def parse_ne(self):
"""Parse Netscape Extension"""
length = parse_int(self.next_byte(), 'big')
bts = self.next_bytes(length)
self.ind_loops = self._ip - length
loops = parse_int(bts[-2:], 'big')
self.loops = "Infinity" if loops == 0 else str(loops)
self.next_byte()
def parse_gce(self):
"""Parse Graphic Control Extension"""
length = parse_int(self.next_byte(), 'big')
bts = self.next_bytes(length)
delay = parse_int(bts[2:], 'little')
bg_ind = parse_int(bts[-1:], 'big')
self.next_byte()
return delay, bg_ind
def parse_lsd(self, byte_arr):
"""Parse Logical Screen Descriptor"""
data = byte_arr[:6]
self.spec = data.decode('utf-8')
if not self.spec.startswith("GIF"):
raise ValueError("Wrong gif format")
width = parse_int(byte_arr[6:8], 'little')
height = parse_int(byte_arr[8:10], 'little')
self.size = width, height
self._parse_bin(byte_arr[10])
self.num_bg_color = 0 if self.ct_flag else parse_int([byte_arr[11]],
'big')
par = parse_int([byte_arr[12]], 'big')
self.aratio = (par + 15) / 64 if par != 0 else 0
def parse_ce(self):
"""Parse Comment Extension"""
length = self.next_byte()
comment = ""
while length != b"\x00" and length:
block = self.next_bytes(parse_int(length, 'big'))
comment += block.decode("utf-8", errors='ignore')
length = self.next_byte()
return comment
def skip(self):
"""Skip not interesting block"""
length = self.next_byte()
while length != b"\x00" and length:
self.next_bytes(parse_int(length, 'big'))
length = self.next_byte()
def _parse_bin(self, byte):
"""Parse some special for gif binary string"""
bin_line = bin(parse_int([byte], 'big'))[2:].rjust(8, "0")
self.ct_flag = bool(int(bin_line[0], 2))
self.ct_len = 3 * 2**(int(bin_line[-3:], 2) + 1) if self.ct_flag else 0
self.colors_count = 2**(3 * (int(bin_line[1:4], 2) + 1))