https://github.com/mossblaser/svgoutline

A Python library which extracts strokes (outlines) from an SVG file as a series of line segments appropriate for driving pen plotters
https://github.com/mossblaser/svgoutline

Last synced: 8 months ago
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A Python library which extracts strokes (outlines) from an SVG file as a series of line segments appropriate for driving pen plotters

• Host: GitHub
• URL: https://github.com/mossblaser/svgoutline
• Owner: mossblaser
• License: lgpl-3.0
• Created: 2019-01-14T16:33:25.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2024-06-04T06:31:18.000Z (over 1 year ago)
• Last Synced: 2025-03-22T08:11:08.036Z (9 months ago)
• Language: Python
• Size: 93.8 KB
• Stars: 20
• Watchers: 1
• Forks: 4
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-plotters - svgoutline - Python library to extract strokes and outlines from SVGs as line segments. (Software / Vector Utilities)

README

          
svgoutline

==========

This Python library extracts all strokes (outlines) from an SVG vector graphics

file as a series of straight line segments appropriate for driving pen plotters

or desktop cutting machines.

Features

--------

* **Supports most common SVG features** including beziers, shapes, simple text,

  dashed lines and object/layer visibility. Converts all of these

  into simple straight line segments with no transformations required:

  

  ![Input SVG](./samples/basic_sample_input_text_as_outlines_for_readme.svg)

  ![Arrow](./samples/arrow.svg)

  ![Output SVG](./samples/basic_sample_output.svg)

* **Ignores out non-stroked objects.**

  

  ![Input SVG](./samples/outline_only_sample_input.svg)

  ![Arrow](./samples/arrow.svg)

  ![Output SVG](./samples/outline_only_sample_output.svg)

* **Curves are approximated by straight lines** with user-defined fidelity.

  

  ![Input SVG](./samples/curve_resolution_sample_input.svg)

  ![Arrow](./samples/arrow.svg)

  ![Output SVG](./samples/curve_resolution_sample_output_0.2.svg)

  ![Output SVG](./samples/curve_resolution_sample_output_1.0.svg)

  ![Output SVG](./samples/curve_resolution_sample_output_5.0.svg)

* **Captures stroke colours** in RGBA format and millimetres respectively (e.g.

  to allow colour/thickness dependent cutting/plotting settings).

  

  ![Input SVG](./samples/colours_sample_input.svg)

  ![Arrow](./samples/arrow.svg)

  ![Output SVG](./samples/colours_sample_output.svg)

Usage

-----

Install from PyPI:

    $ pip install svgoutline

Provide a valid SVG deserialised from XML using Python's [`ElementTree`

API](https://docs.python.org/3/library/xml.etree.elementtree.html):

    >>> import xml.etree.ElementTree as ET

    >>> from svgoutline import svg_to_outlines

    

    >>> tree = ET.parse("example.svg")

    >>> root = tree.getroot()

    

    >>> outlines = svg_to_outlines(root)

Where `outlines` will be a `list` of lines of the form:

    [

        ((r, g, b, a), line_width, [(x, y), ...]),

        ...

    ]

With `r`, `g`, `b` and `a` being between 0.0 and 1.0, and with `line_width` and

the coordinates being given in millimetres.

See `help(svg_to_outlines)` (or

[`svg_to_outlines.py`](./svgoutline/svg_to_outlines.py)) for full usage

information.

Alternatively, a quick'n'dirty demo script is provided in `samples/demo.py`

which generates the examples above given an SVG file as input. See `python

samples/demo.py --help` for more information.

Limitations

-----------

* **Only [SVG Tiny 1.2](https://www.w3.org/TR/SVGTiny12/) is supported** due to the

  use of [Qt SVG](http://doc.qt.io/qt-5/qtsvg-index.html) internally. The

  following significant features are missing which you might otherwise expect:

  * Clipping masks are not supported and will be ignored.

  * Many text features beyond simple single-line text strings are not

    supported, for example text on path, line wrapping or style changes mid

    text element.

* **Depends on [Qt for Python (a.k.a.

  PySide6)](https://wiki.qt.io/Qt_for_Python).**  This is a relatively

  non-trivial dependency but is easy to install from

  [PyPI](https://pypi.org/project/PySide6/) on most platforms. Unfortunately it

  makes svgoutline subject to the same bugs (e.g.

  [QTBUG-72997](https://bugreports.qt.io/browse/QTBUG-72997) which at the time

  of writing causes text outlines and dash patterns to render too small).

* **Oblivious to fills and overlaps.** Consequently, if two shapes overlap,

  their full outlines will be included in the output regardless of what parts

  of their outlines are actually visible. For plotting purposes this should not

  be a significant problem as input SVGs are unlikely to contain filled

  elements.

* **Output does not distinguish between closed paths and paths whose start and

  end coordinates are the same.** This distinction is not important for most

  plotting applications.

Tests

-----

The tests are written using [py.test](https://docs.pytest.org/en/latest/) and

test dependencies can be installed and the tests executed with:

    $ pip install -r requirements-test.txt

    $ py.test tests

The code adheres to the Python [PEP8 style

guide](https://www.python.org/dev/peps/pep-0008/) and is checked using

[flake8](http://flake8.pycqa.org/en/latest/) (installed with py.test in the

commands above). Run it using:

    $ flake8 tests svgoutline

License

-------

GNU Lesser General Public License v3 (LGPLv3)