webtex.py

#!/usr/bin/env python3

import sys
import os
import requests
import argparse
import base64
from urllib.parse import quote

stdout = sys.stdout
IS_ITERM = os.getenv('TERM_PROGRAM', default='').startswith('iTerm') and os.isatty(1)
IS_SCREEN = os.getenv('TERM', default='').startswith('screen')


def b64encode(s):
    if type(s) is str:
        s = s.encode()
    return base64.b64encode(s).decode()


# iTerm2 on macOS only
def print_image(image_data, extension='.png'):
    if IS_SCREEN:
        stdout.write('\033Ptmux;\033\033]')
    else:
        stdout.write('\033]')
    stdout.write('1337;File=')
    stdout.write('name=')
    stdout.write(b64encode(f'webtex-output{extension}'))
    stdout.write(';')
    stdout.write(f'size={len(image_data)}')
    stdout.write(';')
    stdout.write('inline=1')
    stdout.write(':')
    stdout.write(b64encode(image_data))
    if IS_SCREEN:
        stdout.write('\a\033\\')
    else:
        stdout.write('\a')
    stdout.write('\n')


def webtex_google_chart(tex):
    params = {
            'cht': 'tx',
            'chl': tex
            }
    r = requests.get('https://chart.googleapis.com/chart', params)
    if r.status_code != 200:
        raise Exception(f'status code is {r.status_code}')
    return r.content


def webtex_codecogs(tex):
    # webtex use a strange request format, will do manual urlencode here
    r = requests.get('https://latex.codecogs.com/png.latex?' + quote(tex))
    if r.status_code != 200:
        raise Exception(f'status code is {r.status_code}')
    return r.content


def render_tex(tex, provider=webtex_codecogs, **kw):
    return provider(tex, **kw)

def write_image(fp, img):
    if fp is sys.stdout and IS_ITERM:
        print_image(img)
    elif fp.buffer is not None:
        fp.buffer.write(img)
        fp.flush()
    else:
        fp.write(img)
        fp.flush()

def main():
    img = render_tex(sys.argv[1])
    write_image(stdout, img)

if __name__ == '__main__':
    main()