in infrastructure/pillow-layer/python/PIL/GifImagePlugin.py [0:0]
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(f"cannot seek to frame {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)
info = {}
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:
info["transparency"] = i8(block[3])
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) == 254:
#
# comment extension
#
while block:
if "comment" in info:
info["comment"] += block
else:
info["comment"] = block
block = self.data()
continue
elif i8(s) == 255:
#
# application extension
#
info["extension"] = block, self.fp.tell()
if block[:11] == b"NETSCAPE2.0":
block = self.data()
if len(block) >= 3 and i8(block[0]) == 1:
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:])
if x1 > self.size[0] or y1 > self.size[1]:
self._size = max(x1, self.size[0]), max(y1, self.size[1])
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 OSError, "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
Image._decompression_bomb_check(self.size)
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._crop(self.dispose, self.dispose_extent)
except (AttributeError, KeyError):
pass
if not self.tile:
# self.__fp = None
raise EOFError
for k in ["transparency", "duration", "comment", "extension", "loop"]:
if k in info:
self.info[k] = info[k]
elif k in self.info:
del self.info[k]
self.mode = "L"
if self.palette:
self.mode = "P"