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https://github.com/kovidgoyal/calibre.git
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Added support to libprs500 to read and write meta information from LRF files
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Kovid Goyal
parent
f31caad22a
commit
e6b1f2e829
21
libprs500/lrf/__init__.py
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21
libprs500/lrf/__init__.py
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## Copyright (C) 2006 Kovid Goyal kovid@kovidgoyal.net
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## This program is free software; you can redistribute it and/or modify
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## it under the terms of the GNU General Public License as published by
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## the Free Software Foundation; either version 2 of the License, or
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## (at your option) any later version.
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##
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## This program is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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## You should have received a copy of the GNU General Public License along
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## with this program; if not, write to the Free Software Foundation, Inc.,
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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"""
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This package contains logic to read and write LRF files. The LRF file format is documented at U{http://www.sven.de/librie/Librie/LrfFormat}.
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At the time fo writing, this package only supports reading and writing LRF meat information. See L{meta}.
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"""
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__docformat__ = "epytext"
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__author__ = "Kovid Goyal <kovid@kovidgoyal.net>"
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253
libprs500/lrf/meta.py
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libprs500/lrf/meta.py
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## Copyright (C) 2006 Kovid Goyal kovid@kovidgoyal.net
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## This program is free software; you can redistribute it and/or modify
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## it under the terms of the GNU General Public License as published by
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## the Free Software Foundation; either version 2 of the License, or
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## (at your option) any later version.
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##
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## This program is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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## You should have received a copy of the GNU General Public License along
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## with this program; if not, write to the Free Software Foundation, Inc.,
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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"""
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This module presents an easy to use interface for getting and setting meta information in LRF files.
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Just create an L{LRFMetaFile} object and use its properties to get and set meta information. For example:
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lrf = LRFMetaFile("mybook.lrf")
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print lrf.title, lrf.author
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lrf.category = "History"
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"""
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import struct, array, zlib, StringIO
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import xml.dom.minidom as dom
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from xml.dom.ext import Print as Print
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from libprs500.prstypes import field
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BYTE = "<B" #: Unsigned char little endian encoded in 1 byte
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WORD = "<H" #: Unsigned short little endian encoded in 2 bytes
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DWORD = "<I" #: Unsigned integer little endian encoded in 4 bytes
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QWORD = "<Q" #: Unsigned long long little endian encoded in 8 bytes
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class versioned_field(field):
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def __init__(self, vfield, version, start=0, fmt=WORD):
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field.__init__(self, start=start, fmt=fmt)
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self.vfield, self.version = vfield, version
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def enabled(self):
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return self.vfield > self.version
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def __get__(self, obj, typ=None):
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if self.enabled(): return field.__get__(self, obj, typ=typ)
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else: return None
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def __set__(self, obj, val):
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if not self.enabled(): raise LRFException("Trying to set disabled field")
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else: field.__set__(self, obj, val)
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class LRFException(Exception):
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pass
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class fixed_stringfield(object):
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""" A field storing a variable length string. """
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def __init__(self, length=8, start=0):
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"""
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@param length: Size of this string
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@param start: The byte at which this field is stored in the buffer
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"""
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self._length = length
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self._start = start
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def __get__(self, obj, typ=None):
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length = str(self._length)
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return obj.unpack(start=self._start, fmt="<"+length+"s")[0]
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def __set__(self, obj, val):
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if val.__class__.__name__ != 'str': val = str(val)
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if len(val) != self._length: raise LRFException("Trying to set fixed_stringfield with a string of incorrect length")
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obj.pack(val, start=self._start, fmt="<"+str(len(val))+"s")
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def __repr__(self):
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return "A string of length " + str(self._length) + " starting at byte " + str(self._start)
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class xml_field(object):
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def __init__(self, tag_name):
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self.tag_name = tag_name
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def __get__(self, obj, typ=None):
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document = dom.parseString(obj.info)
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elem = document.getElementsByTagName(self.tag_name)[0]
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elem.normalize()
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if not elem.hasChildNodes(): return ""
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return elem.firstChild.data.strip()
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def __set__(self, obj, val):
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document = dom.parseString(obj.info)
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elem = document.getElementsByTagName(self.tag_name)[0]
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elem.normalize()
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while elem.hasChildNodes(): elem.removeChild(elem.lastChild)
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elem.appendChild(dom.Text())
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elem.firstChild.data = val
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s = StringIO.StringIO()
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Print(document, s)
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obj.info = s.getvalue()
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s.close()
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class LRFMetaFile(object):
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LRF_HEADER = "L\0R\0F\0\0\0"
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lrf_header = fixed_stringfield(length=8, start=0)
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version = field(fmt=WORD, start=8)
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xor_key = field(fmt=WORD, start=10)
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root_object_id = field(fmt=DWORD, start=12)
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number_of_objets = field(fmt=QWORD, start=16)
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object_table_offset = field(fmt=QWORD, start=24)
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binding = field(fmt=BYTE, start=36)
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dpi = field(fmt=WORD, start=38)
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width = field(fmt=WORD, start=42)
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height = field(fmt=WORD, start=44)
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color_depth = field(fmt=BYTE, start=46)
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toc_object_id = field(fmt=DWORD, start=0x44)
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toc_object_offset = field(fmt=DWORD, start=0x48)
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compressed_info_size = field(fmt=WORD, start=0x4c)
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thumbnail_type = versioned_field(version, 800, fmt=WORD, start=0x4e)
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thumbnail_size = versioned_field(version, 800, fmt=DWORD, start=0x50)
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uncompressed_info_size = versioned_field(compressed_info_size, 0, fmt=DWORD, start=0x54)
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title = xml_field("Title")
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author = xml_field("Author")
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book_id = xml_field("BookID")
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publisher = xml_field("Publisher")
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label = xml_field("Label")
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category = xml_field("Category")
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language = xml_field("Language")
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creator = xml_field("Creator")
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creation_date = xml_field("CreationDate") #: Format is %Y-%m-%d
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producer = xml_field("Producer")
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page = xml_field("Page")
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def safe(func):
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def restore_pos(*args, **kwargs):
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obj = args[0]
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pos = obj._file.tell()
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res = func(*args, **kwargs)
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obj._file.seek(0,2)
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if obj._file.tell() >= pos: obj._file.seek(pos)
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return res
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return restore_pos
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def safe_property(func):
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def decorator(f):
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def restore_pos(*args, **kwargs):
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obj = args[0]
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pos = obj._file.tell()
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res = f(*args, **kwargs)
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obj._file.seek(0,2)
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if obj._file.tell() >= pos: obj._file.seek(pos)
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return res
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return restore_pos
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locals_ = func()
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if locals_.has_key("fget"): locals_["fget"] = decorator(locals_["fget"])
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if locals_.has_key("fset"): locals_["fset"] = decorator(locals_["fset"])
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return property(**locals_)
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@safe_property
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def info():
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doc=""" Document meta information in raw XML format """
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def fget(self):
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if self.compressed_info_size == 0:
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raise LRFException("This document has no meta info")
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size = self.compressed_info_size - 4
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self._file.seek(self.info_start)
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try:
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stream = zlib.decompress(self._file.read(size))
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if len(stream) != self.uncompressed_info_size:
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raise LRFException("Decompression of document meta info yielded unexpected results")
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return stream
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except zlib.error, e:
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raise LRFException("Unable to decompress document meta information")
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def fset(self, info):
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self.uncompressed_info_size = len(info)
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stream = zlib.compress(info)
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self.compressed_info_size = len(stream) + 4
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self._file.seek(self.info_start)
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self._file.write(stream)
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self._file.flush()
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return locals()
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@safe_property
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def thumbail_pos():
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def fget(self):
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return self.info_start+ self.compressed_info_size-4
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return locals()
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@safe_property
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def thumbnail():
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def fget(self):
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if self.thumbnail_size:
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self._file.seek(self.thumbail_pos)
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print hex(self._file.tell())
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return self._file.read(self.thumbnail_size)
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def fset(self, data):
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if self.version <= 800: raise LRFException("Cannot store thumbnails in LRF files of version <= 800")
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orig_size = self.thumbnail_size
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self._file.seek(self.thumbail_pos+orig_size)
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rest_of_file = self._file.read()
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self.thumbnail_size = len(data)
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self._file.seek(self.thumbnail_pos)
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self.file.write(data+rest_of_file)
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delta = len(data) - orig_size
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self.object_table_offset = self.object_table_offset + delta
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self.toc_object_offset = self.toc_object_offset + delta
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self._file.flush()
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return locals()
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def __init__(self, file):
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""" @param file: A file object opened in the r+b mode """
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file.seek(0,2)
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self.size = file.tell()
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self._file = file
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if self.lrf_header != LRFFile.LRF_HEADER:
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raise LRFException(file.name + " has an invalid LRF header. Are you sure it is an LRF file?")
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self.info_start = 0x58 if self.version > 800 else 0x53 #: Byte at which the compressed meta information starts
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@safe
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def unpack(self, fmt=DWORD, start=0):
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"""
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Return decoded data from file.
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@param fmt: See U{struct<http://docs.python.org/lib/module-struct.html>}
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@param start: Position in file from which to decode
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"""
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end = start + struct.calcsize(fmt)
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self._file.seek(start)
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ret = struct.unpack(fmt, self._file.read(end-start))
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return ret
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@safe
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def pack(self, *args, **kwargs):
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"""
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Encode C{args} and write them to file. C{kwargs} must contain the keywords C{fmt} and C{start}
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@param args: The values to pack
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@param fmt: See U{struct<http://docs.python.org/lib/module-struct.html>}
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@param start: Position in file at which to write encoded data
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"""
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encoded = struct.pack(kwargs["fmt"], *args)
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self._file.seek(kwargs["start"])
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self._file.write(encoded)
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self._file.flush()
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def __add__(self, tb):
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""" Return a LRFFile rather than a list as the sum """
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return LRFFile(list.__add__(self, tb))
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def __getslice__(self, start, end):
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""" Return a LRFFile rather than a list as the slice """
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return LRFFile(list.__getslice__(self, start, end))
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