Added flip extension

This commit is contained in:
leyghisbb 2021-04-09 18:16:33 +02:00
parent 2ab27300e0
commit 5dda2bedc3
3 changed files with 56 additions and 3 deletions

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<?xml version="1.0" encoding="UTF-8"?>
<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
<name>Flip</name>
<id>fablabchemnitz.de.Flip</id>
<effect>
<object-type>path</object-type>
<effects-menu>
<submenu name="FabLab Chemnitz">
<submenu name="Modify existing Path(s)"/>
</submenu>
</effects-menu>
</effect>
<script>
<command reldir="inx" interpreter="python">flip.py</command>
</script>
</inkscape-extension>

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import math
from inkex import EffectExtension, PathElement, transforms as T
# https://en.wikipedia.org/wiki/Rotations_and_reflections_in_two_dimensions
def reflection_matrix(theta):
theta2 = 2 * theta
return [
[math.cos(theta2), math.sin(theta2), 0],
[math.sin(theta2), -math.cos(theta2), 0],
]
def svg_matrix_order(mat):
((a, c, e), (b, d, f)) = mat
return a, b, c, d, e, f
class FlipPath(EffectExtension):
"""Extension to flip a path about the line from the start to end node"""
def effect(self):
for node in self.svg.selection.filter(PathElement).values():
points = list(node.path.end_points)
if len(points) < 2 or points[0] == points[-1]:
continue
start = points[0]
end = points[-1]
v = end - start
theta = math.atan2(v.y, v.x)
# transforms go in reverse order
mat = T.Transform()
mat.add_translate(start)
mat.add_matrix(*svg_matrix_order(reflection_matrix(theta)))
mat.add_translate(-start)
node.path = node.path.transform(mat)
if __name__ == '__main__':
FlipPath().run()

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@ -11,8 +11,7 @@
<option value="cross">Cross</option>
<option value="square">Square</option>
<option value="triangle">Triangle</option></param>
<label> </label>
<label> </label>
<spacer/>
<label>v1.1.0</label>
</page>
<page name="corners" gui-text="Corners">