Jean-Pierre MartineauandClaude Fable 5.1
1838ee3768
The thin chevron between two chips the reader can't tell apart is now drawn in the previous chip's own fill stepped SEAM_SHADE darker (lighter for a dark fill) on the fill ahead, so nothing on the ribbon is a colour that isn't a chip's. The step is measured from whichever fill is further along, so the mark clears the fill it sits on by the full shade however close the two are. Whether two fills blur is now a perceptual distance, not a hue gap: ui/oklab.py is the reference OKLab transform (from_hex, to_hex, distance, shaded), and the seam interlocks only where the fills sit SEAM_BLUR (0.10) or more apart. The hue rule mis-sized the wheel badly: sixteen first-byte steps measure 0.026 across the greens and 0.165 across the cyans, so it blurred too little on one side and too much on the other, and an sRGB distance would only have restated the hue gap, a fixed byte step being a near-constant 55-60 of 8-bit RGB all the way round. 0.10 is five noticeable differences, the typical 0x10 pair with a little to spare, erring toward the thin chevron because a wrong blur still draws a legible seam and a wrong interlock draws none. The greys need no exemption any more: the keyless grey and the faded slate sit 0.18 apart and keep their interlock on the metric alone. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
69 lines
3.1 KiB
Python
69 lines
3.1 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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"""``ui/oklab.py`` — the perceptual colour space the seam and its shade are measured in."""
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from __future__ import annotations
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import pytest
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from meshterm.ui import oklab
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from meshterm.ui.theme import _node_style_spectrum
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def _fill(key: str) -> str:
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return _node_style_spectrum(key).split()[-1]
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def test_every_node_fill_round_trips_through_oklab_exactly() -> None:
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"""Hex → Lab → hex is lossless on all 256 spectrum fills and the fixed greys."""
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for byte in range(256):
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colour = _fill(f"{byte:02x}")
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assert oklab.to_hex(oklab.from_hex(colour)) == colour
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for grey in ("#000000", "#ffffff", "#64748b", "#334155", "#3f3f46"):
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assert oklab.to_hex(oklab.from_hex(grey)) == grey
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def test_lightness_runs_black_to_white_and_distance_is_a_metric() -> None:
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"""``L`` spans 0–1, black to white is distance 1, and distance is symmetric."""
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black, white = oklab.from_hex("#000000"), oklab.from_hex("#ffffff")
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assert black[0] == pytest.approx(0.0, abs=1e-6) and white[0] == pytest.approx(1.0, abs=1e-3)
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assert oklab.distance("#000000", "#ffffff") == pytest.approx(1.0, abs=1e-3)
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assert oklab.distance("#f25555", "#f25555") == 0.0
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assert oklab.distance("#f25555", "#5557f2") == oklab.distance("#5557f2", "#f25555")
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def test_the_wheel_is_not_uniform_to_the_eye() -> None:
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"""The reason this module exists: one hue step is a whisper in green, a shout in cyan."""
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green = oklab.distance(_fill("4c"), _fill("5c"))
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cyan = oklab.distance(_fill("80"), _fill("90"))
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assert green < 0.03 < 0.15 < cyan
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def test_shaded_moves_lightness_alone_away_from_the_nearer_end() -> None:
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"""A light colour comes back darker, a dark one lighter, chroma untouched."""
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light, dark = "#55f255", "#334155"
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for colour, sign in ((light, -1), (dark, +1)):
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before, after = oklab.from_hex(colour), oklab.from_hex(oklab.shaded(colour, 0.1))
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assert (after[0] - before[0]) * sign == pytest.approx(0.1, abs=0.01)
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assert after[1] == pytest.approx(before[1], abs=0.02) # in-gamut: chroma kept
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assert after[2] == pytest.approx(before[2], abs=0.02)
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def test_shaded_floor_clears_a_second_colour_too() -> None:
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"""With a floor, the shift starts from whichever lightness is further along."""
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a, b = _fill("4c"), _fill("5c") # b is the darker of two near greens
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plain = oklab.shaded(a, 0.15)
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floored = oklab.shaded(a, 0.15, floor=oklab.from_hex(b)[0])
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assert oklab.from_hex(floored)[0] <= oklab.from_hex(plain)[0]
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assert oklab.from_hex(b)[0] - oklab.from_hex(floored)[0] == pytest.approx(0.15, abs=0.01)
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slate, lighter_slate = "#334155", "#3f3f46" # dark: the floor pushes *up* instead
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floored = oklab.shaded(slate, 0.15, floor=oklab.from_hex(lighter_slate)[0])
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assert oklab.from_hex(floored)[0] >= oklab.from_hex(oklab.shaded(slate, 0.15))[0]
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def test_from_hex_rejects_anything_but_six_digits() -> None:
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"""Six hex digits, ``#`` and case optional; anything else is a ``ValueError``."""
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with pytest.raises(ValueError):
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oklab.from_hex("#fff")
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assert oklab.from_hex("F25555") == oklab.from_hex("#f25555")
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