110 lines
2.6 KiB
Python
110 lines
2.6 KiB
Python
import curses
|
|
import hashlib
|
|
import math
|
|
|
|
# BT.601 (YCbCr) constants, see XEP-0392
|
|
K_R = 0.299
|
|
K_G = 0.587
|
|
K_B = 1 - K_R - K_G
|
|
|
|
|
|
def ncurses_color_to_rgb(color):
|
|
if color <= 15:
|
|
try:
|
|
(r, g, b) = curses.color_content(color)
|
|
except: # fallback in faulty terminals (e.g. xterm)
|
|
(r, g, b) = curses.color_content(color % 8)
|
|
r = r / 1000 * 5
|
|
g = g / 1000 * 5
|
|
b = b / 1000 * 5
|
|
elif color <= 231:
|
|
color = color - 16
|
|
b = color % 6
|
|
color = color // 6
|
|
g = color % 6
|
|
color = color // 6
|
|
r = color % 6
|
|
else:
|
|
color -= 232
|
|
r = g = b = color / 24 * 5
|
|
return r / 5, g / 5, b / 5
|
|
|
|
|
|
def rgb_to_ycbcr(r, g, b):
|
|
y = K_R * r + K_G * g + K_B * b
|
|
cr = (r - y) / (1 - K_R) / 2
|
|
cb = (b - y) / (1 - K_B) / 2
|
|
return y, cb, cr
|
|
|
|
|
|
def generate_ccg_palette(curses_palette, reference_y):
|
|
cbcr_palette = {}
|
|
for curses_color in curses_palette:
|
|
r, g, b = ncurses_color_to_rgb(curses_color)
|
|
# drop grayscale
|
|
if r == g == b:
|
|
continue
|
|
y, cb, cr = rgb_to_ycbcr(r, g, b)
|
|
key = round(cbcr_to_angle(cb, cr), 2)
|
|
try:
|
|
existing_y, *_ = cbcr_palette[key]
|
|
except KeyError:
|
|
pass
|
|
else:
|
|
if abs(existing_y - reference_y) <= abs(y - reference_y):
|
|
continue
|
|
cbcr_palette[key] = y, curses_color
|
|
return {
|
|
angle: curses_color
|
|
for angle, (_, curses_color) in cbcr_palette.items()
|
|
}
|
|
|
|
|
|
def text_to_angle(text):
|
|
hf = hashlib.sha1()
|
|
hf.update(text.encode("utf-8"))
|
|
hue = int.from_bytes(hf.digest()[:2], "little")
|
|
return hue / 65535 * math.pi * 2
|
|
|
|
|
|
def angle_to_cbcr_edge(angle):
|
|
cr = math.sin(angle)
|
|
cb = math.cos(angle)
|
|
if abs(cr) > abs(cb):
|
|
factor = 0.5 / abs(cr)
|
|
else:
|
|
factor = 0.5 / abs(cb)
|
|
return cb * factor, cr * factor
|
|
|
|
|
|
def cbcr_to_angle(cb, cr):
|
|
magn = math.sqrt(cb**2 + cr**2)
|
|
if magn > 0:
|
|
cr /= magn
|
|
cb /= magn
|
|
return math.atan2(cr, cb) % (2 * math.pi)
|
|
|
|
|
|
def ccg_palette_lookup(palette, angle):
|
|
# try quick lookup first
|
|
try:
|
|
color = palette[round(angle, 2)]
|
|
except KeyError:
|
|
pass
|
|
else:
|
|
return color
|
|
|
|
best_metric = float("inf")
|
|
best = None
|
|
for anglep, color in palette.items():
|
|
metric = abs(anglep - angle)
|
|
if metric < best_metric:
|
|
best_metric = metric
|
|
best = color
|
|
|
|
return best
|
|
|
|
|
|
def ccg_text_to_color(palette, text):
|
|
angle = text_to_angle(text)
|
|
return ccg_palette_lookup(palette, angle)
|