811 lines
24 KiB
Python
811 lines
24 KiB
Python
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#
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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 __future__ import annotations
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import abc
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import io
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import itertools
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import struct
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import sys
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from typing import IO, Any, NamedTuple
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from . import Image
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from ._deprecate import deprecate
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from ._util import is_path
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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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"""Whether or not to load truncated image files. User code may change this."""
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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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"""
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Dict of known error codes returned from :meth:`.PyDecoder.decode`,
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:meth:`.PyEncoder.encode` :meth:`.PyEncoder.encode_to_pyfd` and
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:meth:`.PyEncoder.encode_to_file`.
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"""
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#
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# --------------------------------------------------------------------
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# Helpers
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def _get_oserror(error: int, *, encoder: bool) -> OSError:
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try:
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msg = Image.core.getcodecstatus(error)
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except AttributeError:
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msg = ERRORS.get(error)
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if not msg:
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msg = f"{'encoder' if encoder else 'decoder'} error {error}"
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msg += f" when {'writing' if encoder else 'reading'} image file"
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return OSError(msg)
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def raise_oserror(error: int) -> OSError:
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deprecate(
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"raise_oserror",
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12,
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action="It is only useful for translating error codes returned by a codec's "
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"decode() method, which ImageFile already does automatically.",
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)
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raise _get_oserror(error, encoder=False)
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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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class _Tile(NamedTuple):
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codec_name: str
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extents: tuple[int, int, int, int]
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offset: int
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args: tuple[Any, ...] | str | None
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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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super().__init__()
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self._min_frame = 0
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self.custom_mimetype = None
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self.tile = None
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""" A list of tile descriptors, or ``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 is_path(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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self._exclusive_fp = True
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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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# can be overridden
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self._exclusive_fp = None
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try:
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try:
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self._open()
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except (
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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,
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) as v:
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raise SyntaxError(v) from v
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if not self.mode or self.size[0] <= 0 or self.size[1] <= 0:
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msg = "not identified by this driver"
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raise SyntaxError(msg)
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except BaseException:
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# close the file only if we have opened it this constructor
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if self._exclusive_fp:
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self.fp.close()
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raise
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def get_format_mimetype(self) -> str | None:
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if self.custom_mimetype:
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return self.custom_mimetype
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if self.format is not None:
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return Image.MIME.get(self.format.upper())
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return None
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def __setstate__(self, state):
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self.tile = []
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super().__setstate__(state)
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def verify(self) -> None:
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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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if self._exclusive_fp:
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self.fp.close()
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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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if self.tile is None:
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msg = "cannot load this image"
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raise OSError(msg)
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pixel = Image.Image.load(self)
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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 isinstance(args, str):
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args = (args, 0, 1)
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if (
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decoder_name == "raw"
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and len(args) >= 3
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and args[0] == self.mode
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and args[0] in Image._MAPMODES
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):
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try:
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# use mmap, if possible
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import mmap
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with open(self.filename) as fp:
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self.map = mmap.mmap(fp.fileno(), 0, access=mmap.ACCESS_READ)
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if offset + self.size[1] * args[1] > self.map.size():
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msg = "buffer is not large enough"
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raise OSError(msg)
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self.im = Image.core.map_buffer(
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self.map, self.size, decoder_name, offset, args
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)
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readonly = 1
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# After trashing self.im,
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# 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, OSError, ImportError):
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self.map = None
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self.load_prepare()
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err_code = -3 # initialize to unknown error
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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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# Remove consecutive duplicates that only differ by their offset
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self.tile = [
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list(tiles)[-1]
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for _, tiles in itertools.groupby(
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self.tile, lambda tile: (tile[0], tile[1], tile[3])
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)
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]
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for decoder_name, extents, offset, args in self.tile:
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seek(offset)
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decoder = Image._getdecoder(
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self.mode, decoder_name, args, self.decoderconfig
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)
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try:
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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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err_code = decoder.decode(b"")[1]
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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) as e:
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# 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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msg = "image file is truncated"
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raise OSError(msg) from e
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if not s: # truncated jpeg
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if LOAD_TRUNCATED_IMAGES:
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break
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else:
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msg = (
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"image file is truncated "
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f"({len(b)} bytes not processed)"
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)
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raise OSError(msg)
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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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finally:
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# Need to cleanup here to prevent leaks
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decoder.cleanup()
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self.tile = []
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self.readonly = readonly
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self.load_end()
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if self._exclusive_fp and self._close_exclusive_fp_after_loading:
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self.fp.close()
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self.fp = None
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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 _get_oserror(err_code, encoder=False)
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return Image.Image.load(self)
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def load_prepare(self) -> None:
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# create image memory if necessary
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if not self.im or 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) -> None:
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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: int) -> None:
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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, read_bytes: int) -> bytes:
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# pass
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def _seek_check(self, frame):
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if (
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frame < self._min_frame
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# Only check upper limit on frames if additional seek operations
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# are not required to do so
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or (
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not (hasattr(self, "_n_frames") and self._n_frames is None)
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and frame >= self.n_frames + self._min_frame
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)
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):
|
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msg = "attempt to seek outside sequence"
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raise EOFError(msg)
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return self.tell() != frame
|
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class StubHandler:
|
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|
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def open(self, im: StubImageFile) -> None:
|
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pass
|
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|
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|
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@abc.abstractmethod
|
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def load(self, im: StubImageFile) -> Image.Image:
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pass
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|
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class StubImageFile(ImageFile):
|
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|
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"""
|
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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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"""
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def _open(self) -> None:
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msg = "StubImageFile subclass must implement _open"
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raise NotImplementedError(msg)
|
||
|
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def load(self):
|
||
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loader = self._load()
|
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|
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if loader is None:
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||
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msg = f"cannot find loader for this {self.format} file"
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raise OSError(msg)
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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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return image.load()
|
||
|
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|
||
|
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def _load(self) -> StubHandler | None:
|
||
|
|
"""(Hook) Find actual image loader."""
|
||
|
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msg = "StubImageFile subclass must implement _load"
|
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|
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raise NotImplementedError(msg)
|
||
|
|
|
||
|
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|
||
|
|
class Parser:
|
||
|
|
"""
|
||
|
|
Incremental image parser. This class implements the standard
|
||
|
|
feed/close consumer interface.
|
||
|
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"""
|
||
|
|
|
||
|
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incremental = None
|
||
|
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image: Image.Image | None = 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) -> None:
|
||
|
|
"""
|
||
|
|
(Consumer) Reset the parser. Note that you can only call this
|
||
|
|
method immediately after you've created a parser; parser
|
||
|
|
instances cannot be reused.
|
||
|
|
"""
|
||
|
|
assert self.data is None, "cannot reuse parsers"
|
||
|
|
|
||
|
|
def feed(self, data):
|
||
|
|
"""
|
||
|
|
(Consumer) Feed data to the parser.
|
||
|
|
|
||
|
|
:param data: A string buffer.
|
||
|
|
:exception OSError: If the parser failed to parse the image file.
|
||
|
|
"""
|
||
|
|
# collect data
|
||
|
|
|
||
|
|
if self.finished:
|
||
|
|
return
|
||
|
|
|
||
|
|
if self.data is None:
|
||
|
|
self.data = data
|
||
|
|
else:
|
||
|
|
self.data = self.data + data
|
||
|
|
|
||
|
|
# parse what we have
|
||
|
|
if self.decoder:
|
||
|
|
if self.offset > 0:
|
||
|
|
# skip header
|
||
|
|
skip = min(len(self.data), self.offset)
|
||
|
|
self.data = self.data[skip:]
|
||
|
|
self.offset = self.offset - skip
|
||
|
|
if self.offset > 0 or not self.data:
|
||
|
|
return
|
||
|
|
|
||
|
|
n, e = self.decoder.decode(self.data)
|
||
|
|
|
||
|
|
if n < 0:
|
||
|
|
# end of stream
|
||
|
|
self.data = None
|
||
|
|
self.finished = 1
|
||
|
|
if e < 0:
|
||
|
|
# decoding error
|
||
|
|
self.image = None
|
||
|
|
raise _get_oserror(e, encoder=False)
|
||
|
|
else:
|
||
|
|
# end of image
|
||
|
|
return
|
||
|
|
self.data = self.data[n:]
|
||
|
|
|
||
|
|
elif self.image:
|
||
|
|
# if we end up here with no decoder, this file cannot
|
||
|
|
# be incrementally parsed. wait until we've gotten all
|
||
|
|
# available data
|
||
|
|
pass
|
||
|
|
|
||
|
|
else:
|
||
|
|
# attempt to open this file
|
||
|
|
try:
|
||
|
|
with io.BytesIO(self.data) as fp:
|
||
|
|
im = Image.open(fp)
|
||
|
|
except OSError:
|
||
|
|
pass # not enough data
|
||
|
|
else:
|
||
|
|
flag = hasattr(im, "load_seek") or hasattr(im, "load_read")
|
||
|
|
if flag or len(im.tile) != 1:
|
||
|
|
# custom load code, or multiple tiles
|
||
|
|
self.decode = None
|
||
|
|
else:
|
||
|
|
# initialize decoder
|
||
|
|
im.load_prepare()
|
||
|
|
d, e, o, a = im.tile[0]
|
||
|
|
im.tile = []
|
||
|
|
self.decoder = Image._getdecoder(im.mode, d, a, im.decoderconfig)
|
||
|
|
self.decoder.setimage(im.im, e)
|
||
|
|
|
||
|
|
# calculate decoder offset
|
||
|
|
self.offset = o
|
||
|
|
if self.offset <= len(self.data):
|
||
|
|
self.data = self.data[self.offset :]
|
||
|
|
self.offset = 0
|
||
|
|
|
||
|
|
self.image = im
|
||
|
|
|
||
|
|
def __enter__(self):
|
||
|
|
return self
|
||
|
|
|
||
|
|
def __exit__(self, *args: object) -> None:
|
||
|
|
self.close()
|
||
|
|
|
||
|
|
def close(self):
|
||
|
|
"""
|
||
|
|
(Consumer) Close the stream.
|
||
|
|
|
||
|
|
:returns: An image object.
|
||
|
|
:exception OSError: If the parser failed to parse the image file either
|
||
|
|
because it cannot be identified or cannot be
|
||
|
|
decoded.
|
||
|
|
"""
|
||
|
|
# finish decoding
|
||
|
|
if self.decoder:
|
||
|
|
# get rid of what's left in the buffers
|
||
|
|
self.feed(b"")
|
||
|
|
self.data = self.decoder = None
|
||
|
|
if not self.finished:
|
||
|
|
msg = "image was incomplete"
|
||
|
|
raise OSError(msg)
|
||
|
|
if not self.image:
|
||
|
|
msg = "cannot parse this image"
|
||
|
|
raise OSError(msg)
|
||
|
|
if self.data:
|
||
|
|
# incremental parsing not possible; reopen the file
|
||
|
|
# not that we have all data
|
||
|
|
with io.BytesIO(self.data) as fp:
|
||
|
|
try:
|
||
|
|
self.image = Image.open(fp)
|
||
|
|
finally:
|
||
|
|
self.image.load()
|
||
|
|
return self.image
|
||
|
|
|
||
|
|
|
||
|
|
# --------------------------------------------------------------------
|
||
|
|
|
||
|
|
|
||
|
|
def _save(im, fp, tile, bufsize=0) -> None:
|
||
|
|
"""Helper to save image based on tile list
|
||
|
|
|
||
|
|
:param im: Image object.
|
||
|
|
:param fp: File object.
|
||
|
|
:param tile: Tile list.
|
||
|
|
:param bufsize: Optional buffer size
|
||
|
|
"""
|
||
|
|
|
||
|
|
im.load()
|
||
|
|
if not hasattr(im, "encoderconfig"):
|
||
|
|
im.encoderconfig = ()
|
||
|
|
tile.sort(key=_tilesort)
|
||
|
|
# FIXME: make MAXBLOCK a configuration parameter
|
||
|
|
# It would be great if we could have the encoder specify what it needs
|
||
|
|
# But, it would need at least the image size in most cases. RawEncode is
|
||
|
|
# a tricky case.
|
||
|
|
bufsize = max(MAXBLOCK, bufsize, im.size[0] * 4) # see RawEncode.c
|
||
|
|
try:
|
||
|
|
fh = fp.fileno()
|
||
|
|
fp.flush()
|
||
|
|
_encode_tile(im, fp, tile, bufsize, fh)
|
||
|
|
except (AttributeError, io.UnsupportedOperation) as exc:
|
||
|
|
_encode_tile(im, fp, tile, bufsize, None, exc)
|
||
|
|
if hasattr(fp, "flush"):
|
||
|
|
fp.flush()
|
||
|
|
|
||
|
|
|
||
|
|
def _encode_tile(im, fp, tile: list[_Tile], bufsize, fh, exc=None):
|
||
|
|
for encoder_name, extents, offset, args in tile:
|
||
|
|
if offset > 0:
|
||
|
|
fp.seek(offset)
|
||
|
|
encoder = Image._getencoder(im.mode, encoder_name, args, im.encoderconfig)
|
||
|
|
try:
|
||
|
|
encoder.setimage(im.im, extents)
|
||
|
|
if encoder.pushes_fd:
|
||
|
|
encoder.setfd(fp)
|
||
|
|
errcode = encoder.encode_to_pyfd()[1]
|
||
|
|
else:
|
||
|
|
if exc:
|
||
|
|
# compress to Python file-compatible object
|
||
|
|
while True:
|
||
|
|
errcode, data = encoder.encode(bufsize)[1:]
|
||
|
|
fp.write(data)
|
||
|
|
if errcode:
|
||
|
|
break
|
||
|
|
else:
|
||
|
|
# slight speedup: compress to real file object
|
||
|
|
errcode = encoder.encode_to_file(fh, bufsize)
|
||
|
|
if errcode < 0:
|
||
|
|
raise _get_oserror(errcode, encoder=True) from exc
|
||
|
|
finally:
|
||
|
|
encoder.cleanup()
|
||
|
|
|
||
|
|
|
||
|
|
def _safe_read(fp, size):
|
||
|
|
"""
|
||
|
|
Reads large blocks in a safe way. Unlike fp.read(n), this function
|
||
|
|
doesn't trust the user. If the requested size is larger than
|
||
|
|
SAFEBLOCK, the file is read block by block.
|
||
|
|
|
||
|
|
:param fp: File handle. Must implement a <b>read</b> method.
|
||
|
|
:param size: Number of bytes to read.
|
||
|
|
:returns: A string containing <i>size</i> bytes of data.
|
||
|
|
|
||
|
|
Raises an OSError if the file is truncated and the read cannot be completed
|
||
|
|
|
||
|
|
"""
|
||
|
|
if size <= 0:
|
||
|
|
return b""
|
||
|
|
if size <= SAFEBLOCK:
|
||
|
|
data = fp.read(size)
|
||
|
|
if len(data) < size:
|
||
|
|
msg = "Truncated File Read"
|
||
|
|
raise OSError(msg)
|
||
|
|
return data
|
||
|
|
data = []
|
||
|
|
remaining_size = size
|
||
|
|
while remaining_size > 0:
|
||
|
|
block = fp.read(min(remaining_size, SAFEBLOCK))
|
||
|
|
if not block:
|
||
|
|
break
|
||
|
|
data.append(block)
|
||
|
|
remaining_size -= len(block)
|
||
|
|
if sum(len(d) for d in data) < size:
|
||
|
|
msg = "Truncated File Read"
|
||
|
|
raise OSError(msg)
|
||
|
|
return b"".join(data)
|
||
|
|
|
||
|
|
|
||
|
|
class PyCodecState:
|
||
|
|
def __init__(self) -> None:
|
||
|
|
self.xsize = 0
|
||
|
|
self.ysize = 0
|
||
|
|
self.xoff = 0
|
||
|
|
self.yoff = 0
|
||
|
|
|
||
|
|
def extents(self) -> tuple[int, int, int, int]:
|
||
|
|
return self.xoff, self.yoff, self.xoff + self.xsize, self.yoff + self.ysize
|
||
|
|
|
||
|
|
|
||
|
|
class PyCodec:
|
||
|
|
fd: IO[bytes] | None
|
||
|
|
|
||
|
|
def __init__(self, mode, *args):
|
||
|
|
self.im = None
|
||
|
|
self.state = PyCodecState()
|
||
|
|
self.fd = None
|
||
|
|
self.mode = mode
|
||
|
|
self.init(args)
|
||
|
|
|
||
|
|
def init(self, args):
|
||
|
|
"""
|
||
|
|
Override to perform codec specific initialization
|
||
|
|
|
||
|
|
:param args: Array of args items from the tile entry
|
||
|
|
:returns: None
|
||
|
|
"""
|
||
|
|
self.args = args
|
||
|
|
|
||
|
|
def cleanup(self) -> None:
|
||
|
|
"""
|
||
|
|
Override to perform codec specific cleanup
|
||
|
|
|
||
|
|
:returns: None
|
||
|
|
"""
|
||
|
|
pass
|
||
|
|
|
||
|
|
def setfd(self, fd):
|
||
|
|
"""
|
||
|
|
Called from ImageFile to set the Python file-like object
|
||
|
|
|
||
|
|
:param fd: A Python file-like object
|
||
|
|
:returns: None
|
||
|
|
"""
|
||
|
|
self.fd = fd
|
||
|
|
|
||
|
|
def setimage(self, im, extents: tuple[int, int, int, int] | None = None) -> None:
|
||
|
|
"""
|
||
|
|
Called from ImageFile to set the core output image for the codec
|
||
|
|
|
||
|
|
:param im: A core image object
|
||
|
|
:param extents: a 4 tuple of (x0, y0, x1, y1) defining the rectangle
|
||
|
|
for this tile
|
||
|
|
:returns: None
|
||
|
|
"""
|
||
|
|
|
||
|
|
# following c code
|
||
|
|
self.im = im
|
||
|
|
|
||
|
|
if extents:
|
||
|
|
(x0, y0, x1, y1) = extents
|
||
|
|
else:
|
||
|
|
(x0, y0, x1, y1) = (0, 0, 0, 0)
|
||
|
|
|
||
|
|
if x0 == 0 and x1 == 0:
|
||
|
|
self.state.xsize, self.state.ysize = self.im.size
|
||
|
|
else:
|
||
|
|
self.state.xoff = x0
|
||
|
|
self.state.yoff = y0
|
||
|
|
self.state.xsize = x1 - x0
|
||
|
|
self.state.ysize = y1 - y0
|
||
|
|
|
||
|
|
if self.state.xsize <= 0 or self.state.ysize <= 0:
|
||
|
|
msg = "Size cannot be negative"
|
||
|
|
raise ValueError(msg)
|
||
|
|
|
||
|
|
if (
|
||
|
|
self.state.xsize + self.state.xoff > self.im.size[0]
|
||
|
|
or self.state.ysize + self.state.yoff > self.im.size[1]
|
||
|
|
):
|
||
|
|
msg = "Tile cannot extend outside image"
|
||
|
|
raise ValueError(msg)
|
||
|
|
|
||
|
|
|
||
|
|
class PyDecoder(PyCodec):
|
||
|
|
"""
|
||
|
|
Python implementation of a format decoder. Override this class and
|
||
|
|
add the decoding logic in the :meth:`decode` method.
|
||
|
|
|
||
|
|
See :ref:`Writing Your Own File Codec in Python<file-codecs-py>`
|
||
|
|
"""
|
||
|
|
|
||
|
|
_pulls_fd = False
|
||
|
|
|
||
|
|
@property
|
||
|
|
def pulls_fd(self) -> bool:
|
||
|
|
return self._pulls_fd
|
||
|
|
|
||
|
|
def decode(self, buffer: bytes) -> tuple[int, int]:
|
||
|
|
"""
|
||
|
|
Override to perform the decoding process.
|
||
|
|
|
||
|
|
:param buffer: A bytes object with the data to be decoded.
|
||
|
|
:returns: A tuple of ``(bytes consumed, errcode)``.
|
||
|
|
If finished with decoding return -1 for the bytes consumed.
|
||
|
|
Err codes are from :data:`.ImageFile.ERRORS`.
|
||
|
|
"""
|
||
|
|
msg = "unavailable in base decoder"
|
||
|
|
raise NotImplementedError(msg)
|
||
|
|
|
||
|
|
def set_as_raw(self, data: bytes, rawmode=None) -> None:
|
||
|
|
"""
|
||
|
|
Convenience method to set the internal image from a stream of raw data
|
||
|
|
|
||
|
|
:param data: Bytes to be set
|
||
|
|
:param rawmode: The rawmode to be used for the decoder.
|
||
|
|
If not specified, it will default to the mode of the image
|
||
|
|
:returns: None
|
||
|
|
"""
|
||
|
|
|
||
|
|
if not rawmode:
|
||
|
|
rawmode = self.mode
|
||
|
|
d = Image._getdecoder(self.mode, "raw", rawmode)
|
||
|
|
assert self.im is not None
|
||
|
|
d.setimage(self.im, self.state.extents())
|
||
|
|
s = d.decode(data)
|
||
|
|
|
||
|
|
if s[0] >= 0:
|
||
|
|
msg = "not enough image data"
|
||
|
|
raise ValueError(msg)
|
||
|
|
if s[1] != 0:
|
||
|
|
msg = "cannot decode image data"
|
||
|
|
raise ValueError(msg)
|
||
|
|
|
||
|
|
|
||
|
|
class PyEncoder(PyCodec):
|
||
|
|
"""
|
||
|
|
Python implementation of a format encoder. Override this class and
|
||
|
|
add the decoding logic in the :meth:`encode` method.
|
||
|
|
|
||
|
|
See :ref:`Writing Your Own File Codec in Python<file-codecs-py>`
|
||
|
|
"""
|
||
|
|
|
||
|
|
_pushes_fd = False
|
||
|
|
|
||
|
|
@property
|
||
|
|
def pushes_fd(self) -> bool:
|
||
|
|
return self._pushes_fd
|
||
|
|
|
||
|
|
def encode(self, bufsize: int) -> tuple[int, int, bytes]:
|
||
|
|
"""
|
||
|
|
Override to perform the encoding process.
|
||
|
|
|
||
|
|
:param bufsize: Buffer size.
|
||
|
|
:returns: A tuple of ``(bytes encoded, errcode, bytes)``.
|
||
|
|
If finished with encoding return 1 for the error code.
|
||
|
|
Err codes are from :data:`.ImageFile.ERRORS`.
|
||
|
|
"""
|
||
|
|
msg = "unavailable in base encoder"
|
||
|
|
raise NotImplementedError(msg)
|
||
|
|
|
||
|
|
def encode_to_pyfd(self) -> tuple[int, int]:
|
||
|
|
"""
|
||
|
|
If ``pushes_fd`` is ``True``, then this method will be used,
|
||
|
|
and ``encode()`` will only be called once.
|
||
|
|
|
||
|
|
:returns: A tuple of ``(bytes consumed, errcode)``.
|
||
|
|
Err codes are from :data:`.ImageFile.ERRORS`.
|
||
|
|
"""
|
||
|
|
if not self.pushes_fd:
|
||
|
|
return 0, -8 # bad configuration
|
||
|
|
bytes_consumed, errcode, data = self.encode(0)
|
||
|
|
if data:
|
||
|
|
assert self.fd is not None
|
||
|
|
self.fd.write(data)
|
||
|
|
return bytes_consumed, errcode
|
||
|
|
|
||
|
|
def encode_to_file(self, fh, bufsize):
|
||
|
|
"""
|
||
|
|
:param fh: File handle.
|
||
|
|
:param bufsize: Buffer size.
|
||
|
|
|
||
|
|
:returns: If finished successfully, return 0.
|
||
|
|
Otherwise, return an error code. Err codes are from
|
||
|
|
:data:`.ImageFile.ERRORS`.
|
||
|
|
"""
|
||
|
|
errcode = 0
|
||
|
|
while errcode == 0:
|
||
|
|
status, errcode, buf = self.encode(bufsize)
|
||
|
|
if status > 0:
|
||
|
|
fh.write(buf[status:])
|
||
|
|
return errcode
|