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e1ced61 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | """Node-map ownership mask (``docs/02`` §9, ``docs/07`` §8 P6).
``node_map.uint32.png`` records, per pixel, the index of the semantic node that
owns it (``0`` = background / unowned). The encoding is little-endian ``uint32``
packed into the RGBA channels of a standard PNG — lossless and renderer-version
independent. Anti-alias boundaries are resolved by an alpha-aware ownership mask
(the highest-alpha node wins, ties break to the lower index), built in the same
draw pass as the RGBA canvas in :mod:`renderers.base`.
This module exposes the encode/decode helpers and a coverage verdict the P6 gate
("every visible semantic node has node-map coverage") consumes.
"""
from __future__ import annotations
from collections.abc import Mapping, Sequence
from .base import (
_encode_uint32_png, # noqa: F401 (re-exported for tests/CLI)
decode_uint32_png,
)
def coverage_verdict(
visible_node_ids: Sequence[str], node_pixel_counts: Mapping[str, int]
) -> tuple[bool, list[str]]:
"""``(all_covered, missing)`` — every visible node needs ≥1 node-map pixel."""
missing = [nid for nid in visible_node_ids if node_pixel_counts.get(nid, 0) <= 0]
return (not missing, missing)
def read_owners(png: bytes) -> object:
"""Decode a node-map PNG to its ``uint32`` owner-index array."""
return decode_uint32_png(png)
def index_table(visible_node_ids: Sequence[str]) -> list[str]:
"""The index→node-id table (index 0 is the background sentinel)."""
return ["__background__", *visible_node_ids]
__all__ = [
"coverage_verdict",
"decode_uint32_png",
"index_table",
"read_owners",
]
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