136        y1 = f(x1)
137        y2 = f(x2)
138        if polar:
139            xp1 = y1 * cos(x1)
140            yp1 = y1 * sin(x1)
141            xp2 = y2 * cos(x2)
142            yp2 = y2 * sin(x2)
143            x1 = xp1
144            y1 = yp1
145            x2 = xp2
146            y2 = yp2
147        if fponum or polar:  # numerical derivative
148            dx1 = (x1 - x2) / ds
149            dy1 = (y1 - y2) / ds
150        else:  # derivative given by the user
151            dx1 = 1  # Only works for rectangular coordinates
152            dy1 = fp(x1)
153        # create curve
154        a.append(['C',
155                  [coordx(x0 + (dx0 * third)), coordy(y0 + (dy0 * third)),
156                   coordx(x1 - (dx1 * third)), coordy(y1 - (dy1 * third)),
157                   coordx(x1), coordy(y1)]
158                  ])
159        x0 = x1  # Next segment's start is this segments end
160        y0 = y1
161        dx0 = dx1  # Assume the function is smooth everywhere, so carry over the derivative too
162        dy0 = dy1
163    if endpts:
164        a.append(['L', [left + width, coordy(0)]])
165    return a
166
167
168class FuncPlot(inkex.EffectExtension):
169    def add_arguments(self, pars):
170        pars.add_argument("--tab")
171        pars.add_argument("--xstart", type=float, default=0.0, help="Start x-value")
172        pars.add_argument("--xend", type=float, default=1.0, help="End x-value")
173        pars.add_argument("--times2pi", type=inkex.Boolean, default=True, help="* x-range by 2*pi")
174        pars.add_argument("--polar", type=inkex.Boolean, default=False, help="Use polar coords")
175        pars.add_argument("--ybottom", type=float, default=-1.0, help="y-value of rect's bottom")
176        pars.add_argument("--ytop", type=float, default=1.0, help="y-value of rectangle's top")
177        pars.add_argument("--samples", type=int, default=8, help="Samples")
178        pars.add_argument("--fofx", default="sin(x)", help="f(x) for plotting")
179        pars.add_argument("--fponum", type=inkex.Boolean, default=True, help="Numerical 1st deriv")
180        pars.add_argument("--fpofx", default="cos(x)", help="f'(x) for plotting")
181        pars.add_argument("--clip", type=inkex.Boolean, default=False, help="Clip with source rect")
182        pars.add_argument("--remove", type=inkex.Boolean, default=True, help="Remove source rect")
183        pars.add_argument("--isoscale", type=inkex.Boolean, default=True, help="Isotropic scaling")
184        pars.add_argument("--drawaxis", type=inkex.Boolean, default=True, help="Draw axis")
185        pars.add_argument("--endpts", type=inkex.Boolean, default=False, help="Add end points")
186
187    def effect(self):
188        newpath = None
189        for node in self.svg.selected.values():
190            if isinstance(node, Rectangle):
191                # create new path with basic dimensions of selected rectangle
192                newpath = inkex.PathElement()
193                x = float(node.get('x'))
194                y = float(node.get('y'))
195                w = float(node.get('width'))
196                h = float(node.get('height'))
197
198                # copy attributes of rect
199                newpath.style = node.style
200                newpath.transform = node.transform
201
202                # top and bottom were exchanged
203                newpath.path = \
204                        drawfunction(self.options.xstart,
205                                     self.options.xend,
206                                     self.options.ybottom,
207                                     self.options.ytop,
208                                     self.options.samples,
209                                     w, h, x, y + h,
210                                     self.options.fofx,
211                                     self.options.fpofx,
212                                     self.options.fponum,
213                                     self.options.times2pi,
214                                     self.options.polar,
215                                     self.options.isoscale,
216                                     self.options.drawaxis,
217                                     self.options.endpts)
218                newpath.set('title', self.options.fofx)
219
220                # add path into SVG structure
221                node.getparent().append(newpath)
222                # option whether to clip the path with rect or not.
223                if self.options.clip:
224                    clip = self.svg.defs.add(ClipPath())
225                    clip.set_random_id()
226                    clip.append(node.copy())
227                    newpath.set('clip-path', clip.get_id(as_url=2))
228                # option whether to remove the rectangle or not.
229                if self.options.remove:
230                    node.getparent().remove(node)
231        if newpath is None:
232            raise inkex.AbortExtension(_("Please select a rectangle"))
233
234
235if __name__ == '__main__':
236    FuncPlot().run()
237