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