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pathops — Skia path boolean operations

Version: skia-pathops 0.9.2 Type: Native iOS arm64 Cython extension (_pathops.abi3.so) SPM target: Bundled in Manim (no standalone target) Auto-included by: Manim (via svgelements / vector-graphics ops) Total Python modules: 3 (__init__.py, operations.py, _version.py) + the .so

Python bindings around Google Skia's SkPathOps — boolean operations on filled vector paths: union, intersection, difference, reverse_difference, xor, plus path simplification. Manim uses it to combine SVG-imported shapes (e.g. for Difference(), Union(), Intersection() mobjects) and to clean up self-intersecting paths.

The wheel name is skia-pathops on PyPI but it imports as pathops — that's why the SPM bundle and the file all use pathops/.

Modules

Module What it does
pathops.__init__ Re-exports the Cython extension's public API: Path, PathPen, PathVerb, PathOp, FillType, LineCap, LineJoin, ArcSize, Direction, op, simplify, OpBuilder, plus errors (PathOpsError, UnsupportedVerbError, OpenPathError, NumberOfPointsError) and conversion helpers (bits2float, float2bits, decompose_quadratic_segment). Also handles a Python 3.11+ IntFlag iteration quirk
pathops.operations Friendly named wrappers around op(...) — union, intersection, difference, reverse_difference, xor. These accept lists of "drawable contours" (fontTools-style pen-protocol objects) instead of raw paths, which is what tools like manim and fontTools work with natively
pathops._version __version__ = '0.9.2' (setuptools-scm generated)
pathops._pathops.abi3.so The Cython extension (uses Python's abi3 stable ABI, so it works across CPython 3.x versions on iOS arm64)

iOS-specific notes

The extension is abi3-tagged (_pathops.abi3.so), meaning it's compatible with any CPython 3.x on iOS arm64 — no recompile needed when the system Python version bumps from 3.13 → 3.14. This is unusual in our bundle (most extensions are Python-version-locked .cpython-314-iphoneos.so) and is a deliberate upstream design choice from skia-pathops.

The underlying Skia path-ops library is a small subset of Skia (geometry only, no rasterization), so the build doesn't drag in Skia's full GPU/text/image stack. It links statically.

Standalone example

from pathops import Path, op, PathOp, simplify

# Build two overlapping circles
a = Path()
pen_a = a.getPen()
pen_a.moveTo((-1, 0))
pen_a.curveTo((-1, 0.55), (-0.55, 1), (0, 1))
pen_a.curveTo((0.55, 1), (1, 0.55), (1, 0))
pen_a.curveTo((1, -0.55), (0.55, -1), (0, -1))
pen_a.curveTo((-0.55, -1), (-1, -0.55), (-1, 0))
pen_a.closePath()

b = Path()
pen_b = b.getPen()
pen_b.moveTo((0, 0))
pen_b.curveTo((0, 0.55), (0.45, 1), (1, 1))
pen_b.curveTo((1.55, 1), (2, 0.55), (2, 0))
pen_b.curveTo((2, -0.55), (1.55, -1), (1, -1))
pen_b.curveTo((0.45, -1), (0, -0.55), (0, 0))
pen_b.closePath()

# Union of the two circles → a single combined path
result = Path()
op(a, b, PathOp.UNION, fix_winding=True, result=result)

# Iterate the resulting path's segments
for verb, points in result:
    print(verb, points)

# High-level wrappers for fontTools-style "draw onto a pen" inputs:
from pathops.operations import union, difference
out = Path()
out_pen = out.getPen()
union([a, b], out_pen)        # same effect as op(...) above

Use simplify(path) to remove self-intersections and combine overlapping sub-paths into a single fill region — handy after combining manually authored SVG geometry.

See also