545 lines
16 KiB
Python
545 lines
16 KiB
Python
#
|
|
# The Python Imaging Library.
|
|
# $Id$
|
|
#
|
|
# GIF file handling
|
|
#
|
|
# History:
|
|
# 1995-09-01 fl Created
|
|
# 1996-12-14 fl Added interlace support
|
|
# 1996-12-30 fl Added animation support
|
|
# 1997-01-05 fl Added write support, fixed local colour map bug
|
|
# 1997-02-23 fl Make sure to load raster data in getdata()
|
|
# 1997-07-05 fl Support external decoder (0.4)
|
|
# 1998-07-09 fl Handle all modes when saving (0.5)
|
|
# 1998-07-15 fl Renamed offset attribute to avoid name clash
|
|
# 2001-04-16 fl Added rewind support (seek to frame 0) (0.6)
|
|
# 2001-04-17 fl Added palette optimization (0.7)
|
|
# 2002-06-06 fl Added transparency support for save (0.8)
|
|
# 2004-02-24 fl Disable interlacing for small images
|
|
#
|
|
# Copyright (c) 1997-2004 by Secret Labs AB
|
|
# Copyright (c) 1995-2004 by Fredrik Lundh
|
|
#
|
|
# See the README file for information on usage and redistribution.
|
|
#
|
|
|
|
|
|
__version__ = "0.9"
|
|
|
|
|
|
from PIL import Image, ImageFile, ImagePalette, _binary
|
|
|
|
|
|
# --------------------------------------------------------------------
|
|
# Helpers
|
|
|
|
i8 = _binary.i8
|
|
i16 = _binary.i16le
|
|
o8 = _binary.o8
|
|
o16 = _binary.o16le
|
|
|
|
|
|
# --------------------------------------------------------------------
|
|
# Identify/read GIF files
|
|
|
|
def _accept(prefix):
|
|
return prefix[:6] in [b"GIF87a", b"GIF89a"]
|
|
|
|
|
|
##
|
|
# Image plugin for GIF images. This plugin supports both GIF87 and
|
|
# GIF89 images.
|
|
|
|
class GifImageFile(ImageFile.ImageFile):
|
|
|
|
format = "GIF"
|
|
format_description = "Compuserve GIF"
|
|
global_palette = None
|
|
|
|
def data(self):
|
|
s = self.fp.read(1)
|
|
if s and i8(s):
|
|
return self.fp.read(i8(s))
|
|
return None
|
|
|
|
def _open(self):
|
|
|
|
# Screen
|
|
s = self.fp.read(13)
|
|
if s[:6] not in [b"GIF87a", b"GIF89a"]:
|
|
raise SyntaxError("not a GIF file")
|
|
|
|
self.info["version"] = s[:6]
|
|
self.size = i16(s[6:]), i16(s[8:])
|
|
self.tile = []
|
|
flags = i8(s[10])
|
|
bits = (flags & 7) + 1
|
|
|
|
if flags & 128:
|
|
# get global palette
|
|
self.info["background"] = i8(s[11])
|
|
# check if palette contains colour indices
|
|
p = self.fp.read(3 << bits)
|
|
for i in range(0, len(p), 3):
|
|
if not (i//3 == i8(p[i]) == i8(p[i+1]) == i8(p[i+2])):
|
|
p = ImagePalette.raw("RGB", p)
|
|
self.global_palette = self.palette = p
|
|
break
|
|
|
|
self.__fp = self.fp # FIXME: hack
|
|
self.__rewind = self.fp.tell()
|
|
self.seek(0) # get ready to read first frame
|
|
|
|
def seek(self, frame):
|
|
|
|
if frame == 0:
|
|
# rewind
|
|
self.__offset = 0
|
|
self.dispose = None
|
|
self.dispose_extent = [0, 0, 0, 0] # x0, y0, x1, y1
|
|
self.__frame = -1
|
|
self.__fp.seek(self.__rewind)
|
|
self._prev_im = None
|
|
self.disposal_method = 0
|
|
else:
|
|
# ensure that the previous frame was loaded
|
|
if not self.im:
|
|
self.load()
|
|
|
|
if frame != self.__frame + 1:
|
|
raise ValueError("cannot seek to frame %d" % frame)
|
|
self.__frame = frame
|
|
|
|
self.tile = []
|
|
|
|
self.fp = self.__fp
|
|
if self.__offset:
|
|
# backup to last frame
|
|
self.fp.seek(self.__offset)
|
|
while self.data():
|
|
pass
|
|
self.__offset = 0
|
|
|
|
if self.dispose:
|
|
self.im.paste(self.dispose, self.dispose_extent)
|
|
|
|
from copy import copy
|
|
self.palette = copy(self.global_palette)
|
|
|
|
while True:
|
|
|
|
s = self.fp.read(1)
|
|
if not s or s == b";":
|
|
break
|
|
|
|
elif s == b"!":
|
|
#
|
|
# extensions
|
|
#
|
|
s = self.fp.read(1)
|
|
block = self.data()
|
|
if i8(s) == 249:
|
|
#
|
|
# graphic control extension
|
|
#
|
|
flags = i8(block[0])
|
|
if flags & 1:
|
|
self.info["transparency"] = i8(block[3])
|
|
self.info["duration"] = i16(block[1:3]) * 10
|
|
|
|
# disposal method - find the value of bits 4 - 6
|
|
dispose_bits = 0b00011100 & flags
|
|
dispose_bits = dispose_bits >> 2
|
|
if dispose_bits:
|
|
# only set the dispose if it is not
|
|
# unspecified. I'm not sure if this is
|
|
# correct, but it seems to prevent the last
|
|
# frame from looking odd for some animations
|
|
self.disposal_method = dispose_bits
|
|
elif i8(s) == 255:
|
|
#
|
|
# application extension
|
|
#
|
|
self.info["extension"] = block, self.fp.tell()
|
|
if block[:11] == b"NETSCAPE2.0":
|
|
block = self.data()
|
|
if len(block) >= 3 and i8(block[0]) == 1:
|
|
self.info["loop"] = i16(block[1:3])
|
|
while self.data():
|
|
pass
|
|
|
|
elif s == b",":
|
|
#
|
|
# local image
|
|
#
|
|
s = self.fp.read(9)
|
|
|
|
# extent
|
|
x0, y0 = i16(s[0:]), i16(s[2:])
|
|
x1, y1 = x0 + i16(s[4:]), y0 + i16(s[6:])
|
|
self.dispose_extent = x0, y0, x1, y1
|
|
flags = i8(s[8])
|
|
|
|
interlace = (flags & 64) != 0
|
|
|
|
if flags & 128:
|
|
bits = (flags & 7) + 1
|
|
self.palette =\
|
|
ImagePalette.raw("RGB", self.fp.read(3 << bits))
|
|
|
|
# image data
|
|
bits = i8(self.fp.read(1))
|
|
self.__offset = self.fp.tell()
|
|
self.tile = [("gif",
|
|
(x0, y0, x1, y1),
|
|
self.__offset,
|
|
(bits, interlace))]
|
|
break
|
|
|
|
else:
|
|
pass
|
|
# raise IOError, "illegal GIF tag `%x`" % i8(s)
|
|
|
|
try:
|
|
if self.disposal_method < 2:
|
|
# do not dispose or none specified
|
|
self.dispose = None
|
|
elif self.disposal_method == 2:
|
|
# replace with background colour
|
|
self.dispose = Image.core.fill("P", self.size,
|
|
self.info["background"])
|
|
else:
|
|
# replace with previous contents
|
|
if self.im:
|
|
self.dispose = self.im.copy()
|
|
|
|
# only dispose the extent in this frame
|
|
if self.dispose:
|
|
self.dispose = self.dispose.crop(self.dispose_extent)
|
|
except (AttributeError, KeyError):
|
|
pass
|
|
|
|
if not self.tile:
|
|
# self.__fp = None
|
|
raise EOFError("no more images in GIF file")
|
|
|
|
self.mode = "L"
|
|
if self.palette:
|
|
self.mode = "P"
|
|
|
|
def tell(self):
|
|
return self.__frame
|
|
|
|
def load_end(self):
|
|
ImageFile.ImageFile.load_end(self)
|
|
|
|
# if the disposal method is 'do not dispose', transparent
|
|
# pixels should show the content of the previous frame
|
|
if self._prev_im and self.disposal_method == 1:
|
|
# we do this by pasting the updated area onto the previous
|
|
# frame which we then use as the current image content
|
|
updated = self.im.crop(self.dispose_extent)
|
|
self._prev_im.paste(updated, self.dispose_extent,
|
|
updated.convert('RGBA'))
|
|
self.im = self._prev_im
|
|
self._prev_im = self.im.copy()
|
|
|
|
# --------------------------------------------------------------------
|
|
# Write GIF files
|
|
|
|
try:
|
|
import _imaging_gif
|
|
except ImportError:
|
|
_imaging_gif = None
|
|
|
|
RAWMODE = {
|
|
"1": "L",
|
|
"L": "L",
|
|
"P": "P",
|
|
}
|
|
|
|
|
|
def _save(im, fp, filename):
|
|
|
|
if _imaging_gif:
|
|
# call external driver
|
|
try:
|
|
_imaging_gif.save(im, fp, filename)
|
|
return
|
|
except IOError:
|
|
pass # write uncompressed file
|
|
|
|
if im.mode in RAWMODE:
|
|
imOut = im
|
|
else:
|
|
# convert on the fly (EXPERIMENTAL -- I'm not sure PIL
|
|
# should automatically convert images on save...)
|
|
if Image.getmodebase(im.mode) == "RGB":
|
|
palette_size = 256
|
|
if im.palette:
|
|
palette_size = len(im.palette.getdata()[1]) // 3
|
|
imOut = im.convert("P", palette=1, colors=palette_size)
|
|
else:
|
|
imOut = im.convert("L")
|
|
|
|
# header
|
|
try:
|
|
palette = im.encoderinfo["palette"]
|
|
except KeyError:
|
|
palette = None
|
|
im.encoderinfo["optimize"] = im.encoderinfo.get("optimize", True)
|
|
|
|
header, usedPaletteColors = getheader(imOut, palette, im.encoderinfo)
|
|
for s in header:
|
|
fp.write(s)
|
|
|
|
flags = 0
|
|
|
|
try:
|
|
interlace = im.encoderinfo["interlace"]
|
|
except KeyError:
|
|
interlace = 1
|
|
|
|
# workaround for @PIL153
|
|
if min(im.size) < 16:
|
|
interlace = 0
|
|
|
|
if interlace:
|
|
flags = flags | 64
|
|
|
|
try:
|
|
transparency = im.encoderinfo["transparency"]
|
|
except KeyError:
|
|
pass
|
|
else:
|
|
transparency = int(transparency)
|
|
# optimize the block away if transparent color is not used
|
|
transparentColorExists = True
|
|
# adjust the transparency index after optimize
|
|
if usedPaletteColors is not None and len(usedPaletteColors) < 256:
|
|
for i in range(len(usedPaletteColors)):
|
|
if usedPaletteColors[i] == transparency:
|
|
transparency = i
|
|
transparentColorExists = True
|
|
break
|
|
else:
|
|
transparentColorExists = False
|
|
|
|
# transparency extension block
|
|
if transparentColorExists:
|
|
fp.write(b"!" +
|
|
o8(249) + # extension intro
|
|
o8(4) + # length
|
|
o8(1) + # transparency info present
|
|
o16(0) + # duration
|
|
o8(transparency) # transparency index
|
|
+ o8(0))
|
|
|
|
# local image header
|
|
fp.write(b"," +
|
|
o16(0) + o16(0) + # bounding box
|
|
o16(im.size[0]) + # size
|
|
o16(im.size[1]) +
|
|
o8(flags) + # flags
|
|
o8(8)) # bits
|
|
|
|
imOut.encoderconfig = (8, interlace)
|
|
ImageFile._save(imOut, fp, [("gif", (0, 0)+im.size, 0,
|
|
RAWMODE[imOut.mode])])
|
|
|
|
fp.write(b"\0") # end of image data
|
|
|
|
fp.write(b";") # end of file
|
|
|
|
try:
|
|
fp.flush()
|
|
except:
|
|
pass
|
|
|
|
|
|
def _save_netpbm(im, fp, filename):
|
|
|
|
#
|
|
# 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
|
|
import tempfile
|
|
file = im._dump()
|
|
|
|
if im.mode != "RGB":
|
|
with open(filename, 'wb') as f:
|
|
stderr = tempfile.TemporaryFile()
|
|
check_call(["ppmtogif", file], stdout=f, stderr=stderr)
|
|
else:
|
|
with open(filename, 'wb') as f:
|
|
|
|
# Pipe ppmquant output into ppmtogif
|
|
# "ppmquant 256 %s | ppmtogif > %s" % (file, filename)
|
|
quant_cmd = ["ppmquant", "256", file]
|
|
togif_cmd = ["ppmtogif"]
|
|
stderr = tempfile.TemporaryFile()
|
|
quant_proc = Popen(quant_cmd, stdout=PIPE, stderr=stderr)
|
|
stderr = tempfile.TemporaryFile()
|
|
togif_proc = Popen(togif_cmd, stdin=quant_proc.stdout, stdout=f,
|
|
stderr=stderr)
|
|
|
|
# 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:
|
|
pass
|
|
|
|
|
|
# --------------------------------------------------------------------
|
|
# GIF utilities
|
|
|
|
def getheader(im, palette=None, info=None):
|
|
"""Return a list of strings representing a GIF header"""
|
|
|
|
optimize = info and info.get("optimize", 0)
|
|
|
|
# Header Block
|
|
# http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
|
|
header = [
|
|
b"GIF87a" + # signature + version
|
|
o16(im.size[0]) + # canvas width
|
|
o16(im.size[1]) # canvas height
|
|
]
|
|
|
|
if im.mode == "P":
|
|
if palette and isinstance(palette, bytes):
|
|
sourcePalette = palette[:768]
|
|
else:
|
|
sourcePalette = im.im.getpalette("RGB")[:768]
|
|
else: # L-mode
|
|
if palette and isinstance(palette, bytes):
|
|
sourcePalette = palette[:768]
|
|
else:
|
|
sourcePalette = bytearray([i//3 for i in range(768)])
|
|
|
|
usedPaletteColors = paletteBytes = None
|
|
|
|
if im.mode in ("P", "L") and optimize:
|
|
usedPaletteColors = []
|
|
|
|
# check which colors are used
|
|
i = 0
|
|
for count in im.histogram():
|
|
if count:
|
|
usedPaletteColors.append(i)
|
|
i += 1
|
|
|
|
# create the new palette if not every color is used
|
|
if len(usedPaletteColors) < 256:
|
|
paletteBytes = b""
|
|
newPositions = {}
|
|
|
|
i = 0
|
|
# pick only the used colors from the palette
|
|
for oldPosition in usedPaletteColors:
|
|
paletteBytes += sourcePalette[oldPosition*3:oldPosition*3+3]
|
|
newPositions[oldPosition] = i
|
|
i += 1
|
|
|
|
# replace the palette color id of all pixel with the new id
|
|
imageBytes = bytearray(im.tobytes())
|
|
for i in range(len(imageBytes)):
|
|
imageBytes[i] = newPositions[imageBytes[i]]
|
|
im.frombytes(bytes(imageBytes))
|
|
newPaletteBytes = (paletteBytes +
|
|
(768 - len(paletteBytes)) * b'\x00')
|
|
im.putpalette(newPaletteBytes)
|
|
im.palette = ImagePalette.ImagePalette("RGB", palette=paletteBytes,
|
|
size=len(paletteBytes))
|
|
|
|
if not paletteBytes:
|
|
paletteBytes = sourcePalette
|
|
|
|
# Logical Screen Descriptor
|
|
# calculate the palette size for the header
|
|
import math
|
|
colorTableSize = int(math.ceil(math.log(len(paletteBytes)//3, 2)))-1
|
|
if colorTableSize < 0:
|
|
colorTableSize = 0
|
|
# size of global color table + global color table flag
|
|
header.append(o8(colorTableSize + 128))
|
|
# background + reserved/aspect
|
|
header.append(o8(0) + o8(0))
|
|
# end of Logical Screen Descriptor
|
|
|
|
# add the missing amount of bytes
|
|
# the palette has to be 2<<n in size
|
|
actualTargetSizeDiff = (2 << colorTableSize) - len(paletteBytes)//3
|
|
if actualTargetSizeDiff > 0:
|
|
paletteBytes += o8(0) * 3 * actualTargetSizeDiff
|
|
|
|
# Header + Logical Screen Descriptor + Global Color Table
|
|
header.append(paletteBytes)
|
|
return header, usedPaletteColors
|
|
|
|
|
|
def getdata(im, offset=(0, 0), **params):
|
|
"""Return a list of strings representing this image.
|
|
The first string is a local image header, the rest contains
|
|
encoded image data."""
|
|
|
|
class collector:
|
|
data = []
|
|
|
|
def write(self, data):
|
|
self.data.append(data)
|
|
|
|
im.load() # make sure raster data is available
|
|
|
|
fp = collector()
|
|
|
|
try:
|
|
im.encoderinfo = params
|
|
|
|
# local image header
|
|
fp.write(b"," +
|
|
o16(offset[0]) + # offset
|
|
o16(offset[1]) +
|
|
o16(im.size[0]) + # size
|
|
o16(im.size[1]) +
|
|
o8(0) + # flags
|
|
o8(8)) # bits
|
|
|
|
ImageFile._save(im, fp, [("gif", (0, 0)+im.size, 0, RAWMODE[im.mode])])
|
|
|
|
fp.write(b"\0") # end of image data
|
|
|
|
finally:
|
|
del im.encoderinfo
|
|
|
|
return fp.data
|
|
|
|
|
|
# --------------------------------------------------------------------
|
|
# Registry
|
|
|
|
Image.register_open(GifImageFile.format, GifImageFile, _accept)
|
|
Image.register_save(GifImageFile.format, _save)
|
|
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)
|