LaTeX Math to GitHub Image URL

lateximgurl

#!/usr/bin/env python3
"""
Converts LaTeX math code to a URL that will render an image
via GitHub's math renderer URL.
Inspired by the discussion found at
https://gist.github.com/a-rodin/fef3f543412d6e1ec5b6cf55bf197d7b
"""
#
# Copyright 2020 Michael Shafae
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#

import urllib.parse
#import sys
import platform
from subprocess import Popen, PIPE, DEVNULL
import argparse

def copy_cmd():
    """ Shell ommand to copy the URL to the pasteboard. """
    p = platform.system( )
    cmd = None
    args = []
    if p == 'Linux':
        cmd = ['xclip']
        args = ['-selection', 'clipboard', '-f']
    elif p == 'Darwin':
        cmd = ['pbcopy']
    else:
        print('No copy command available; URL not saved to pastboard.')
    return (cmd, args)

def send_to_pasteboard(s, cmd, args):
    """ Sends the string s to the pasteboard. """
    c = cmd + args
    p = Popen(c, stdin=PIPE, stdout=DEVNULL)
    p.communicate(input=s.encode( ))

def mkbigger(n = 0):
    """ Return the LaTeX size string relative to the value of n. """
    sizes = [None, '\\larger', '\\Large', '\\LARGE', '\\huge',
    '\\Huge', '\\Huge']
    if n > len(sizes):
        n = len(sizes)
    return sizes[n]

def main( ):
    """ Main function, given a LaTeX equation, return a URL for rendering it. """
    parser = argparse.ArgumentParser(prog=__file__,
    description='Convert LaTeX math to a render.githubusercontent.com URL.')
    parser.add_argument('-b', '--bigger',
    help='Need to make it bigger? Specify an integer between 1 and 5.',
    dest='bigger', type=int, required=False)
    parser.add_argument('equation', help='LaTeX Math equation', type=str)

    github_math_render_url = 'https://render.githubusercontent.com/render/math?math={}'

    args = parser.parse_args( )
    eqn = args.equation
    # The shell replaces all the '\\ ' with '\ '.
    # \b is backspace, so before going any further replace the backspaces
    # with \\b (ex. \begin{} -> \\begin{}).
    eqn = eqn.replace('\b', '\\b')
    # Replace the '\\ ' with '\\\\ ' for matrices and other multiline statements
    if '\\ ' in eqn and not '\\\n' in eqn:
        # There's a bug probably on the GitHub side where it doesn't handle
        # more than one matrix correctly.
        # Probably can fix it by throwing in a \n in the right spot.
        """
        \begin{pmatrix} 1 & 2 & 3\\ a & b & c \end{pmatrix} = \begin{pmatrix} 1 & 2 & 3 \\ a & b & c \end{pmatrix} = \begin{pmatrix} 1 & 2 & 3\\ a & b & c \end{pmatrix}
        """
        eqn = eqn.replace('\\ ', '\\\\ ')
    # Replace the '\\\n' with '\\\\ ' for matrices and other multiline
    # statements
    if '\\\n' in eqn:
        #This works as exepcted!
        """
        \begin{pmatrix} 1 & 2 & 3\\
        a & b & c
        \end{pmatrix} =
        \begin{pmatrix}
        1 & 2 & 3 \\
        a & b & c
        \end{pmatrix} =
        \begin{pmatrix}
        1 & 2 & 3\\
        a & b & c
        \end{pmatrix}
        """
        eqn = eqn.replace('\\\n', '\\\\\n')
    size = mkbigger(args.bigger)
    if size != "":
        eqn = size + "{" + eqn + "}"
    eqn_encoded = urllib.parse.quote(eqn)

    url = github_math_render_url.format(eqn_encoded)
    s = '![{}]({})'.format(eqn, url)
    print(s)
    cmd, args = copy_cmd( )
    send_to_pasteboard(s, cmd, args)

if __name__ == '__main__':
    main( )