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#
# The Python Imaging Library.
#
# QOI support for PIL
#
# See the README file for information on usage and redistribution.
#
import os
from . import Image, ImageFile
from ._binary import i32be as i32
from ._binary import o8
def _accept(prefix):
return prefix[:4] == b"qoif"
class QoiImageFile(ImageFile.ImageFile):
format = "QOI"
format_description = "Quite OK Image"
def _open(self):
if not _accept(self.fp.read(4)):
msg = "not a QOI file"
raise SyntaxError(msg)
self._size = tuple(i32(self.fp.read(4)) for i in range(2))
channels = self.fp.read(1)[0]
self._mode = "RGB" if channels == 3 else "RGBA"
self.fp.seek(1, os.SEEK_CUR) # colorspace
self.tile = [("qoi", (0, 0) + self._size, self.fp.tell(), None)]
class QoiDecoder(ImageFile.PyDecoder):
_pulls_fd = True
def _add_to_previous_pixels(self, value):
self._previous_pixel = value
r, g, b, a = value
hash_value = (r * 3 + g * 5 + b * 7 + a * 11) % 64
self._previously_seen_pixels[hash_value] = value
def decode(self, buffer):
self._previously_seen_pixels = {}
self._previous_pixel = None
self._add_to_previous_pixels(b"".join(o8(i) for i in (0, 0, 0, 255)))
data = bytearray()
bands = Image.getmodebands(self.mode)
while len(data) < self.state.xsize * self.state.ysize * bands:
byte = self.fd.read(1)[0]
if byte == 0b11111110: # QOI_OP_RGB
value = self.fd.read(3) + self._previous_pixel[3:]
elif byte == 0b11111111: # QOI_OP_RGBA
value = self.fd.read(4)
else:
op = byte >> 6
if op == 0: # QOI_OP_INDEX
op_index = byte & 0b00111111
value = self._previously_seen_pixels.get(op_index, (0, 0, 0, 0))
elif op == 1: # QOI_OP_DIFF
value = (
(self._previous_pixel[0] + ((byte & 0b00110000) >> 4) - 2)
% 256,
(self._previous_pixel[1] + ((byte & 0b00001100) >> 2) - 2)
% 256,
(self._previous_pixel[2] + (byte & 0b00000011) - 2) % 256,
)
value += (self._previous_pixel[3],)
elif op == 2: # QOI_OP_LUMA
second_byte = self.fd.read(1)[0]
diff_green = (byte & 0b00111111) - 32
diff_red = ((second_byte & 0b11110000) >> 4) - 8
diff_blue = (second_byte & 0b00001111) - 8
value = tuple(
(self._previous_pixel[i] + diff_green + diff) % 256
for i, diff in enumerate((diff_red, 0, diff_blue))
)
value += (self._previous_pixel[3],)
elif op == 3: # QOI_OP_RUN
run_length = (byte & 0b00111111) + 1
value = self._previous_pixel
if bands == 3:
value = value[:3]
data += value * run_length
continue
value = b"".join(o8(i) for i in value)
self._add_to_previous_pixels(value)
if bands == 3:
value = value[:3]
data += value
self.set_as_raw(bytes(data))
return -1, 0
Image.register_open(QoiImageFile.format, QoiImageFile, _accept)
Image.register_decoder("qoi", QoiDecoder)
Image.register_extension(QoiImageFile.format, ".qoi")
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