Image that tells you your user agent

hi.py

#!/usr/bin/env python3
"Image that dynamically tells you your user agent"
# save this as  ./cgi-bin/index.png
# run           python -m http.server --cgi
# go to         http://localhost:8000/cgi-bin/hi.png

import os, sys
from PIL import Image, ImageDraw

def serve_png(io, file=sys.stdout):
    # streamless beast.
    file.write("Content-Type: image/png\n")
    f = io.read()
    file.write(f"Content-Length: {len(f)}\n\n")
    file.flush()
    file.buffer.write(f)
    
def get_font(*names, size=20):
    # this is sloooow and needs a local cache. if you care
    from PIL import ImageFont
    from matplotlib import font_manager as fm
    names = names or ['Helvetica', 'Arial']
    path = fm.findfont(fm.FontProperties(family=names))
    return ImageFont.truetype(path, size=size)

def chunk(seq, n: int):
    for i in range(0, len(seq), n): yield seq[i:i+n]

AGENT = os.environ.get('HTTP_USER_AGENT', 'Unknown')
BG = '#EBDFB7'; FG = '#63476C'; W = 700; H = 100
BIG = get_font('Calamity', size=20)
SMOL = get_font('Fantasque Sans Mono', size=14)

if __name__ == '__main__':
    image = Image.new('RGB', (W, H))
    draw = ImageDraw.Draw(image)
    draw.rectangle([0, 0, W, H], BG)
    draw.text((10, 10), "Hey there! You're using", fill=FG, font=BIG)
    for i, txt in enumerate(chunk(AGENT, 93)):
        draw.text((10, 20 + 15*(i+1)), txt, fill=FG, font=SMOL)
    image.save('tmp.png')
    with open('tmp.png', 'rb') as f:
        serve_png(f)
    # os.unlink('tmp.png')