lumina-svg-core

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A native SVG geometry engine for print workflows. lumina-svg-core resolves SVG paint operations, converts them into polygons, and exposes the result to Python as read-only NumPy arrays. It preserves paint order, holes, clipping, solid-color alpha compositing, and the identity of contributing paints.

Originally developed for Lumina Studio, this independent repository contains the geometry engine, Python bindings, test fixtures, and build tools. It has no runtime dependency on Lumina Studio, its UI, printer settings, or application services. It does not generate meshes or 3MF files.

Status: version 0.3.3 (alpha). CPython 3.12, 3.13 and 3.14 are supported. The geometry result contract is schema version 4.

Installation

Prebuilt wheels

Install the current public release from PyPI:

python -m pip install lumina-svg-core==0.3.3

See the PyPI version page and publishing workflow for the released files and their build/installation checks.

No C++ compiler, third-party checkout, manual patch, or local wheelhouse is needed for a matching prebuilt wheel. LunaSVG/PlutoVG and Clipper2 are compiled into the extension by maintainers.

Alternatively, download a matching wheel from GitHub Releases and install the downloaded file:

python -m pip install /path/to/lumina_svg_core-0.3.3-cp314-cp314-platform.whl

Replace the example filename with the actual downloaded wheel. Wheels are built for Windows x86-64, macOS Apple Silicon, macOS Intel, and Linux x86-64. macOS requires version 12 or newer for Python 3.12/3.13, and version 14 or newer for Python 3.14. Linux wheels use manylinux_2_28 and require glibc 2.28 or newer; Alpine/musl, Windows ARM and free-threaded Python are not covered. Match the wheel's OS, CPU and Python tags.

Build the native library from source (contributors)

You need CPython 3.12–3.14, Git, and a C++17 compiler: MSVC on Windows, Apple Clang on macOS, or GCC/Clang on Linux. The build installs its pinned Python build tools and fetches pinned LunaSVG and Clipper2 source revisions, so network access is required for a fresh build.

This is the library contributor workflow, not a prerequisite for running Lumina Studio from its Python/TypeScript source.

git clone https://github.com/lumina-layer-studio/lumina-svg-core.git
cd lumina-svg-core
python3.12 -m venv .venv
source .venv/bin/activate
python -m pip install --upgrade pip
python -m pip install .

On Windows, use py -3.12 -m venv .venv and activate it with .venv\Scripts\Activate.ps1 in PowerShell. Run the build from a Visual Studio developer shell if MSVC is not already available on your command line.

Quick start

import lumina_svg_core

svg = """<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 10">
  <rect width="20" height="10" fill="#e63946"/>
  <circle cx="10" cy="5" r="3" fill="#457b9d" fill-opacity="0.5"/>
</svg>"""

result = lumina_svg_core.analyze_svg_svg(
    svg,
    target_width_mm=40.0,
    tolerance_mm=0.02,
)
if result.status != "supported":
    raise RuntimeError(f"SVG analysis failed: {result.status}: {result.reason_code}")

print(result.visible.geometry_count)
print(result.visible.rgba_f64)

# Coordinates are an integer working grid, not SVG units or millimetres.
coordinates_mm = (
    result.visible.coordinates.astype("float64")
    * result.grid_to_source_unit
    * result.scale_factor
)

To read a file, use lumina_svg_core.analyze_svg("drawing.svg", target_width_mm=40.0, tolerance_mm=0.02). Paths may also be pathlib.Path instances. Both analysis entry points accept allow_strokes=False to omit stroke paints while retaining fills.

Inspect the installed build with lumina_svg_core.__version__, lumina_svg_core.__source_revision__ and lumina_svg_core.__source_dirty__. Git-free source builds report unknown provenance unless the builder supplies it explicitly. Distribution preparation describes the build identity and checked file receipts.

See the API reference for ring traversal, result statuses, source identity, coordinate units, and the lower-level recording and grid APIs.

SVG support

The SVG root begins transparent. The engine introduces no white background or printer-material matte. Fully opaque documents use reverse-order occlusion; translucent documents are partitioned and composited in premultiplied sRGB.

Masks, gradients, patterns, text, embedded images, external resources, non-normal blend modes, non-sRGB interpolation, and other unsupported semantics return a whole-document unsupported result. Zero-length dash entries are also unsupported. See support and numerical limits.

The recorder refactor reduces upstream patch additions by 46.5% while preserving the public API and geometry schema. Its prior comparison of 508 private SVGs at 220 mm / 0.02 mm with strokes enabled found the same 504 supported results and four native_geometry_error failures in both builds, with zero output differences. Those failures were not counted as passes. Version 0.3.3 addresses the canonical-boundary arithmetic and incomplete noding mechanisms, without adding printer policy or a fallback; see the fix and validation scope.

Geometry contract

• raw contains area-bearing paint geometry before paint-order occlusion; visible contains the final non-overlapping painted regions; silhouette contains their combined footprint.
• Coordinates use an integer working grid with an explicit conversion factor. Arrays preserve polygon components, holes, colors, and paint provenance.
• rgba_f64 is authoritative straight-sRGB RGBA in [0, 1]; rgba is a compatibility byte representation.
• Point-only, line-only, empty, and collapsed fragments are reported separately in unprintable_fragments. They are not fabricated into printable polygons.
• Unsupported or invalid documents are rejected as a whole. The standalone package does not retry them through another parser or silently discard unsupported elements.
• The parser performs no morphological closing, printer-grid snapping, minimum-area filtering, triangulation, or mesh repair.

Independent normalization work can run in parallel. Set LUMINA_SVG_REPLAY_THREADS to a positive integer to select a worker count; the engine caps it at 16. Parallel and serial replay preserve the same ordered geometry and provenance.

Development and validation

python -m pip install ".[test]" build
python -m pytest tests -q
python -m build
python tools/verify_wheel.py dist/<actual-wheel-filename>.whl --contents-only

CI builds and installs wheels for all three Python versions on all four platform targets, runs the complete Python suite, checks binary/license contents, and exercises installed extensions. A separate Linux job builds a wheel from the source distribution and runs the native canonical-boundary regression. See CONTRIBUTING.md for the development workflow and benchmarks/README.md for reproducible measurements.

Performance numbers depend on the input, compiler, CPU, and thread count. The checked-in benchmark report describes its reference host; it is not a universal latency guarantee.

License and acknowledgements

The project is licensed under the GNU Affero General Public License, version 3 only (AGPL-3.0-only). See LICENSE for the full terms.

The implementation uses pinned LunaSVG/PlutoVG and Clipper2 sources, pybind11 bindings, and adapted hole-selection criteria from ChromaPrint3D. Their licenses and attributions remain separate and are documented in THIRD_PARTY_NOTICES.md and THIRD_PARTY_LICENSES/.

Report reproducible problems through GitHub Issues. For sensitive reports, follow SECURITY.md.