825 lines
26 KiB
Python
825 lines
26 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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from . import Image, ImageFile, ImagePalette, ImageChops, ImageSequence
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from ._binary import i8, i16le as i16, o8, o16le as o16
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import itertools
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__version__ = "0.9"
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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 i8(s):
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return self.fp.read(i8(s))
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return None
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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 s[:6] not in [b"GIF87a", b"GIF89a"]:
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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 = i8(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"] = i8(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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for i in range(0, len(p), 3):
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if not (i//3 == i8(p[i]) == i8(p[i+1]) == i8(p[i+2])):
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p = ImagePalette.raw("RGB", p)
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self.global_palette = self.palette = p
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break
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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)
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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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try:
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self.seek(1)
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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._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:
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self.seek(last_frame)
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raise EOFError("no more images in GIF file")
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def _seek(self, frame):
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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.dispose_extent = [0, 0, 0, 0] # x0, y0, x1, y1
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self.__frame = -1
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self.__fp.seek(self.__rewind)
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self._prev_im = None
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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 not self.im:
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self.load()
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if frame != self.__frame + 1:
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raise ValueError("cannot seek to frame %d" % frame)
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self.__frame = frame
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self.tile = []
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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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if self.dispose:
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self.im.paste(self.dispose, self.dispose_extent)
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from copy import copy
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self.palette = copy(self.global_palette)
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info = {}
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while True:
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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 i8(s) == 249:
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#
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# graphic control extension
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#
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flags = i8(block[0])
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if flags & 1:
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info["transparency"] = i8(block[3])
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info["duration"] = i16(block[1:3]) * 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 i8(s) == 254:
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#
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# comment extension
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#
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info["comment"] = block
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elif i8(s) == 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 i8(block[0]) == 1:
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info["loop"] = i16(block[1:3])
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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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self.dispose_extent = x0, y0, x1, y1
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flags = i8(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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self.palette =\
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ImagePalette.raw("RGB", self.fp.read(3 << bits))
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# image data
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bits = i8(self.fp.read(1))
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self.__offset = self.fp.tell()
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self.tile = [("gif",
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(x0, y0, x1, y1),
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self.__offset,
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(bits, interlace))]
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break
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else:
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pass
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# raise IOError, "illegal GIF tag `%x`" % i8(s)
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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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self.dispose = Image.core.fill("P", self.size,
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self.info["background"])
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else:
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# replace with previous contents
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if self.im:
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self.dispose = self.im.copy()
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# only dispose the extent in this frame
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if self.dispose:
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self.dispose = self._crop(self.dispose, self.dispose_extent)
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except (AttributeError, KeyError):
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pass
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if not self.tile:
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# self.__fp = None
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raise EOFError
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for k in ["transparency", "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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self.mode = "L"
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if self.palette:
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self.mode = "P"
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def tell(self):
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return self.__frame
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def load_end(self):
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ImageFile.ImageFile.load_end(self)
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# if the disposal method is 'do not dispose', transparent
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# pixels should show the content of the previous frame
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if self._prev_im and self.disposal_method == 1:
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# we do this by pasting the updated area onto the previous
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# frame which we then use as the current image content
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updated = self._crop(self.im, self.dispose_extent)
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self._prev_im.paste(updated, self.dispose_extent,
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updated.convert('RGBA'))
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self.im = self._prev_im
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self._prev_im = self.im.copy()
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# --------------------------------------------------------------------
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# Write GIF files
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RAWMODE = {
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"1": "L",
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"L": "L",
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"P": "P"
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}
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def _normalize_mode(im, initial_call=False):
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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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UNDONE: What is the point of mucking with the initial call palette, for
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an image that shouldn't have a palette, or it would be a mode 'P' and
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get returned in the RAWMODE clause.
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:param im: Image object
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:param initial_call: Default false, set to true for a single frame.
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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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if initial_call:
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palette_size = 256
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if im.palette:
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palette_size = len(im.palette.getdata()[1]) // 3
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return im.convert("P", palette=Image.ADAPTIVE, colors=palette_size)
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else:
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return im.convert("P")
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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(itertools.chain.from_iterable(
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zip(palette.palette[:256],
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palette.palette[256:512],
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palette.palette[512:768])))
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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",
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palette=source_palette)
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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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im.palette.palette = source_palette
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return im
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def _write_single_frame(im, fp, palette):
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im_out = _normalize_mode(im, True)
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im_out = _normalize_palette(im_out, palette, im.encoderinfo)
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for s in _get_global_header(im_out, im.encoderinfo):
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fp.write(s)
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# local image header
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flags = 0
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if get_interlace(im):
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flags = flags | 64
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_write_local_header(fp, im, (0, 0), flags)
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im_out.encoderconfig = (8, get_interlace(im))
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ImageFile._save(im_out, fp, [("gif", (0, 0)+im.size, 0,
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RAWMODE[im_out.mode])])
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fp.write(b"\0") # end of image data
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def _write_multiple_frames(im, fp, palette):
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duration = im.encoderinfo.get("duration", None)
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disposal = im.encoderinfo.get('disposal', None)
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im_frames = []
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frame_count = 0
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for imSequence in itertools.chain([im],
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im.encoderinfo.get("append_images", [])):
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for im_frame in ImageSequence.Iterator(imSequence):
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# a copy is required here since seek can still mutate the image
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im_frame = _normalize_mode(im_frame.copy())
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im_frame = _normalize_palette(im_frame, palette, im.encoderinfo)
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encoderinfo = im.encoderinfo.copy()
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if isinstance(duration, (list, tuple)):
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encoderinfo['duration'] = duration[frame_count]
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if isinstance(disposal, (list, tuple)):
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encoderinfo["disposal"] = disposal[frame_count]
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frame_count += 1
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if im_frames:
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# delta frame
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previous = im_frames[-1]
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if _get_palette_bytes(im_frame) == \
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_get_palette_bytes(previous['im']):
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delta = ImageChops.subtract_modulo(im_frame,
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previous['im'])
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else:
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delta = ImageChops.subtract_modulo(
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im_frame.convert('RGB'), previous['im'].convert('RGB'))
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bbox = delta.getbbox()
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if not bbox:
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# This frame is identical to the previous frame
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if duration:
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previous['encoderinfo']['duration'] += \
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encoderinfo['duration']
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continue
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else:
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bbox = None
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im_frames.append({
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'im': im_frame,
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'bbox': bbox,
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'encoderinfo': encoderinfo
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})
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if len(im_frames) > 1:
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for frame_data in im_frames:
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im_frame = frame_data['im']
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if not frame_data['bbox']:
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# global header
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for s in _get_global_header(im_frame,
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frame_data['encoderinfo']):
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fp.write(s)
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offset = (0, 0)
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else:
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# compress difference
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frame_data['encoderinfo']['include_color_table'] = True
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im_frame = im_frame.crop(frame_data['bbox'])
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offset = frame_data['bbox'][:2]
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_write_frame_data(fp, im_frame, offset, frame_data['encoderinfo'])
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return True
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def _save_all(im, fp, filename):
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_save(im, fp, filename, save_all=True)
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def _save(im, fp, filename, save_all=False):
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for k, v in im.info.items():
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im.encoderinfo.setdefault(k, v)
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# header
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try:
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palette = im.encoderinfo["palette"]
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except KeyError:
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palette = None
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im.encoderinfo["optimize"] = im.encoderinfo.get("optimize", True)
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if not save_all or not _write_multiple_frames(im, fp, palette):
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_write_single_frame(im, fp, palette)
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fp.write(b";") # end of file
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if hasattr(fp, "flush"):
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fp.flush()
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def get_interlace(im):
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interlace = im.encoderinfo.get("interlace", 1)
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# workaround for @PIL153
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if min(im.size) < 16:
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interlace = 0
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return interlace
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def _write_local_header(fp, im, offset, flags):
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transparent_color_exists = False
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try:
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transparency = im.encoderinfo["transparency"]
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except KeyError:
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pass
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else:
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transparency = int(transparency)
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# optimize the block away if transparent color is not used
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transparent_color_exists = True
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used_palette_colors = _get_optimize(im, im.encoderinfo)
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if used_palette_colors is not None:
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# adjust the transparency index after optimize
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try:
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transparency = used_palette_colors.index(transparency)
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except ValueError:
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transparent_color_exists = False
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if "duration" in im.encoderinfo:
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duration = int(im.encoderinfo["duration"] / 10)
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else:
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duration = 0
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disposal = int(im.encoderinfo.get('disposal', 0))
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if transparent_color_exists or duration != 0 or disposal:
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packed_flag = 1 if transparent_color_exists else 0
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packed_flag |= disposal << 2
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if not transparent_color_exists:
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transparency = 0
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fp.write(b"!" +
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o8(249) + # extension intro
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o8(4) + # length
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o8(packed_flag) + # packed fields
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o16(duration) + # duration
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o8(transparency) + # transparency index
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o8(0))
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if "comment" in im.encoderinfo and \
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1 <= len(im.encoderinfo["comment"]) <= 255:
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fp.write(b"!" +
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o8(254) + # extension intro
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o8(len(im.encoderinfo["comment"])) +
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im.encoderinfo["comment"] +
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o8(0))
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if "loop" in im.encoderinfo:
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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.
|
|
|
|
import os
|
|
from subprocess import Popen, check_call, PIPE, CalledProcessError
|
|
file = im._dump()
|
|
|
|
with open(filename, 'wb') as f:
|
|
if im.mode != "RGB":
|
|
with open(os.devnull, 'wb') as devnull:
|
|
check_call(["ppmtogif", file], stdout=f, stderr=devnull)
|
|
else:
|
|
# Pipe ppmquant output into ppmtogif
|
|
# "ppmquant 256 %s | ppmtogif > %s" % (file, filename)
|
|
quant_cmd = ["ppmquant", "256", file]
|
|
togif_cmd = ["ppmtogif"]
|
|
with open(os.devnull, 'wb') as devnull:
|
|
quant_proc = Popen(quant_cmd, stdout=PIPE, stderr=devnull)
|
|
togif_proc = Popen(togif_cmd, stdin=quant_proc.stdout,
|
|
stdout=f, stderr=devnull)
|
|
|
|
# Allow ppmquant to receive SIGPIPE if ppmtogif exits
|
|
quant_proc.stdout.close()
|
|
|
|
retcode = quant_proc.wait()
|
|
if retcode:
|
|
raise CalledProcessError(retcode, quant_cmd)
|
|
|
|
retcode = togif_proc.wait()
|
|
if retcode:
|
|
raise CalledProcessError(retcode, togif_cmd)
|
|
|
|
try:
|
|
os.unlink(file)
|
|
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
|
|
import math
|
|
color_table_size = int(math.ceil(math.log(len(palette_bytes)//3, 2)))-1
|
|
if color_table_size < 0:
|
|
color_table_size = 0
|
|
return color_table_size
|
|
|
|
|
|
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_global_header(im, info):
|
|
"""Return a list of strings representing a GIF header"""
|
|
|
|
# Header Block
|
|
# http://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"
|
|
|
|
palette_bytes = _get_palette_bytes(im)
|
|
color_table_size = _get_color_table_size(palette_bytes)
|
|
|
|
background = info["background"] if "background" in info else 0
|
|
|
|
return [
|
|
b"GIF"+version + # signature + 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
|
|
|
|
|
|
# To specify duration, add the time in milliseconds to getdata(),
|
|
# e.g. getdata(im_frame, duration=1000)
|
|
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.
|
|
|
|
: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(object):
|
|
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)
|