# -*- coding: utf-8 -*-
"""
从反白 logo 提取左侧图形生成 favicon（180x180 PNG）：
深色圆角底（与站内卡片底色一致）+ 图形居中占 72%
标签栏明暗模式均以深色块呈现，反白图形恒清晰。
用法: uv run --with pillow python3 tools/make_favicon.py
"""
from PIL import Image, ImageDraw

SRC = 'assets/img/logo-light.png'
OUT = 'assets/img/favicon.png'
SIZE = 180
PAD_GRAPHIC = 0.72  # 图形占画布比例

# logo 左侧图形实测内容段（x 投影分析）：x[47:224] y[44:260]，取 bbox 略收边
CROP = (47, 44, 224, 260)
BG = (7, 11, 22)      # 站内 --bg-1
RADIUS = 38

graphic = Image.open(SRC).convert('RGBA').crop(CROP)

canvas = Image.new('RGBA', (SIZE, SIZE), (0, 0, 0, 0))
# 圆角深色底
mask = Image.new('L', (SIZE, SIZE), 0)
ImageDraw.Draw(mask).rounded_rectangle((0, 0, SIZE, SIZE), RADIUS, fill=255)
canvas.paste(Image.new('RGBA', (SIZE, SIZE), BG + (255,)), (0, 0), mask)

# 图形等比缩放到 72% 高度内居中
target = round(SIZE * PAD_GRAPHIC)
scale = min(target / graphic.width, target / graphic.height)
graphic = graphic.resize((round(graphic.width * scale), round(graphic.height * scale)), Image.LANCZOS)
canvas.alpha_composite(graphic, ((SIZE - graphic.width) // 2, (SIZE - graphic.height) // 2))

# 自检：中心应有不透明图形像素，四角透明
px = canvas.load()
assert px[SIZE // 2, SIZE // 2][3] > 0, '中心无图形'
assert px[2, 2][3] == 0 and px[SIZE - 3, SIZE - 3][3] == 0, '圆角未生效'
canvas.save(OUT, 'PNG', optimize=True)
print(f'完成: {OUT} {SIZE}x{SIZE}，图形 {graphic.size}')