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Fixed bug in setting of thumbnails

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Added documentation
This commit is contained in:
Kovid Goyal 2006-11-23 01:51:18 +00:00
parent e6b1f2e829
commit 391ab780b3
1 changed files with 108 additions and 17 deletions
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125
libprs500/lrf/meta.py
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@ -73,7 +73,12 @@ class fixed_stringfield(object):
return "A string of length " + str(self._length) + " starting at byte " + str(self._start)
class xml_field(object):
"""
Descriptor that gets and sets XML based meta information from an LRF file.
Works for simple XML fields of the form <tagname>data</tagname>
"""
def __init__(self, tag_name):
""" @param tag_name: The XML tag whoose data we operate on """
self.tag_name = tag_name
def __get__(self, obj, typ=None):
@ -94,17 +99,23 @@ class xml_field(object):
Print(document, s)
obj.info = s.getvalue()
s.close()
def __str__(self):
return self.tag_name
def __repr__(self):
return "XML Field: " + self.tag_name
class LRFMetaFile(object):
LRF_HEADER = "L\0R\0F\0\0\0"
""" Has properties to read and write all Meta information in a LRF file. """
LRF_HEADER = "L\0R\0F\0\0\0" #: The first 8 bytes of all valid LRF files
lrf_header = fixed_stringfield(length=8, start=0)
version = field(fmt=WORD, start=8)
xor_key = field(fmt=WORD, start=10)
root_object_id = field(fmt=DWORD, start=12)
number_of_objets = field(fmt=QWORD, start=16)
object_table_offset = field(fmt=QWORD, start=24)
object_index_offset = field(fmt=QWORD, start=24)
binding = field(fmt=BYTE, start=36)
dpi = field(fmt=WORD, start=38)
width = field(fmt=WORD, start=42)
@ -131,6 +142,7 @@ class LRFMetaFile(object):
page = xml_field("Page")
def safe(func):
""" Decorator that ensures that function calls leave the pos in the underlying file unchanged """
def restore_pos(*args, **kwargs):
obj = args[0]
pos = obj._file.tell()
@ -141,6 +153,7 @@ class LRFMetaFile(object):
return restore_pos
def safe_property(func):
""" Decorator that ensures that read or writing a property leaves the position in the underlying file unchanged """
def decorator(f):
def restore_pos(*args, **kwargs):
obj = args[0]
@ -181,30 +194,44 @@ class LRFMetaFile(object):
return locals()
@safe_property
def thumbail_pos():
def thumbnail_pos():
doc=""" The position of the thumbnail in the LRF file """
def fget(self):
return self.info_start+ self.compressed_info_size-4
return locals()
@safe_property
def thumbnail():
def thumbnail():
doc=\
""" The thumbnail. Represented as a string. The string you would get from the file read function. """
def fget(self):
if self.thumbnail_size:
self._file.seek(self.thumbail_pos)
print hex(self._file.tell())
return self._file.read(self.thumbnail_size)
size = self.thumbnail_size
if size:
self._file.seek(self.thumbnail_pos)
return self._file.read(size)
def fset(self, data):
if self.version <= 800: raise LRFException("Cannot store thumbnails in LRF files of version <= 800")
orig_size = self.thumbnail_size
self._file.seek(self.thumbail_pos+orig_size)
rest_of_file = self._file.read()
self._file.seek(self.toc_object_offset)
toc = self._file.read(self.object_index_offset - self.toc_object_offset)
self._file.seek(self.object_index_offset)
objects = self._file.read()
self.thumbnail_size = len(data)
self._file.seek(self.thumbnail_pos)
self.file.write(data+rest_of_file)
delta = len(data) - orig_size
self.object_table_offset = self.object_table_offset + delta
self.toc_object_offset = self.toc_object_offset + delta
self._file.write(data)
orig_offset = self.toc_object_offset
self.toc_object_offset = self._file.tell()
self._file.write(toc)
self.object_index_offset = self._file.tell()
self._file.write(objects)
ttype = 0x14
if data[1:4] == "PNG": ttype = 0x12
if data[0:2] == "BM": ttype = 0x13
if data[0:4] == "JIFF": ttype = 0x11
self.thumbnail_type = ttype
self._file.flush()
self.update_object_offsets(self.toc_object_offset - orig_offset) # Needed as new thumbnail may have different size than old thumbnail
return locals()
def __init__(self, file):
@ -212,10 +239,25 @@ class LRFMetaFile(object):
file.seek(0,2)
self.size = file.tell()
self._file = file
if self.lrf_header != LRFFile.LRF_HEADER:
if self.lrf_header != LRFMetaFile.LRF_HEADER:
raise LRFException(file.name + " has an invalid LRF header. Are you sure it is an LRF file?")
self.info_start = 0x58 if self.version > 800 else 0x53 #: Byte at which the compressed meta information starts
@safe
def update_object_offsets(self, delta):
""" Run through the LRF Object index changing the offset by C{delta}. """
self._file.seek(self.object_index_offset)
while(True):
try: self._file.read(4)
except EOFError: break
pos = self._file.tell()
try: offset = self.unpack(fmt=DWORD, start=pos)[0] + delta
except struct.error: break
self.pack(offset, fmt=DWORD, start=pos)
try: self._file.read(12)
except EOFError: break
self._file.flush()
@safe
def unpack(self, fmt=DWORD, start=0):
"""
@ -250,4 +292,53 @@ class LRFMetaFile(object):
def __getslice__(self, start, end):
""" Return a LRFFile rather than a list as the slice """
return LRFFile(list.__getslice__(self, start, end))
def thumbail_extension(self):
ext = "gif"
ttype = self.thumbnail_type
if ttype == 0x11: ext = "jpeg"
elif ttype == 0x12: ext = "png"
elif ttype == 0x13: ext = "bm"
return ext
def main():
import sys, os.path
from optparse import OptionParser
from libprs500 import __version__ as VERSION
parser = OptionParser(usage="usage: %prog [options] mybook.lrf", version=VERSION)
parser.add_option("-t", "--title", action="store", type="string", dest="title", help="Set the book title")
parser.add_option("-a", "--author", action="store", type="string", dest="author", help="Set the author")
parser.add_option("-c", "--category", action="store", type="string", dest="category", help="The category this book belongs to. E.g.: History")
parser.add_option("--thumbnail", action="store", type="string", dest="thumbnail", help="Path to a graphic that will be set as this files' thumbnail")
parser.add_option("-p", "--page", action="store", type="string", dest="page", help="Set the current page number (I think)")
options, args = parser.parse_args()
if len(args) != 1:
parser.print_help()
sys.exit(1)
lrf = LRFMetaFile(open(args[0], "r+b"))
if options.title: lrf.title = options.title
if options.author: lrf.author = options.author
if options.category: lrf.category = options.category
if options.page: lrf.page = options.page
if options.thumbnail:
f = open(options.thumbnail, "r")
lrf.thumbnail = f.read()
f.close()
t = lrf.thumbnail
td = "None"
if t and len(t) > 0:
td = os.path.basename(args[0])+"_thumbnail_."+lrf.thumbail_extension()
f = open(td, "w")
f.write(t)
f.close()
fields = LRFMetaFile.__dict__.items()
for f in fields:
if "XML" in str(f):
print str(f[1]) + ":", lrf.__getattribute__(f[0])
print "Thumbnail:", td
print "object index offset:", hex(lrf.object_index_offset)
print "toc object offset", hex(lrf.toc_object_offset)