https://github.com/taoari/inkscape-filletandchamfer added

extensions/fablabchemnitz_filletchamfer.inx

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+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+    <_name>Fillet And Chamfer</_name>
+    <id>fablabchemnitz.de.filletchamfer</id>
+    <dependency type="executable" location="extensions">fablabchemnitz_filletchamfer.py</dependency>
+    <dependency type="executable" location="extensions">inkex.py</dependency>
+    <param name="type" type="enum" _gui-text="Fillet or Chamfer:">
+        <_item value="fillet">Fillet</_item>
+        <_item value="chamfer">Chamfer</_item>
+    </param>
+    <param name="radius" type="float" min="0.0" max="1000.0" _gui-text="Radius (px):">20.0</param>
+    <effect>
+        <object-type>all</object-type>
+        <effects-menu>
+            <submenu _name="FabLab Chemnitz">
+                <submenu _name="Modify existing Path(s)" />
+            </submenu>
+        </effects-menu>
+    </effect>
+    <script>
+        <command reldir="extensions" interpreter="python">fablabchemnitz_filletchamfer.py</command>
+    </script>
+</inkscape-extension>

extensions/fablabchemnitz_filletchamfer.py

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+#! /usr/bin/python2
+'''
+Copyright (C) 2018 Tao Wei taowei@buffalo.edu
+
+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.
+'''
+import inkex, simplestyle, math
+from simpletransform import computePointInNode
+import svgpathtools
+
+KAPPA = 4/3. * (math.sqrt(2)-1)
+
+def cround(cnumber, ndigits):
+    return round(cnumber.real, ndigits) + round(cnumber.imag, ndigits)*1j
+
+def round_seg(seg, ndigits):
+    seg.start = cround(seg.start, ndigits)
+    seg.end = cround(seg.end, ndigits)
+    return seg
+        
+def round_path(p, ndigits=6):
+    """fix for precision issue"""
+    for seg in p:
+        round_seg(seg, ndigits)
+    return p
+
+def remove_zero_length_segments(p, eps=1e-6):
+    "z will add a zero length line segment"
+    return svgpathtools.Path(*filter(lambda seg: seg.length() > eps, p))
+
+def iscontinuous(p):
+    for seg1, seg2 in zip(p[:-1], p[1:]):
+        if abs(seg1.end-seg2.start) >= 1e-6:
+            return False
+    return True
+
+def isclosedac(p):
+    return abs(p.start-p.end) < 1e-6
+
+def isclosed(p):
+    assert iscontinuous(p)
+    return isclosedac(p)
+    
+from svgpathtools.path import Line, CubicBezier, QuadraticBezier, Arc
+
+def d_str(self, useSandT=False, use_closed_attrib=False, rel=False):
+    """Returns a path d-string for the path object.
+    For an explanation of useSandT and use_closed_attrib, see the
+    compatibility notes in the README."""
+
+    if use_closed_attrib:
+        self_closed = self.iscontinuous() and self.isclosed()
+        if self_closed:
+            segments = self[:-1]
+        else:
+            segments = self[:]
+    else:
+        self_closed = False
+        segments = self[:]
+
+    current_pos = None
+    parts = []
+    previous_segment = None
+    end = self[-1].end
+
+    for segment in segments:
+        seg_start = segment.start
+        # If the start of this segment does not coincide with the end of
+        # the last segment or if this segment is actually the close point
+        # of a closed path, then we should start a new subpath here.
+        if current_pos != seg_start or \
+                (self_closed and seg_start == end and use_closed_attrib):
+            if rel:
+                _seg_start = seg_start - current_pos if current_pos is not None else seg_start
+            else:
+                _seg_start = seg_start
+            parts.append('M {},{}'.format(_seg_start.real, _seg_start.imag))
+
+        if isinstance(segment, Line):
+            if rel:
+                _seg_end = segment.end - seg_start
+            else:
+                _seg_end = segment.end
+            parts.append('L {},{}'.format(_seg_end.real, _seg_end.imag))
+        elif isinstance(segment, CubicBezier):
+            if useSandT and segment.is_smooth_from(previous_segment,
+                                                   warning_on=False):
+                if rel:
+                    _seg_control2 = segment.control2 - seg_start
+                    _seg_end = segment.end - seg_start
+                else:
+                    _seg_control2 = segment.control2
+                    _seg_end = segment.end
+                args = (_seg_control2.real, _seg_control2.imag,
+                        _seg_end.real, _seg_end.imag)
+                parts.append('S {},{} {},{}'.format(*args))
+            else:
+                if rel:
+                    _seg_control1 = segment.control1 - seg_start
+                    _seg_control2 = segment.control2 - seg_start
+                    _seg_end = segment.end - seg_start
+                else:
+                    _seg_control1 = segment.control1
+                    _seg_control2 = segment.control2
+                    _seg_end = segment.end
+                args = (_seg_control1.real, _seg_control1.imag,
+                        _seg_control2.real, _seg_control2.imag,
+                        _seg_end.real, _seg_end.imag)
+                parts.append('C {},{} {},{} {},{}'.format(*args))
+        elif isinstance(segment, QuadraticBezier):
+            if useSandT and segment.is_smooth_from(previous_segment,
+                                                   warning_on=False):
+                if rel:
+                    _seg_end = segment.end - seg_start
+                else:
+                    _seg_end = segment.end
+                args = _seg_end.real, _seg_end.imag
+                parts.append('T {},{}'.format(*args))
+            else:
+                if rel:
+                    _seg_control = segment.control - seg_start
+                    _seg_end = segment.end - seg_start
+                else:
+                    _seg_control = segment.control
+                    _seg_end = segment.end
+                args = (_seg_control.real, _seg_control.imag,
+                        _seg_end.real, _seg_end.imag)
+                parts.append('Q {},{} {},{}'.format(*args))
+
+        elif isinstance(segment, Arc):
+            if rel:
+                _seg_end = segment.end - seg_start
+            else:
+                _seg_end = segment.end
+            args = (segment.radius.real, segment.radius.imag,
+                    segment.rotation,int(segment.large_arc),
+                    int(segment.sweep),_seg_end.real, _seg_end.imag)
+            parts.append('A {},{} {} {:d},{:d} {},{}'.format(*args))
+        current_pos = segment.end
+        previous_segment = segment
+
+    if self_closed:
+        parts.append('Z')
+
+    s = ' '.join(parts)
+    return s if not rel else s.lower()
+        
+class FilletChamfer(inkex.Effect):
+    def __init__(self):
+        inkex.Effect.__init__(self)
+        self.OptionParser.add_option("-t", "--type",
+                        action="store", type="string",
+                        dest="fillet_type", default="fillet",
+                        help="Selects whether using fillet or chamfer")
+        self.OptionParser.add_option("-R", "--radius",
+                        action="store", type="float",
+                        dest="radius", default=60.0,
+                        help="The radius")
+        
+    def addEle(self, ele, parent, props):
+        # https://inkscape.org/~pacogarcia/%E2%98%85new-version-of-shapes-extension
+        elem = inkex.etree.SubElement(parent, ele)
+        for n in props: elem.set(n,props[n])
+        return elem
+    
+    def circle(self, c, r):
+        return svgpathtools.parse_path("m %f,%f a %f,%f 0 0 1 -%f,%f %f,%f 0 0 1 -%f,-%f %f,%f 0 0 1 %f,-%f %f,%f 0 0 1 %f,%f z" % tuple((c.real+r, c.imag) + (r,)*16))
+        
+    def _calc_fillet_for_joint(self, p, i):
+        seg1 = p[(i) % len(p)]
+        seg2 = p[(i+1) % len(p)]
+        
+        ori_p = svgpathtools.Path(seg1, seg2)
+        new_p = svgpathtools.Path()
+        
+        # ignore the node if G1 continuity
+        tg1 = seg1.unit_tangent(1.0)
+        tg2 = seg2.unit_tangent(0.0)
+        cosA = abs(tg1.real * tg2.real + tg1.imag * tg2.imag)
+        if abs(cosA - 1.0) < 1e-6:
+            new_p.append(seg1.cropped(self._prev_t, 1.0))
+            self._prev_t = 0.0
+            if self._very_first_t is None:
+                self._very_first_t = 1.0
+            if not isclosedac(p) and i == len(p) - 2:
+                new_p.append(seg2.cropped(0.0, 1.0)) # add last segment if not closed
+        else:
+            cir = self.circle(seg1.end, self.options.radius)
+    #        new_p.extend(cir)
+    
+            intersects = ori_p.intersect(cir)
+            if len(intersects) != 2:
+                inkex.errormsg("Some fillet or chamfer may not be drawn: %d intersections!" % len(intersects))
+                new_p.append(seg1.cropped(self._prev_t, 1.0))
+                self._prev_t = 0.0
+                if self._very_first_t is None:
+                    self._very_first_t = 1.0
+                if not isclosedac(p) and i == len(p) - 2:
+                    new_p.append(seg2.cropped(0.0, 1.0)) # add last segment if not closed
+            else:
+                cb = []; segs = []; ts = []
+                for (T1, seg1, t1), (T2, seg2, t2) in intersects:
+                    c1 = seg1.point(t1)
+                    tg1 = seg1.unit_tangent(t1) * (self.options.radius * KAPPA)
+                    cb.extend([c1, tg1])
+                    segs.append(seg1); ts.append(t1)
+                    
+    #                cir1 = self.circle(c1, self.options.radius * KAPPA)
+    #                new_p.extend(cir1)
+    #                new_p.append(svgpathtools.Line(c1, c1+tg1))
+                    
+                assert len(cb) == 4
+                new_p.append(segs[0].cropped(self._prev_t, ts[0]))
+                if self.options.fillet_type == 'fillet':
+                    fillet = svgpathtools.CubicBezier(cb[0], cb[0]+cb[1], cb[2]-cb[3], cb[2])
+                else:
+                    fillet = svgpathtools.Line(cb[0], cb[2])
+                new_p.append(fillet)
+                self._prev_t = ts[1]
+                if self._very_first_t is None:
+                    self._very_first_t = ts[0]
+                
+                if isclosedac(p) and i == len(p) - 1:
+                    new_p.append(segs[1].cropped(ts[1], self._very_first_t)) # update first segment if closed
+                elif not isclosedac(p) and i == len(p) - 2:
+                    new_p.append(segs[1].cropped(ts[1], 1.0)) # add last segment if not closed
+                
+#            # fix for the first segment
+#            if p.isclosed():
+#                new_p[0] = p[0].cropped(ts[1], self._very_first_t)
+            
+#            new_p.append(segs[0].cropped(ts[0], 1.0))
+#            new_p.append(segs[1].cropped(0.0, ts[1]))
+#            if self.options.fillet_type == 'fillet':
+#                fillet = svgpathtools.CubicBezier(cb[0], cb[0]+cb[1], cb[2]-cb[3], cb[2])
+#            else:
+#                fillet = svgpathtools.Line(cb[0], cb[2])
+#            new_p.append(fillet.reversed())
+            
+        return new_p
+    
+    def add_fillet_to_path(self, d):
+        p = svgpathtools.parse_path(d)
+        p = remove_zero_length_segments(p) # for z, a zero length line segment is possibly added
+        
+        if len(p) <= 1:
+            return d
+        
+        new_p = svgpathtools.Path()
+        self._prev_t = 0 # used as cache
+        self._very_first_t = None # update first segment if closed
+        if isclosedac(p):
+            for i in range(len(p)):
+                new_p.extend(self._calc_fillet_for_joint(p, i))
+            if not isclosedac(new_p):
+                del new_p[0] # remove first segment if closed
+        else:
+            for i in range(len(p)-1):
+                new_p.extend(self._calc_fillet_for_joint(p, i)) 
+        new_p = round_path(new_p, 6)
+        # inkex.errormsg(d_str(new_p, use_closed_attrib=True, rel=True))
+        return d_str(new_p, use_closed_attrib=True, rel=True)
+
+    def effect(self):
+        self.options.radius = self.unittouu(str(self.options.radius) + 'px')
+        
+        if self.options.radius == 0:
+            return
+        
+        for id, node in self.selected.iteritems():
+            _shape = inkex.etree.QName(node.tag).localname
+            if _shape != "path":
+                inkex.errormsg("Fillet and chamfer only operates on path: %s is %s" % (id, _shape))
+            else:
+                # inkex.errormsg(inkex.etree.tostring(node))
+                attrib = {k:v for k,v in node.attrib.items()}
+                attrib['d'] = self.add_fillet_to_path(attrib['d'])
+                self.addEle(inkex.addNS('path','svg'), node.getparent(), attrib)
+
+if __name__ == '__main__':
+    e = FilletChamfer()
+    e.affect()