When I'm using Inkscape, there are some tasks which I frequently do. These are the tasks that I frequently do:

1. Set the opacity of the selected path to 10%
2. Export selection to PNG in 600 DPI and insert it to my clipboard

I wish I could map a key to do those repetitive tasks. That is, I want to do (1) or (2) by pressing a single key in my keyboard.

I have been searching for a while and I found out that some people have created Inkscape extensions using Python. I have never created an Inkscape extension, but I have used Python in the past and it seems that Inkscape can be widely controlled using Python so I'm planning to learn how to write my custom extensions, so that I could find a way to map a key to a Python function that do (1) and (2).

So far, I have been able to execute this extension https://inkscapetutorial.org/hello-extension.html in my computer.

I'm creating this post so that others can share their experiences mapping a key to a custom function which you created in Python. Any information on this topic is appreciated.

I managed to create an extension to create an extension for setting the opacity and I was able to map it to a key by going to "Preferences" > "Keyboard". Below is the code of the extension.

Now, I need to learn how to export the selection to a PNG file and insert it to my clipboard.

~/.config/inkscape/extensions/my_set_opacity_to_10_percent/my_set_opacity_to_10_percent.inx

<?xml version="1.0" encoding="UTF-8"?>
<inkscape-extension
    xmlns="http://www.inkscape.org/namespace/inkscape/extension">
    <name>Set opacity of selection to 10%</name>
    <id>user.my_set_opacity_to_10_percent</id>
    <effect>
        <object-type>all</object-type>
        <effects-menu>
            <submenu name="Custom"/>
        </effects-menu>
    </effect>
    <script>
        <command location="inx" interpreter="python">my_set_opacity_to_10_percent.py</command>
    </script>
</inkscape-extension>

~/.config/inkscape/extensions/my_set_opacity_to_10_percent/my_set_opacity_to_10_percent.py

import inkex
from inkex import TextElement

class Hello(inkex.EffectExtension):
    def effect(self):
        for elem in self.svg.selection:
            elem.style['opacity'] = 0.1

if __name__ == '__main__':
    Hello().run()

It's not possible to replicate the gui export to .png function directly with pure python (inkex)

It requires a command call to the main Inkscape program to export to a file in the system tempfolder

You can then open the .png file with PIL (pillow) which is bundled with Inkscape on Windows.

(Please note there was a slight issue with one of the 1.4.x releases and PIL which has been reported)

Then you would need to go from the PIL Image to the Windows clipboard.

I requires a pypi library to be installed, there are a couple of examples if you search

"python 3 PIL image to clipboard"

I think some also work with Linux.

I managed to create an extension that exports the selection to a PNG file using the code below. I would appreciate some feedback from more experienced users on the code that I wrote. Any suggestion/improvement to my code is appreciated.

~/.config/inkscape/extensions/my_export_selection_to_png/my_export_selection_to_png.inx

<?xml version="1.0" encoding="UTF-8"?>
<inkscape-extension
    xmlns="http://www.inkscape.org/namespace/inkscape/extension">
    <name>Export selection to PNG</name>
    <id>user.my_export_selection_to_png</id>
    <effect>
        <object-type>all</object-type>
        <effects-menu>
            <submenu name="Custom"/>
        </effects-menu>
    </effect>
    <script>
        <command location="inx" interpreter="python">my_export_selection_to_png.py</command>
    </script>
</inkscape-extension>

~/.config/inkscape/extensions/my_export_selection_to_png/my_export_selection_to_png.py

import inkex
import subprocess
import copy

class MyExportSelectionToPng(inkex.EffectExtension):
    def effect(self):
        # Create copy of the SVG file
        document = copy.deepcopy(self.document)
        # Get the ID of elements in the selection
        selected_elements_ids = []
        for elem in self.svg.selection:
            selected_elements_ids.append(elem.eid)
        # Remove elements that are not in the selection
        g = document.xpath('/svg:svg/svg:g', namespaces=inkex.NSS)[0]
        for element in g.getchildren():
            if element.eid not in selected_elements_ids:
                g.remove(element)
        # Write document to a temporary file
        document.write('/tmp/a.svg')
        # Export PNG file to SVG file
        command = [
            'inkscape',
            '/tmp/a.svg',
            '--export-area-drawing',
            '--export-dpi=600',
            '--export-type', 'png',
            '--export-filename', '/tmp/a.png',
        ]
        try:
            subprocess.check_call(command)
        except Exception as e:
            raise Exception(
                f'Failed to convert.')
        # TODO: Insert PNG file to clipboard
        #
        # Note: Calling xclip through subprocess.run makes Inkscape
        # get stuck. For the time being, I'll write a separate shell
        # scripts that inserts the image into the clipboard.
        #
        # subprocess.run(['xclip', '-selection', 'clipboard', '-t', 'image/png', '/tmp/a.png'])

if __name__ == '__main__':script
    MyExportSelectionToPng().run()

Sidenote: In Preferences, I then mapped "x" to call "Set opacity to 10%" and "c" to call "Export selection to PNG" so that I can quickly call those functions with my left hand. While I'm editing in Inkscape, I mainly use my right hand to do actions with the mouse and my left hand remains in the keyboard.