91 lines
2.4 KiB
Python
91 lines
2.4 KiB
Python
from typing import Tuple, Dict, List
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import curses
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import hashlib
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import math
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from . import hsluv
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Palette = Dict[float, int]
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# BT.601 (YCbCr) constants, see XEP-0392
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K_R = 0.299
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K_G = 0.587
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K_B = 1 - K_R - K_G
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def ncurses_color_to_rgb(color: int) -> Tuple[float, float, float]:
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if color <= 15:
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try:
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(r, g, b) = curses.color_content(color)
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except: # fallback in faulty terminals (e.g. xterm)
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(r, g, b) = curses.color_content(color % 8)
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r = r / 1000 * 5
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g = g / 1000 * 5
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b = b / 1000 * 5
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elif color <= 231:
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color = color - 16
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b = color % 6
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color = color // 6
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g = color % 6
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color = color // 6
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r = color % 6
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else:
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color -= 232
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r = g = b = color / 24 * 5
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return r / 5, g / 5, b / 5
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def generate_ccg_palette(curses_palette: List[int],
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reference_y: float) -> Palette:
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cbcr_palette = {} # type: Dict[float, Tuple[float, int]]
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for curses_color in curses_palette:
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r, g, b = ncurses_color_to_rgb(curses_color)
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# drop grayscale
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if r == g == b:
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continue
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h, _, y = hsluv.rgb_to_hsluv((r, g, b))
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# this is to keep the code compatible with earlier versions of XEP-0392
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y = y / 100
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key = round(h)
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try:
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existing_y, *_ = cbcr_palette[key]
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except KeyError:
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pass
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else:
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if abs(existing_y - reference_y) <= abs(y - reference_y):
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continue
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cbcr_palette[key] = y, curses_color
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return {
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angle: curses_color
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for angle, (_, curses_color) in cbcr_palette.items()
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}
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def text_to_angle(text: str) -> float:
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hf = hashlib.sha1()
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hf.update(text.encode("utf-8"))
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hue = int.from_bytes(hf.digest()[:2], "little")
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return hue / 65535 * 360
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def ccg_palette_lookup(palette: Palette, angle: float) -> int:
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# try quick lookup first
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try:
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return palette[round(angle)]
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except KeyError:
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pass
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best_metric = float("inf")
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best = None
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for anglep, color in palette.items():
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metric = abs(anglep - angle)
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if metric < best_metric:
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best_metric = metric
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best = color
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return best
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def ccg_text_to_color(palette, text: str) -> int:
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angle = text_to_angle(text)
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return ccg_palette_lookup(palette, angle)
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