IPython/nbconvert/preprocessors/svg2pdf.py

"""Module containing a preprocessor that converts outputs in the notebook from 
one format to another.
"""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

import base64
import io
import os
import sys
import subprocess

from IPython.utils.tempdir import TemporaryDirectory
from IPython.utils.traitlets import Unicode

from .convertfigures import ConvertFiguresPreprocessor


INKSCAPE_APP = '/Applications/Inkscape.app/Contents/Resources/bin/inkscape'


class SVG2PDFPreprocessor(ConvertFiguresPreprocessor):
    """
    Converts all of the outputs in a notebook from SVG to PDF.
    """
    
    def _from_format_default(self):
        return 'image/svg+xml'
    def _to_format_default(self):
        return 'application/pdf'
    
    command = Unicode(config=True,
        help="""The command to use for converting SVG to PDF
        
        This string is a template, which will be formatted with the keys
        to_filename and from_filename.
        
        The conversion call must read the SVG from {from_flename},
        and write a PDF to {to_filename}.
        """)
    
    def _command_default(self):
        return self.inkscape + \
               ' --without-gui --export-pdf="{to_filename}" "{from_filename}"'
    
    inkscape = Unicode(config=True, help="The path to Inkscape, if necessary")
    def _inkscape_default(self):
        if sys.platform == "darwin":
            if os.path.isfile(INKSCAPE_APP):
                return INKSCAPE_APP
        return "inkscape"


    def convert_figure(self, data_format, data):
        """
        Convert a single SVG figure to PDF.  Returns converted data.
        """

        #Work in a temporary directory
        with TemporaryDirectory() as tmpdir:
            
            #Write fig to temp file
            input_filename = os.path.join(tmpdir, 'figure.' + data_format)
            # SVG data is unicode text
            with io.open(input_filename, 'w', encoding='utf8') as f:
                f.write(data)

            #Call conversion application
            output_filename = os.path.join(tmpdir, 'figure.pdf')
            shell = self.command.format(from_filename=input_filename, 
                                   to_filename=output_filename)
            subprocess.call(shell, shell=True) #Shell=True okay since input is trusted.

            #Read output from drive
            # return value expects a filename
            if os.path.isfile(output_filename):
                with open(output_filename, 'rb') as f:
                    # PDF is a nb supported binary, data type, so base64 encode.
                    return base64.encodestring(f.read())
            else:
                raise TypeError("Inkscape svg to pdf conversion failed")