a small utility script to rasterize an illustrator file with ghostscript and graphicsmagick

doodler.py

"""
doodler.py - (c) 2012 Marcos Ojeda <marcos@khanacademy.org>

--"Quis leget haec?"

requires 
  graphicsmagick  - brew install graphicsmagick
  ghostscript - brew install ghostscript

"""

import os
import sys
import subprocess
import tempfile

def popen_results(args):
    proc = subprocess.Popen(args, stdout=subprocess.PIPE)
    return proc.communicate()[0]

def convert_png(source, output, page=None, size=None, dpi=72):
    """convert an ai file to a transparent png
    
    dpi/density is 72 by default
    page is 1-indexed and if set, will output only a single artboard
    If you specify size, you should also specify a dpi to match

    for context, a dpi for preventing jaggy edges isin the 1200-2400 range!
    """
    basename = source.split(".")[0]
    base_output = output.split(".")[0]
    command = ['gs',
        '-q', '-dNOPAUSE', '-dBATCH', '-dNOPROMPT',
        '-sDEVICE=pngalpha', '-dEPSCrop',
        '-dTextAlphaBits=4', '-dGraphicsAlphaBits=4',
        '-r%s' % dpi]
    if page:
        command.extend(['-dFirstPage=%s' % page,'-dLastPage=%s' % page])
    if size:
        temp = tempfile.mktemp()
        command.append('-sOutputFile=%s.png' % temp)
    else:
        if page:
            command.append('-sOutputFile=%s.png' % base_output)
        else:
            command.append('-sOutputFile=%s-%%02d.png' % base_output)
    command.append(source)

    # run the command
    popen_results(command)
    # if size is specified, route through graphicsmagick
    if size:
        command = ['gm', 'convert', 
        '-background', 'transparent', 
        '-resize', size, '-size', size,
        '%s.png' % temp, output]

        res = popen_results(command)

    # clean out the temp file
    os.remove("%s.png" % temp)

    pass