---
title: Using boolean operations in an Inkscape extension
topics: ["inkscape", "python", "tip"]
DATE: 2025-11-22
---

I've wasted 3 days doing this, so I will at least publish my findings on the web
so you don't have to waste another 3 days. I wasn't able to find a good example
online and the docs are not well-made (not saying that they should be a
priority), so figuring it out does require some code research.

The `inkex` module provides lots of things, but boolean operations aren't one of
them. Thus, you will have to call Inkscape yourself; luckily, `inkex` does
provide that.

Even though they are listed as arguments, no special processing is done to the
values, which are still strings.

I leave a minimal example:

~~~python
import inkex
import io

class UnionTwoPaths(inkex.EffectExtension):
    def effect(self):
        selected = list(self.svg.selection)

        if len(selected) != 2:
            inkex.errormsg("Select exactly two paths!")
            return

        # Make a string of the IDs
        ids = ",".join([elem.get_id() for elem in selected])

        # Call Inkscape to make a union
        union_svg_bytes = inkex.command.inkscape_command(
            self.document,
            select=ids,
            actions="path-union"
        )

        # Send the drawing back
        self.document = inkex.load_svg(union_svg_bytes)


if __name__ == "__main__":
    UnionTwoPaths().run()
~~~

~~~xml
<?xml version="1.0" encoding="UTF-8"?>
<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
    <name>Union of two paths</name>
    <id>org.inkscape.boolean.union_two_paths</id>
    <effect>
        <!-- Enable only on path objects (could use 'all' if preferred) -->
        <object-type>path</object-type>
        <effects-menu>
            <submenu name="Generate from Path"/>
        </effects-menu>
    </effect>
    <script>
        <command reldir="extensions" interpreter="python">union_two_paths.py</command>
    </script>
</inkscape-extension>
~~~