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645 lines
19 KiB
Python
645 lines
19 KiB
Python
#
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# The Python Imaging Library.
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# $Id$
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#
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# base class for image file handlers
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#
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# history:
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# 1995-09-09 fl Created
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# 1996-03-11 fl Fixed load mechanism.
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# 1996-04-15 fl Added pcx/xbm decoders.
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# 1996-04-30 fl Added encoders.
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# 1996-12-14 fl Added load helpers
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# 1997-01-11 fl Use encode_to_file where possible
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# 1997-08-27 fl Flush output in _save
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# 1998-03-05 fl Use memory mapping for some modes
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# 1999-02-04 fl Use memory mapping also for "I;16" and "I;16B"
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# 1999-05-31 fl Added image parser
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# 2000-10-12 fl Set readonly flag on memory-mapped images
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# 2002-03-20 fl Use better messages for common decoder errors
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# 2003-04-21 fl Fall back on mmap/map_buffer if map is not available
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# 2003-10-30 fl Added StubImageFile class
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# 2004-02-25 fl Made incremental parser more robust
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#
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# Copyright (c) 1997-2004 by Secret Labs AB
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# Copyright (c) 1995-2004 by Fredrik Lundh
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#
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# See the README file for information on usage and redistribution.
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#
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from . import Image
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from ._util import isPath
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import io
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import os
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import sys
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import struct
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MAXBLOCK = 65536
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SAFEBLOCK = 1024*1024
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LOAD_TRUNCATED_IMAGES = False
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ERRORS = {
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-1: "image buffer overrun error",
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-2: "decoding error",
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-3: "unknown error",
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-8: "bad configuration",
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-9: "out of memory error"
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}
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def raise_ioerror(error):
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try:
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message = Image.core.getcodecstatus(error)
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except AttributeError:
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message = ERRORS.get(error)
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if not message:
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message = "decoder error %d" % error
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raise IOError(message + " when reading image file")
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#
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# --------------------------------------------------------------------
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# Helpers
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def _tilesort(t):
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# sort on offset
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return t[2]
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#
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# --------------------------------------------------------------------
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# ImageFile base class
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class ImageFile(Image.Image):
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"Base class for image file format handlers."
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def __init__(self, fp=None, filename=None):
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Image.Image.__init__(self)
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self.tile = None
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self.readonly = 1 # until we know better
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self.decoderconfig = ()
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self.decodermaxblock = MAXBLOCK
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if isPath(fp):
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# filename
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self.fp = open(fp, "rb")
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self.filename = fp
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else:
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# stream
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self.fp = fp
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self.filename = filename
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try:
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self._open()
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except (IndexError, # end of data
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TypeError, # end of data (ord)
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KeyError, # unsupported mode
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EOFError, # got header but not the first frame
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struct.error) as v:
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raise SyntaxError(v)
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if not self.mode or self.size[0] <= 0:
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raise SyntaxError("not identified by this driver")
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def draft(self, mode, size):
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"Set draft mode"
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pass
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def verify(self):
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"Check file integrity"
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# raise exception if something's wrong. must be called
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# directly after open, and closes file when finished.
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self.fp = None
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def load(self):
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"Load image data based on tile list"
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pixel = Image.Image.load(self)
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if self.tile is None:
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raise IOError("cannot load this image")
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if not self.tile:
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return pixel
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self.map = None
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use_mmap = self.filename and len(self.tile) == 1
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# As of pypy 2.1.0, memory mapping was failing here.
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use_mmap = use_mmap and not hasattr(sys, 'pypy_version_info')
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readonly = 0
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# look for read/seek overrides
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try:
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read = self.load_read
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# don't use mmap if there are custom read/seek functions
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use_mmap = False
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except AttributeError:
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read = self.fp.read
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try:
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seek = self.load_seek
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use_mmap = False
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except AttributeError:
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seek = self.fp.seek
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if use_mmap:
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# try memory mapping
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decoder_name, extents, offset, args = self.tile[0]
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if decoder_name == "raw" and len(args) >= 3 and args[0] == self.mode \
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and args[0] in Image._MAPMODES:
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try:
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if hasattr(Image.core, "map"):
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# use built-in mapper WIN32 only
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self.map = Image.core.map(self.filename)
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self.map.seek(offset)
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self.im = self.map.readimage(
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self.mode, self.size, args[1], args[2]
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)
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else:
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# use mmap, if possible
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import mmap
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fp = open(self.filename, "r")
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size = os.path.getsize(self.filename)
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self.map = mmap.mmap(fp.fileno(), size, access=mmap.ACCESS_READ)
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self.im = Image.core.map_buffer(
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self.map, self.size, decoder_name, extents, offset, args
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)
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readonly = 1
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# After trashing self.im, we might need to reload the palette data.
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if self.palette:
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self.palette.dirty = 1
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except (AttributeError, EnvironmentError, ImportError):
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self.map = None
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self.load_prepare()
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if not self.map:
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# sort tiles in file order
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self.tile.sort(key=_tilesort)
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try:
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# FIXME: This is a hack to handle TIFF's JpegTables tag.
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prefix = self.tile_prefix
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except AttributeError:
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prefix = b""
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for decoder_name, extents, offset, args in self.tile:
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decoder = Image._getdecoder(self.mode, decoder_name,
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args, self.decoderconfig)
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seek(offset)
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decoder.setimage(self.im, extents)
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if decoder.pulls_fd:
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decoder.setfd(self.fp)
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status, err_code = decoder.decode(b"")
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else:
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b = prefix
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while True:
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try:
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s = read(self.decodermaxblock)
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except (IndexError, struct.error): # truncated png/gif
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if LOAD_TRUNCATED_IMAGES:
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break
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else:
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raise IOError("image file is truncated")
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if not s: # truncated jpeg
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self.tile = []
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# JpegDecode needs to clean things up here either way
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# If we don't destroy the decompressor,
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# we have a memory leak.
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decoder.cleanup()
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if LOAD_TRUNCATED_IMAGES:
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break
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else:
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raise IOError("image file is truncated "
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"(%d bytes not processed)" % len(b))
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b = b + s
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n, err_code = decoder.decode(b)
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if n < 0:
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break
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b = b[n:]
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# Need to cleanup here to prevent leaks in PyPy
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decoder.cleanup()
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self.tile = []
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self.readonly = readonly
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self.fp = None # might be shared
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if not self.map and not LOAD_TRUNCATED_IMAGES and err_code < 0:
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# still raised if decoder fails to return anything
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raise_ioerror(err_code)
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self.load_end()
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return Image.Image.load(self)
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def load_prepare(self):
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# create image memory if necessary
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if not self.im or\
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self.im.mode != self.mode or self.im.size != self.size:
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self.im = Image.core.new(self.mode, self.size)
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# create palette (optional)
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if self.mode == "P":
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Image.Image.load(self)
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def load_end(self):
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# may be overridden
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pass
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# may be defined for contained formats
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# def load_seek(self, pos):
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# pass
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# may be defined for blocked formats (e.g. PNG)
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# def load_read(self, bytes):
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# pass
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class StubImageFile(ImageFile):
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"""
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Base class for stub image loaders.
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A stub loader is an image loader that can identify files of a
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certain format, but relies on external code to load the file.
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"""
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def _open(self):
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raise NotImplementedError(
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"StubImageFile subclass must implement _open"
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)
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def load(self):
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loader = self._load()
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if loader is None:
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raise IOError("cannot find loader for this %s file" % self.format)
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image = loader.load(self)
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assert image is not None
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# become the other object (!)
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self.__class__ = image.__class__
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self.__dict__ = image.__dict__
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def _load(self):
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"(Hook) Find actual image loader."
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raise NotImplementedError(
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"StubImageFile subclass must implement _load"
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)
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class Parser(object):
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"""
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Incremental image parser. This class implements the standard
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feed/close consumer interface.
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"""
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incremental = None
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image = None
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data = None
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decoder = None
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offset = 0
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finished = 0
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def reset(self):
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"""
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(Consumer) Reset the parser. Note that you can only call this
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method immediately after you've created a parser; parser
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instances cannot be reused.
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"""
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assert self.data is None, "cannot reuse parsers"
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def feed(self, data):
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"""
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(Consumer) Feed data to the parser.
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:param data: A string buffer.
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:exception IOError: If the parser failed to parse the image file.
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"""
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# collect data
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if self.finished:
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return
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if self.data is None:
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self.data = data
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else:
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self.data = self.data + data
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# parse what we have
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if self.decoder:
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if self.offset > 0:
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# skip header
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skip = min(len(self.data), self.offset)
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self.data = self.data[skip:]
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self.offset = self.offset - skip
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if self.offset > 0 or not self.data:
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return
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n, e = self.decoder.decode(self.data)
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if n < 0:
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# end of stream
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self.data = None
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self.finished = 1
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if e < 0:
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# decoding error
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self.image = None
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raise_ioerror(e)
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else:
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# end of image
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return
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self.data = self.data[n:]
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elif self.image:
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# if we end up here with no decoder, this file cannot
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# be incrementally parsed. wait until we've gotten all
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# available data
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pass
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else:
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# attempt to open this file
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try:
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try:
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fp = io.BytesIO(self.data)
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im = Image.open(fp)
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finally:
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fp.close() # explicitly close the virtual file
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except IOError:
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# traceback.print_exc()
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pass # not enough data
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else:
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flag = hasattr(im, "load_seek") or hasattr(im, "load_read")
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if flag or len(im.tile) != 1:
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# custom load code, or multiple tiles
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self.decode = None
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else:
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# initialize decoder
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im.load_prepare()
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d, e, o, a = im.tile[0]
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im.tile = []
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self.decoder = Image._getdecoder(
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im.mode, d, a, im.decoderconfig
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)
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self.decoder.setimage(im.im, e)
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# calculate decoder offset
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self.offset = o
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if self.offset <= len(self.data):
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self.data = self.data[self.offset:]
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self.offset = 0
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self.image = im
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def close(self):
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"""
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(Consumer) Close the stream.
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:returns: An image object.
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:exception IOError: If the parser failed to parse the image file either
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because it cannot be identified or cannot be
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decoded.
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"""
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# finish decoding
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if self.decoder:
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# get rid of what's left in the buffers
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self.feed(b"")
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self.data = self.decoder = None
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if not self.finished:
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raise IOError("image was incomplete")
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if not self.image:
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raise IOError("cannot parse this image")
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if self.data:
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# incremental parsing not possible; reopen the file
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# not that we have all data
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try:
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fp = io.BytesIO(self.data)
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self.image = Image.open(fp)
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finally:
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self.image.load()
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fp.close() # explicitly close the virtual file
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return self.image
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# --------------------------------------------------------------------
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def _save(im, fp, tile, bufsize=0):
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"""Helper to save image based on tile list
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:param im: Image object.
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:param fp: File object.
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:param tile: Tile list.
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:param bufsize: Optional buffer size
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"""
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im.load()
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if not hasattr(im, "encoderconfig"):
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im.encoderconfig = ()
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tile.sort(key=_tilesort)
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# FIXME: make MAXBLOCK a configuration parameter
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# It would be great if we could have the encoder specify what it needs
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# But, it would need at least the image size in most cases. RawEncode is
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# a tricky case.
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bufsize = max(MAXBLOCK, bufsize, im.size[0] * 4) # see RawEncode.c
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if fp == sys.stdout:
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fp.flush()
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return
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try:
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fh = fp.fileno()
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fp.flush()
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except (AttributeError, io.UnsupportedOperation):
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# compress to Python file-compatible object
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for e, b, o, a in tile:
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e = Image._getencoder(im.mode, e, a, im.encoderconfig)
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if o > 0:
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fp.seek(o, 0)
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e.setimage(im.im, b)
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if e.pushes_fd:
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e.setfd(fp)
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l, s = e.encode_to_pyfd()
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else:
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while True:
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l, s, d = e.encode(bufsize)
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fp.write(d)
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if s:
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break
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if s < 0:
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raise IOError("encoder error %d when writing image file" % s)
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e.cleanup()
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else:
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# slight speedup: compress to real file object
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for e, b, o, a in tile:
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e = Image._getencoder(im.mode, e, a, im.encoderconfig)
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if o > 0:
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fp.seek(o, 0)
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e.setimage(im.im, b)
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if e.pushes_fd:
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e.setfd(fp)
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l, s = e.encode_to_pyfd()
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else:
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s = e.encode_to_file(fh, bufsize)
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if s < 0:
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raise IOError("encoder error %d when writing image file" % s)
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e.cleanup()
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if hasattr(fp, "flush"):
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fp.flush()
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def _safe_read(fp, size):
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"""
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Reads large blocks in a safe way. Unlike fp.read(n), this function
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doesn't trust the user. If the requested size is larger than
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SAFEBLOCK, the file is read block by block.
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:param fp: File handle. Must implement a <b>read</b> method.
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:param size: Number of bytes to read.
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:returns: A string containing up to <i>size</i> bytes of data.
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"""
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if size <= 0:
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return b""
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if size <= SAFEBLOCK:
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return fp.read(size)
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data = []
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while size > 0:
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block = fp.read(min(size, SAFEBLOCK))
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if not block:
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break
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data.append(block)
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size -= len(block)
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return b"".join(data)
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class PyCodecState(object):
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def __init__(self):
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self.xsize = 0
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self.ysize = 0
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self.xoff = 0
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self.yoff = 0
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def extents(self):
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return (self.xoff, self.yoff,
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self.xoff+self.xsize, self.yoff+self.ysize)
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class PyDecoder(object):
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"""
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Python implementation of a format decoder. Override this class and
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add the decoding logic in the `decode` method.
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See :ref:`Writing Your Own File Decoder in Python<file-decoders-py>`
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"""
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_pulls_fd = False
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def __init__(self, mode, *args):
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self.im = None
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self.state = PyCodecState()
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self.fd = None
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self.mode = mode
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self.init(args)
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def init(self, args):
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"""
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Override to perform decoder specific initialization
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:param args: Array of args items from the tile entry
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:returns: None
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"""
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self.args = args
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@property
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def pulls_fd(self):
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return self._pulls_fd
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def decode(self, buffer):
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"""
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Override to perform the decoding process.
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:param buffer: A bytes object with the data to be decoded. If `handles_eof`
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is set, then `buffer` will be empty and `self.fd` will be set.
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:returns: A tuple of (bytes consumed, errcode). If finished with decoding
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return <0 for the bytes consumed. Err codes are from `ERRORS`
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"""
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raise NotImplementedError()
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def cleanup(self):
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"""
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Override to perform decoder specific cleanup
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:returns: None
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"""
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pass
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def setfd(self, fd):
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"""
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Called from ImageFile to set the python file-like object
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:param fd: A python file-like object
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:returns: None
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"""
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self.fd = fd
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def setimage(self, im, extents=None):
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"""
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Called from ImageFile to set the core output image for the decoder
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:param im: A core image object
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:param extents: a 4 tuple of (x0, y0, x1, y1) defining the rectangle
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for this tile
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:returns: None
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"""
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# following c code
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self.im = im
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if extents:
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(x0, y0, x1, y1) = extents
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else:
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(x0, y0, x1, y1) = (0, 0, 0, 0)
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if x0 == 0 and x1 == 0:
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self.state.xsize, self.state.ysize = self.im.size
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else:
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self.state.xoff = x0
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self.state.yoff = y0
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self.state.xsize = x1 - x0
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self.state.ysize = y1 - y0
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if self.state.xsize <= 0 or self.state.ysize <= 0:
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raise ValueError("Size cannot be negative")
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if (self.state.xsize + self.state.xoff > self.im.size[0] or
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self.state.ysize + self.state.yoff > self.im.size[1]):
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raise ValueError("Tile cannot extend outside image")
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def set_as_raw(self, data, rawmode=None):
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"""
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|
Convenience method to set the internal image from a stream of raw data
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:param data: Bytes to be set
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|
:param rawmode: The rawmode to be used for the decoder. If not specified,
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it will default to the mode of the image
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|
:returns: None
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"""
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|
|
|
if not rawmode:
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|
rawmode = self.mode
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d = Image._getdecoder(self.mode, 'raw', (rawmode))
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|
d.setimage(self.im, self.state.extents())
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|
s = d.decode(data)
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|
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if s[0] >= 0:
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raise ValueError("not enough image data")
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|
if s[1] != 0:
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|
raise ValueError("cannot decode image data")
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