Source code for uw.local.teaching.db.pdf

"""PDF processing.

This module implements additional PDF processing routines.
"""

from subprocess import Popen, PIPE

def embed_fonts (pdf):
    """Embed all fonts in the given PDF document.
    
    :param pdf: The PDF document.
    :return: A 2-tuple consisting of a boolean success indication and either
        the PDF with fonts embedded or the error report from the sub-process.
    """
    
    # TODO: This can hang after printing an error message on stderr.
    # So really we need to simultaneously wait on output to stderr and
    # on process termination.  If we see output, wait a few seconds to
    # capture any more output, then report an error.
    pdftops_process = Popen (['pdftops', '-origpagesizes', '-', '-'], stdin=PIPE, stdout=PIPE, stderr=PIPE)
    
    pdftops_process.stdin.write (pdf)
    pdftops_process.stdin.close ()
    
    # There doesn't seem to be any acceptable documentation of these
    # options, but these are widely suggested as reasonable.
    ps2pdf_process = Popen (['ps2pdf', '-dSAFER', '-dNOPLATFONTS', '-dEmbedAllFonts=true', '-dPDFSETTINGS=/prepress', '-', '-'], stdin=pdftops_process.stdout, stdout=PIPE, stderr=PIPE)
    
    stdoutdata, stderrdata = ps2pdf_process.communicate ()
    
    result = pdftops_process.wait ()
    if result != 0:
        return False, pdftops_process.stderr
    
    result = ps2pdf_process.wait ()
    if result != 0:
        return False, stderrdata.split ('\n')
    
    return True, stdoutdata