#
# 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"
import Image, ImageFile, ImagePalette
# --------------------------------------------------------------------
# Helpers
def i16(c):
return ord(c[0]) + (ord(c[1])<<8)
def o16(i):
return chr(i&255) + chr(i>>8&255)
# --------------------------------------------------------------------
# Identify/read GIF files
def _accept(prefix):
return prefix[:6] in ["GIF87a", "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 ord(s):
return self.fp.read(ord(s))
return None
def _open(self):
# Screen
s = self.fp.read(13)
if s[:6] not in ["GIF87a", "GIF89a"]:
raise SyntaxError, "not a GIF file"
self.info["version"] = s[:6]
self.size = i16(s[6:]), i16(s[8:])
self.tile = []
flags = ord(s[10])
bits = (flags & 7) + 1
if flags & 128:
# get global palette
self.info["background"] = ord(s[11])
# check if palette contains colour indices
p = self.fp.read(3<<bits)
for i in range(0, len(p), 3):
if not (chr(i/3) == p[i] == p[i+1] == 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.__frame = -1
self.__fp.seek(self.__rewind)
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 = self.dispose
self.dispose = None
self.palette = self.global_palette
while 1:
s = self.fp.read(1)
if not s or s == ";":
break
elif s == "!":
#
# extensions
#
s = self.fp.read(1)
block = self.data()
if ord(s) == 249:
#
# graphic control extension
#
flags = ord(block[0])
if flags & 1:
self.info["transparency"] = ord(block[3])
self.info["duration"] = i16(block[1:3]) * 10
try:
# disposal methods
if flags & 8:
# replace with background colour
self.dispose = Image.core.fill("P", self.size,
self.info["background"])
elif flags & 16:
# replace with previous contents
self.dispose = self.im.copy()
except (AttributeError, KeyError):
pass
elif ord(s) == 255:
#
# application extension
#
self.info["extension"] = block, self.fp.tell()
if block[:11] == "NETSCAPE2.0":
block = self.data()
if len(block) >= 3 and ord(block[0]) == 1:
self.info["loop"] = i16(block[1:3])
while self.data():
pass
elif s == ",":
#
# 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:])
flags = ord(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 = ord(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`" % ord(s)
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
# --------------------------------------------------------------------
# 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
try:
rawmode = RAWMODE[im.mode]
imOut = im
except KeyError:
# convert on the fly (EXPERIMENTAL -- I'm not sure PIL
# should automatically convert images on save...)
if Image.getmodebase(im.mode) == "RGB":
imOut = im.convert("P")
rawmode = "P"
else:
imOut = im.convert("L")
rawmode = "L"
# header
for s in getheader(imOut, im.encoderinfo):
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 extension block
fp.write("!" +
chr(249) + # extension intro
chr(4) + # length
chr(1) + # transparency info present
o16(0) + # duration
chr(int(transparency)) # transparency index
+ chr(0))
# local image header
fp.write("," +
o16(0) + o16(0) + # bounding box
o16(im.size[0]) + # size
o16(im.size[1]) +
chr(flags) + # flags
chr(8)) # bits
imOut.encoderconfig = (8, interlace)
ImageFile._save(imOut, fp, [("gif", (0,0)+im.size, 0, rawmode)])
fp.write("\0") # end of image data
fp.write(";") # 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
file = im._dump()
if im.mode != "RGB":
os.system("ppmtogif %s >%s" % (file, filename))
else:
os.system("ppmquant 256 %s | ppmtogif >%s" % (file, filename))
try: os.unlink(file)
except: pass
# --------------------------------------------------------------------
# GIF utilities
def getheader(im, info=None):
"""Return a list of strings representing a GIF header"""
optimize = info and info.get("optimize", 0)
s = [
"GIF87a" + # magic
o16(im.size[0]) + # size
o16(im.size[1]) +
chr(7 + 128) + # flags: bits + palette
chr(0) + # background
chr(0) # reserved/aspect
]
if optimize:
# minimize color palette
i = 0
maxcolor = 0
for count in im.histogram():
if count:
maxcolor = i
i = i + 1
else:
maxcolor = 256
# global palette
if im.mode == "P":
# colour palette
s.append(im.im.getpalette("RGB")[:maxcolor*3])
else:
# greyscale
for i in range(maxcolor):
s.append(chr(i) * 3)
return s
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("," +
o16(offset[0]) + # offset
o16(offset[1]) +
o16(im.size[0]) + # size
o16(im.size[1]) +
chr(0) + # flags
chr(8)) # bits
ImageFile._save(im, fp, [("gif", (0,0)+im.size, 0, RAWMODE[im.mode])])
fp.write("\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)
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