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mightyscape-1.1-deprecated/extensions/fablabchemnitz/circle_tangents/circle_tangents.py

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2020-08-01 02:16:55 +02:00
#!/usr/bin/env python3
'''
Copyright (C) 2012 Rhys Owen, rhysun@gmail.com
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 3 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, see <http://www.gnu.org/licenses/>.
A
|\
| \
| \
| \
| \
b| \h
| \
| \
|_ \
|_|_______\
C a B
'''
import inkex
from inkex.paths import Path
from inkex import Transform
from math import *
from lxml import etree
def poltocar(r, rad, negx=False, negy=False):
# converts polar coords to cartesian
x = r * cos(rad)
y = r * sin(rad)
if negx and not negy:
return [-x, y]
elif not negx and negy:
return [x, -y]
elif not negx and not negy:
return [-x, -y]
else:
return [x, y]
def deuclid(x1, y1, x2, y2):
# euclidean distance between two cartesian coords
squarex = (x1 - x2)**2
squarey = (y1 - y2)**2
d = sqrt(squarex + squarey)
return d
def getAngle(b, h):
angle = asin(b / h)
return angle
def aLength(b, h):
a = sqrt(h**2-b**2)
return a
def getPathData(obj):
if obj.get("d"):# If the circle has been converted to a path object
d = obj.get("d")
p = Path(d)
if obj.get("transform"):
trans = Transform(obj.get("transform"))
scalex = trans[0][0]
scaley = trans[1][1]
data = {'rx' : p[1][1][0]*scalex,
'ry' : p[1][1][1]*scaley,
'x' : (trans[0][0]*p[0][1][0])+(trans[0][1]*p[0][1][1])+trans[0][2]-(p[1][1][0]*scalex),
'y' : (trans[1][0]*p[0][1][0])+(trans[1][1]*p[0][1][1])+trans[1][2]}
else:
data = {'rx': p[1][1][0],
'ry': p[1][1][1],
'x' : p[0][1][0]-p[1][1][0],
'y' : p[0][1][1]}
elif obj.get("r"):# For a pure circle object
r = obj.get("r")
cx = obj.get("cx")
cy = obj.get("cy")
data = {'rx' : float(r),
'ry' : float(r),
'x' : float(cx),
'y' : float(cy)}
elif obj.get("rx"):# For ellipses
rx = obj.get("rx")
ry = obj.get("ry")
cx = obj.get("cx")
cy = obj.get("cy")
data = {'rx' : float(rx),
'ry' : float(ry),
'x' : float(cx),
'y' : float(cy)}
else:
stockErrorMsg("4")
return data
class CircleTangents(inkex.EffectExtension):
def add_arguments(self, pars):
pars.add_argument("--position", default="inner", help="Choose either inner or outer tangent lines")
pars.add_argument("--selector", default="both", help="Choose which tangents you want to get")
pars.add_argument("--use_style_from_first", type=inkex.Boolean, default=False, help="Use style from first selected")
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def effect(self):
if len(self.options.ids) != 2:
inkex.errormsg("Please select exactly two circles and try again!")
return
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c1object = self.svg.selected[self.options.ids[0]]
c2object = self.svg.selected[self.options.ids[1]]
if c1object.tag != inkex.addNS('circle','svg') or c2object.tag != inkex.addNS('circle','svg'):
self.msg("One or both objects are not svg:circle elements!")
return
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c1 = getPathData(c1object)
c2 = getPathData(c2object)
# Create a third 'virtual' circle
if c1['rx'] <= c2['rx']:
c3x = c2['x']
c3y = c2['y']
if self.options.position == "outer":
c3r = c2['rx'] - c1['rx']
else:
c3r = c2['rx'] + c1['rx']
cyfA = [c1['x'], c1['y']]
cyfB = [c2['x'], c2['y']]
elif c1['rx'] > c2['rx']:
c3x = c1['x']
c3y = c1['y']
if self.options.position == "outer":
c3r = c1['rx'] - c2['rx']
else:
c3r = c1['rx'] + c2['rx']
cyfA = [c2['x'], c2['y']]
cyfB = [c1['x'], c1['y']]
# Test whether the circles are actually circles!
if c1['rx'] != c1['ry'] or c2['rx'] != c2['ry']:
inkex.errormsg("One or both objects may be elliptical. Ensure you have circles!")
return
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# Hypotenus of the triangle - Euclidean distance between c1 x, y and c2 x, y.
h = deuclid(c1['x'], c1['y'], c2['x'], c2['y'])
b = c3r
B = None
try:
B = getAngle(b, h)
except ValueError as e:
if self.options.position == "inner":
inkex.errormsg("Error calculating angle. Maybe your circles are overlapping each other")
else:
inkex.errormsg("Error calculating angle.")
return
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a = aLength(b, h)
# Angle of hypotenuse to x-axis
E = getAngle(max(c1['y'], c2['y']) - min(c1['y'], c2['y']), h)
# To test if the smallest circle is lower than the other
if cyfB[1] <= cyfA[1]:
negx = False
else:
negx = True
# To test if it's the smallest circle to the right of the other
if cyfB[0] <= cyfA[0]:
negy = False
else:
negy = True
angleTop = -B+E
angleBottom = B+E
if self.options.position == "outer":# External
perpTop = -(pi/2)
perpBottom = pi/2
else:# Internal
perpTop = pi/2
perpBottom = -(pi/2)
# Top coordinates of the top line
cyfC = poltocar(a, angleTop, negx, negy)
# Information for converting top 90grade coordinates
conversionTop = poltocar(min(c1['rx'], c2['rx']), perpTop+angleTop, negx, negy)#1.5707964 1.57079632679
# Bottom line coordinates
cyfD = poltocar(a, angleBottom, negx, negy)
# Information for converting the bottom 90 degree coordinates
conversionBottom = poltocar(min(c1['rx'], c2['rx']), perpBottom+angleBottom, negx, negy)
# Draw a line
llx1 = cyfA[0]
lly1 = cyfA[1]
if self.options.use_style_from_first is True:
llsteil = (c1object.get("style")) #note: if the selected objects do not contain a stroke width the tangents will be invisible!
else:
llsteil = "stroke:#000000; stroke-width:1px; fill:none;"
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# Line 1
if self.options.selector == "first" or self.options.selector == "both":
ll1x2 = cyfC[0]
ll1y2 = cyfC[1]
parent = c1object.getparent()
attribsLine1 = {'style':llsteil,
inkex.addNS('label','inkscape'):"line1",
'd':'m '+str(llx1+conversionTop[0])+','+str(lly1+conversionTop[1])+' l '+str(ll1x2)+','+str(ll1y2)}
elfen1 = etree.SubElement(parent, inkex.addNS('path','svg'), attribsLine1 )
#Line 2
if self.options.selector == "second" or self.options.selector == "both":
ll2x2 = cyfD[0]
ll2y2 = cyfD[1]
parent = c1object.getparent()
attribsLine1 = {'style':llsteil,
inkex.addNS('label','inkscape'):"line2",
'd':'m '+str(llx1+conversionBottom[0])+','+str(lly1+conversionBottom[1])+' l '+str(ll2x2)+','+str(ll2y2)}
etree.SubElement(parent, inkex.addNS('path','svg'), attribsLine1 )
if __name__ == '__main__':
CircleTangents().run()