latexpng.py

#!/usr/bin/python
import os, sys, argparse, tempfile, shutil, subprocess

parser = argparse.ArgumentParser(description='Convert LaTeX equation to png image')
parser.add_argument('equation', help='LaTeX equation to convert')
parser.add_argument('--confirm', help='Don\'t ask about outputting to terminal')

args = parser.parse_args()

if sys.stdout.isatty() and not args.confirm:
    response = input('Are you sure you want to output binary PNG data to the terminal? [y/N] ')
    if not (response and response[0] in 'yY'):
        sys.exit()

dvipng_args = ['-T', 'tight', '-bg', 'transparent']

for program in ('latex', 'dvipng'):
    if not shutil.which(program):
        sys.exit('Error: {0} not installed'.format(program))

cwd = os.getcwd()

with tempfile.TemporaryDirectory() as tempdir:
    os.chdir(tempdir)
    try:
        with open('file.tex', 'w') as latexfile:
            latexfile.write(
                "\\nonstopmode\\documentclass[12pt]{article}\n"
                "\\usepackage{amsmath}\n"
                "\\usepackage{amssymb}\n"
                "\\usepackage{cancel}\n"
                "\\pagestyle{empty}\n"
                "\\begin{document}\n$$\n"
                + args.equation +
                "\n$$\n\\end{document}\n"
            )
        latexprocess = subprocess.run(
            ['latex', 'file.tex', '-output-directory', tempdir],
            stdout=subprocess.DEVNULL)
        if latexprocess.returncode != 0:
            print('Error running latex', file=sys.stderr)
            sys.exit()
        dvipngprocess = subprocess.run(
            ['dvipng', 'file.dvi'] + dvipng_args,
            stdout=subprocess.DEVNULL)
        if dvipngprocess.returncode != 0:
            print('Error running dvipng', file=sys.stderr)
            subprocess.run(['zsh'])
            sys.exit()
        with open('file1.png', 'rb') as pngfile:
            shutil.copyfileobj(pngfile, sys.stdout.buffer)
    finally:
        os.chdir(cwd)