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https://github.com/python-pillow/Pillow.git
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1040 lines
34 KiB
Python
1040 lines
34 KiB
Python
#
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# The Python Imaging Library.
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# $Id$
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#
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# GIF file handling
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#
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# History:
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# 1995-09-01 fl Created
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# 1996-12-14 fl Added interlace support
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# 1996-12-30 fl Added animation support
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# 1997-01-05 fl Added write support, fixed local colour map bug
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# 1997-02-23 fl Make sure to load raster data in getdata()
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# 1997-07-05 fl Support external decoder (0.4)
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# 1998-07-09 fl Handle all modes when saving (0.5)
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# 1998-07-15 fl Renamed offset attribute to avoid name clash
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# 2001-04-16 fl Added rewind support (seek to frame 0) (0.6)
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# 2001-04-17 fl Added palette optimization (0.7)
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# 2002-06-06 fl Added transparency support for save (0.8)
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# 2004-02-24 fl Disable interlacing for small images
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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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import itertools
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import math
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import os
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import subprocess
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from enum import IntEnum
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from . import Image, ImageChops, ImageFile, ImagePalette, ImageSequence
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from ._binary import i16le as i16
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from ._binary import o8
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from ._binary import o16le as o16
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class LoadingStrategy(IntEnum):
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""".. versionadded:: 9.1.0"""
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RGB_AFTER_FIRST = 0
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RGB_AFTER_DIFFERENT_PALETTE_ONLY = 1
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RGB_ALWAYS = 2
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#: .. versionadded:: 9.1.0
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LOADING_STRATEGY = LoadingStrategy.RGB_AFTER_FIRST
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# --------------------------------------------------------------------
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# Identify/read GIF files
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def _accept(prefix):
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return prefix[:6] in [b"GIF87a", b"GIF89a"]
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##
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# Image plugin for GIF images. This plugin supports both GIF87 and
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# GIF89 images.
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class GifImageFile(ImageFile.ImageFile):
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format = "GIF"
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format_description = "Compuserve GIF"
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_close_exclusive_fp_after_loading = False
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global_palette = None
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def data(self):
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s = self.fp.read(1)
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if s and s[0]:
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return self.fp.read(s[0])
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return None
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def _is_palette_needed(self, p):
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for i in range(0, len(p), 3):
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if not (i // 3 == p[i] == p[i + 1] == p[i + 2]):
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return True
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return False
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def _open(self):
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# Screen
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s = self.fp.read(13)
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if not _accept(s):
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raise SyntaxError("not a GIF file")
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self.info["version"] = s[:6]
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self._size = i16(s, 6), i16(s, 8)
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self.tile = []
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flags = s[10]
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bits = (flags & 7) + 1
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if flags & 128:
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# get global palette
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self.info["background"] = s[11]
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# check if palette contains colour indices
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p = self.fp.read(3 << bits)
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if self._is_palette_needed(p):
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p = ImagePalette.raw("RGB", p)
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self.global_palette = self.palette = p
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self.__fp = self.fp # FIXME: hack
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self.__rewind = self.fp.tell()
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self._n_frames = None
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self._is_animated = None
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self._seek(0) # get ready to read first frame
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@property
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def n_frames(self):
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if self._n_frames is None:
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current = self.tell()
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try:
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while True:
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self._seek(self.tell() + 1, False)
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except EOFError:
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self._n_frames = self.tell() + 1
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self.seek(current)
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return self._n_frames
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@property
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def is_animated(self):
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if self._is_animated is None:
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if self._n_frames is not None:
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self._is_animated = self._n_frames != 1
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else:
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current = self.tell()
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if current:
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self._is_animated = True
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else:
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try:
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self._seek(1, False)
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self._is_animated = True
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except EOFError:
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self._is_animated = False
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self.seek(current)
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return self._is_animated
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def seek(self, frame):
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if not self._seek_check(frame):
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return
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if frame < self.__frame:
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self.im = None
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self._seek(0)
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last_frame = self.__frame
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for f in range(self.__frame + 1, frame + 1):
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try:
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self._seek(f)
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except EOFError as e:
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self.seek(last_frame)
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raise EOFError("no more images in GIF file") from e
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def _seek(self, frame, update_image=True):
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if frame == 0:
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# rewind
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self.__offset = 0
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self.dispose = None
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self.__frame = -1
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self.__fp.seek(self.__rewind)
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self.disposal_method = 0
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else:
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# ensure that the previous frame was loaded
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if self.tile and update_image:
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self.load()
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if frame != self.__frame + 1:
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raise ValueError(f"cannot seek to frame {frame}")
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self.fp = self.__fp
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if self.__offset:
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# backup to last frame
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self.fp.seek(self.__offset)
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while self.data():
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pass
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self.__offset = 0
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s = self.fp.read(1)
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if not s or s == b";":
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raise EOFError
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self.__frame = frame
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self.tile = []
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palette = None
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info = {}
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frame_transparency = None
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interlace = None
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frame_dispose_extent = None
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while True:
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if not s:
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s = self.fp.read(1)
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if not s or s == b";":
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break
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elif s == b"!":
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#
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# extensions
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#
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s = self.fp.read(1)
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block = self.data()
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if s[0] == 249:
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#
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# graphic control extension
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#
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flags = block[0]
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if flags & 1:
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frame_transparency = block[3]
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info["duration"] = i16(block, 1) * 10
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# disposal method - find the value of bits 4 - 6
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dispose_bits = 0b00011100 & flags
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dispose_bits = dispose_bits >> 2
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if dispose_bits:
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# only set the dispose if it is not
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# unspecified. I'm not sure if this is
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# correct, but it seems to prevent the last
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# frame from looking odd for some animations
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self.disposal_method = dispose_bits
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elif s[0] == 254:
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#
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# comment extension
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#
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while block:
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if "comment" in info:
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info["comment"] += block
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else:
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info["comment"] = block
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block = self.data()
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s = None
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continue
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elif s[0] == 255:
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#
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# application extension
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#
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info["extension"] = block, self.fp.tell()
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if block[:11] == b"NETSCAPE2.0":
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block = self.data()
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if len(block) >= 3 and block[0] == 1:
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info["loop"] = i16(block, 1)
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while self.data():
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pass
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elif s == b",":
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#
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# local image
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#
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s = self.fp.read(9)
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# extent
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x0, y0 = i16(s, 0), i16(s, 2)
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x1, y1 = x0 + i16(s, 4), y0 + i16(s, 6)
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if (x1 > self.size[0] or y1 > self.size[1]) and update_image:
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self._size = max(x1, self.size[0]), max(y1, self.size[1])
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frame_dispose_extent = x0, y0, x1, y1
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flags = s[8]
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interlace = (flags & 64) != 0
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if flags & 128:
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bits = (flags & 7) + 1
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p = self.fp.read(3 << bits)
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if self._is_palette_needed(p):
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palette = ImagePalette.raw("RGB", p)
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# image data
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bits = self.fp.read(1)[0]
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self.__offset = self.fp.tell()
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break
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else:
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pass
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# raise OSError, "illegal GIF tag `%x`" % s[0]
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s = None
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if interlace is None:
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# self.__fp = None
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raise EOFError
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if not update_image:
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return
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if self.dispose:
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self.im.paste(self.dispose, self.dispose_extent)
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self._frame_palette = palette or self.global_palette
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if frame == 0:
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if self._frame_palette:
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self.mode = (
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"RGB" if LOADING_STRATEGY == LoadingStrategy.RGB_ALWAYS else "P"
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)
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else:
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self.mode = "L"
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if not palette and self.global_palette:
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from copy import copy
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palette = copy(self.global_palette)
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self.palette = palette
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else:
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self._frame_transparency = frame_transparency
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if self.mode == "P":
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if (
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LOADING_STRATEGY != LoadingStrategy.RGB_AFTER_DIFFERENT_PALETTE_ONLY
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or palette
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):
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self.pyaccess = None
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if "transparency" in self.info:
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self.im.putpalettealpha(self.info["transparency"], 0)
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self.im = self.im.convert("RGBA", Image.Dither.FLOYDSTEINBERG)
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self.mode = "RGBA"
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del self.info["transparency"]
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else:
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self.mode = "RGB"
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self.im = self.im.convert("RGB", Image.Dither.FLOYDSTEINBERG)
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def _rgb(color):
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if self._frame_palette:
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color = tuple(self._frame_palette.palette[color * 3 : color * 3 + 3])
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else:
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color = (color, color, color)
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return color
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self.dispose_extent = frame_dispose_extent
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try:
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if self.disposal_method < 2:
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# do not dispose or none specified
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self.dispose = None
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elif self.disposal_method == 2:
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# replace with background colour
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# only dispose the extent in this frame
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x0, y0, x1, y1 = self.dispose_extent
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dispose_size = (x1 - x0, y1 - y0)
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Image._decompression_bomb_check(dispose_size)
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# by convention, attempt to use transparency first
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dispose_mode = "P"
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color = self.info.get("transparency", frame_transparency)
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if color is not None:
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if self.mode in ("RGB", "RGBA"):
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dispose_mode = "RGBA"
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color = _rgb(color) + (0,)
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else:
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color = self.info.get("background", 0)
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if self.mode in ("RGB", "RGBA"):
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dispose_mode = "RGB"
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color = _rgb(color)
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self.dispose = Image.core.fill(dispose_mode, dispose_size, color)
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else:
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# replace with previous contents
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if self.im is not None:
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# only dispose the extent in this frame
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self.dispose = self._crop(self.im, self.dispose_extent)
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elif frame_transparency is not None:
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x0, y0, x1, y1 = self.dispose_extent
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dispose_size = (x1 - x0, y1 - y0)
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Image._decompression_bomb_check(dispose_size)
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dispose_mode = "P"
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color = frame_transparency
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if self.mode in ("RGB", "RGBA"):
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dispose_mode = "RGBA"
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color = _rgb(frame_transparency) + (0,)
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self.dispose = Image.core.fill(dispose_mode, dispose_size, color)
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except AttributeError:
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pass
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if interlace is not None:
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transparency = -1
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if frame_transparency is not None:
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if frame == 0:
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self.info["transparency"] = frame_transparency
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elif self.mode not in ("RGB", "RGBA"):
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transparency = frame_transparency
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self.tile = [
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(
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"gif",
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(x0, y0, x1, y1),
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self.__offset,
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(bits, interlace, transparency),
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)
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]
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for k in ["duration", "comment", "extension", "loop"]:
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if k in info:
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self.info[k] = info[k]
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elif k in self.info:
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del self.info[k]
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def load_prepare(self):
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temp_mode = "P" if self._frame_palette else "L"
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self._prev_im = None
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if self.__frame == 0:
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if "transparency" in self.info:
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self.im = Image.core.fill(
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temp_mode, self.size, self.info["transparency"]
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)
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elif self.mode in ("RGB", "RGBA"):
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self._prev_im = self.im
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if self._frame_palette:
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self.im = Image.core.fill("P", self.size, self._frame_transparency or 0)
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self.im.putpalette(*self._frame_palette.getdata())
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else:
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self.im = None
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self.mode = temp_mode
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self._frame_palette = None
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super().load_prepare()
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def load_end(self):
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if self.__frame == 0:
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if self.mode == "P" and LOADING_STRATEGY == LoadingStrategy.RGB_ALWAYS:
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self.mode = "RGB"
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self.im = self.im.convert("RGB", Image.Dither.FLOYDSTEINBERG)
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return
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if self.mode == "P" and self._prev_im:
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if self._frame_transparency is not None:
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self.im.putpalettealpha(self._frame_transparency, 0)
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frame_im = self.im.convert("RGBA")
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else:
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frame_im = self.im.convert("RGB")
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else:
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if not self._prev_im:
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return
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frame_im = self.im
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frame_im = self._crop(frame_im, self.dispose_extent)
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self.im = self._prev_im
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self.mode = self.im.mode
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if frame_im.mode == "RGBA":
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self.im.paste(frame_im, self.dispose_extent, frame_im)
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else:
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self.im.paste(frame_im, self.dispose_extent)
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def tell(self):
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return self.__frame
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def _close__fp(self):
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try:
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if self.__fp != self.fp:
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self.__fp.close()
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except AttributeError:
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pass
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finally:
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self.__fp = None
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# --------------------------------------------------------------------
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# Write GIF files
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RAWMODE = {"1": "L", "L": "L", "P": "P"}
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def _normalize_mode(im):
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"""
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Takes an image (or frame), returns an image in a mode that is appropriate
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for saving in a Gif.
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It may return the original image, or it may return an image converted to
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palette or 'L' mode.
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:param im: Image object
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:returns: Image object
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"""
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if im.mode in RAWMODE:
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im.load()
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return im
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if Image.getmodebase(im.mode) == "RGB":
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im = im.convert("P", palette=Image.Palette.ADAPTIVE)
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if im.palette.mode == "RGBA":
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for rgba in im.palette.colors.keys():
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if rgba[3] == 0:
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im.info["transparency"] = im.palette.colors[rgba]
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break
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return im
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return im.convert("L")
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def _normalize_palette(im, palette, info):
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"""
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Normalizes the palette for image.
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- Sets the palette to the incoming palette, if provided.
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- Ensures that there's a palette for L mode images
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- Optimizes the palette if necessary/desired.
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:param im: Image object
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:param palette: bytes object containing the source palette, or ....
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:param info: encoderinfo
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:returns: Image object
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"""
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source_palette = None
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if palette:
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# a bytes palette
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if isinstance(palette, (bytes, bytearray, list)):
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source_palette = bytearray(palette[:768])
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if isinstance(palette, ImagePalette.ImagePalette):
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source_palette = bytearray(palette.palette)
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|
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if im.mode == "P":
|
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if not source_palette:
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source_palette = im.im.getpalette("RGB")[:768]
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else: # L-mode
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if not source_palette:
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source_palette = bytearray(i // 3 for i in range(768))
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im.palette = ImagePalette.ImagePalette("RGB", palette=source_palette)
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if palette:
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used_palette_colors = []
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for i in range(0, len(source_palette), 3):
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source_color = tuple(source_palette[i : i + 3])
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try:
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index = im.palette.colors[source_color]
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except KeyError:
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index = None
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used_palette_colors.append(index)
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for i, index in enumerate(used_palette_colors):
|
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if index is None:
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for j in range(len(used_palette_colors)):
|
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if j not in used_palette_colors:
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used_palette_colors[i] = j
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break
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im = im.remap_palette(used_palette_colors)
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else:
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used_palette_colors = _get_optimize(im, info)
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if used_palette_colors is not None:
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return im.remap_palette(used_palette_colors, source_palette)
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|
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im.palette.palette = source_palette
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return im
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|
|
|
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def _write_single_frame(im, fp, palette):
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im_out = _normalize_mode(im)
|
|
for k, v in im_out.info.items():
|
|
im.encoderinfo.setdefault(k, v)
|
|
im_out = _normalize_palette(im_out, palette, im.encoderinfo)
|
|
|
|
for s in _get_global_header(im_out, im.encoderinfo):
|
|
fp.write(s)
|
|
|
|
# local image header
|
|
flags = 0
|
|
if get_interlace(im):
|
|
flags = flags | 64
|
|
_write_local_header(fp, im, (0, 0), flags)
|
|
|
|
im_out.encoderconfig = (8, get_interlace(im))
|
|
ImageFile._save(im_out, fp, [("gif", (0, 0) + im.size, 0, RAWMODE[im_out.mode])])
|
|
|
|
fp.write(b"\0") # end of image data
|
|
|
|
|
|
def _write_multiple_frames(im, fp, palette):
|
|
|
|
duration = im.encoderinfo.get("duration", im.info.get("duration"))
|
|
disposal = im.encoderinfo.get("disposal", im.info.get("disposal"))
|
|
|
|
im_frames = []
|
|
frame_count = 0
|
|
background_im = None
|
|
for imSequence in itertools.chain([im], im.encoderinfo.get("append_images", [])):
|
|
for im_frame in ImageSequence.Iterator(imSequence):
|
|
# a copy is required here since seek can still mutate the image
|
|
im_frame = _normalize_mode(im_frame.copy())
|
|
if frame_count == 0:
|
|
for k, v in im_frame.info.items():
|
|
im.encoderinfo.setdefault(k, v)
|
|
im_frame = _normalize_palette(im_frame, palette, im.encoderinfo)
|
|
|
|
encoderinfo = im.encoderinfo.copy()
|
|
if isinstance(duration, (list, tuple)):
|
|
encoderinfo["duration"] = duration[frame_count]
|
|
if isinstance(disposal, (list, tuple)):
|
|
encoderinfo["disposal"] = disposal[frame_count]
|
|
frame_count += 1
|
|
|
|
if im_frames:
|
|
# delta frame
|
|
previous = im_frames[-1]
|
|
if encoderinfo.get("disposal") == 2:
|
|
if background_im is None:
|
|
color = im.encoderinfo.get(
|
|
"transparency", im.info.get("transparency", (0, 0, 0))
|
|
)
|
|
background = _get_background(im_frame, color)
|
|
background_im = Image.new("P", im_frame.size, background)
|
|
background_im.putpalette(im_frames[0]["im"].palette)
|
|
base_im = background_im
|
|
else:
|
|
base_im = previous["im"]
|
|
if _get_palette_bytes(im_frame) == _get_palette_bytes(base_im):
|
|
delta = ImageChops.subtract_modulo(im_frame, base_im)
|
|
else:
|
|
delta = ImageChops.subtract_modulo(
|
|
im_frame.convert("RGB"), base_im.convert("RGB")
|
|
)
|
|
bbox = delta.getbbox()
|
|
if not bbox:
|
|
# This frame is identical to the previous frame
|
|
if duration:
|
|
previous["encoderinfo"]["duration"] += encoderinfo["duration"]
|
|
continue
|
|
else:
|
|
bbox = None
|
|
im_frames.append({"im": im_frame, "bbox": bbox, "encoderinfo": encoderinfo})
|
|
|
|
if len(im_frames) > 1:
|
|
for frame_data in im_frames:
|
|
im_frame = frame_data["im"]
|
|
if not frame_data["bbox"]:
|
|
# global header
|
|
for s in _get_global_header(im_frame, frame_data["encoderinfo"]):
|
|
fp.write(s)
|
|
offset = (0, 0)
|
|
else:
|
|
# compress difference
|
|
if not palette:
|
|
frame_data["encoderinfo"]["include_color_table"] = True
|
|
|
|
im_frame = im_frame.crop(frame_data["bbox"])
|
|
offset = frame_data["bbox"][:2]
|
|
_write_frame_data(fp, im_frame, offset, frame_data["encoderinfo"])
|
|
return True
|
|
elif "duration" in im.encoderinfo and isinstance(
|
|
im.encoderinfo["duration"], (list, tuple)
|
|
):
|
|
# Since multiple frames will not be written, add together the frame durations
|
|
im.encoderinfo["duration"] = sum(im.encoderinfo["duration"])
|
|
|
|
|
|
def _save_all(im, fp, filename):
|
|
_save(im, fp, filename, save_all=True)
|
|
|
|
|
|
def _save(im, fp, filename, save_all=False):
|
|
# header
|
|
if "palette" in im.encoderinfo or "palette" in im.info:
|
|
palette = im.encoderinfo.get("palette", im.info.get("palette"))
|
|
else:
|
|
palette = None
|
|
im.encoderinfo["optimize"] = im.encoderinfo.get("optimize", True)
|
|
|
|
if not save_all or not _write_multiple_frames(im, fp, palette):
|
|
_write_single_frame(im, fp, palette)
|
|
|
|
fp.write(b";") # end of file
|
|
|
|
if hasattr(fp, "flush"):
|
|
fp.flush()
|
|
|
|
|
|
def get_interlace(im):
|
|
interlace = im.encoderinfo.get("interlace", 1)
|
|
|
|
# workaround for @PIL153
|
|
if min(im.size) < 16:
|
|
interlace = 0
|
|
|
|
return interlace
|
|
|
|
|
|
def _write_local_header(fp, im, offset, flags):
|
|
transparent_color_exists = False
|
|
try:
|
|
if "transparency" in im.encoderinfo:
|
|
transparency = im.encoderinfo["transparency"]
|
|
else:
|
|
transparency = im.info["transparency"]
|
|
transparency = int(transparency)
|
|
except (KeyError, ValueError):
|
|
pass
|
|
else:
|
|
# optimize the block away if transparent color is not used
|
|
transparent_color_exists = True
|
|
|
|
used_palette_colors = _get_optimize(im, im.encoderinfo)
|
|
if used_palette_colors is not None:
|
|
# adjust the transparency index after optimize
|
|
try:
|
|
transparency = used_palette_colors.index(transparency)
|
|
except ValueError:
|
|
transparent_color_exists = False
|
|
|
|
if "duration" in im.encoderinfo:
|
|
duration = int(im.encoderinfo["duration"] / 10)
|
|
else:
|
|
duration = 0
|
|
|
|
disposal = int(im.encoderinfo.get("disposal", 0))
|
|
|
|
if transparent_color_exists or duration != 0 or disposal:
|
|
packed_flag = 1 if transparent_color_exists else 0
|
|
packed_flag |= disposal << 2
|
|
if not transparent_color_exists:
|
|
transparency = 0
|
|
|
|
fp.write(
|
|
b"!"
|
|
+ o8(249) # extension intro
|
|
+ o8(4) # length
|
|
+ o8(packed_flag) # packed fields
|
|
+ o16(duration) # duration
|
|
+ o8(transparency) # transparency index
|
|
+ o8(0)
|
|
)
|
|
|
|
if "comment" in im.encoderinfo and 1 <= len(im.encoderinfo["comment"]):
|
|
fp.write(b"!" + o8(254)) # extension intro
|
|
comment = im.encoderinfo["comment"]
|
|
if isinstance(comment, str):
|
|
comment = comment.encode()
|
|
for i in range(0, len(comment), 255):
|
|
subblock = comment[i : i + 255]
|
|
fp.write(o8(len(subblock)) + subblock)
|
|
fp.write(o8(0))
|
|
if "loop" in im.encoderinfo:
|
|
number_of_loops = im.encoderinfo["loop"]
|
|
fp.write(
|
|
b"!"
|
|
+ o8(255) # extension intro
|
|
+ o8(11)
|
|
+ b"NETSCAPE2.0"
|
|
+ o8(3)
|
|
+ o8(1)
|
|
+ o16(number_of_loops) # number of loops
|
|
+ o8(0)
|
|
)
|
|
include_color_table = im.encoderinfo.get("include_color_table")
|
|
if include_color_table:
|
|
palette_bytes = _get_palette_bytes(im)
|
|
color_table_size = _get_color_table_size(palette_bytes)
|
|
if color_table_size:
|
|
flags = flags | 128 # local color table flag
|
|
flags = flags | color_table_size
|
|
|
|
fp.write(
|
|
b","
|
|
+ o16(offset[0]) # offset
|
|
+ o16(offset[1])
|
|
+ o16(im.size[0]) # size
|
|
+ o16(im.size[1])
|
|
+ o8(flags) # flags
|
|
)
|
|
if include_color_table and color_table_size:
|
|
fp.write(_get_header_palette(palette_bytes))
|
|
fp.write(o8(8)) # bits
|
|
|
|
|
|
def _save_netpbm(im, fp, filename):
|
|
|
|
# Unused by default.
|
|
# To use, uncomment the register_save call at the end of the file.
|
|
#
|
|
# If you need real GIF compression and/or RGB quantization, you
|
|
# can use the external NETPBM/PBMPLUS utilities. See comments
|
|
# below for information on how to enable this.
|
|
tempfile = im._dump()
|
|
|
|
try:
|
|
with open(filename, "wb") as f:
|
|
if im.mode != "RGB":
|
|
subprocess.check_call(
|
|
["ppmtogif", tempfile], stdout=f, stderr=subprocess.DEVNULL
|
|
)
|
|
else:
|
|
# Pipe ppmquant output into ppmtogif
|
|
# "ppmquant 256 %s | ppmtogif > %s" % (tempfile, filename)
|
|
quant_cmd = ["ppmquant", "256", tempfile]
|
|
togif_cmd = ["ppmtogif"]
|
|
quant_proc = subprocess.Popen(
|
|
quant_cmd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL
|
|
)
|
|
togif_proc = subprocess.Popen(
|
|
togif_cmd,
|
|
stdin=quant_proc.stdout,
|
|
stdout=f,
|
|
stderr=subprocess.DEVNULL,
|
|
)
|
|
|
|
# Allow ppmquant to receive SIGPIPE if ppmtogif exits
|
|
quant_proc.stdout.close()
|
|
|
|
retcode = quant_proc.wait()
|
|
if retcode:
|
|
raise subprocess.CalledProcessError(retcode, quant_cmd)
|
|
|
|
retcode = togif_proc.wait()
|
|
if retcode:
|
|
raise subprocess.CalledProcessError(retcode, togif_cmd)
|
|
finally:
|
|
try:
|
|
os.unlink(tempfile)
|
|
except OSError:
|
|
pass
|
|
|
|
|
|
# Force optimization so that we can test performance against
|
|
# cases where it took lots of memory and time previously.
|
|
_FORCE_OPTIMIZE = False
|
|
|
|
|
|
def _get_optimize(im, info):
|
|
"""
|
|
Palette optimization is a potentially expensive operation.
|
|
|
|
This function determines if the palette should be optimized using
|
|
some heuristics, then returns the list of palette entries in use.
|
|
|
|
:param im: Image object
|
|
:param info: encoderinfo
|
|
:returns: list of indexes of palette entries in use, or None
|
|
"""
|
|
if im.mode in ("P", "L") and info and info.get("optimize", 0):
|
|
# Potentially expensive operation.
|
|
|
|
# The palette saves 3 bytes per color not used, but palette
|
|
# lengths are restricted to 3*(2**N) bytes. Max saving would
|
|
# be 768 -> 6 bytes if we went all the way down to 2 colors.
|
|
# * If we're over 128 colors, we can't save any space.
|
|
# * If there aren't any holes, it's not worth collapsing.
|
|
# * If we have a 'large' image, the palette is in the noise.
|
|
|
|
# create the new palette if not every color is used
|
|
optimise = _FORCE_OPTIMIZE or im.mode == "L"
|
|
if optimise or im.width * im.height < 512 * 512:
|
|
# check which colors are used
|
|
used_palette_colors = []
|
|
for i, count in enumerate(im.histogram()):
|
|
if count:
|
|
used_palette_colors.append(i)
|
|
|
|
if optimise or (
|
|
len(used_palette_colors) <= 128
|
|
and max(used_palette_colors) > len(used_palette_colors)
|
|
):
|
|
return used_palette_colors
|
|
|
|
|
|
def _get_color_table_size(palette_bytes):
|
|
# calculate the palette size for the header
|
|
if not palette_bytes:
|
|
return 0
|
|
elif len(palette_bytes) < 9:
|
|
return 1
|
|
else:
|
|
return math.ceil(math.log(len(palette_bytes) // 3, 2)) - 1
|
|
|
|
|
|
def _get_header_palette(palette_bytes):
|
|
"""
|
|
Returns the palette, null padded to the next power of 2 (*3) bytes
|
|
suitable for direct inclusion in the GIF header
|
|
|
|
:param palette_bytes: Unpadded palette bytes, in RGBRGB form
|
|
:returns: Null padded palette
|
|
"""
|
|
color_table_size = _get_color_table_size(palette_bytes)
|
|
|
|
# add the missing amount of bytes
|
|
# the palette has to be 2<<n in size
|
|
actual_target_size_diff = (2 << color_table_size) - len(palette_bytes) // 3
|
|
if actual_target_size_diff > 0:
|
|
palette_bytes += o8(0) * 3 * actual_target_size_diff
|
|
return palette_bytes
|
|
|
|
|
|
def _get_palette_bytes(im):
|
|
"""
|
|
Gets the palette for inclusion in the gif header
|
|
|
|
:param im: Image object
|
|
:returns: Bytes, len<=768 suitable for inclusion in gif header
|
|
"""
|
|
return im.palette.palette
|
|
|
|
|
|
def _get_background(im, info_background):
|
|
background = 0
|
|
if info_background:
|
|
background = info_background
|
|
if isinstance(background, tuple):
|
|
# WebPImagePlugin stores an RGBA value in info["background"]
|
|
# So it must be converted to the same format as GifImagePlugin's
|
|
# info["background"] - a global color table index
|
|
try:
|
|
background = im.palette.getcolor(background, im)
|
|
except ValueError as e:
|
|
if str(e) == "cannot allocate more than 256 colors":
|
|
# If all 256 colors are in use,
|
|
# then there is no need for the background color
|
|
return 0
|
|
else:
|
|
raise
|
|
return background
|
|
|
|
|
|
def _get_global_header(im, info):
|
|
"""Return a list of strings representing a GIF header"""
|
|
|
|
# Header Block
|
|
# https://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
|
|
|
|
version = b"87a"
|
|
for extensionKey in ["transparency", "duration", "loop", "comment"]:
|
|
if info and extensionKey in info:
|
|
if (extensionKey == "duration" and info[extensionKey] == 0) or (
|
|
extensionKey == "comment" and not (1 <= len(info[extensionKey]) <= 255)
|
|
):
|
|
continue
|
|
version = b"89a"
|
|
break
|
|
else:
|
|
if im.info.get("version") == b"89a":
|
|
version = b"89a"
|
|
|
|
background = _get_background(im, info.get("background"))
|
|
|
|
palette_bytes = _get_palette_bytes(im)
|
|
color_table_size = _get_color_table_size(palette_bytes)
|
|
|
|
return [
|
|
b"GIF" # signature
|
|
+ version # version
|
|
+ o16(im.size[0]) # canvas width
|
|
+ o16(im.size[1]), # canvas height
|
|
# Logical Screen Descriptor
|
|
# size of global color table + global color table flag
|
|
o8(color_table_size + 128), # packed fields
|
|
# background + reserved/aspect
|
|
o8(background) + o8(0),
|
|
# Global Color Table
|
|
_get_header_palette(palette_bytes),
|
|
]
|
|
|
|
|
|
def _write_frame_data(fp, im_frame, offset, params):
|
|
try:
|
|
im_frame.encoderinfo = params
|
|
|
|
# local image header
|
|
_write_local_header(fp, im_frame, offset, 0)
|
|
|
|
ImageFile._save(
|
|
im_frame, fp, [("gif", (0, 0) + im_frame.size, 0, RAWMODE[im_frame.mode])]
|
|
)
|
|
|
|
fp.write(b"\0") # end of image data
|
|
finally:
|
|
del im_frame.encoderinfo
|
|
|
|
|
|
# --------------------------------------------------------------------
|
|
# Legacy GIF utilities
|
|
|
|
|
|
def getheader(im, palette=None, info=None):
|
|
"""
|
|
Legacy Method to get Gif data from image.
|
|
|
|
Warning:: May modify image data.
|
|
|
|
:param im: Image object
|
|
:param palette: bytes object containing the source palette, or ....
|
|
:param info: encoderinfo
|
|
:returns: tuple of(list of header items, optimized palette)
|
|
|
|
"""
|
|
used_palette_colors = _get_optimize(im, info)
|
|
|
|
if info is None:
|
|
info = {}
|
|
|
|
if "background" not in info and "background" in im.info:
|
|
info["background"] = im.info["background"]
|
|
|
|
im_mod = _normalize_palette(im, palette, info)
|
|
im.palette = im_mod.palette
|
|
im.im = im_mod.im
|
|
header = _get_global_header(im, info)
|
|
|
|
return header, used_palette_colors
|
|
|
|
|
|
def getdata(im, offset=(0, 0), **params):
|
|
"""
|
|
Legacy Method
|
|
|
|
Return a list of strings representing this image.
|
|
The first string is a local image header, the rest contains
|
|
encoded image data.
|
|
|
|
To specify duration, add the time in milliseconds,
|
|
e.g. ``getdata(im_frame, duration=1000)``
|
|
|
|
:param im: Image object
|
|
:param offset: Tuple of (x, y) pixels. Defaults to (0, 0)
|
|
:param \\**params: e.g. duration or other encoder info parameters
|
|
:returns: List of bytes containing GIF encoded frame data
|
|
|
|
"""
|
|
|
|
class Collector:
|
|
data = []
|
|
|
|
def write(self, data):
|
|
self.data.append(data)
|
|
|
|
im.load() # make sure raster data is available
|
|
|
|
fp = Collector()
|
|
|
|
_write_frame_data(fp, im, offset, params)
|
|
|
|
return fp.data
|
|
|
|
|
|
# --------------------------------------------------------------------
|
|
# Registry
|
|
|
|
Image.register_open(GifImageFile.format, GifImageFile, _accept)
|
|
Image.register_save(GifImageFile.format, _save)
|
|
Image.register_save_all(GifImageFile.format, _save_all)
|
|
Image.register_extension(GifImageFile.format, ".gif")
|
|
Image.register_mime(GifImageFile.format, "image/gif")
|
|
|
|
#
|
|
# Uncomment the following line if you wish to use NETPBM/PBMPLUS
|
|
# instead of the built-in "uncompressed" GIF encoder
|
|
|
|
# Image.register_save(GifImageFile.format, _save_netpbm)
|