generate-icons.py

#!/usr/bin/env python3
"""
generate-icons.py
Run this once to create the PWA icon PNGs.
Usage: python3 generate-icons.py
"""
import struct, zlib, math, os

def make_png(size, bg_color, text_color):
    pixels = []
    cx, cy = size // 2, size // 2
    r = size // 2
    for y in range(size):
        row = []
        for x in range(size):
            dx, dy = x - cx, y - cy
            dist = math.sqrt(dx*dx + dy*dy)
            if dist > r - 0.5:
                row.extend([0, 0, 0, 0])
                continue
            br, bg, bb = bg_color
            margin = int(size * 0.28)
            stroke = max(2, int(size * 0.09))
            mid_y = int(size * 0.45)
            top_y = int(size * 0.25)
            bot_y = int(size * 0.75)
            right_x = int(size * 0.68)
            on_f = False
            if margin <= x <= margin + stroke and top_y <= y <= bot_y:
                on_f = True
            if top_y <= y <= top_y + stroke and margin <= x <= right_x:
                on_f = True
            if mid_y <= y <= mid_y + stroke and margin <= x <= int(size * 0.60):
                on_f = True
            if on_f:
                tr, tg, tb = text_color
                row.extend([tr, tg, tb, 255])
            else:
                row.extend([br, bg, bb, 255])
        pixels.append(row)

    def chunk(tag, data):
        c = zlib.crc32(tag + data) & 0xffffffff
        return struct.pack('>I', len(data)) + tag + data + struct.pack('>I', c)

    raw = b''
    for row in pixels:
        raw += b'\x00' + bytes(row)
    compressed = zlib.compress(raw, 9)
    png = b'\x89PNG\r\n\x1a\n'
    png += chunk(b'IHDR', struct.pack('>IIBBBBB', size, size, 8, 6, 0, 0, 0))
    png += chunk(b'IDAT', compressed)
    png += chunk(b'IEND', b'')
    return png

script_dir = os.path.dirname(os.path.abspath(__file__))
icons_dir = os.path.join(script_dir, 'icons')
os.makedirs(icons_dir, exist_ok=True)

bg = (123, 140, 255)
fg = (255, 255, 255)

for sz, name in [(192, 'icon-192.png'), (512, 'icon-512.png')]:
    data = make_png(sz, bg, fg)
    path = os.path.join(icons_dir, name)
    with open(path, 'wb') as f:
        f.write(data)
    print(f'Created {name} ({len(data):,} bytes)')

print('Done!')