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#!/usr/bin/env python3


__license__ = 'GPL v3'
__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'

import sys
from struct import unpack_from
from collections import namedtuple

from calibre.utils.wmf import create_bmp_from_dib, to_png
from polyglot.builtins import iteritems

# Record types {{{
# See: http://msdn.microsoft.com/en-us/library/cc231166.aspx
RECORD_TYPES = {
    'EMR_BITBLT' : 0x4C,
    'EMR_STRETCHBLT' : 0x4D,
    'EMR_MASKBLT' : 0x4E,
    'EMR_PLGBLT' : 0x4F,
    'EMR_SETDIBITSTODEVICE' : 0x50,
    'EMR_STRETCHDIBITS' : 0x51,
    'EMR_ALPHABLEND' : 0x72,
    'EMR_TRANSPARENTBLT' : 0x74,
    'EOF' : 0xe,
    'HEADER' : 0x1,
}
RECORD_RMAP = {v:k for k, v in iteritems(RECORD_TYPES)}

# See http://msdn.microsoft.com/en-us/library/cc230601.aspx
StretchDiBits = namedtuple(
    'StretchDiBits', 'left top right bottom x_dest y_dest x_src y_src cx_src'
    ' cy_src bmp_hdr_offset bmp_header_size bmp_bits_offset'
    ' bmp_bits_size usage op dest_width dest_height')
# }}}


class EMF:

    def __init__(self, raw, verbose=0):
        self.pos = 0
        self.found_eof = False
        self.verbose = verbose
        self.func_map = {v:getattr(self, 'handle_%s' % (k.replace('EMR_', '').lower()), self.handle_unknown) for k, v in iteritems(RECORD_TYPES)}
        self.bitmaps = []
        while self.pos < len(raw) and not self.found_eof:
            self.read_record(raw)
        self.has_raster_image = bool(self.bitmaps)

    def handle_unknown(self, rtype, size, raw):
        if self.verbose:
            print('Ignoring unknown record:', RECORD_RMAP.get(rtype, hex(rtype).upper()))

    def handle_header(self, rtype, size, raw):
        pass

    def handle_stretchdibits(self, rtype, size, raw):
        data = StretchDiBits(*unpack_from(b'<18I', raw, 8))
        hdr = raw[data.bmp_hdr_offset:data.bmp_hdr_offset + data.bmp_header_size]
        bits = raw[data.bmp_bits_offset:data.bmp_bits_offset + data.bmp_bits_size]
        bmp = create_bmp_from_dib(hdr + bits)
        self.bitmaps.append(bmp)

    def handle_eof(self, rtype, size, raw):
        self.found_eof = True

    def read_record(self, raw):
        rtype, size = unpack_from(b'<II', raw, self.pos)
        record = raw[self.pos:self.pos+size]
        self.pos += size
        self.func_map.get(rtype, self.handle_unknown)(rtype, size, record)

    def to_png(self):
        bmps = list(sorted(self.bitmaps, key=lambda x: len(x)))
        bmp = bmps[-1]
        return to_png(bmp)


def emf_unwrap(raw, verbose=0):
    '''
    Return the largest embedded raster image in the EMF.
    The returned data is in PNG format.
    '''
    w = EMF(raw, verbose=verbose)
    if not w.has_raster_image:
        raise ValueError('No raster image found in the EMF')
    return w.to_png()


if __name__ == '__main__':
    with open(sys.argv[-1], 'rb') as f:
        raw = f.read()
    emf = EMF(raw, verbose=4)
    open('/t/test.bmp', 'wb').write(emf.bitmaps[0])
    open('/t/test.png', 'wb').write(emf.to_png())

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